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1. Fractionation of 226Ra and Ba in the Upper North Pacific Ocean

Author

Pieter van Beek, Roger François, Makio Honda, Matthew A. Charette, Jean-Louis Reyss, Raja Ganeshram, Christophe Monnin, and Susumu Honjo

Subjects
radium, barium, seawater, ratio, fractionation, dating, Science, General. Including nature conservation, geographical distribution, QH1-199.5
Abstract

Investigations conducted during the GEOSECS program concluded that radium-226 (T1/2 = 1602 y) and barium are tightly correlated in waters above 2500 m in the Atlantic, Pacific and Antarctic Oceans, with a fairly uniform 226Ra/Ba ratio of 2.3 ± 0.2 dpm µmol-1 (4.6 nmol 226Ra/mol Ba). Here, we report new 226Ra and Ba data obtained at three different stations in the Pacific Ocean: stations K1 and K3 in the North-West Pacific and station old Hale Aloha, off Hawaii Island. The relationship between 226Ra and Ba found at these stations is broadly consistent with that reported during the GEOSECS program. At the three investigated stations, however, we find that the 226Ra/Ba ratios are significantly lower in the upper 500 m of the water column than at greater depths, a pattern that was overlooked during the GEOSECS program, either because of the precision of the measurements or because of the relatively low sampling resolution in the upper 500 m. Although not always apparent in individual GEOSECS profiles, this trend was noted before from the non-zero intercept of the linear regression when plotting the global data set of Ba versus 226Ra seawater concentration and was attributed, at least in part, to the predominance of surface input from rivers for Ba versus bottom input from sediments for 226Ra. Similarly, low 226Ra/Ba ratios in the upper 500 m have been reported in other oceanic basins (e.g. Atlantic Ocean). Parallel to the low 226Ra/Ba ratios in seawater, higher 226Ra/Ba ratios were found in suspended particles collected in the upper 500 m. This suggests that fractionation between the two elements may contribute to the lower 226Ra/Ba ratios found in the upper 500 m, with 226Ra being preferentially removed from surface water, possibly as a result of mass fractionation during celestite formation by acantharians and/or barite precipitation, since both chemical elements have similar ionic radius and the same configuration of valence electrons. This finding has implications for dating of marine carbonates by 226Ra, which requires a constant initial 226Ra/Ba ratio incorporated in the shells and for using 226Ra as an abyssal circulation and mixing tracer.

Published
2022
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2. Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba

Author

Kimberley K. Mayfield, Anton Eisenhauer, Danielle P. Santiago Ramos, John A. Higgins, Tristan J. Horner, Maureen Auro, Tomas Magna, Nils Moosdorf, Matthew A. Charette, Meagan Eagle Gonneea, Carolyn E. Brady, Nemanja Komar, Bernhard Peucker-Ehrenbrink, and Adina Paytan

Subjects
Science
Abstract

Groundwater discharge is a mechanism that transports chemicals from inland systems to the ocean, but it has been considered of secondary influence compared to rivers. Here the authors assess the global significance of groundwater discharge, finding that it has a unique and important contribution to ocean chemistry and Earth-system models.

Published
2021
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3. The Volume of Earth’s Ocean

Author

Matthew A. Charette and Walter H.F. Smith

Subjects
ocean volume, satellite altimetry, Oceanography, GC1-1581
Abstract

Despite playing a significant role in the global water cycle, ocean volume has not been re-examined in over 25 years. The main uncertainty associated with ocean volume is the mean ocean depth. The earliest studies tended to overestimate ocean depth due to undersampling of seamounts and ocean ridges. The advent of the echosounder in the 1920s and subsequent ship-borne technologies rapidly increased aerial coverage of the ocean; hence, over time there has been a gradual decrease in calculated mean ocean depth. Today, however, in situ measurements span only ~ 10% of the ocean’s surface area. Here, we use satellite altimetry data to estimate the ocean’s volume, which is lower by a volume equivalent to 500 times the Great Lakes or five times the Gulf of Mexico when compared to the most recent published estimates.

Published
2010

5. Radium Inputs Into the Arctic Ocean From Rivers

Author

Kristina Brown, Matthew A. Charette, Willard S. Moore, Lauren Kipp, Paul B. Henderson, Jessica S. Dabrowski, Emma Bullock, Paul J. Mann, and Earth and Climate

Subjects
chemistry.chemical_element, F700, Structural basin, Oceanography, river fluxes, The arctic, Radium, Geophysics, radium isotopes, chemistry, Space and Planetary Science, Geochemistry and Petrology, Arctic Ocean, Earth and Planetary Sciences (miscellaneous), Environmental science, SDG 14 - Life Below Water
Abstract

Radium isotopes have been used to trace nutrient, carbon, and trace metal fluxes inputs from ocean margins. However, these approaches require a full accounting of radium sources to the coastal ocean including rivers. Here, we aim to quantify river radium inputs into the Arctic Ocean for the first time for 226Ra and to refine the estimates for 228Ra. Using new and existing data, we find that the estimated combined (dissolved plus desorbed) annual 226Ra and 228Ra fluxes to the Arctic Ocean are [7.0–9.4] × 1014 dpm y−1 and [15–18] × 1014 dpm y−1, respectively. Of these totals, 44% and 60% of the river 226Ra and 228Ra, respectively are from suspended sediment desorption, which were estimated from laboratory incubation experiments. Using Ra isotope data from 20 major rivers around the world, we derived global annual 226Ra and 228Ra fluxes of [7.4–17] × 1015 and [15–27] × 1015 dpm y−1, respectively. As climate change spurs rapid Arctic warming, hydrological cycles are intensifying and coastal ice cover and permafrost are diminishing. These river radium inputs to the Arctic Ocean will serve as a valuable baseline as we attempt to understand the changes that warming temperatures are having on fluxes of biogeochemically important elements to the Arctic coastal zone.

Published
2022
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7. Dissolved and Particulate Barium Distributions Along the US GEOTRACES North Atlantic and East Pacific Zonal Transects (GA03 and GP16): Global Implications for the Marine Barium Cycle

Author

Shaily Rahman, Alan M. Shiller, Robert F. Anderson, Matthew A. Charette, Christopher T. Hayes, Melissa Gilbert, Karen R. Grissom, Phoebe J. Lam, Daniel C. Ohnemus, Frank J. Pavia, Benjamin S. Twining, and Sebastian M. Vivancos

Subjects
Atmospheric Science, Global and Planetary Change, Environmental Chemistry, General Environmental Science
Abstract

Processes controlling dissolved barium (dBa) were investigated along the GEOTRACES GA03 North Atlantic and GP16 Eastern Tropical Pacific transects, which traversed similar physical and biogeochemical provinces. Dissolved Ba concentrations are lowest in surface waters (∼35–50 nmol kg⁻¹) and increase to 70–80 and 140–150 nmol kg⁻¹ in deep waters of the Atlantic and Pacific transects, respectively. Using water mass mixing models, we estimate conservative mixing that accounts for most of dBa variability in both transects. To examine nonconservative processes, particulate excess Ba (pBa_(xs)) formation and dissolution rates were tracked by normalizing particulate excess ²³⁰Th activities. Th-normalized pBa_(xs) fluxes, with barite as the likely phase, have subsurface maxima in the top 1,000 m (∼100–200 μmol m⁻² year⁻¹ average) in both basins. Barite precipitation depletes dBa within oxygen minimum zones from concentrations predicted by water mass mixing, whereas inputs from continental margins, particle dissolution in the water column, and benthic diffusive flux raise dBa above predications. Average pBa_(xs) burial efficiencies along GA03 and GP16 are ∼37% and 17%–100%, respectively, and do not seem to be predicated on barite saturation indices in the overlying water column. Using published values, we reevaluate the global freshwater dBa river input as 6.6 ± 3.9 Gmol year⁻¹. Estuarine mixing processes may add another 3–13 Gmol year⁻¹. Dissolved Ba inputs from broad shallow continental margins, previously unaccounted for in global marine summaries, are substantial (∼17 Gmol year⁻¹), exceeding terrestrial freshwater inputs. Revising river and shelf dBa inputs may help bring the marine Ba isotope budget more into balance.

Published
2022
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8. Deltaic and Estuarine Controls on Mackenzie River Solute Fluxes to the Arctic Ocean

Author

Matthew A. Charette, Zhaohui Aleck Wang, Lauren Kipp, and Paul B. Henderson

Subjects
0106 biological sciences, geography, geography.geographical_feature_category, River delta, 010504 meteorology & atmospheric sciences, Ecology, 010604 marine biology & hydrobiology, Trace element, Alkalinity, Estuary, Aquatic Science, 01 natural sciences, Arctic, Benthic zone, Environmental chemistry, Dissolved organic carbon, Environmental science, Trace metal, Ecology, Evolution, Behavior and Systematics, 0105 earth and related environmental sciences
Abstract

River discharge has an important influence on the chemistry of Arctic shelf seas and surface waters. In this study, we examined the changes in nutrient, trace metal, dissolved organic matter, dissolved inorganic carbon, alkalinity, and radium isotope distributions across the Mackenzie River delta and estuary in June 2016, and estimated trace element and isotopes fluxes from the Mackenzie River to the Western Arctic Ocean. While inorganic nutrient, dissolved inorganic carbon, alkalinity, trace metal, and radium levels remained fairly constant through the delta, dissolved organic matter concentrations were 2–3.5 times higher at the mouth of the river, reflecting inputs from the delta. In the estuarine mixing zone, radium isotope ratios indicated that both desorption from suspended sediments and benthic inputs affected solute concentrations. Similarly, most of the measured trace metals (Ba, Co, Cu, Mn, Ni) exhibited non-conservative addition in the freshwater-saltwater transition zone, while Pb was removed and U was mixed conservatively. Inorganic nutrients were affected by both addition and removal processes in the estuary. Dissolved inorganic carbon and alkalinity exhibited net removal, likely due to a combination of biological uptake, gas exchange, CaCO3 precipitation, and surface ion exchange processes. Approximately 45% and 60% of dissolved organic carbon and nitrogen, respectively, were removed rapidly at low salinities, in contrast with previous studies suggesting conservative mixing through Arctic estuaries. This study highlights the need to take deltaic and estuarine processes into account when determining the flux of riverine solutes to the coastal ocean.

Published
2020
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9. The distribution of 227Ac along the GA01 section in the North Atlantic

Author

Emilie Le Roy, Pieter van Beek, François Lacan, Marc Souhaut, Virginie Sanial, Matthew A. Charette, Paul B. Henderson, Feifei Deng, Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université de Toulon - UFR Sciences et Techniques (UTLN UFR ScT), Université de Toulon (UTLN), Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), Max-Planck-Institut, ANR-13-BS06-0014,GEOVIDE,GEOVIDE, Une étude internationale GEOTRACES le long de la section OVIDE en Atlantique Nord et en Mer du Labrador(2013), ANR-12-PDOC-0025,BITMAP,Biodisponibilité du fer et des métaux traces dans les particules marines(2012), and ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)

Subjects
GEOTRACES, Actinium, Actinium-227, North Atlantic, [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry, Environmental Chemistry, General Chemistry, Oceanography, [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography, Water Science and Technology
Abstract

International audience; Actinium-227 is a powerful tool to study vertical mixing in the ocean, and was more recently proposed as a tracer of hydrothermal plumes. However, because 227 Ac activities are especially low in the ocean, relatively few studies have been conducted to date, and none has been done on the large scale, as is reported in the present study. Here, we report a section of dissolved 227 Ac in the North Atlantic Ocean between Portugal-Greenland-Canada based on nine full-depth profiles obtained in the framework of the international GEOTRACES program (GA01 section-GEOVIDE cruise, May-July 2014). The simultaneous determination of 231 Pa, the parent nuclide of 227 Ac, along the section allowed us to report a section of excess 227 Ac activities (227 Ac ex). Actinium-227 activities were especially low along the section (< 0.4 dpm m 3) compared to other ocean basins. In most cases, 227 Ac activities reached secular equilibrium with 231 Pa in the water column 500 m above the seafloor. Secular equilibrium is considered reached after ~five half-lives of the daughter. Secular equilibrium therefore suggests no external input over the last ~100 years. The highest 227 Ac activities were often found close to the seafloor, indicating that 227 Ac diffuses out of the sediments. However, two different patterns question the traditional one-dimensional vertical mixing model typically applied to 227 Ac released by deep-sea sediments: first, significant 227 Ac ex were found in the upper 500 m of the water column at several stations located near the Iberian margin. In the upper 500 m, the high 227 Ac ex activities could indicate lateral advection of waters that interacted with the margins. Second, mid-water peaks of 227 Ac ex were occasionally observed along the transect. At station 44 in the Irminger Basin, a peak of 227 Ac ex activity at 2500 m that was co-located with high dissolved Fe concentrations could be interpreted as the signature of a hydrothermal plume. Near the seafloor, we often observed bottom nepheloid layers and we cannot exclude that these layers impact the 227 Ac distributions.

Published
2023
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10. Shelf‐Basin Interactions and Water Mass Residence Times in the Western Arctic Ocean: Insights Provided by Radium Isotopes

Author

Paul B. Henderson, Matthew A. Charette, David Kadko, Willard S. Moore, Robert S. Pickart, and Lauren Kipp

Subjects
Water mass, Isotope, Geotraces, chemistry.chemical_element, Structural basin, Oceanography, Radium, Geophysics, chemistry, Arctic, Space and Planetary Science, Geochemistry and Petrology, Earth and Planetary Sciences (miscellaneous), Environmental science, Residence
Published
2019
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11. Dissolved silica in the subterranean estuary and the impact of submarine groundwater discharge on the global marine silica budget

Author

J. Kirk Cochran, Shaily Rahman, Matthew A. Charette, and Joseph Tamborski

Subjects
0106 biological sciences, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Dissolved silica, 010604 marine biology & hydrobiology, Sediment, Aquifer, Estuary, General Chemistry, Biogenic silica, Oceanography, 01 natural sciences, Submarine groundwater discharge, Environmental Chemistry, Environmental science, Literature survey, Groundwater, 0105 earth and related environmental sciences, Water Science and Technology
Abstract

Groundwater's role in the global marine budget of dissolved silica (DSi), an essential nutrient, is constrained using DSi groundwater concentrations from multiple endmember lithologies and a global terrestrial submarine groundwater discharge (SGD) model. We report new DSi concentrations in nine subterranean estuaries throughout the world, including Panama, Mauritius, Guam, Yucatan (Mexico), Chile, Argentina, Southwest Florida (USA), Long Island Sound (USA) and Waquoit Bay (USA). These new data are augmented with a literature survey of DSi endmember concentrations in the subterranean estuary to determine the global DSi endmember in SGD, classified by the regional lithology (carbonate, shale, sandstone, extrusive igneous, shield and “complex”). DSi fluxes to the ocean from terrestrial (fresh) SGD equal 0.7 ± 0.1 Tmol y−1, more than half of which enters the Pacific Ocean. Non-conservative DSi enrichment was observed in marine groundwaters circulated through extrusive igneous and complex lithology sediments for twenty different study sites. Dissolution rate calculations indicate that non-conservative DSi enrichments in marine groundwaters can be supported, in part, by lithogenic dissolution of the coastal sediment, rather than biogenic silica dissolution. We make preliminary estimates of DSi inputs via marine SGD in shallow coastal aquifers of ~3 Tmol y−1. Considering recent revisions to the marine silica budget (e.g., increased estimates of biogenic silica storage via reverse weathering reactions, increased estimates of standing stocks of biogenic silica, and changing estimates of silica burial efficiency), sources and sinks in the marine Si budget can be balanced when taking into account estimates of new DSi inputs from total SGD (terrestrial and marine flow paths). These findings impact the residence time of oceanic Si and mass balances of the stable Si isotopes, as well as associated silicate weathering products, including Li and Ge.

Published
2019
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13. Biogeochemical processes controlling the marine Ba cycle: dissolved and particulate barium distributions along the US GEOTRACES North Atlantic and South Pacific Zonal Transects (GA03 and GP16)

Author

Christopher T. Hayes, Benjamin S. Twining, Sebastian M. Vivancos, Daniel C. Ohnemus, Shaily Rahman, Phoebe J. Lam, Matthew A. Charette, Karen Grissom, Melissa Gilbert, Frank J. Pavia, Alan M. Shiller, and Robert F. Anderson

Subjects
Biogeochemical cycle, Oceanography, chemistry, Geotraces, Environmental science, chemistry.chemical_element, Barium, Particulates, Transect
Published
2021
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14. Updating the biogeochemical cycle of silicon in the modern ocean

Author

Natalia Llopis Monferrer, Matthew A. Charette, Jill N. Sutton, Olivier Rouxel, María López-Acosta, Stephanie Dutkiewicz, Jon R. Hawkings, Tim DeVries, Manuel Maldonado, Aude Leynaert, Paul Tréguer, Shaily Rahman, Brzezinski Mark, Sumei Liu, Lihua Ran, and Claudia Ehlert

Subjects
Biogeochemical cycle, Silicon, chemistry, Earth science, Environmental science, chemistry.chemical_element
Published
2021
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15. Controls on barium and radium-226 distributions along GEOTRACES GP15

Author

Paul B. Henderson, Willard S. Moore, Alan M. Shiller, Pieter van Beek, Marc Souhaut, Matthew A. Charette, Maureen E. Auro, Emilie Le Roy, Avanti Shrikumar, Tristan J. Horner, Karen L. Casciotti, and Rian Lawrence

Subjects
Radium, chemistry, Geotraces, Radiochemistry, Environmental science, chemistry.chemical_element, Barium
Published
2021
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17. Observational and Modeling Evidence of Seasonal Trends in Sediment‐Derived Material Inputs to the Chukchi Sea

Author

David Kadko, Michael A. Spall, Lauren Kipp, Jessica S. Dabrowski, Willard S. Moore, Robert S. Pickart, and Matthew A. Charette

Subjects
Geophysics, Oceanography, 010504 meteorology & atmospheric sciences, Space and Planetary Science, Geochemistry and Petrology, Geotraces, Earth and Planetary Sciences (miscellaneous), Sediment, Redistribution (cultural anthropology), 01 natural sciences, Geology, 0105 earth and related environmental sciences
Abstract

Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(5), (2020): e2019JC016007, doi:10.1029/2019JC016007.

Published
2020
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18. Using radon to quantify groundwater discharge and methane fluxes to a shallow, tundra lake on the Yukon-Kuskokwim Delta, Alaska

Author

Robert M. Holmes, Paul B. Henderson, John D. Schade, S. Ludwig, Margaret Powell, Susan M. Natali, Paul J. Mann, Matthew A. Charette, and Jessica S. Dabrowski

Subjects
Delta, 010504 meteorology & atmospheric sciences, F800, 04 agricultural and veterinary sciences, Atmospheric sciences, Permafrost, 01 natural sciences, Methane, Tundra, Atmosphere, chemistry.chemical_compound, chemistry, Arctic, 13. Climate action, 040103 agronomy & agriculture, 0401 agriculture, forestry, and fisheries, Environmental Chemistry, Environmental science, Groundwater discharge, Groundwater, 0105 earth and related environmental sciences, Earth-Surface Processes, Water Science and Technology
Abstract

Northern lakes are a source of greenhouse gases to the atmosphere and contribute substantially to the global carbon budget. However, the sources of methane (CH4) to northern lakes are poorly constrained limiting our ability to the assess impacts of future Arctic change. Here we present measurements of the natural groundwater tracer, radon, and CH4 in a shallow lake on the Yukon-Kuskokwim Delta, AK and quantify groundwater discharge rates and fluxes of groundwater-derived CH4. We found that groundwater was significantly enriched (2000%) in radon and CH4 relative to lake water. Using a mass balance approach, we calculated average groundwater fluxes of 1.2 ± 0.6 and 4.3 ± 2.0 cm day−1, respectively as conservative and upper limit estimates. Groundwater CH4 fluxes were 7—24 mmol m−2 day−1 and significantly exceeded diffusive air–water CH4 fluxes (1.3–2.3 mmol m−2 day−1) from the lake to the atmosphere, suggesting that groundwater is an important source of CH4 to Arctic lakes and may drive observed CH4 emissions. Isotopic signatures of CH4 were depleted in groundwaters, consistent with microbial production. Higher methane concentrations in groundwater compared to other high latitude lakes were likely the source of the comparatively higher CH4 diffusive fluxes, as compared to those reported previously in high latitude lakes. These findings indicate that deltaic lakes across warmer permafrost regions may act as important hotspots for CH4 release across Arctic landscapes.

Published
2020

19. The Transpolar Drift as a Source of Riverine and Shelf-Derived Trace Elements to the Central Arctic Ocean

Author

Willard S. Moore, Carl H. Lamborg, Andrew R. Margolin, Tatiana Williford, Mak A. Saito, Elizabeth M. Jones, Randelle M. Bundy, Hans A. Slagter, Laramie T. Jensen, Robert F. Anderson, Jeroen E. Sonke, Sebastian M. Vivancos, Katlin L. Bowman, Benjamin Rabe, Mats A. Granskog, Alison M. Agather, Paul B. Henderson, Brian A. Haley, Chad R. Hammerschmidt, Frank J. Millero, Rob Middag, Jessica N. Fitzsimmons, Karl Kaiser, Aridane G. González, Rainer M. W. Amon, Mariko Hatta, Per Andersson, Lauren Kipp, Dennis A. Hansell, Robert Newton, Ryan J. Woosley, Micha J. A. Rijkenberg, Ole Valk, R. Lawrence Edwards, Laura M. Whitmore, Angelica Pasqualini, Jessica S. Dabrowski, Loes J. A. Gerringa, Yang Xiang, Matthew A. Charette, Ronald Benner, Martin Levier, Ronja Paffrath, David Kadko, Seth G. John, Jan van Ooijen, Michiel M Rutgers van der Loeff, Xianglei Li, Hélène Planquette, Dorothea Bauch, Robert Rember, Patrick Laan, Phoebe J. Lam, Colin A. Stedmon, Ursula Schauer, Katharina Pahnke, Heather E. Reader, Alan M. Shiller, Mariia V. Petrova, Adam Ulfsbo, Christopher I. Measures, Ruifeng Zhang, Peter Schlosser, Sandra Gdaniec, Robert M. Sherrell, Matthieu Roy-Barman, Lars Eric Heimburger-Boavida, Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), Dalhousie University [Halifax], Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Texas A&M University [College Station], University of Southern Mississippi (USM), Department of Marine Sciences [Gothenburg], University of Gothenburg (GU), Tromsø department (IMR), Institute of Marine Research [Bergen] (IMR), University of Bergen (UiB)-University of Bergen (UiB), School of Oceanography [Seattle], University of Washington [Seattle], Department of earth and environmental sciences and the Lamont-Doherty earth observatory, Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Department of Earth Sciences [USC Los Angeles], University of Southern California (USC), Ocean Sciences Department, University of California [USA], University of California [Santa Cruz] (UC Santa Cruz), University of California (UC)-University of California (UC), Department of Oceanography [Honolulu], University of Hawai‘i [Mānoa] (UHM), Université de Toulon (UTLN), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Department of Earth and Environmental Engineering [New York], Wright State University, Swedish Museum of Natural History (NRM), Department of Biological Sciences [Columbia], University of South Carolina [Columbia], University of California (UC), Department of Geology and Geophysics, University of Minnesota [Twin Cities] (UMN), University of Minnesota System-University of Minnesota System, Department of Geological Sciences [Stockholm], Stockholm University, Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Géochimie Des Impacts (GEDI), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Royal Netherlands Institute for Sea Research (NIOZ), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Instituto de Oceanografía y Cambio Global (IOCAG), Université de Las Palmas de Gran Canaria [Espagne] (ULPGC), Norwegian Polar Institute, College of Earth, Ocean and Atmospheric Sciences [Corvallis] (CEOAS), Oregon State University (OSU), Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami [Coral Gables], Florida International University [Miami] (FIU), Texas A&M University [Galveston], University of British Columbia (UBC), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), DTU Aqua, National Institute of Aquatic Resources, Danmarks Tekniske Universitet = Technical University of Denmark (DTU), Memorial University of Newfoundland = Université Memorial de Terre-Neuve [St. John's, Canada] (MUN), International Arctic Research Center (IARC), University of Alaska [Fairbanks] (UAF), Arizona State University [Tempe] (ASU), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, Géosciences Environnement Toulouse (GET), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Center for Global Change Science, Massachusetts Institute of Technology (MIT), Alfred Wegener Institute for Polar and Marine Research (AWI), Shanghai Jiao Tong University [Shanghai], Funding for Arctic GEOTRACES was provided by the U.S. National Science Foundation, Swedish Research Council Formas, French Agence Nationale de la Recherche and LabexMER, Netherlands Organization for Scientific Research, and Independent Research Fund Denmark, ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), ANR-13-BS06-0014,GEOVIDE,GEOVIDE, Une étude internationale GEOTRACES le long de la section OVIDE en Atlantique Nord et en Mer du Labrador(2013), University of California [Santa Cruz] (UCSC), University of California-University of California, University of California, Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Technical University of Denmark [Lyngby] (DTU), Memorial University of Newfoundland [St. John's], Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)

Subjects
010504 meteorology & atmospheric sciences, Geotraces, [SDE.MCG]Environmental Sciences/Global Changes, Flux, Oceanografi, hydrologi och vattenresurser, Oceanography, 01 natural sciences, Oceanography, Hydrology and Water Resources, Geochemistry and Petrology, Dissolved organic carbon, Arctic Ocean, Earth and Planetary Sciences (miscellaneous), 14. Life underwater, Water cycle, 0105 earth and related environmental sciences, Transpolar Drift, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Trace elements, ACL, Lead (sea ice), Trace element, Nutrients, Carbon, Geophysics, GEOTRACES, Arctic, 13. Climate action, Space and Planetary Science, Meteoric water, Environmental science, [SDE.BE]Environmental Sciences/Biodiversity and Ecology
Abstract

Data from GEOTRACES cruises GN01 (HLY1502) and GN04 (PS94) have been archived at the Biological & Chemical Oceanography Data Management Office (BCO-DMO; https://www.bco-dmo.org/deployment/638807) and PANGAEA (https://www.pangaea.de/?q=PS94&f.campaign%5B%5D=PS94) websites, respectively. The inorganic carbon data are available at the NOAA Ocean Carbon Data System (OCADS ; doi :10.3334/CDIAC/OTG.CLIVAR_ARC01_33HQ20150809). In addition to these national data archives, the data used in this paper is available as a supplementary downloadable excel file; International audience; A major surface circulation feature of the Arctic Ocean is the Transpolar Drift (TPD), a current that transports river‐influenced shelf water from the Laptev and East Siberian Seas toward the center of the basin and Fram Strait. In 2015, the international GEOTRACES program included a high‐resolution pan‐Arctic survey of carbon, nutrients, and a suite of trace elements and isotopes (TEIs). The cruises bisected the TPD at two locations in the central basin, which were defined by maxima in meteoric water and dissolved organic carbon concentrations that spanned 600 km horizontally and ~25‐50 m vertically. Dissolved TEIs such as Fe, Co, Ni, Cu, Hg, Nd, and Th, which are generally particle‐reactive but can be complexed by organic matter, were observed at concentrations much higher than expected for the open ocean setting. Other trace element concentrations such as Al, V, Ga, and Pb were lower than expected due to scavenging over the productive East Siberian and Laptev shelf seas. Using a combination of radionuclide tracers and ice drift modeling, the transport rate for the core of the TPD was estimated at 0.9 ± 0.4 Sv (106 m3 s‐1). This rate was used to derive the mass flux for TEIs that were enriched in the TPD, revealing the importance of lateral transport in supplying materials beneath the ice to the central Arctic Ocean and potentially to the North Atlantic Ocean via Fram Strait. Continued intensification of the Arctic hydrologic cycle and permafrost degradation will likely lead to an increase in the flux of TEIs into the Arctic Ocean.

Published
2020
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20. Using 226Ra and 228Ra isotopes to distinguish water mass distribution in the Canadian Arctic Archipelago

Author

Helmuth Thomas, Hugh L. MacIntyre, Christophe Monnin, Frank Dehairs, Alfonso Mucci, Matthew A. Charette, Paul B. Henderson, Chantal Mears, Dalhousie University [Halifax], Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), Analytical, Environmental and Geo- Chemistry, Vrije Universiteit Brussel (VUB), Géosciences Environnement Toulouse (GET), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Centre de recherche sur la dynamique du système Terre (GEOTOP), Université de Montréal (UdeM)-McGill University = Université McGill [Montréal, Canada]-École Polytechnique de Montréal (EPM)-Concordia University [Montreal]-Université du Québec à Rimouski (UQAR)-Université du Québec à Montréal = University of Québec in Montréal (UQAM)-Université du Québec en Abitibi-Témiscamingue (UQAT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and École Polytechnique de Montréal (EPM)-McGill University = Université McGill [Montréal, Canada]-Université de Montréal (UdeM)-Université du Québec en Abitibi-Témiscamingue (UQAT)-Université du Québec à Rimouski (UQAR)-Concordia University [Montreal]-Université du Québec à Montréal = University of Québec in Montréal (UQAM)

Subjects
Water mass, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, 010505 oceanography, δ18O, Continental shelf, Geotraces, Halocline, 01 natural sciences, Isotopes of oxygen, Oceanography, Arctic, 13. Climate action, [SDE]Environmental Sciences, [CHIM]Chemical Sciences, 14. Life underwater, Hydrography, Ecology, Evolution, Behavior and Systematics, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Earth-Surface Processes
Abstract

As a shelf-dominated basin, the Arctic Ocean and its biogeochemistry are heavily influenced by continental and riverine sources. Radium isotopes (226Ra, 228Ra, 224Ra, and 223Ra), are transferred from the sediments to seawater, making them ideal tracers of sediment–water exchange processes and ocean mixing. As the two long-lived isotopes of the radium quartet, 226Ra and 228Ra (226Ra with a t1∕2 of 1600 years and 228Ra with a t1∕2 of 5.8 years) can provide insight into the water mass compositions, distribution patterns, as well as mixing processes and their associated timescales throughout the Canadian Arctic Archipelago (CAA). The wide range of 226Ra and 228Ra activities, as well as of the 228Ra∕226Ra, measured in water samples collected during the 2015 GEOTRACES cruise, complemented by additional chemical tracers – dissolved inorganic carbon (DIC), total alkalinity (AT), barium (Ba), and the stable oxygen isotope composition of water (δ18O) – highlight the dominant biogeochemical, hydrographic, and bathymetric features of the CAA. Bathymetric features, such as the continental shelf and shallow coastal sills, are critical in modulating circulation patterns within the CAA, including the bulk flow of Pacific waters and the inhibited eastward flow of denser Atlantic waters through the CAA. Using a principal component analysis, we unravel the dominant mechanisms and apparent water mass end-members that shape the tracer distributions. We identify two distinct water masses located above and below the upper halocline layer throughout the CAA and distinctly differentiate surface waters in the eastern and western CAA. Furthermore, we highlight water exchange across 80∘ W, inferring a draw of Atlantic water (originating from Baffin Bay) into the CAA. This underscores the presence of an Atlantic water “U-turn” located at Barrow Strait, where the same water mass is seen along the northernmost edge at 80∘ W as well as along the southeasternmost confines of Lancaster Sound. Overall, this study provides a stepping stone for future research initiatives within the Canadian Arctic Archipelago, revealing how quantifying disparities in the distributions of radioactive tracers can provide valuable information on water mass distributions, flow patterns, and mixing within vulnerable areas such as the CAA.

Published
2020
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23. Nutrient release to oceans from buoyancy-driven upwelling at Greenland tidewater glaciers

Author

Fiammetta Straneo, Mattias R. Cape, Randelle M. Bundy, Matthew A. Charette, and Nicholas Beaird

Subjects
geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Continental shelf, Greenland ice sheet, Fjord, Glacier, 010502 geochemistry & geophysics, 01 natural sciences, Oceanography, General Earth and Planetary Sciences, Environmental science, Upwelling, Glacial period, Ice sheet, Meltwater, 0105 earth and related environmental sciences
Abstract

The discharge of nutrient-rich meltwater from the Greenland Ice Sheet has emerged as a potentially important contributor to regional marine primary production and nutrient cycling. While significant, this direct nutrient input by the ice sheet may be secondary to the upwelling of deep-ocean-sourced nutrients driven by the release of meltwater at depth in glacial fjords. Here, we present a comprehensive suite of micro- and macronutrient observations collected in Sermilik Fjord at the margin of Helheim, one of Greenland’s largest glaciers, and quantitatively decompose glacial and ocean contributions to fjord dissolved nutrient inventories. We show that the substantial enrichment in nitrate, phosphate and silicate observed in the upper 250 m of the glacial fjord is the result of upwelling of warm subtropical waters present at depth throughout the fjord. These nutrient-enriched fjord waters are subsequently exported subsurface to the continental shelf. The upwelled nutrient transport within Sermilik rivals exports by the largest Arctic rivers and the ice sheet as a whole, suggesting that glacier-induced pumping of deep nutrients may constitute a major source of macronutrients to the surrounding coastal ocean. The importance of this mechanism is likely to grow given projected increases in surface melt of the ice sheet. Glacial meltwater from the Greenland Ice Sheet causes buoyancy-driven upwelling of nutrient-rich, subtropical waters from depth to the continental shelf. This nutrient transport may exceed the direct ice sheet inputs, according to geochemical analyses of transect samples from Sermilik Fjord.

Published
2018
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24. A New Perspective for Assessing Water Transport and Associated Retention Effects in a Large Reservoir

Author

Xinying Huang, Matthew A. Charette, Xiangbin Ran, Sumei Liu, William C. Burnett, Peng Yao, Disong Yang, Bochao Xu, and Zhigang Yu

Subjects
Water transport, 010504 meteorology & atmospheric sciences, Perspective (graphical), chemistry.chemical_element, 010501 environmental sciences, 01 natural sciences, Radium, Geophysics, Nutrient, chemistry, Water age, General Earth and Planetary Sciences, Environmental science, Water resource management, 0105 earth and related environmental sciences
Published
2018
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25. Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean

Author

David Andrew Barry, Ling Li, Isaac R. Santos, Clare Robinson, Matthew A. Charette, and Pei Xin

Subjects
010504 meteorology & atmospheric sciences, 0208 environmental biotechnology, Interacting effects, Climate change, Aquifer, 02 engineering and technology, Tides, 01 natural sciences, Organic contaminants, Temporal scales, 0105 earth and related environmental sciences, Water Science and Technology, geography, geography.geographical_feature_category, Groundwater-ocean interactions, Nutrients, Submarine groundwater discharge, 020801 environmental engineering, Water resources, Oceanography, Metals, Sustainable management, Greenhouse gas, Waves, Geology, Groundwater
Abstract

Sustainable coastal resource management requires sound understanding of interactions between coastal unconfined aquifers and the ocean as these interactions influence the flux of chemicals to the coastal ocean and the availability of fresh groundwater resources. The importance of submarine groundwater discharge in delivering chemical fluxes to the coastal ocean and the critical role of the subterranean estuary (STE) in regulating these fluxes is well recognized. STEs are complex and dynamic systems exposed to various physical, hydrological, geological, and chemical conditions that act on disparate spatial and temporal scales. This paper provides a review of the effect of factors that influence flow and salt transport in STEs, evaluates current understanding on the interactions between these influences, and synthesizes understanding of drivers of nutrient, carbon, greenhouse gas, metal and organic contaminant fluxes to the ocean. Based on this review, key research needs are identified. While the effects of density and tides are well understood, episodic and longer-period forces as well as the interactions between multiple influences remain poorly understood. Many studies continue to focus on idealized nearshore aquifer systems and future work needs to consider real world complexities such as geological heterogeneities, and non-uniform and evolving alongshore and cross-shore morphology. There is also a significant need for multidisciplinary research to unravel the interactions between physical and biogeochemical processes in STEs, as most existing studies treat these processes in isolation. Better understanding of this complex and dynamic system can improve sustainable management of coastal water resources under the influence of anthropogenic pressures and climate change.

Published
2018
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26. Mercury flux from salt marsh sediments: Insights from a comparison between 224Ra/228Th disequilibrium and core incubation methods

Author

Pinghe Cai, Robert P. Mason, Xiangming Shi, Nashaat M. Mazrui, and Matthew A. Charette

Subjects
Biogeochemical cycle, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Aquatic ecosystem, Sediment, chemistry.chemical_element, 010501 environmental sciences, 01 natural sciences, Mercury (element), chemistry.chemical_compound, Oceanography, chemistry, Geochemistry and Petrology, Benthic zone, Environmental chemistry, Salt marsh, Bioaccumulation, Environmental science, Methylmercury, 0105 earth and related environmental sciences
Abstract

In aquatic environments, sediments are the main location of mercury methylation. Thus, accurate quantification of methylmercury (MeHg) fluxes at the sediment-water interface is vital to understanding the biogeochemical cycling of mercury, especially the toxic MeHg species, and their bioaccumulation. Traditional approaches, such as core incubations, are difficult to maintain at in-situ conditions during assays, leading to over/underestimation of benthic fluxes. Alternatively, the 224Ra/228Th disequilibrium method for tracing the transfer of dissolved substances across the sediment-water interface, has proven to be a reliable approach for quantifying benthic fluxes. In this study, the 224Ra/228Th disequilibrium and core incubation methods were compared to examine the benthic fluxes of both 224Ra and MeHg in salt marsh sediments of Barn Island, Connecticut, USA from May to August, 2016. The two methods were comparable for 224Ra but contradictory for MeHg. The radiotracer approach indicated that sediments were always the dominant source of both total mercury (THg) and MeHg. The core incubation method for MeHg produced similar results in May and August, but an opposite pattern in June and July, which suggested sediments were a sink of MeHg, contrary to the evidence of significant MeHg gradients between overlying water and porewater at the sediment-water interface. The potential reasons for such differences are discussed. Overall, we conclude that the 224Ra/228Th disequilibrium approach is preferred for estimating the benthic flux of MeHg and that sediment is indeed an important MeHg source in this marshland, and likely in other shallow coastal waters.

Published
2018
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27. Radium isotopes as submarine groundwater discharge (SGD) tracers: Review and recommendations

Author

Valentí Rodellas, Marc Diego-Feliu, Jan Scholten, Holly A. Michael, Yishai Weinstein, Jordi Garcia-Orellana, Aaron Alorda-Kleinglass, Thomas Stieglitz, Matthew A. Charette, P. van Beek, Joseph Tamborski, Universitat Autònoma de Barcelona (UAB), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Bar-Ilan University [Israël], Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), DEPARTMENT OF CIVILAND ENVIRONMENTAL ENGINEERING DELAWARE USA, Partenaires IRSTEA, Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Christian-Albrechts University of Kiel, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
010504 meteorology & atmospheric sciences, Isotope, chemistry.chemical_element, Research needs, 010502 geochemistry & geophysics, 01 natural sciences, 6. Clean water, Submarine groundwater discharge, Radium, Oceanography, Continental margin, chemistry, 13. Climate action, General Earth and Planetary Sciences, Environmental science, Seawater, 14. Life underwater, Water cycle, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Groundwater, 0105 earth and related environmental sciences
Abstract

Submarine groundwater discharge (SGD) is now recognized as an important process of the hydrological cycle worldwide and plays a major role as a conveyor of dissolved compounds to the ocean. Naturally occurring radium isotopes (223Ra, 224Ra, 226Ra and 228Ra) are widely employed geochemical tracers in marine environments. Whilst Ra isotopes were initially predominantly applied to study open ocean processes and fluxes across the continental margins, their most common application in the marine environment has undoubtedly become the identification and quantification of SGD. This review focuses on the application of Ra isotopes as tracers of SGD and associated inputs of water and solutes to the coastal ocean. In addition, we review i) the processes controlling Ra enrichment and depletion in coastal groundwater and seawater; ii) the systematics applied to estimate SGD using Ra isotopes and iii) we summarize additional applications of Ra isotopes in groundwater and marine studies. We also provide some considerations that will help refine SGD estimates and identify the critical knowledge gaps and research needs related to the current use of Ra isotopes as SGD tracers.

Published
2021
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28. Relationship between water and aragonite barium concentrations in aquaria reared juvenile corals

Author

Thomas M. DeCarlo, Matthew A. Charette, Anne L. Cohen, and Meagan Eagle Gonneea

Subjects
Favia fragum, 010504 meteorology & atmospheric sciences, biology, Coral, Aragonite, Porites, chemistry.chemical_element, Coralline algae, Barium, engineering.material, 010502 geochemistry & geophysics, biology.organism_classification, 01 natural sciences, Oceanography, chemistry, Geochemistry and Petrology, engineering, Upwelling, Seawater, Geology, 0105 earth and related environmental sciences
Abstract

Coral barium to calcium (Ba/Ca) ratios have been used to reconstruct records of upwelling, river and groundwater discharge, and sediment and dust input to the coastal ocean. However, this proxy has not yet been explicitly tested to determine if Ba inclusion in the coral skeleton is directly proportional to seawater Ba concentration and to further determine how additional factors such as temperature and calcification rate control coral Ba/Ca ratios. We measured the inclusion of Ba within aquaria reared juvenile corals ( Favia fragum ) at three temperatures (∼27.7, 24.6 and 22.5 °C) and three seawater Ba concentrations (73, 230 and 450 nmol kg −1 ). Coral polyps were settled on tiles conditioned with encrusting coralline algae, which complicated chemical analysis of the coral skeletal material grown during the aquaria experiments. We utilized Sr/Ca ratios of encrusting coralline algae (as low as 3.4 mmol mol −1 ) to correct coral Ba/Ca for this contamination, which was determined to be 26 ± 11% using a two end member mixing model. Notably, there was a large range in Ba/Ca across all treatments, however, we found that Ba inclusion was linear across the full concentration range. The temperature sensitivity of the distribution coefficient is within the range of previously reported values. Finally, calcification rate, which displayed large variability, was not correlated to the distribution coefficient. The observed temperature dependence predicts a change in coral Ba/Ca ratios of 1.1 μmol mol −1 from 20 to 28 °C for typical coastal ocean Ba concentrations of 50 nmol kg −1 . Given the linear uptake of Ba by corals observed in this study, coral proxy records that demonstrate peaks of 10–25 μmol mol −1 would require coastal seawater Ba of between 60 and 145 nmol kg −1 . Further validation of the coral Ba/Ca proxy requires evaluation of changes in seawater chemistry associated with the environmental perturbation recorded by the coral as well as verification of these results for Porites species, which are widely used in paleo reconstructions.

Published
2017
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29. Kinetics of thorium and particle cycling along the U.S. GEOTRACES North Atlantic Transect

Author

Paul Lerner, Phoebe J. Lam, Ken O. Buesseler, Olivier Marchal, and Matthew A. Charette

Subjects
010504 meteorology & atmospheric sciences, Chemistry, Geotraces, Analytical chemistry, Mineralogy, Thorium, chemistry.chemical_element, Sorption, Aquatic Science, 010402 general chemistry, Oceanography, 01 natural sciences, 0104 chemical sciences, Partition coefficient, Reaction rate constant, Desorption, Particle, Isotopes of thorium, 0105 earth and related environmental sciences
Abstract

The high particle reactivity of thorium has resulted in its widespread use in tracing processes impacting marine particles and their chemical constituents. The use of thorium isotopes as tracers of particle dynamics, however, largely relies on our understanding of how the element scavenges onto particles. Here, we estimate apparent rate constants of Th adsorption (k1), Th desorption (k−1), bulk particle degradation (β-1), and bulk particle sinking speed (w) along the water column at 11 open-ocean stations occupied during the GEOTRACES North Atlantic Section (GA03). First, we provide evidence that the budgets of Th isotopes and particles at these stations appear to be generally dominated by radioactive production and decay sorption reactions, particle degradation, and particle sinking. Rate parameters are then estimated by fitting a Th and particle cycling model to data of dissolved and particulate 228,230,234Th, 228Ra, particle concentrations, and 234,238U estimates based on salinity, using a nonlinear programming technique. We find that the adsorption rate constant (k1) generally decreases with depth across the section: broadly, the time scale 1 / k 1 averages 1.0 yr in the upper 1000 m and (1.4–1.5) yr below. A positive relationship between k1 and particle concentration (P) is found, i.e., k 1 ∝ P b , where b ≥ 1 , consistent with the notion that k1 increases with the number of surface sites available for adsorption. The rate constant ratio, K = k 1 / ( k − 1 + β − 1 ) , which measures the collective influence of rate parameters on Th scavenging, averages 0.2 for most stations and most depths. We clarify the conditions under which K / P is equivalent to the distribution coefficient, KD, test that the conditions are met at the stations, and find that K / P decreases with P, in line with a particle concentration effect ( dK D / dP 0 ). In contrast to the influence of colloids as envisioned by the Brownian pumping hypothesis, we provide evidence that the particle concentration effect arises from the joint effect of P on the rate constants for thorium attachment to, and detachment from, particles.

Published
2017
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30. Carbonate system biogeochemistry in a subterranean estuary – Waquoit Bay, USA

Author

Paul B. Henderson, Daniel C. McCorkle, Crystaline F. Breier, Matthew A. Charette, William R. Martin, Qian Liu, and Minhan Dai

Subjects
Hydrology, geography, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Biogeochemistry, Estuary, Ocean acidification, 010501 environmental sciences, 01 natural sciences, Submarine groundwater discharge, Salinity, Oceanography, Total inorganic carbon, Geochemistry and Petrology, Surface water, Bay, Geology, 0105 earth and related environmental sciences
Abstract

Quantifying carbon fluxes associated with submarine groundwater discharge (SGD) remains challenging due to the complex biogeochemistry of the carbonate system in the subterranean estuary (STE). Here we conducted time series measurements of total alkalinity (TAlk) and dissolved inorganic carbon (DIC) in a well-studied coastal aquifer (Waquoit Bay, Massachusetts, USA). Groundwater samples were collected monthly from May 2009 to June 2010 across the freshwater-saltwater mixing zone of the Waquoit Bay (WB) STE. The concentrations of both TAlk and DIC in zero-salinity groundwater were variable, but were lower than those in the bay water (S ∼ 28). DIC underwent slightly non-conservative mixing between low and intermediate salinities while there was an apparent additional DIC source at high salinity (>20) in all seasons. TAlk concentrations exhibited even stronger variations, with evidence of both production and consumption in high salinity zones, and consistent TAlk consumption at intermediate salinity in summer and fall (June–December, 2009). The increases in DIC and TAlk at high salinity were attributed to aerobic respiration and denitrification in WB sediments during bay water recharge of the STE. We infer that the loss of TAlk at intermediate salinity reflects H+ production as reduced compounds (e.g. Fe2+) are oxidized within the STE. In terms of impacts on surface water inorganic carbon budgets, the SGD-derived DIC flux was mainly controlled by seasonal changes in SGD while a combination of TAlk concentration variability and SGD drove the TAlk flux. SGD-derived DIC, aqueous CO2, and H+ fluxes to the bay were ∼40–50% higher in summer vs. in winter, a result of enhanced marine groundwater flux and significant TAlk removal (proton addition) during periods of high seawater intrusion. Furthermore, the SGD-derived DIC flux was consistently greater than TAlk flux regardless of season, indicating that SGD serves to reduce the CO2 buffering capacity of surface water. Our results highlight the importance of seasonality and subsurface biogeochemical processes on the subterranean estuary carbonate system and the resulting impact on SGD-derived TAlk, DIC, aqueous CO2, and H+ fluxes to the coastal ocean.

Published
2017
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31. Does submarine groundwater discharge contribute to summer hypoxia in the Changjiang (Yangtze) River Estuary?

Author

Chen Guangquan, Bochao Xu, William C. Burnett, Shibin Zhao, Haiming Nan, Ergang Lian, Zhigang Yu, Qinsheng Wei, Xiaoyi Guo, and Matthew A. Charette

Subjects
chemistry.chemical_classification, geography, Environmental Engineering, geography.geographical_feature_category, 010504 meteorology & atmospheric sciences, Hypoxia (environmental), Estuary, 010501 environmental sciences, 01 natural sciences, Pollution, Anoxic waters, Submarine groundwater discharge, Bottom water, Nutrient, Oceanography, chemistry, Yangtze river, Environmental Chemistry, Environmental science, Organic matter, Waste Management and Disposal, 0105 earth and related environmental sciences
Abstract

The Changjiang (Yangtze) River Estuary (CJE) is one of the largest and most intense seasonal hypoxic zones in the world. Here we examine the possibility that submarine groundwater discharge (SGD) may contribute to the summer hypoxia. Spatial distributions of bottom water 222Rn suggest a hotspot discharge area in the northern section of the CJE. SGD fluxes were estimated based on a 222Rn mass balance model and were found to range from 0.002 ± 0.004 to 0.022 ± 0.011 m3/m2/day. Higher SGD fluxes were observed during summer hypoxia period. The well-developed overlap of the distribution patterns for SGD flux and dissolved oxygen (DO) implies that SGD could be an important contributor to summer hypoxia in the region off the CJE. We suggest that SGD contributes to the seasonal hypoxia either: (1) directly via discharge of anoxic groundwaters together with reducing substances; and/or (2) indirectly by delivering excess nutrients that stimulate primary productivity with consequent consumption of DO during organic matter decomposition.

Published
2019

32. Insight into the measurement of dissolved 227Ac in seawater using radium delayed coincidence counter

Author

Paul B. Henderson, Virginie Sanial, François Lacan, Marc Souhaut, Pieter van Beek, Matthew A. Charette, Emilie Le Roy, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), GEOMAR LEGOS, Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), Division of Marine Science [Mississippi], University of Southern Mississippi (USM), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), ISBlue - Interdisciplinary Graduate School for the Blue planet (2017), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), and Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3)

Subjects
0106 biological sciences, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Radionuclide, Reproducibility, Materials science, 010504 meteorology & atmospheric sciences, 010604 marine biology & hydrobiology, Extraction (chemistry), Analytical chemistry, chemistry.chemical_element, General Chemistry, Repeatability, Secular equilibrium, Oceanography, 01 natural sciences, Radium, chemistry, 13. Climate action, Environmental Chemistry, Seawater, Nuclide, 0105 earth and related environmental sciences, Water Science and Technology
Abstract

International audience; Due to the low abundance of 227 Ac in seawater, the analysis of this radionuclide requires the use of high-sensitivity, low-background instruments and the collection of large volume samples. A promising technique relies on the pre-concentration of 227 Ac in seawater using cartridges impregnated with manganese oxide (Mn-cartridges) that are mounted on in situ pumps, and its measurement on a Radium Delayed Coincidence Counter (RaDeCC), usually used to analyze short-lived radium isotopes. In this work, we present an evaluation of this technique, including 1) the study of the performance of the RaDeCC measurements for 227 Ac fixed on Mn-cartridges (backgrounds, detector efficiency, repeatability), and 2) the determination of the efficiency of seawater 227 Ac extraction of the Mn-cartridges and its reproducibility for the first time, by using Mn-cartridges placed in series. Overall, we found a Mn-cartridge extraction efficiency of 47 ± 12% (1 SD). Repeatability experiments allowed us to estimate the uncertainties of the entire measurement of 19% (1 SD). Finally, in the aim to validate the method, the 227 Ac activities thus obtained are compared 1) to the 227 Ac activities determined in several samples using Mn-fibers (assuming 100% yield of 227 Ac extraction) and 2) to the 231 Pa activities determined at the same stations during the GEOVIDE cruise (GEOTRACES GA01), 231 Pa being the parent nuclide of 227 Ac (Deng et al., 2018). Only few studies 227 Ac and 231 Pa have been published so far due to the difficulty to analyze these two nuclides. First, the 227 Ac activities determined using Mn-cartridges agree well with the 227 Ac activities determined using Mn-fibers. Second, at depths where 227 Ac is usually found to be in secular equilibrium with 231 Pa (0-2000 m), we found good agreement between 227 Ac and 231 Pa, which validates the method used to determine 227 Ac activities, including the estimate of the Mn-cartridge extraction efficiency.

Published
2019
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33. Timescales of hydrothermal scavenging in the South Pacific Ocean from 234 Th, 230 Th, and 228 Th

Author

Yanbin Lu, Virginie Sanial, Willard S. Moore, Sebastian M. Vivancos, Hai Cheng, Erin E. Black, R. Lawrence Edwards, Pu Zhang, Martin Q. Fleisher, Matthew A. Charette, Mikael Hult, Robert F. Anderson, Frank J. Pavia, Lauren Kipp, Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), and Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, Geotraces, Thorium, chemistry.chemical_element, 010502 geochemistry & geophysics, 01 natural sciences, Deep sea, Hydrothermal circulation, Plume, Geophysics, chemistry, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, Environmental chemistry, Earth and Planetary Sciences (miscellaneous), Seawater, 14. Life underwater, Scavenging, Geology, Isotopes of thorium, 0105 earth and related environmental sciences
Abstract

International audience; Hydrothermal activity in the deep ocean generates plumes of metal-rich particles capable of removing certain trace elements from seawater by adsorption and sedimentation. This removal process, known as scavenging, can be probed using the insoluble radiogenic isotopes of thorium (Th), which are produced at a known rate in the water column via the decay of soluble uranium (234 Th, 230 Th) and radium (228 Th) isotopes. We present dissolved and particulate measurements of these three thorium isotopes in a hydrothermal plume observed in the southeast Pacific Ocean on the GEOTRACES GP16 section. Since their half-lives vary from days (234 Th) to years (228 Th) to tens of thousands of years (230 Th), the combination of their signals can be used to understand scavenging processes occurring on a wide range of timescales. Scavenging is a multi-step process involving adsorption and desorption onto particles, followed by particle aggregation, sinking, and eventual sedimentation. We use thorium isotopes to study how hydrothermal activity affects these steps. The rate constants for net adsorption of 234 Th determined here are comparable to previous estimates from hydrothermal plumes in the Atlantic and North Pacific Oceans. The partitioning of 234 Th and 230 Th between large and small particles is more similar in the hydrothermal plume than above it, indicating faster aggregation of particles within the hydrothermal plume at stations nearby the East Pacific Rise than in waters outside the plume. In addition to rapid scavenging and aggregation near the ridge axis, we also infer continuous off-axis scavenging from observations and modeling of 228 Th/ 228 Ra activity ratios. The degree of depletion of the three thorium isotopes increases in order of half-life, with total 234 Th activity close to that of its parent 238 U, but 230 Th showing nearly 70% depletion compared to expected values from reversible scavenging. By modeling the variations in depletion for the different isotopes, we show that much of the 230 Th removal is inherited from scavenging events happening long before the most recent hydrothermal inputs.

Published
2019
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35. Nutrient-rich submarine groundwater discharge fuels the largest green tide in the world

Author

Qinzhen Yao, Matthew A. Charette, William C. Burnett, Shibin Zhao, Ergang Lian, Rongguo Su, Zhigang Yu, and Bochao Xu

Subjects
China, Environmental Engineering, 010504 meteorology & atmospheric sciences, 010501 environmental sciences, 01 natural sciences, Nutrient, Rivers, Hotspot (geology), Environmental Chemistry, Groundwater, Waste Management and Disposal, 0105 earth and related environmental sciences, geography, geography.geographical_feature_category, biology, Discharge, Ulva prolifera, Shoal, Nutrients, biology.organism_classification, Pollution, Submarine groundwater discharge, Oceanography, Environmental science, Surface runoff, Origination, Environmental Monitoring
Abstract

One of the largest “green tide” (Ulva prolifera) outbreaks in the world has occurred every year from 2007 to present in the Southern Yellow Sea, China. Currently, the coastal area around Jiangsu Province (Subei Shoal region) is thought to be the origination point of these giant green tide blooms. The combination of high nutrient demand but low river discharge and other inputs suggests that there is a significant flux of submarine groundwater discharge (SGD) in this area. By using a radium mass balance model, we estimated the SGD flux in the area to be (0.7–1.4) × 109 m3 d−1 (6.1–12 cm d−1), at the high end of SGD fluxes worldwide. Geographically, Subei Shoal is less than 5% of the entire Southern Yellow Sea area, while our calculated SGD flux just for the shoal area is ~3 times larger than previously documented for the whole Southern Yellow Sea. Therefore, Subei Shoal may be considered a SGD hotspot that plays an important role in SGD associated material fluxes. Compared to inputs from local rivers, atmospheric deposition, and anthropogenic activities, SGD-derived nutrients are the main source term that can support the growth of macroalgae. We specifically highlight that this type of areas that are shallow, intensively mixed, anthropogenically polluted, sandy or muddy with heavy bio-irrigation, may have a higher risk of suffering harmful ecological problems, even with limited terrestrial runoff.

Published
2021
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36. Radium isotopes as tracers of boundary inputs of nutrients and trace elements to the coastal and open ocean

Author

Matthew A. Charette., Woods Hole Oceanographic Institution., Joint Program in Oceanography/Applied Ocean Science and Engineering., Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences., Kipp, Lauren Elizabeth, Matthew A. Charette., Woods Hole Oceanographic Institution., Joint Program in Oceanography/Applied Ocean Science and Engineering., Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences., and Kipp, Lauren Elizabeth

Abstract

Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2018., Cataloged from PDF version of thesis., Includes bibliographical references., Nutrients and trace metals are vital for supporting life in the ocean, but the boundary processes that control the distributions of these elements are poorly constrained. Radium isotopes are well suited to studying inputs of elements from ocean margins because they are produced in sediments and soluble in seawater. The half-lives of the four isotopes (223Ra, 224Ra, 228Ra, 226Ra) range from days to thousands of years, thus these isotopes can be used to study oceanographic processes occurring over a range of time scales. In this thesis I have applied the quartet of radium isotopes to investigate boundary inputs, including seafloor hydrothermal vents, continental shelves, and rivers. First, radium isotope ratios were used to constrain the age of hydrothermal plumes emanating from vents along the Mid-Atlantic Ridge and East Pacific Rise. These radium-derived ages were applied to determine the iron residence time in the Pacific plume that emanates from near 15°S, providing an important constraint on the hydrothermal delivery of iron to the deep ocean. Next, 228Ra was used to show that shelf inputs to the Arctic Ocean have increased over the last decade, implying that the fluxes of other shelf-derived materials are also increasing and could impact primary production in this basin. The ratio of 228Ra and 226Ra was also applied to determine the ventilation time of Arctic intermediate waters with respect to shelf inputs, and the first measurements of 226Ra in the deep Canada Basin were used to estimate the residence time of deep waters with respect to benthic sediment inputs. Finally, a study of the Mackenzie River Estuary illustrated the importance of deltaic and estuarine processing on the ultimate delivery of nutrients, trace metals, dissolved organic matter, and radium to the Arctic Ocean. By applying radium isotopes as tracers of boundary inputs in these diverse environments, the work presented in this thesis improves our understanding of nutrient and trace metal inputs, by Lauren Elizabeth Kipp., Ph. D.

Published
2019

37. How significant is submarine groundwater discharge and its associated dissolved inorganic carbon in a river-dominated shelf system?

Author

Chih-An Huh, Qian Liu, Q. Li, Guihua Wang, Minhan Dai, Matthew A. Charette, and W. Chen

Subjects
Hydrology, lcsh:QE1-996.5, lcsh:Life, New production, Submarine groundwater discharge, lcsh:Geology, lcsh:QH501-531, Oceanography, lcsh:QH540-549.5, Dissolved organic carbon, Upwelling, Seawater, lcsh:Ecology, Subsurface flow, Surface water, Ecology, Evolution, Behavior and Systematics, Groundwater, Geology, Earth-Surface Processes
Abstract

In order to assess the role of submarine groundwater discharge (SGD) and its impact on the carbonate system on the northern South China Sea (NSCS) shelf, we measured seawater concentrations of four radium isotopes 223,224,226,228Ra along with carbonate system parameters in June–July, 2008. Complementary groundwater sampling was conducted in coastal areas in December 2008 and October 2010 to constrain the groundwater end-members. The distribution of Ra isotopes in the NSCS was largely controlled by the Pearl River plume and coastal upwelling. Long-lived Ra isotopes (228Ra and 226Ra) were enriched in the river plume but low in the offshore surface water and subsurface water/upwelling zone. In contrast, short-lived Ra isotopes (224Ra and 223Ra) were elevated in the subsurface water/upwelling zone as well as in the river plume but depleted in the offshore surface water. In order to quantify SGD, we adopted two independent mathematical approaches. Using a three end-member mixing model with total alkalinity (TAlk) and Ra isotopes, we derived a SGD flux into the NSCS shelf of 2.3–3.7 × 108 m3 day−1. Our second approach involved a simple mass balance of 228Ra and 226Ra and resulted in a first order but consistent SGD flux estimate of 2.2–3.7 × 108 m3 day−1. These fluxes were equivalent to 12–21 % of the Pearl River discharge, but the source of the SGD was mostly recirculated seawater. Despite the relatively small SGD volume flow compared to the river, the associated material fluxes were substantial given their elevated concentrations of dissolved inorganic solutes. In this case, dissolved inorganic carbon (DIC) flux through SGD was 153–347 × 109 mol yr−1, or ~23–53 % of the riverine DIC export flux. Our estimates of the groundwater-derived phosphate flux ranged 3–68 × 107 mol yr−1, which may be responsible for new production on the shelf up to 0.3–6.3 mmol C m−2 d−1. This rate of new production would at most consume 11 % of the DIC contribution delivered by SGD. Hence, SGD may play an important role in the carbon balance over the NSCS shelf.

Published
2018

38. The GEOTRACES Intermediate Data Product 2017

Author

Thomas J. Browning, Hans-Jürgen Brumsack, Katharina Pahnke, Saeed Roshan, Stephanie Owens, Rosie Chance, Peter Croot, Steven van Heuven, Alison E. Hartman, Mercedes López-Lora, Pu Zhang, Heather A. Bouman, Géraldine Sarthou, François Lacan, Robyn E. Tuerena, José Marcus Godoy, Ester Garcia-Solsona, Steven L. Goldstein, Hans A. Slagter, Celia Venchiarutti, A. Russell Flegal, Emily Townsend, Ralph Till, Christopher T. Hayes, Melanie Gault-Ringold, Ros Watson, Peter N. Sedwick, Chandranath Basak, Bronwyn Wake, Loes J. A. Gerringa, Noriko Nakayama, Lars-Eric Heimbürger, Paul J. Morris, François Fripiat, Paul B. Henderson, Chris J. Daniels, Catherine Jeandel, Helen M. Snaith, Patrizia Ziveri, Toshitaka Gamo, Yanbin Lu, Oliver J. Lechtenfeld, Yingzhe Wu, Andreas Wisotzki, Hajime Obata, Cynthia Dumousseaud, Ashley T. Townsend, Sebastian Mieruch, Donna Cockwell, Laurent Bopp, Elena Masferrer Dodas, Bernhard Schnetger, J. K. Klar, Sunil K. Singh, Joaquin E. Chaves, Kuo-Fang Huang, Louise A. Zimmer, Laura F. Robinson, Michiel M Rutgers van der Loeff, Corey Archer, Feifei Deng, Karen Grissom, Robert Rember, Nicholas J. Hawco, Jingfeng Wu, Robert M. Sherrell, Rachel U. Shelley, Jan-Lukas Menzel Barraqueta, E. Malcolm S. Woodward, Fanny Chever, Yuichiro Kumamoto, Hélène Planquette, Dorothea Bauch, Frank Dehairs, Daniel C. Ohnemus, Akira Nishiuchi, Paul D. Quay, Sanjin Mehic, Zichen Xue, Maxi Castrillejo, Brian Peters, Michael J. Ellwood, Stephen R. Rintoul, Tobias Roeske, Jing Zhang, Gretchen J. Swarr, Peng Ho, Ken O. Buesseler, Gwenaelle Moncoiffe, Martin Frank, Maureen E. Auro, Abby Bull, David Kadko, Montserrat Roca-Martí, Maeve C. Lohan, Roulin Khondoker, Patricia Cámara Mor, Melissa Gilbert, Sebastian M. Vivancos, Erin E. Black, Santiago R. Gonzalez, Gideon M. Henderson, David J. Janssen, Sylvain Rigaud, Amandine Radic, Maxence Paul, Cyril Abadie, Ana Aguliar-Islas, Seth G. John, Marie Boye, Evgenia Ryabenko, Abigail E. Noble, Luke Bridgestock, Brian Duggan, Hisayuki Yoshikawa, Jun Nishioka, Kathrin Wuttig, Pieter van Beek, Jana Friedrich, Thomas M. Church, Maija Heller, Stephen J.G. Galer, Pier van der Merwe, Claire P. Till, Xin Yuan Zheng, Henning Fröllje, John Niedermiller, Howie D. Scher, Johnny Stutsman, Patricia Zunino, Christel S. Hassler, Ye Zhao, Tim M. Conway, William M. Landing, Yang Xiang, Katrin Bluhm, Maria T. Maldonado, Elena Chamizo, Sabrina Speich, Claudine H. Stirling, Guillaume Brissebrat, Matthew A. Charette, Jeremy E. Jacquot, Yu-Te Hsieh, Pinghe Cai, Ivia Closset, Yoshiki Sohrin, Ejin George, Jong-Mi Lee, Leopoldo D. Pena, Edward Mawji, Damien Cardinal, Catherine Pradoux, Martin Q. Fleisher, Virginie Sanial, Derek Vance, Craig A. Carlson, Pere Masqué, Katlin L. Bowman, Evaline M. van Weerlee, Oliver Baars, Ruifang C. Xie, María Villa-Alfageme, Hein J W de Baar, M. Alexandra Weigand, Tina van de Flierdt, J. Bown, Timothy C. Kenna, Kenneth W. Bruland, Jeroen E. Sonke, Hai Cheng, Mark J. Warner, Sven Ober, Rob Middag, Jessica N. Fitzsimmons, Emilie Le Roy, Yishai Weinstein, Nicholas R. Bates, Joerg Rickli, Daniel M. Sigman, Hendrik M. van Aken, Angela Milne, Cheryl M. Zurbrick, Gregory A. Cutter, Igor Semiletov, Marie Labatut, Torben Stichel, Pascale Lherminier, Gabriel Dulaquais, Jay T. Cullen, Christopher I. Measures, Mark Rosenberg, Tomoharu Minami, Mariko Hatta, Alexander L. Thomas, Gonzalo Carrasco, Karel Bakker, Clifton S. Buck, Maarten B Klunder, Willard S. Moore, Reiner Schlitzer, Tomas A. Remenyi, Susan H. Little, Eberhard Fahrbach, Charles R. McClain, Edward A. Boyle, Ursula Schauer, Linjie Zheng, Alex R. Baker, Emma Slater, Kay Thorne, Patrick Laan, Christina Schallenberg, Reiner Steinfeldt, Benjamin S. Twining, Yolanda Echegoyen-Sanz, Neil J. Wyatt, Alison M. Agather, Viena Puigcorbé, Peter Scott, Gillian Stewart, Matthew P. Humphreys, Frédéric A. C. Le Moigne, Phoebe J. Lam, Núria Casacuberta, Josh Helgoe, Edward C.V. Butler, Mark Rehkämper, Elizabeth M. Jones, Karen L. Casciotti, James W. Moffett, Tristan J. Horner, Sue Velazquez, Yuzuru Nakaguchi, Micha J.A. Rijkenberg, Antje H L Voelker, Joseph A. Resing, Lesley Salt, Eric P. Achterberg, Sven Kretschmer, Jan van Ooijen, Dominik J. Weiss, Moritz Zieringer, Carl H. Lamborg, Rick Kayser, Pierre Branellec, John M. Rolison, Sara Rauschenberg, Walter Geibert, Raja S. Ganeshram, Myriam Lambelet, Janice L. Jones, Chad R. Hammerschmidt, William J. Jenkins, Jordi Garcia-Orellana, Alessandro Tagliabue, Philip W. Boyd, Alan M. Shiller, Marcus Christl, Mark Baskaran, Mak A. Saito, Huong Thi Dieu, Morten B. Andersen, Kenji Isshiki, Taejin Kim, Christian Schlosser, Melanie K. Behrens, Albert S. Colman, Frédéric Planchon, Bettina Sohst, Andrew R. Bowie, Mark A. Brzezinski, R. Lawrence Edwards, Kristen N. Buck, Jeanette O'Sullivan, William M. Smethie, Wafa Abouchami, Valentí Rodellas, Ed C Hathorne, Robert F. Anderson, James H. Swift, Frank J. Pavia, Daniel Cossa, Lauren Kipp, Peter L. Morton, Fabien Quéroué, Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Centre for Automotive Safety Research, University of Adelaide, University of California, National Oceanography Centre (NOC), Scottish Association for Marine Science (SAMS), Department of Oceanography [Cape Town], University of Cape Town, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Max Planck Institute for Chemistry (MPIC), Max-Planck-Gesellschaft, University of Toyama, Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), Royal Netherlands Institute for Sea Research (NIOZ), Leibniz-Institut für Meereswissenschaften (IFM-GEOMAR), Department of Geology, Wayne State University [Detroit], The Bartlett, University College of London [London] (UCL), Institute for Environmental Research, Rheinisch-Westfälische Technische Hochschule Aachen (RWTH), Laboratoire de Météorologie Dynamique (UMR 8539) (LMD), Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-École des Ponts ParisTech (ENPC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Département des Géosciences - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris), Department of Earth Sciences [Oxford], University of Oxford [Oxford], Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Universitaire Européen de la Mer (IUEM), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Université de Brest (UBO)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Cycles biogéochimiques marins : processus et perturbations (CYBIOM), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institute for Research on Learning, Services communs OMP - UMS 831 (UMS 831), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées, Marine Science Institute [Santa Barbara] (MSI), University of California [Santa Barbara] (UCSB), University of California-University of California, National Oceanography Centre [Southampton] (NOC), University of Southampton, Institut Français de Recherche pour l'Exploitation de la Mer - Nantes (IFREMER Nantes), Université de Nantes (UN), University of Victoria [Canada] (UVIC), Massachusetts Institute of Technology (MIT), Universidad de Dakota del Sur, Analytical, Environmental and Geo- Chemistry, Vrije Universiteit [Brussels] (VUB), Wright State University, School of Geography, Earth and Environmental Sciences [Plymouth] (SoGEES), Plymouth University, Lamont-Doherty Earth Observatory (LDEO), Columbia University [New York], Alfred Wegener Institute [Potsdam], Institute of Global Environmental Change [China] (IGEC), Xi'an Jiaotong University (Xjtu), Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Department of Mathematics and Science, National Taiwan Normal University (NTNU), School of Information Technology [Kharagpur], Indian Institute of Technology Kharagpur (IIT Kharagpur), GEOMAR - Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), University of California [Davis] (UC Davis), Institut de Ciencia i Tecnologia Ambientals (ICTA), Universitat Autònoma de Barcelona [Barcelona] (UAB), Institute of Low Temperature Science, Hokkaido University, The University of Tokyo, Institute for Marine and Antarctic Studies [Horbat] (IMAS), University of Tasmania (UTAS), Joint Institute for the Study of the Atmosphere and Ocean (JISAO), University of Washington [Seattle], Institute of Geochemistry and Petrology, Détection, évaluation, gestion des risques CHROniques et éMErgents (CHROME) / Université de Nîmes (CHROME), Université de Nîmes (UNIMES), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Collège de France (CdF)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Institut National de la Recherche Agronomique (INRA), School of Earth and Ocean Sciences, University of Victoria, Knowledge Media Institute (KMI), The Open University [Milton Keynes] (OU), Bermuda Biological Station for Research (BBSR), Bermuda Biological Station for Research, Department of Geosciences [Princeton], Princeton University, Kyoto University [Kyoto], Géochimie des Isotopes Stables (GIS), Géosciences Environnement Toulouse (GET), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National d'Études Spatiales [Toulouse] (CNES), School of Earth and Environmental Sciences [Queens New York], Queens College [New York], City University of New York [New York] (CUNY)-City University of New York [New York] (CUNY), SOEST, University of Hawai‘i [Mānoa] (UHM), Catholic University of Leuven - Katholieke Universiteit Leuven (KU Leuven), Bigelow Laboratory for Ocean Sciences, Department of Earth Science and Technology [Imperial College London], Imperial College London, Plymouth Marine Laboratory, Rosenstiel School of Marine and Atmospheric Science (RSMAS), University of Miami [Coral Gables], Tsinghua National Laboratory for Information Science and Technology (TNList), RITE, Research Institute of Innovative Technology for the Earth, Agricultural Information Institute (AII), Chinese Academy of Agricultural Sciences (CAAS), Department of Mathematics [Shanghai], Shanghai Jiao Tong University [Shanghai], University of California [Irvine] (UCI), Institute of Environmental Science and Technology [Barcelona] (ICTA), University of California (UC), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Rheinisch-Westfälische Technische Hochschule Aachen University (RWTH), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of Oxford, Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), University of Southern California (USC), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Services communs OMP (UMS 831), Université Toulouse III - Paul Sabatier (UT3), Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France, University of California [Santa Barbara] (UC Santa Barbara), University of California (UC)-University of California (UC), Institut des Sciences de la Terre (ISTerre), Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR219-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Vrije Universiteit Brussel (VUB), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS), Florida International University [Miami] (FIU), Department of Earth Science and Engineering [Imperial College London], Helmholtz Centre for Ocean Research [Kiel] (GEOMAR), Universitat Autònoma de Barcelona (UAB), British Oceanographic Data Centre (BODC), Institute of Low Temperature Science [Sapporo], Hokkaido University [Sapporo, Japan], The University of Tokyo (UTokyo), Institute of Geochemistry and Petrology [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), College of Earth, Ocean, and Environment [Newark] (CEOE), University of Delaware [Newark], Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Knowledge Media Institute (KMi), Kyoto University, Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Academia Sinica, University of California [Irvine] (UC Irvine), Danish Technological Institute (DTI), Scientific Committee on Oceanic Research (SCOR) from the U.S. National Science Foundation [OCE-0608600, OCE-0938349, OCE-1243377, OCE-1546580], UK Natural Environment Research Council (NERC), Ministry of Earth Science of India, Centre National de Recherche Scientifique, l'Universite Paul Sabatier de Toulouse, Observatoire Midi-Pyrenees Toulouse, Universitat Autonoma de Barcelona, Kiel Excellence Cluster The Future Ocean, Swedish Museum of Natural History, University of Tokyo, University of British Columbia, Royal Netherlands Institute for Sea Research, GEOMAR-Helmholtz Centre for Ocean Research Kiel, Alfred Wegener Institute, Scientific Committee on Oceanic Research, National Science Foundation (US), Natural Environment Research Council (UK), Ministry of Earth Sciences (India), Centre National de la Recherche Scientifique (France), Université Toulouse III Paul Sabatier, Observatoire Midi-Pyrénées (France), Universidad Autónoma de Barcelona, Helmholtz Centre for Ocean Research Kiel, Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (Germany), Schlitzer, Reiner [0000-0002-3740-6499], Masferrer Dodas, Elena [0000-0003-0879-1954], Chamizo, Elena [0000-0001-8266-6129], Christl, M. [0000-0002-3131-6652], Masqué, Pere [0000-0002-1789-320X], Villa-Alfageme, María [0000-0001-7157-8588], Universitat de Barcelona, Natural Environment Research Council (NERC), Leverhulme Trust, Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences, Carrasco Rebaza, Gonzalo, Echegoyen Sanz, Yolanda, Kayser, Richard A, Isotope Research, Ocean Ecosystems, Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Collège de France (CdF (institution))-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Recherche Agronomique (INRA), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Hassler, Christel, Schlitzer, Reiner, Masferrer Dodas, Elena, Chamizo, Elena, Christl, M., Masqué, Pere, and Villa-Alfageme, María

Subjects
Geochemistry & Geophysics, 010504 meteorology & atmospheric sciences, Isòtops, sub-01, Geotraces, MODELS, Digital data, Context (language use), 010502 geochemistry & geophysics, 01 natural sciences, IDP2017, Isotopes, Geochemistry and Petrology, Oceans, Electronic atlas, ddc:550, 0402 Geochemistry, 14. Life underwater, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, NetCDF, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, Trace elements, Science & Technology, Information retrieval, ACL, Geology, computer.file_format, Ocean Data View, Metadata, Data processing, GEOTRACES, 0403 Geology, Data extraction, 13. Climate action, Data quality, Physical Sciences, [SDE]Environmental Sciences, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, 0406 Physical Geography and Environmental Geoscience, computer, Processament de dades, Trace elements Isotopes
Abstract

The GEOTRACES Intermediate Data Product 2017 (IDP2017) is the second publicly available data product of the international GEOTRACES programme, and contains data measured and quality controlled before the end of 2016. The IDP2017 includes data from the Atlantic, Pacific, Arctic, Southern and Indian oceans, with about twice the data volume of the previous IDP2014. For the first time, the IDP2017 contains data for a large suite of biogeochemical parameters as well as aerosol and rain data characterising atmospheric trace element and isotope (TEI) sources. The TEI data in the IDP2017 are quality controlled by careful assessment of intercalibration results and multi-laboratory data comparisons at crossover stations. The IDP2017 consists of two parts: (1) a compilation of digital data for more than 450 TEIs as well as standard hydrographic parameters, and (2) the eGEOTRACES Electronic Atlas providing an on-line atlas that includes more than 590 section plots and 130 animated 3D scenes. The digital data are provided in several formats, including ASCII, Excel spreadsheet, netCDF, and Ocean Data View collection. Users can download the full data packages or make their own custom selections with a new on-line data extraction service. In addition to the actual data values, the IDP2017 also contains data quality flags and 1-σ data error values where available. Quality flags and error values are useful for data filtering and for statistical analysis. Metadata about data originators, analytical methods and original publications related to the data are linked in an easily accessible way. The eGEOTRACES Electronic Atlas is the visual representation of the IDP2017 as section plots and rotating 3D scenes. The basin-wide 3D scenes combine data from many cruises and provide quick overviews of large-scale tracer distributions. These 3D scenes provide geographical and bathymetric context that is crucial for the interpretation and assessment of tracer plumes near ocean margins or along ridges. The IDP2017 is the result of a truly international effort involving 326 researchers from 25 countries. This publication provides the critical reference for unpublished data, as well as for studies that make use of a large cross-section of data from the IDP2017. This article is part of a special issue entitled: Conway GEOTRACES - edited by Tim M. Conway, Tristan Horner, Yves Plancherel, and Aridane G. González., National Science Foundation (U.S.) (Grant OCE-0608600), National Science Foundation (U.S.) (Grant OCE0938349), National Science Foundation (U.S.) (Grant OCE-1243377), National Science Foundation (U.S.) (Grant OCE-1546580)

Published
2018
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39. Radium isotopes as tracers of hydrothermal inputs and neutrally buoyant plume dynamics in the deep ocean

Author

Willard S. Moore, Jean-Louis Reyss, Pieter van Beek, Matthew A. Charette, Virginie Sanial, Paul B. Henderson, Lauren Kipp, Douglas E. Hammond, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Océan et Interfaces (OCEANIS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'études en Géophysique et océanographie spatiales ( LEGOS ), Université Paul Sabatier - Toulouse 3 ( UPS ) -Centre National d'Etudes Spatiales ( CNES ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire Midi-Pyrénées ( OMP ) -Centre National de la Recherche Scientifique ( CNRS ), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] ( LSCE ), Université de Versailles Saint-Quentin-en-Yvelines ( UVSQ ) -Commissariat à l'énergie atomique et aux énergies alternatives ( CEA ) -Université Paris-Saclay-Centre National de la Recherche Scientifique ( CNRS ), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National d'Études Spatiales [Toulouse] (CNES)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), and Université Paris-Saclay-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[ SDU.OCEAN ] Sciences of the Universe [physics]/Ocean, Atmosphere, [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere, 010504 meteorology & atmospheric sciences, Isotope, Geotraces, Trace element, Mineralogy, General Chemistry, Mid-Atlantic Ridge, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Deep sea, Hydrothermal circulation, Plume, 13. Climate action, [ SDU.ENVI ] Sciences of the Universe [physics]/Continental interfaces, environment, Environmental Chemistry, 14. Life underwater, [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces, environment, Scavenging, Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, Water Science and Technology
Abstract

Radium (Ra) isotopes are enriched in hydrothermal fluids, have a wide range of half-lives and are minimally impacted by scavenging removal processes; therefore, they have the ability to provide key information on the fate of trace elements in both near- and far- field hydrothermal plumes. To expand our understanding of Ra isotopes and their usefulness as tracers of hydrothermal activity, we measured Ra isotopes in both high and low temperature vent fluids, and in neutrally buoyant plumes. The time scales of plume transport were derived from Ra isotopes in neutrally buoyant plumes emanating from 15°S on the East Pacific Rise (EPR) and the TAG vent field on the Mid Atlantic Ridge (MAR) relative to their source ratio in high-temperature vent fluids. In near-field ( 223 Ra: t 1/2 = 11.4 d, 224 Ra: t 1/2 = 3.66 d) suggest plume ages of ~ 1 month and ~ 5 d over the EPR and MAR, respectively. Farther afield (> 100 km from vent), the distribution of the longer-lived 228 Ra (t 1/2 = 5.75 y) is indicative of hydrothermal plumes with different points of origin along the EPR. Radium-228 derived plume ages were used to calculate the residence time of hydrothermal dissolved Fe, which was in the range of 9–20 y (with an upper limit of 50 y depending on model assumptions). These are shorter than typical deep ocean Fe residence times, a result of scavenging removal of Fe from the neutrally buoyant plume during transport. This study highlights the utility of Ra isotopes in providing time-scales of hydrothermally derived trace element cycling in the deep ocean.

Published
2018
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40. Radium-228 as a tracer of dissolved trace element inputs from the Peruvian continental margin

Author

Paul B. Henderson, Matthew A. Charette, Willard S. Moore, Virginie Sanial, Peter N. Sedwick, Nicholas J. Hawco, P. van Beek, Douglas E. Hammond, Mak A. Saito, Lauren Kipp, Joseph A. Resing, Jean-Louis Reyss, Department of Marine Chemistry and Geochemistry (WHOI), Woods Hole Oceanographic Institution (WHOI), Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette] (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Océan et Interfaces (OCEANIS), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), and Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)

Subjects
010504 meteorology & atmospheric sciences, Geotraces, [SDE.MCG]Environmental Sciences/Global Changes, Radium isotopes, Sediment inputs, 010502 geochemistry & geophysics, Oceanography, 01 natural sciences, Water column, Continental margin, Environmental Chemistry, 14. Life underwater, 0105 earth and related environmental sciences, Water Science and Technology, geography, Trace elements, geography.geographical_feature_category, Continental shelf, [SDE.IE]Environmental Sciences/Environmental Engineering, Trace element, Sediment, General Chemistry, [SHS.GEO]Humanities and Social Sciences/Geography, [SDE.ES]Environmental Sciences/Environmental and Society, GEOTRACES, 13. Climate action, Seawater, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, Surface water, Geology
Abstract

International audience; Continental margins play a central role in the composition of seawater by being an important source of trace element essentials to the functioning of the ocean ecosystems. Here, we measured long-lived radium isotopes (Ra-226, Ra-228) along a zonal transect at 12 degrees S (US GEOTRACES GP16) in the eastern tropical South Pacific Ocean. We used Ra-228 to quantify the trace element and isotope (TEI) fluxes (DMn, DFe, and DCo) delivered from the Peruvian continental i) shelf and ii) slope. First, elevated Ra-228 activities were measured in surface water over the entire transect (similar to 8500 km), evidence that the continental shelf is an important source of sediment-derived TEIs not only to coastal areas, but to central Pacific Ocean waters. Modeled Ra-228 shelf fluxes combined with water column dissolved TEI/Ra-228 ratios were used to quantify the shelf-ocean input rates (normalized to shelf-area) for DMn (3.3 x 10(3) mu mol m(-2) y(-1)), DFe (1.5 x 10(3) mu mol m(-2) y(-1)), and DCo (1.0 x 10(2) mu mol m(-2) y(-1)). Second, co-occurring plumes of Ra-228, DFe, and DMn extended over 1800 km from the margin at 1000-2500 m depth, indicative of a continental slope sediment TEI input to the intermediate water column. The Ra-228 gradient allowed us to derive an effective horizontal eddy diffusion coefficient (K-h) of 46 m(2) s(-1), which in turn permitted the calculation of slope sediment DMn (6.4 mu mol m(-2) y(-1)) and DFe (5.9 x 10(2) mu mol m(-2) y(-1)) fluxes based on their offshore concentration gradients. On the scale of the South Pacific continental margin between 0-20 degrees S, the DMn shelf flux is approximately 2-3 orders of magnitude higher than the slope flux, while the DFe shelf/slope flux is similar to 3:1. Both shelf and slope sediment derived DMn was transported over a significant distance towards the ocean interior, while DFe concentration gradients were steep, consistent with longer water column residence time for DMn as compared to DFe in marine systems. These findings highlight the importance of considering the continental slope-ocean boundary in the oceanic budgets of biologically-important trace elements.

Published
2018
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41. Mercury flux from salt marsh sediments: Insights from a comparison between

Author

Xiangming, Shi, Robert P, Mason, Matthew A, Charette, Nashaat M, Mazrui, and Pinghe, Cai

Subjects
Article
Abstract

In aquatic environments, sediments are the main location of mercury methylation. Thus, accurate quantification of methylmercury (MeHg) fluxes at the sediment-water interface is vital to understanding the biogeochemical cycling of mercury, especially the toxic MeHg species, and their bioaccumulation. Traditional approaches, such as core incubations, are difficult to maintain at in-situ conditions during assays, leading to over/underestimation of benthic fluxes. Alternatively, the 224Ra/228Th disequilibrium method for tracing the transfer of dissolved substances across the sediment-water interface, has proven to be a reliable approach for quantifying benthic fluxes. In this study, the 224Ra/228Th disequilibrium and core incubation methods were compared to examine the benthic fluxes of both 224Ra and MeHg in salt marsh sediments of Barn Island, Connecticut, USA from May to August, 2016. The two methods were comparable for 224Ra but contradictory for MeHg. The radiotracer approach indicated that sediments were always the dominant source of both total mercury (THg) and MeHg. The core incubation method for MeHg produced similar results in May and August, but an opposite pattern in June and July, which suggested sediments were a sink of MeHg, contrary to the evidence of significant MeHg gradients between overlying water and porewater at the sediment-water interface. The potential reasons for such differences are discussed. Overall, we conclude that the 224Ra/228Th disequilibrium approach is preferred for estimating the benthic flux of MeHg and that sediment is indeed an important MeHg source in this marshland, and likely in other shallow coastal waters.

Published
2018

42. Increased fluxes of shelf-derived materials to the central Arctic Ocean

Author

Lauren Kipp, Paul B. Henderson, Ignatius Rigor, Matthew A. Charette, and Willard S. Moore

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, Climate change, Permafrost, 01 natural sciences, Carbon cycle, Dissolved organic carbon, 14. Life underwater, Research Articles, 0105 earth and related environmental sciences, geography, Multidisciplinary, geography.geographical_feature_category, Continental shelf, 010604 marine biology & hydrobiology, Ocean chemistry, fungi, SciAdv r-articles, Chemical oceanography, Geochemistry, Oceanography, Arctic, 13. Climate action, Environmental science, geographic locations, Research Article
Abstract

Shelf inputs in the Arctic Ocean appear to be increasing, which could change the nutrient balance of the central basin., Rising temperatures in the Arctic Ocean region are responsible for changes such as reduced ice cover, permafrost thawing, and increased river discharge, which, together, alter nutrient and carbon cycles over the vast Arctic continental shelf. We show that the concentration of radium-228, sourced to seawater through sediment-water exchange processes, has increased substantially in surface waters of the central Arctic Ocean over the past decade. A mass balance model for 228Ra suggests that this increase is due to an intensification of shelf-derived material inputs to the central basin, a source that would also carry elevated concentrations of dissolved organic carbon and nutrients. Therefore, we suggest that significant changes in the nutrient, carbon, and trace metal balances of the Arctic Ocean are underway, with the potential to affect biological productivity and species assemblages in Arctic surface waters.

Published
2018
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43. Radium Isotopes Across the Arctic Ocean Show Time Scales of Water Mass Ventilation and Increasing Shelf Inputs

Author

Michael Karcher, William M. Smethie, Dorothea Bauch, Matthew A. Charette, A. N. Charkin, Lauren Kipp, Michiel M Rutgers van der Loeff, Thomas Krumpen, Ingrid Stimac, Núria Casacuberta, Robert Rember, Ole Valk, Erin E. Black, and Willard S. Moore

Subjects
Water mass, 010504 meteorology & atmospheric sciences, Mixed layer, Geotraces, Flux, Sediment, Particulates, 010502 geochemistry & geophysics, Oceanography, Atmospheric sciences, 01 natural sciences, Geophysics, Arctic, 13. Climate action, Space and Planetary Science, Geochemistry and Petrology, radium‐228, thorium‐228, Arctic Ocean, transpolar drift, GEOTRACES, Earth and Planetary Sciences (miscellaneous), Environmental science, 14. Life underwater, Scavenging, 0105 earth and related environmental sciences
Abstract

The first full transarctic section of 228Ra in surface waters measured during GEOTRACES cruises PS94 and HLY1502 (2015) shows a consistent distribution with maximum activities in the transpolar drift. Activities in the central Arctic have increased from 2007 through 2011 to 2015. The increased 228Ra input is attributed to stronger wave action on shelves resulting from a longer ice‐free season. A concomitant decrease in the 228Th/228Ra ratio likely results from more rapid transit of surface waters depleted in 228Th by scavenging over the shelf. The 228Ra activities observed in intermediate waters (

Published
2018

44. Determination of particulate and dissolved 228Th in seawater using a delayed coincidence counter

Author

Paul B. Henderson, Willard S. Moore, Lauren Kipp, Kuanbo Zhou, Matthew A. Charette, Ken O. Buesseler, Kanchan Maiti, and Paul J. Morris

Subjects
Radium, Chemistry, Environmental chemistry, Radiochemistry, Environmental Chemistry, chemistry.chemical_element, Seawater, General Chemistry, Particulates, Oceanography, Particle flux, Water Science and Technology
Abstract

article i nfo The application of thorium-228 towardsunderstandingparticle dynamics intheopen ocean islimitedbecauseof its low natural abundanceinseawaterand associated sampling and analytical challenges.Here we describea fast and nondestructivemethod for measuringboth dissolved and particulate 228 Thactivities inthe openocean using Radium Delayed-Coincidence Counters (RaDeCC). Particulate and dissolved samples were collected from the

Published
2015
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45. Hydrothermal vents: A previously unrecognized source of actinium-227 to the deep ocean

Author

Lauren Kipp, Douglas E. Hammond, Willard S. Moore, and Matthew A. Charette

Subjects
Geotraces, Geochemistry, Flux, General Chemistry, Mid-Atlantic Ridge, Oceanography, Deep sea, Hydrothermal circulation, Plume, Abyssal zone, Environmental Chemistry, Geology, Water Science and Technology, Hydrothermal vent
Abstract

Actinium-227 (t 1/2 = 21.77 y) is produced by decay of protactinium-231 (t 1/2 = 32,760 y). Abyssal sediments are enriched in 231 Pa and thus provide a source of the more soluble 227 Ac to the deep-sea, where it can be used as a tracer of deep ocean diapycnal mixing. In this study, we examine the distribution of dissolved and particulate 227 Ac within a neutrally buoyant hydrothermal plume overlying the TAG vent field (26.14°N, 44.83°W, Mid-Atlantic Ridge) collected during the U.S. GEOTRACES North Atlantic Transect (2011). Elevated activities of both particulate and dissolved 227 Ac within the plume indicate that hydrothermal vents may be a previously unrecognized source of this isotope to the marine environment. We contend that vent fluids are the main source of the 227 Ac enrichment. Based on the activities of dissolved and particulate 227 Ac within the plume, a 3 He dilution model was used to derive a hydrothermal 227 Ac end-member activity of 1.5 × 10 4 –2.5 × 10 4 dpm m − 3 . Assuming that TAG is characteristic of all vents along the Mid-Atlantic Ridge, the hydrothermal source of 227 Ac to the deep Atlantic is estimated to be 1.9–5.8% of the flux from Atlantic sediments. Although this hydrothermal flux may not have a large impact on the total oceanic inventory of 227 Ac, it must be considered when using this isotope as a tracer of deep ocean mixing in areas where hydrothermal activity is present.

Published
2015
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46. Radium isotope distributions during the US GEOTRACES North Atlantic cruises

Author

Matthew A. Charette, Paul B. Henderson, Paul J. Morris, and Willard S. Moore

Subjects
Geotraces, chemistry.chemical_element, Context (language use), General Chemistry, Oceanography, Submarine groundwater discharge, Radium, Continental margin, chemistry, Benthic boundary layer, Environmental Chemistry, Upwelling, Geology, Isotopes of thorium, Water Science and Technology
Abstract

Radium isotopes are produced in sediments via the decay of thorium isotopes and are generally soluble in seawater. As such, isotopes of the radium quartet (224Ra, 223Ra, 228Ra, 226Ra) have been used as tracers of ocean boundary inputs and mixing processes. We measured radium isotopes on the US GEOTRACES North Atlantic cruises in 2010 and 2011, which crossed a number of key ocean boundary features including the Mediterranean outflow, the Mauritanian upwelling and oxygen minimum zones (OMZ) along western Africa, a hydrothermal plume over the mid-Atlantic Ridge (MAR), and the broad continental margin of the north-eastern United States. Radium isotope features at these locations are discussed in the context of their potential to quantify fluxes of trace elements and isotopes (TEIs) from common sources. Notable observations include: (1) a Mediterranean outflow spreading rate of 0.52–0.60 cm/s derived from 228Ra, (2) evidence of substantial sediment–water interaction in the benthic boundary layer along the OMZ, (3) decoupling between 223Ra and the other Ra isotope sources over the MAR, and (4) significant continental inputs (e.g. submarine groundwater discharge—SGD) in the western Atlantic. Lastly, 228Ra inventories have remained constant over the past 30 years, which suggests that SGD is steady-state for the North Atlantic on decadal time scales.

Published
2015
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47. Oxygen metabolism and pH in coastal ecosystems: Eddy Covariance Hydrogen ion and Oxygen Exchange System (ECHOES)

Author

William R. Martin, Daniel C. McCorkle, Matthew H. Long, and Matthew A. Charette

Subjects
Flux (metallurgy), Water column, Chemistry, Benthic zone, Environmental chemistry, Dissolved organic carbon, Eddy covariance, Alkalinity, Ocean Engineering, Ocean acidification, Carbon cycle
Abstract

An aquatic eddy covariance (EC) system was developed to measure the exchange of oxygen (O2) and hydrogen ions (H+) across the sediment-water interface. The system uses O2 optodes and a newly developed micro-flow cell H+ ion selective field effect transistor; these sensors displayed sufficient precision and rapid enough response times to measure concentration changes associated with turbulent exchange. Discrete samples of total alkalinity and dissolved inorganic carbon were used to determine the background carbonate chemistry of the water column and relate the O2 and H+ fluxes to benthic processes. The ECHOES system was deployed in a eutrophic estuary (Waquoit Bay), and revealed that the benthos was a sink for acidity during the day and a source of acidity during the night, with H+ and O2 fluxes of ± 0.0001 and ± 10 mmol m−2 h−1, respectively. H+ and O2 fluxes were also determined using benthic flux chambers, for comparison with the EC rates. Chamber fluxes determined in 0.25 h intervals co-varied with EC fluxes but were ∼ 4 times lower in magnitude. This difference was likely due to suppressed pore-water advection in the chambers and changes in the chemistry of the enclosed chamber overlying water. The individual H+ and O2 fluxes were highly correlated in each dataset (EC and chambers), and both methods yielded H+ fluxes that could not be explained by O2 metabolism alone. The ECHOES system provides a new tool for determining the influence of benthic biogeochemical cycling on coastal ocean acidification and carbon cycling.

Published
2015
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49. The 226Ra-Ba relationship in the North Atlantic during GEOTRACES-GA01

Author

Emilie Le Roy, Virginie Sanial, Matthew A. Charette, Pieter van Beek, François Lacan, Stéphanie H. M. Jacquet, Paul B. Henderson, Marc Souhaut, Maribel I. García-Ibáñez, Catherine Jeandel, Fiz F. Pérez, and Géraldine Sarthou

Subjects
0106 biological sciences, 010504 meteorology & atmospheric sciences, 13. Climate action, 010604 marine biology & hydrobiology, 14. Life underwater, 01 natural sciences, 0105 earth and related environmental sciences
Abstract

We report detailed sections of radium-226 (226Ra, T1/2 = 1602 y) activities and barium (Ba) concentrations determined in the North Atlantic (Portugal-Greenland-Canada) in the framework of the international GEOTRACES program (GA01 section – GEOVIDE project, May–July 2014). Dissolved 226Ra and Ba are strongly correlated along the GA01 section, a pattern that reflects their similar chemical behavior. Since 226Ra and Ba have been widely used as tracers of water masses and ocean mixing, we investigated more thoroughly their behavior in this crucial region for thermohaline circulation taking advantage of the contrasting biogeochemical patterns existing along the GA01 section. We used an Optimum Multiparameter (OMP) analysis to distinguish the relative importance of physical transport (water mass mixing) from non-conservative processes (sedimentary, river, or hydrothermal inputs; uptake by particles, and dissolved-particulate dynamics) on the 226Ra and Ba distributions in the North Atlantic. Results show that 72 % of the 226Ra and 68 % of the Ba can be explained by conservative mixing along the section and therefore, they can be considered as conservative tracers of water mass transport in the ocean interior. However, regions where 226Ra and Ba displayed non-conservative behavior were also identified, mostly at the ocean boundaries (seafloor, continental margins, and surface waters). Elevated 226Ra and Ba concentrations found in deep waters of the West European Basin reflect that lower North East Atlantic Deep Water (NEADWl) accumulates excess 226Ra and Ba from sediment diffusion during transport. In the upper 1500 m, deficiencies in 226Ra and Ba are likely explained by their incorporation in planktonic siliceous shells, or in barite (BaSO4) (Bishop, 1988). Finally, since Ba and 226Ra display different source terms (mostly deep-sea sediments for 226Ra and rivers for Ba), strong decoupling between 226Ra and Ba were observed at the land-ocean boundaries. This is especially true in the shallow stations near the coasts of Greenland and Newfoundland where high 226Ra / Ba ratios at depth reflect the diffusion of 226Ra from sediment and low 226Ra / Ba ratios in the upper water column reflect the input of Ba associated with meteoric waters.

Published
2017
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50. Lingering radioactivity at the Bikini and Enewetak Atolls

Author

Steven M. Pike, Ken O. Buesseler, Matthew A. Charette, Paul B. Henderson, and Lauren Kipp

Subjects
Radionuclide, Environmental Engineering, Brackish water, chemistry.chemical_element, 010501 environmental sciences, 010403 inorganic & nuclear chemistry, 01 natural sciences, Pollution, Submarine groundwater discharge, 0104 chemical sciences, Radium, Oceanography, chemistry, Radioactive contamination, Environmental Chemistry, Seawater, Waste Management and Disposal, Surface water, Groundwater, Geology, 0105 earth and related environmental sciences
Abstract

We made an assessment of the levels of radionuclides in the ocean waters, seafloor and groundwater at Bikini and Enewetak Atolls where the US conducted nuclear weapons tests in the 1940's and 50's. This included the first estimates of submarine groundwater discharge (SGD) derived from radium isotopes that can be used here to calculate radionuclide fluxes in to the lagoon waters. While there is significant variability between sites and sample types, levels of plutonium (239,240Pu) remain several orders of magnitude higher in lagoon seawater and sediments than what is found in rest of the world's oceans. In contrast, levels of cesium-137 (137Cs) while relatively elevated in brackish groundwater are only slightly higher in the lagoon water relative to North Pacific surface waters. Of special interest was the Runit dome, a nuclear waste repository created in the 1970's within the Enewetak Atoll. Low seawater ratios of 240Pu/239Pu suggest that this area is the source of about half of the Pu in the Enewetak lagoon water column, yet radium isotopes suggest that SGD from below the dome is not a significant Pu source. SGD fluxes of Pu and Cs at Bikini were also relatively low. Thus radioactivity associated with seafloor sediments remains the largest source and long term repository for radioactive contamination. Overall, Bikini and Enewetak Atolls are an ongoing source of Pu and Cs to the North Pacific, but at annual rates that are orders of magnitude smaller than delivered via close-in fallout to the same area.

Published
2017

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