21 results on '"Hathorne, Edmund"'
Search Results
2. Heavy metal uptake of nearshore benthic foraminifera during multi-metal culturing experiments
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Schmidt, Sarina, Hathorne, Edmund Charles, Schönfeld, Joachim, Garbe-Schönberg, Dieter, Schmidt, Sarina, Hathorne, Edmund Charles, Schönfeld, Joachim, and Garbe-Schönberg, Dieter
- Abstract
Heavy metal pollution originating from anthropogenic sources, e.g., mining, industry and extensive land use, is increasing in many parts of the world and influences coastal marine environments for a long time. The elevated input of heavy metals into the marine system potentially affects the biota because of their toxicity, persistence and bioaccumulation. An emerging tool for environmental applications is the heavy metal incorporation into foraminiferal tests calcite, which facilitates monitoring of anthropogenic footprints on recent and past environmental systems. The aim of this study is to investigate whether the incorporation of heavy metals in foraminifera is a direct function of their concentration in seawater. Culturing experiments with a mixture of dissolved chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), cadmium (Cd), tin (Sn), mercury (Hg) and lead (Pb) in artificial seawater were carried out over a wide concentration range to assess the uptake of heavy metals by the near-shore foraminiferal species Ammonia aomoriensis, Ammonia batava and Elphidium excavatum. Seawater analysis exhibited the increasing metal concentrations between culturing phases and revealed high metal concentrations in the beginning of the culturing phases due to the punctual metal addition. Furthermore, a loss of metals during the culturing process was discovered, which lead to a deviation between the expected and the actual concentrations of the metals in seawater. Laser ablation ICP-MS analysis of the newly formed calcite revealed species-specific differences in the incorporation of heavy metals. The foraminiferal calcite of all three species reveals a strong positive correlation with Pb and Ag concentrations in the culturing medium. Ammonia aomoriensis further showed a correlation with Mn and Cu, A. batava with Mn and Hg and E. excavatum with Cr and Ni, and partially also with Hg. Zn, Sn and Cd showed no clear trend for the species studied, which may
- Published
- 2022
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3. Heavy metal uptake of near-shore benthic foraminifera during multi-metal culturing experiments
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Schmidt, Sarina, Hathorne, Edmund Charles, Schönfeld, Joachim, Garbe-Schönberg, Dieter, Schmidt, Sarina, Hathorne, Edmund Charles, Schönfeld, Joachim, and Garbe-Schönberg, Dieter
- Abstract
Heavy metal pollution originating from anthropogenic sources, e.g., mining, industry and extensive land use, is increasing in many parts of the world and influences coastal marine environments for a long time. The elevated input of heavy metals into the marine system potentially affects the biota because of their toxicity, persistence and bioaccumulation. An emerging tool for environmental applications is the heavy metal incorporation into foraminiferal tests calcite, which facilitates monitoring of anthropogenic footprints on recent and past environmental systems. The aim of this study is to investigate whether the incorporation of heavy metals in foraminifera is a direct function of their concentration in seawater. Culturing experiments with a mixture of dissolved chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), silver (Ag), cadmium (Cd), tin (Sn), mercury (Hg) and lead (Pb) in artificial seawater were carried out over a wide concentration range to assess the uptake of heavy metals by the near-shore foraminiferal species Ammonia aomoriensis, Ammonia batava and Elphidium excavatum. Seawater analysis exhibited the increasing metal concentrations between culturing phases and revealed high metal concentrations in the beginning of the culturing phases due to the punctual metal addition. Furthermore, a loss of metals during the culturing process was discovered, which lead to a deviation between the expected and the actual concentrations of the metals in seawater. Laser ablation ICP-MS analysis of the newly formed calcite revealed species-specific differences in the incorporation of heavy metals. The foraminiferal calcite of all three species reveals a strong positive correlation with Pb and Ag concentrations in the culturing medium. Ammonia aomoriensis further showed a correlation with Mn and Cu, A. batava with Mn and Hg and E. excavatum with Cr and Ni, and partially also with Hg. Zn, Sn and Cd showed no clear trend for the species studied, which may
- Published
- 2021
4. Applicability and reliability of Na/Ca as a direct paleo-salinity proxy in various planktonic foraminifers
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Bertlich, Jacqueline, Nürnberg, Dirk, Hathorne, Edmund C., Siccha, M., Groeneveld, Jeroen, Meilland, J., and Kucera, M.
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- 2019
5. Limited influence of basalt weathering inputs on the seawater neodymium isotope composition of the northern Iceland Basin
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Morrison, Rachel, Waldner, A., Hathorne, Edmund C., Rahlf, Peer, Zieringer, Moritz, Montagna, P., Colin, C., Frank, N., Frank, Martin, Morrison, Rachel, Waldner, A., Hathorne, Edmund C., Rahlf, Peer, Zieringer, Moritz, Montagna, P., Colin, C., Frank, N., and Frank, Martin
- Abstract
Highlights • Icelandic input of radiogenic Nd essentially limited to coastal waters • Offshore bottom water Nd isotope signatures consistent with conservative mixing of intermediate and deep water masses • Decreased bottom water Nd concentrations likely reflect removal by particle scavenging Radiogenic neodymium (Nd) isotopes have been widely used as a proxy for tracing present and past water masses and ocean circulation, yet relatively few data exist for seawater from the important deep water formation area around Iceland. We have analyzed the dissolved seawater Nd isotope compositions (expressed as ƐNd) of 71 seawater samples, as well as Nd concentrations [Nd] of 38 seawater samples, collected at full water column profiles from 18 stations in the shelf area off the southern coast of Iceland. The goal of this work was to determine to what extent weathering inputs from Icelandic basalts, which are characterized by a distinctly radiogenic ƐNd signature within the North Atlantic, contribute to the Nd isotope and concentration signatures of water masses in the northern Iceland Basin. Radiogenic ƐNd values of up to −3.5 and elevated concentrations of up to 21 pmol/kg compared to nearby open ocean sites were found in surface waters at shallow sites closest to shore and to river mouths of Iceland. This documents partial dissolution of highly radiogenic basaltic particles, which are transported northwards by the coastal currents. A comparable signal is not observed, however, in offshore surface waters likely as a result of the advection of surface currents mainly directed onshore, thus isolating these sites from Icelandic weathering contributions. The dominance of Subpolar Mode Waters and Intermediate Water unaffected by Icelandic contributions in the offshore study area is supported by unradiogenic ƐNd signatures between −15 and −12. In agreement with hydrographic data, highly radiogenic bottom waters at one site on the Iceland-Faroe Ridge (ƐNd = −7.5) reveal the presence
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- 2019
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6. Inconsistencies between Fram Strait water mass budget assessments based on radiogenic neodymium isotopes and nutrients.
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Laukert, Georgi, Bauch, Dorothea, Frank, Martin, Hathorne, Edmund C., Dreyer, J., Meulenbroek, Kirsten, Schaffer, J., Rabe, J., Paffrath, R., Pahnke, K., Rutgers van der Loeff, M., Meyer, H., Graeve, M., Laukert, Georgi, Bauch, Dorothea, Frank, Martin, Hathorne, Edmund C., Dreyer, J., Meulenbroek, Kirsten, Schaffer, J., Rabe, J., Paffrath, R., Pahnke, K., Rutgers van der Loeff, M., Meyer, H., and Graeve, M.
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- 2019
7. Pathways of Siberian freshwater and sea ice in the Arctic Ocean traced with radiogenic neodymium isotopes and rare earth elements
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Laukert, Georgi, Frank, Martin, Hathorne, Edmund C., Krumpen, Thomas, Rabe, Benjamin, Bauch, Dorothea, Werner, Kirstin, Peeken, Ilka, Kassens, Heidemarie, Laukert, Georgi, Frank, Martin, Hathorne, Edmund C., Krumpen, Thomas, Rabe, Benjamin, Bauch, Dorothea, Werner, Kirstin, Peeken, Ilka, and Kassens, Heidemarie
- Published
- 2017
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8. Are barium isotopic signals in planktic foraminifera a proxy for palaeosalinity?
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Meulenbroek, Kirsten, Siebert, Christopher, Hathorne, Edmund C., Frank, Martin, Meulenbroek, Kirsten, Siebert, Christopher, Hathorne, Edmund C., and Frank, Martin
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- 2017
9. Stable Barium isotope geochemistry of large river estuaries
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Cao, Zhimian, Hathorne, Edmund C., Siebert, Christopher, Dai, M., Zhai, W., Kuhnert, H., Frank, Martin, Cao, Zhimian, Hathorne, Edmund C., Siebert, Christopher, Dai, M., Zhai, W., Kuhnert, H., and Frank, Martin
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- 2017
10. Trace Metal Chemistry in the Water Column of the Angola Basin - A Contribution to the International GEOTRACES Program - Cruise No. M121, November 22, – December 27, 2015, Walvis Bay (Namibia) – Walvis Bay (Namibia)
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Frank, Martin, Achterberg, Eric, Bristow, Laura, Browning, Thomas, Deng, Feifei, Handmann, Patricia, Hathorne, Edmund Charles, Hopwood, Mark, Lodeiro, Pablo Fernandez, Menzel-Barraqueta, Jan-Lukas, Merschel, Gila, Meyer, Steffi, Pampin Baro, Joaquin, Rahlf, Peer, Rath, Willi, Schlosser, Christian, Stippkugel, Angela, Vieira, Lucia Helena, Zitoun, Rebecca, and Raeke, Andreas
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13. Climate action ,Earth sciences and geology ,Earth Science ,14. Life underwater - Abstract
METEOR Cruise M121 was dedicated to the investigation of the distribution of dissolved and particulate trace metals and their isotopic compositions (TEIs) in the full water column of the Angola Basin and the northernmost Cape Basin. A key aim was to determine the driving factors for the observed distributions, which includes the main external inputs, as well as internal cycling and ocean circulation. The research program of the cruise is official part of the international GEOTRACES program (www.geotraces.org) and cruise M121 corresponds to GEOTRACES cruise GA11. Subject of the cruise was the trace metal clean and contamination-free sampling of waters and particulates for subsequent analyses of the TEIs in the home laboratories of the national and international participants. Besides a standard rosette for the less contaminant prone metals, trace metal clean sampling was realized by using for the first time a new dedicated, coated trace metal clean rosette equipped with Teflon-coated GO-FLO bottles operated via a plastic coated cable from a mobile winch of GEOMAR Kiel. The particulate samples were collected under trace metal clean conditions using established in-situ pump systems operated from METEOR's Aramid line. The cruise track led from Walvis Bay northwards along the West African margin until 3��S, then turned west until the Zero Meridian, which was followed southwards until 30��S. Then the cruise track turned east again until the Namibian margin was reached and then completed the near shore track northwards until Walvis Bay. The track crossed areas of major external inputs including dust from the Namib Desert and exchange with the west African continental margin and with the oxygen depleted shelf sediments of the Benguela upwelling, as well as with the plume of the Congo outflow, that was followed from its mouth northwards. Our investigations of internal cycling included the extremely high productivity associated with the Benguela Upwelling and the elevated productivity of the Congo plume contrasting with the extremely oligotrophic waters of the southeastern Atlantic Gyre. The links between TEI biogeochemistry and the nitrogen cycle forms an important aspect of our study. The major water masses contributing the Atlantic Meridional Overturning Circulation were sampled in order to investigate if particular TEI signatures are suitable as water mass tracers, in particular near the ocean margin and in the restricted deep Angola Basin. A total of 51 full water column stations were sampled for the different dissolved TEIs, which were in most cases accompanied by sampling for particulates and radium isotopes using the in-situ pumps. In addition, surface waters were continuously sampled under trace metal clean conditions using a towed fish and aerosol and rain samples were continuously collected., METEOR-Berichte
- Published
- 2016
11. International Ocean Discovery Program Expedition 353 preliminary report: Indian Monsoon Rainfall, 29 November 2014 – 29 January 2015
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Clemens, Steven C., Kuhnt, Wolfgang, LeVay, Leah J., Anand, P., Ando, T., Bartol, M., Bolton, C. T., Ding, X., Gariboldi, K., Giosan, L., Hathorne, Edmund C., Huang, Y., Jaiswal, P., Kim, Sunghan, Kirkpatrick, J. B., Littler, K., Marino, G., Martinez, P., Naik, D., Peketi, A., Phillips, S. C., Robinson, M. M., Romero, O. E., Sagar, N., Taladay, K. B., Taylor, S. N., Thirumalai, K., Uramoto, G., Usui, Y., Wang, J., Yamamoto, M., and Zhou, L.
- Abstract
International Ocean Discovery Program (IODP) Expedition 353 (29 November 2014–29 January 2015) drilled six sites in the Bay of Bengal, recovering 4280 m of sediments during 32.9 days of on-site drilling. Recovery averaged 97%, including coring with the advanced piston corer, half-length advanced piston corer, and extended core barrel systems. The primary objective of Expedition 353 is to reconstruct changes in Indian monsoon circulation since the Miocene at tectonic to centennial timescales. Analysis of the sediment sections recovered will improve our understanding of how monsoonal climates respond to changes in forcing external to the Earth’s climate system (i.e., insolation) and changes in forcing internal to the Earth’s climate system, including changes in continental ice volume, greenhouse gases, sea level, and the ocean-atmosphere exchange of energy and moisture. All of these mechanisms play critical roles in current and future climate change in monsoonal regions. The primary signal targeted is the exceptionally low salinity surface waters that result, in roughly equal measure, from both direct summer monsoon precipitation to the Bay of Bengal and runoff from the numerous large river basins that drain into the Bay of Bengal. Changes in rainfall and surface ocean salinity are captured and preserved in a number of chemical, physical, isotopic, and biological components of sediments deposited in the Bay of Bengal. Expedition 353 sites are strategically located in key regions where these signals are the strongest and best preserved. Salinity changes at IODP Sites U1445 and U1446 (northeast Indian margin) result from direct precipitation as well as runoff from the Ganges-Brahmaputra river complex and the many river basins of peninsular India. Salinity changes at IODP Sites U1447 and U1448 (Andaman Sea) result from direct precipitation and runoff from the Irrawaddy and Salween river basins. IODP Site U1443 (Ninetyeast Ridge) is an open-ocean site with a modern surface water salinity very near the global mean but is documented to have recorded changes in monsoonal circulation over orbital to tectonic timescales. This site serves as an anchor for establishing the extent to which the north to south (19°N to 5°N) salinity gradient changes over time.
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- 2015
12. South Asian summer monsoon variability during the last ∼54 kyrs inferred from surface water salinity and river runoff proxies
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Gebregiorgis, Daniel, Hathorne, Edmund C., Sijinkumar, A. V., Nath, B. Nagender, Nürnberg, Dirk, Frank, Martin, Gebregiorgis, Daniel, Hathorne, Edmund C., Sijinkumar, A. V., Nath, B. Nagender, Nürnberg, Dirk, and Frank, Martin
- Abstract
Highlights • Ba/Ca and δ18OSW records of Core SK 168 reveal distinct changes in SAM intensity. • SAM over the Irrawaddy strengthened beginning at ∼18 ka leading observed changes in the Arabian sea by ∼2–3 kyrs. • Peak monsoon strength during the mid-Holocene in the Andaman Sea consistent with model simulations. • Changes in upper ocean stratification indicate limited influence of NH insolation. Abstract The past variability of the South Asian Monsoon is mostly known from records of wind strength over the Arabian Sea while high-resolution paleorecords from regions of strong monsoon precipitation are still lacking. Here, we present records of past monsoon variability obtained from sediment core SK 168/GC-1, which was collected at the Alcock Seamount complex in the Andaman Sea. We utilize the ecological habitats of different planktic foraminiferal species to reconstruct freshwater-induced stratification based on paired Mg/Ca and δ18O analyses and to estimate seawater δ18O (δ18Osw). The difference between surface and thermocline temperatures (ΔT) and δ18Osw (Δδ18Osw) is used to investigate changes in upper ocean stratification. Additionally, Ba/Ca in G. sacculifer tests is used as a direct proxy for riverine runoff and sea surface salinity (SSS) changes related to monsoon precipitation on land. Our Δδ18Osw time series reveals that upper ocean salinity stratification did not change significantly throughout the last glacial suggesting little influence of NH insolation changes. The strongest increase in temperature gradients between the mixed layer and the thermocline is recorded for the mid-Holocene and indicate the presence of a significantly shallower thermocline. In line with previous work, the δ18Osw and Ba/Ca records demonstrate that monsoon climate during the LGM was characterized by a significantly weaker southwest monsoon circulation and strongly reduced runoff. Based on our data the South Asian Summer Monsoon (SAM) over the Irrawaddyy strengthened gradually after
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- 2016
13. Synchronicity of Kuroshio Current and climate system variability since the Last Glacial Maximum
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Zheng, Xufeng, Li, Anchun, Kao, ShuhJi, Gong, Xun, Frank, Martin, Kuhn, Gerhard, Cai, Wenju, Yan, Hong, Wan, Shiming, Zhang, Honghai, Jiang, Fuqing, Hathorne, Edmund, Chen, Zhong, Hu, Bangqi, Zheng, Xufeng, Li, Anchun, Kao, ShuhJi, Gong, Xun, Frank, Martin, Kuhn, Gerhard, Cai, Wenju, Yan, Hong, Wan, Shiming, Zhang, Honghai, Jiang, Fuqing, Hathorne, Edmund, Chen, Zhong, and Hu, Bangqi
- Abstract
The Kuroshio Current (KC) is the northward branch of the North Pacific subtropical gyre (NPG) and exerts influence on the exchange of physical, chemical, and biological properties of downstream regions in the Pacific Ocean. Resolving long-term changes in the flow of the KC water masses is, therefore, crucial for advancing our understanding of the Pacific's role in global ocean and climate variability. Here, we reconstruct changes in KC dynamics over the past 20 ka based on grain-size spectra, clay mineral, and Sr–Nd isotope constraints of sediments from the northern Okinawa Trough. Combined with published sediment records surrounding the NPG, we suggest that the KC remained in the Okinawa Trough throughout the Last Glacial Maximum. Together with Earth-System-Model simulations, our results additionally indicate that KC intensified considerably during the early Holocene (EH). The synchronous establishment of the KC “water barrier” and the modern circulation pattern during the EH highstand shaped the sediment transport patterns. This is ascribed to the precession-induced increase in the occurrence of La Niña-like state and the strength of the East Asian summer monsoon. The synchronicity of the shifts in the intensity of the KC, Kuroshio extension, and El Niño/La Niña-Southern Oscillation (ENSO) variability may further indicate that the western branch of the NPG has been subject to basin-scale changes in wind stress curl over the North Pacific in response to low-latitude insolation. Superimposed on this long-term trend are high-amplitude, large century, and millennial-scale variations during last 5 ka, which are ascribed to the advent of modern ENSO when the equatorial oceans experienced stronger insolation during the boreal winter.
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- 2016
14. Pleistocene Indian monsoon rainfall variability dominated by obliquity
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Gebregiorgis, Daniel, Hathorne, Edmund C., Giosan, L., Collett, T. S., Nürnberg, Dirk, Frank, Martin, Gebregiorgis, Daniel, Hathorne, Edmund C., Giosan, L., Collett, T. S., Nürnberg, Dirk, and Frank, Martin
- Published
- 2016
15. Water mass provenance and mixing in the Laptev Sea based on dissolved Nd isotopes and REE distributions
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Laukert, Georgi, Frank, Martin, Hathorne, Edmund C., Wegner, Carolyn, Bauch, Dorothea, Kassens, Heidemarie, Timokhov, L. A., Laukert, Georgi, Frank, Martin, Hathorne, Edmund C., Wegner, Carolyn, Bauch, Dorothea, Kassens, Heidemarie, and Timokhov, L. A.
- Published
- 2016
16. Water mass provenance and mixing at Fram Strait and in the Laptev Sea based on dissolved Nd isotopes and REE distributions
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Laukert, Georgi, Frank, Martin, Hathorne, Edmund C., Bauch, Dorothea, Wegner, Carolyn, Andersen, N., Zieringer, Moritz, Kassens, Heidemarie, Timokhov, L. A., Laukert, Georgi, Frank, Martin, Hathorne, Edmund C., Bauch, Dorothea, Wegner, Carolyn, Andersen, N., Zieringer, Moritz, Kassens, Heidemarie, and Timokhov, L. A.
- Published
- 2016
17. Rare earth element distribution in the Atlantic sector of the Southern Ocean: the balance between particle scavenging and vertical supply
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Hathorne, Edmund C., Stichel, Torben, Brück, Bastian, Frank, Martin, Hathorne, Edmund C., Stichel, Torben, Brück, Bastian, and Frank, Martin
- Abstract
Highlights: • Distinct rare earth element profiles across southern boundary of Antarctic Circumpolar Current • Low particle concentrations and strong vertical exchange cause homogenous vertical profiles • Pronounced deepwater Ce anomalies reflect isolation from new continental sources to seawater The concentrations of rare earth elements (REEs) in seawater display systematic variations related to weathering inputs, particle scavenging and water mass histories. Here we investigate the REE concentrations of water column profiles in the Atlantic sector of the Southern Ocean, a key region of the global circulation and primary production. The data reveal a pronounced contrast between the vertical profiles in the Antarctic Circumpolar Current (ACC) and those to the south of the ACC in the Weddell Gyre (WG). The ACC profiles exhibit the typical increase of REE concentrations with water depth and a change in the shape of the profiles from near linear for the light REEs to more convex for the heavy REEs. In contrast, the WG profiles exhibit high REE concentrations throughout the water column with only the near surface samples showing slightly reduced concentrations indicative of particle scavenging. Seawater normalised REE patterns reveal the strong remineralisation signal in the ACC with the light REEs preferentially removed in surface waters and the mirror image pattern of their preferential release in deep waters. In the WG the patterns are relatively homogenous reflecting the prevalence of well-mixed Lower Circumpolar Deep Water (LCDW) that follows shoaling isopycnals in the region. In the WG particle scavenging of REEs is comparatively small and limited to the summer months by light limitation and winter sea ice cover. Considering the surface water depletion compared to LCDW and that the surface waters of the WG are replaced every few years, the removal rate is estimated to be on the order of 1 nmol m- 3 yr- 1 for La and Nd. The negative cerium anomalies observed in dee
- Published
- 2015
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18. Rare Earth Element distribution in Caribbean seawater: continental inputs versus lateral transport of distinct REE compositions in subsurface water masses
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Osborne, Anne Helen, Haley, Brian A., Hathorne, Edmund C., Plancherel, Yves, Frank, Martin, Osborne, Anne Helen, Haley, Brian A., Hathorne, Edmund C., Plancherel, Yves, and Frank, Martin
- Abstract
Highlights: • Dominant supply of REEs to Caribbean surface waters originates from the Amazon and Orinoco rivers • Lateral advection controls subsurface REE compositions at intermediate depths, particularly evident for Dy/Er in AAIW • Preferential addition of LREE and MREE to Caribbean deep waters The rare earth element (REE) concentrations of full water column profiles from ten stations in the Caribbean, the Gulf of Mexico, and the Florida Straits, as well as of surface waters close to the mouth of the Orinoco River have been analyzed. The results show high concentration of REEs in surface waters, in particular close to the mouth of the Orinoco, and a middle-REE-enrichment that is strongest in the south and east of the study area suggesting that fluvial inputs are the main sources rather than REEs supplied by Saharan dust. The surface waters close to the Orinoco are heavy REE enriched compared to the potential fluvial sources, emphasizing the importance of processes in the estuaries and the surface ocean that preferentially remove light- and middle-REEs. Relatively small heavy-REE enrichments in near-bottom water samples at the mouth of the Orinoco may be the result of preferential release of light REEs from river-transported sediments. The REE patterns of distinct subsurface water masses are largely coherent across the Caribbean basin, suggesting that the lateral transport of preformed compositions is not significantly influenced by vertical processes of scavenging and release. In particular, low Dy/Er molar ratios are associated with Antarctic Intermediate Water and have most likely been advected into the Caribbean from the Southern Ocean. In contrast, deep waters in the Caribbean are enriched in light and middle REEs compared to incoming Upper North Atlantic Deep Water suggesting that release from sinking particles or from sediments is an important source of these REEs in the deep ocean, in particular when deep water residence times are long.
- Published
- 2015
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19. What can Nd isotopes and REEs tell us about the water mass distribution in the Eurasian Arctic Ocean?
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Laukert, Georgi, Frank, Martin, Hathorne, Edmund C., Bauch, Dorothea, Wegner, Carolyn, Kassens, Heidemarie, Laukert, Georgi, Frank, Martin, Hathorne, Edmund C., Bauch, Dorothea, Wegner, Carolyn, and Kassens, Heidemarie
- Published
- 2015
20. Report and preliminary rsults of RV SONNE cruise SO-228, Kaohsiung-Townsville, 04.05.2013-23.06.2013, EISPAC-WESTWIND-SIODP
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Mohtadi, Mahyar, Bergmann, Fenna, Blanquera, Ralph Vinzon C., Buleka, Joe, Carag, John Warner M., Carriérre-Garwood, Jessica, Dassié, Emilie Pauline, Fernando, Allan Gil S., Gernhardt, Fabian, Ghasemifard, Homa, Groeneveld, Jeroen, and Hathorne, Edmund Charles
- Published
- 2013
21. Variability in calcitic Mg/Ca and Sr/Ca ratios in clones of the benthic foraminifer Ammonia tepida
- Author
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de Nooijer, L. J., Hathorne, Edmund C., Reichart, G. J., Langer, G., Bijma, J., de Nooijer, L. J., Hathorne, Edmund C., Reichart, G. J., Langer, G., and Bijma, J.
- Abstract
Biological activity introduces variability in element incorporation during calcification and thereby decreases the precision and accuracy when using foraminifera as geochemical proxies in paleoceanography. This so-called 'vital effect' consists of organismal and environmental components. Whereas organismal effects include uptake of ions from seawater and subsequent processing upon calcification, environmental effects include migration- and seasonality-induced differences. Triggering asexual reproduction and culturing juveniles of the benthic foraminifer Ammonia tepida under constant, controlled conditions allow environmental and genetic variability to be removed and the effect of cell-physiological controls on element incorporation to be quantified. Three groups of clones were cultured under constant conditions while determining their growth rates, size-normalized weights and single-chamber Mg/Ca and Sr/Ca using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Results show no detectable ontogenetic control on the incorporation of these elements in the species studied here. Despite constant culturing conditions, Mg/Ca varies by a factor of similar to 4 within an individual foraminifer while intra-individual Sr/Ca varies by only a factor of 1.6. Differences between clone groups were similar to the intra-clone group variability in element composition, suggesting that any genetic differences between the clone-groups studied here do not affect trace element partitioning. Instead, variability in Mg/Ca appears to be inherent to the process of bio-calcification itself. The variability in Mg/Ca between chambers shows that measurements of at least 6 different chambers are required to determine the mean Mg/Ca value for a cultured foraminiferal test with a precision of <= 10%
- Published
- 2014
- Full Text
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