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International audience; There is growing concern globally about the occurrence of anthropogenic organic contaminants in the environment, including pharmaceuticals and personal care products. This concern extends to groundwater, which is a critical water resource in Europe, and its protection is a priority to the European Commission, the European Union (EU) Member States and national agencies across Europe. Maintaining good groundwater status supports improved public health, economic growth and sustains groundwater dependant ecosystems. A range of measures have been introduced for regulating several substances that have impacted groundwater (e.g. nitrate and pesticides). However, these measures only cover a small fraction of anthropogenic substances that could pollute groundwater. Monitoring for these unregulated substances is currently very limited or not carried out at all. Therefore, a coordinated European-wide approach is needed to identify, monitor and characterise priority substances or groups of substances that have the potential to pollute groundwater. This evidence base is critical for policy development and controls on these currently unregulated substances. The European Commission highlighted this as a need during the review of the EU Groundwater Directive Annexes in 2014, when the requirement to develop a Groundwater Watch List (GWWL) was established. This paper describes the approach that has been developed through a voluntary initiative as part of the EU CIS Working Group Groundwater to establish the voluntary EU GWWL. The process for developing the GWWL is one that has brought together researchers, regulators and industry, and is described here for the first time. A summary of the key principles behind the methodology is presented as well as results from pilot studies using per- and polyfluoroalkyl substances and pharmaceuticals. These explore and support the viability of the GWWL process, an important step towards its adoption and its future use for groundwater protection across Europe.

A common assumption in phosphorus (P) load apportionment studies is that P loads in rivers consist of flow independent point source emissions (mainly from domestic and industrial origins) and flow dependent diffuse source emissions (mainly from agricultural origin). Hence, rivers dominated by point sources will exhibit highest P concentration during low-flow, when flow dilution capacity is minimal, whereas rivers dominated by diffuse sources will exhibit highest P concentration during high flow, when land-to-river hydrological connectivity is maximal. Here, we show that Soluble Reactive P (SRP) concentrations in three forested catchments free of point sources exhibited seasonal maxima during the summer low-flow period, i.e. a pattern expected in point source dominated areas. A load apportionment model (LAM) is used to show how point sources contribution may have been overestimated in previous studies, because of a biogeochemical process mimicking a point source signal. Almost twenty-two years (March 1995-September 2016) of monthly monitoring data of SRP, dissolved iron (Fe) and nitrate-N (NO3) were used to investigate the underlying mechanisms: SRP and Fe exhibited similar seasonal patterns and opposite to that of NO3. We hypothesise that Fe oxyhydroxide reductive dissolution might be the cause of SRP release during the summer period, and that NO3 might act as a redox buffer, controlling the seasonality of SRP release. We conclude that LAMS may overestimate the contribution of P point sources, especially during the summer low-flow period, when eutrophication risk is maximal. (C) 2018 Elsevier B.V. All rights reserved.

International audience; Combined Sewer Overflows (CSO) in small pen-urban streams and rivers are potentially toxic for their biocenosis. Improving the management of CSO discharges requires better knowledge of their dynamics and toxicity. In view to characterizing this toxicity, we sampled the different compartments (benthic and hyporheic zone) of a pen-urban stream located near the city of Lyon in France. The samples were taken at different distances from a CSO and at three period characteristic of different hydrological conditions. Their toxic effects were assessed by bioassays on the dissolved fraction (D. magna, V. fished and B. calyciflorus bioassays) and on the particle fraction (V. fished and H. incongruens bioassays). The results highlighted significant toxicity of the particulate fraction for the benthic and hyporheic samples, in particular downstream of the CSO, but with high spatio-temporal variability. This variability can first be attributed to the variability of CSO discharge sampling as a function of season and rainfall, and the dynamics of polluted particles (trapping of transported particles in infiltration zones, mobilization during floods). These parameters play a fundamental role in the distribution of pollutants according to the geomorphology of stream facies. Regarding dissolved pollutants, the chemical exchanges taking place at the "water-sediment" interface trigger the transfer of pollutants from one phase to another, after which the dispersion of these pollutants is governed by hydraulic flows. Finally, critical zones and periods are identified for the pen-urban river toxicity studied: benthic sediments under mean flow downstream: hyporheic sediments after a storm event downstream, close to the CSO. Recommendations are made on the basis of the knowledge obtained to optimize the management of these discharges.

Global change, in particular climate change, will affect agriculture worldwide in many ways: increased drought or flooding amplitude and frequency, variable temperature increases, loss of natural depuration of waters, soil erosion, loss of soil carbon content, invasion by alien species, increased pest events, changes in plant phenology, increased sensitivity of crops to stress and diseases etc. (Fisher et al. 2005; Howden et al. 2007). These anticipated or even already occurring stresses raise concerns about the sustainability of production and the ability of agriculture to feed human populations. All these changes could lead to an increased use of pesticides (Kattwinkel et al. 2011). Moreover, demographic pressure continues to rise, in particular in tropical and sub-tropical regions, where greater threats to agriculture and food sustainability are anticipated by the Intergovernmental Panel on Climate Change (IPCC) (Easterling et al. 2007). These trends will certainly lead to mounting conflicts involving water uses (irrigation versus drinking water production or freshwater ecosystem maintenance, sanitation etc.) and food production. This appeals to an “ecologically intensive agriculture” (Griffon 2006), i.e. a sustainable agriculture providing ecosystem services more efficiently than today and causing fewer adverse impacts on the environment and water resources. With EU Directive 2009/128/EC (EC 2009a) enforcement, requesting Member States to adopt action plans aiming to reduce risks and impacts related to pesticide uses, there will be a focus in the public and political debates in Europe on achieving a more sustainable use of pesticides. This should consequently lead to a reduction of the risks or impacts of pesticides on the environment. In Europe, there is currently a strong focus on source (including dose) reduction. This approach may nevertheless be too restrictive if the goal is to reduce the agriculture footprint while maintaining or increasing yield. Depending on the chemical properties of pesticides as well as environmental factors, decreasing the amounts of pesticides applied to crops will not automatically produce a decrease in the risk to non-target species or water supply. How could society meet the challenge of the forthcoming climate change? What adaptations should be envisaged for agriculture/pesticide risk management (RM)? These changes will probably have a profound effect on agricultural systems (crop selection, farming practices etc.) and to a lesser extent influence the fate and effects of chemicals (Schiedek et al. 2007). These questions have been addressed by two European research networks, namely Euraqua (the European Network of Freshwater Research Organisations, http://www.euraqua.org/) and PEER (Partnership for European Environmental Research, http://www.peer.eu/), which organised a workshop aiming to identify research needs and strategies induced by these questions in October 2011 in Montpellier, France. The workshop's specific goals were to (1) discuss the pesticide risk assessment (RA) approach, its limitations (e.g. spatial scale and multi-stress situations), the connections between different policies (pesticide regulation and Water Framework Directive), the use of models, (2) review integrated practices and innovative technologies which could or are intended to reduce pesticides' environmental impacts and (3) contribute to the future research and development agenda. This review summarises the workshop discussions.

ISI Document Delivery No.: 094JU Times Cited: 0 Cited Reference Count: 59 Cited References: Alsdorf D, 2001, GEOPHYS RES LETT, V28, P2671, DOI 10.1029/2001GL012962 Alsdorf D., 2003, EOS T AGU, V84, P269, DOI [DOI 10.1029/2003E0290001, DOI 10.1029/2003EO290001] Alsdorf DE, 2007, REV GEOPHYS, V45, DOI 10.1029/2006RG000197 Argyilan EP, 2003, J GREAT LAKES RES, V29, P488 Avakyan A. B., 1998, Lakes Reservoirs Research and Management, V3, P45, DOI 10.1111/j.1440-1770.1998.tb00031.x Becker M, 2010, CR GEOSCI, V342, P223, DOI 10.1016/j.crte.2009.12.010 Berry P. A. M., 2009, PRODUCT HDB, V3 Berry P. A. M., 2002, International Journal on Hydropower & Dams, V9 Berry P. A. M., 2007, ESA Berry PAM, 2010, IAG SYMP, V135, P221, DOI 10.1007/978-3-642-10634-7_29 Berry PAM, 1997, ESA SP PUBL, V414, P403 Berry PAM, 2005, GEOPHYS RES LETT, V32, DOI 10.1029/2005GL022814 Birkett C, 2011, COASTAL ALTIMETRY, P19, DOI 10.1007/978-3-642-12796-0_2 Birkett CM, 2002, J GEOPHYS RES-ATMOS, V107, DOI 10.1029/2001JD000609 Birkett CM, 2000, REMOTE SENS ENVIRON, V72, P218, DOI 10.1016/S0034-4257(99)00105-4 Birkett CM, 1998, WATER RESOUR RES, V34, P1223, DOI 10.1029/98WR00124 Birkett CM, 2010, MAR GEOD, V33, P204, DOI 10.1080/01490419.2010.488983 Birkett CM, 1995, J GEOPHYS RES-OCEANS, V100, P25179, DOI 10.1029/95JC02125 Birkinshaw SJ, 2010, HYDROL PROCESS, V24, P3811, DOI 10.1002/hyp.7811 Bjerklie DM, 2003, J HYDROL, V278, P17, DOI 10.1016/S0022-1694(03)00129-X Calmant S, 2008, SURV GEOPHYS, V29, P247, DOI 10.1007/s10712-008-9051-1 Campos ID, 2001, CR ACAD SCI II A, V333, P633 Carmouze J. P., 1983, LAKE CHAD MONOGRAPHI, V53, P527 Coe M. T., 2004, AGU FALL M ABSTR, V22, P05 Coe M. T., 2004, Water Resources Research, V40, pW10205, DOI 10.1029/2003WR002543 Cretaux JF, 2006, CR GEOSCI, V338, P1098, DOI 10.1016/j.crte.2006.08.002 Cretaux JF, 2011, MAR GEOD, V34, P291, DOI 10.1080/01490419.2011.585110 Cretaux JF, 2005, J GREAT LAKES RES, V31, P520 Cretaux JF, 2009, J GEODESY, V83, P723, DOI 10.1007/s00190-008-0289-7 Cretaux JF, 2011, ADV SPACE RES, V47, P1497, DOI 10.1016/j.asr.2011.01.004 Dumont J. P., 2006, P 15 YEARS PROGR RAD Dumont J. P., 2009, NOAA NESDIS POLAR SE, V1, P67 Frappart F, 2006, REMOTE SENS ENVIRON, V100, P252, DOI 10.1016/j.rse.2005.10.027 Fu L. L., 2001, INT GEOPHYS SERIES, V69, P463 Fu L.-L., 2003, JPL PUBLICATION, V03-002, P67 Getirana ACV, 2009, J HYDROL, V379, P205, DOI 10.1016/j.jhydrol.2009.09.049 Gommenginger C., 2006, ESTEC Isiorho SA, 1996, GROUND WATER, V34, P819, DOI 10.1111/j.1745-6584.1996.tb02076.x Kouraev AV, 2011, COASTAL ALTIMETRY, P331, DOI 10.1007/978-3-642-12796-0_13 Kouraev AV, 2007, REMOTE SENS ENVIRON, V108, P240, DOI 10.1016/j.rse.2006.11.010 Lee H, 2011, TERR ATMOS OCEAN SCI, V22, P169, DOI 10.3319/TAO.2010.08.09.01(TibXS) Magome J., 2004, SCI COMM INT C ORG R, P335 Maheu C, 2003, GEOPHYS RES LETT, V30, DOI 10.1029/2002GL016033 Medina CE, 2008, REMOTE SENS ENVIRON, V112, P3604, DOI 10.1016/j.rse.2008.05.001 Mekong River Commission, 2005, OV HYDR MEK BAS, P82 Mercier F, 2002, GLOBAL PLANET CHANGE, V32, P141, DOI 10.1016/S0921-8181(01)00139-4 Mertes L. A. K., 2004, NATURAL RESOURCES EN, V5 MORRIS CS, 1994, WATER RESOUR RES, V30, P1009, DOI 10.1029/94WR00064 Ngongondo C, 2011, THEOR APPL CLIMATOL, V106, P79, DOI 10.1007/s00704-011-0413-0 Ricko M, 2011, J CLIMATE, V24, P2983, DOI 10.1175/2010JCLI3602.1 Ross K., 2006, VERIFICATION VALIDAT da Silva JS, 2010, REMOTE SENS ENVIRON, V114, P2160, DOI 10.1016/j.rse.2010.04.020 Sarch MT, 2000, GEOGR J, V166, P156, DOI 10.1111/j.1475-4959.2000.tb00015.x Shum C, 2003, MAR GEOD, V26, P335, DOI 10.1080/01490410390253487 Swenson S, 2009, J HYDROL, V370, P163, DOI 10.1016/j.jhydrol.2009.03.008 Tapley B, 2005, J GEODESY, V79, P467, DOI 10.1007/s00190-005-0480-z World Meteorological Organization, 2008, GUID HYDR PRACT, V1, P296 Yua A. W., 2010, P SOC PHOTO-OPT INS, V7578 Zhang GQ, 2011, J APPL REMOTE SENS, V5, DOI 10.1117/1.3601363 Ricko, Martina Birkett, Charon M. Carton, James A. Cretaux, Jean-Franois Ricko, Martina/D-2638-2013; carton, james/C-4807-2009 NASA [NNX10AO99G, NNX08AT886, NNX08AM72G] The authors would like to thank the reviewers and Jerome Benveniste for their valuable comments and suggestions. We also thank Richard Smith and Philippa Berry from EAPRS Laboratory, De Montfort University, UK, and Jerome Benveniste from the European Space Agency for supplying the ERS-2 data products. Altimetric data products used in this study was provided by: LEGOS [www.legos.obs-mip.fr/soa/hydrologie/hydroweb]; NASA/USDA [www.pecad.fas.usda.gov/cropexplorer/global_reservoir/]; ESA-DMU [tethys.eaprs.cse.dmu.ac.uk/RiverLake/shared/main]. Gauge data was provided by John Ratsey from the Ministry of Water Resources for Lake Tana; Francois Delclaux from HydroSciences Montpellier for Lake Chad; the Volta River Authority [www.vra.com]; the Lake Mead Water Database [lakemead.water-data.com/] and the Lake Powell Water Database [lakepowell.water-data.com/], the U.S. Bureau of Reclamation and NOAA [tidesandcurrents.noaa.gov] and the U.S. Geological Survey [waterdata.usgs.gov/nwis] for USA lakes; Environment Canada for Lake Athabasca; and the Venezuelan [opsis.org.ve/home3.html] for Lake Guri. Geoid height data for Lake Ontario was provided by Brian Beckley. Support for MR and JAC has been provided by NASA Grant NNX10AO99G, while support for CMB has been provided by NASA Grants NNX08AT886 and NNX08AM72G. This work forms part of the dissertation research of MR. 0 SPIE-SOC PHOTO-OPTICAL INSTRUMENTATION ENGINEERS BELLINGHAM J APPL REMOTE SENS; Satellite radar altimeter measurements of lake and reservoir water levels complement in situ observations by providing stage information for ungauged basins and by filling data gaps in existing gauge records. Such additional measurements assist both research and operational programs. However, for a particular lake or reservoir, altimetric products offered to end-users may differ due to choice of employed instrument, processing technique, and applied geophysical corrections. To explore these differences, particularly with their potential impact on climate-based research, an intercomparison of three web-based water-level products (produced by Laboratoire d'Etudes en Geophysique et Oceanographie Spatiale, National Aeronautics and Space Administration/United States Department of Agriculture, and European Space Agency/De Montfort University) has been undertaken based on 18 lakes and reservoirs. The products are well correlated with each other (r = 0.87 to 0.99) and where in situ data are available are quite well correlated with the gauge measurements (r = 0.73 to 0.99). Despite variations in data processing, the poorest root-mean-square differences between any altimeter product and gauge data (similar to 0.20 to 1.41 m) occur for the narrow reservoirs and smaller lakes. The largest discrepancies between the altimeter products occur for the lakes that freeze (Lake Athabasca and Woods). The current altimeter products provide acceptable accuracy, long-term trends and seasonality for climate applications. We discuss the merits of each product system, but recommend further validations and the provision of ice-detection flags. (C) 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). [DOI: 10.1117/1.JRS.6.061710]

ISI Document Delivery No.: 903QF Times Cited: 10 Cited Reference Count: 120 Cited References: AAGAARD K, 1981, DEEP-SEA RES, V28, P529, DOI 10.1016/0198-0149(81)90115-1 Alkire MB, 2006, J GEOPHYS RES-OCEANS, V111, DOI 10.1029/2005JC003446 ANDERSON LG, 1990, J GEOPHYS RES-OCEANS, V95, P1703, DOI 10.1029/JC095iC02p01703 Anderson LG, 2001, POLAR RES, V20, P225, DOI 10.1111/j.1751-8369.2001.tb00060.x Anderson LG, 2004, J GEOPHYS RES-OCEANS, V109, DOI [10.1029/2003JC002120, 10.1029/2003JC001773] [Anonymous], 2008, CLIM CHANG 2007 SYNT Arrigo KR, 2004, GEOPHYS RES LETT, V31, DOI 10.1029/2003GL018978 Arrigo KR, 2008, GEOPHYS RES LETT, V35, DOI 10.1029/2008GL035028 Barber DG, 2004, J GEOPHYS RES-OCEANS, V109, DOI 10.1029/2003JC002027 Bates NR, 2009, BIOGEOSCIENCES, V6, P2433 Bauch D, 2005, GLOBAL PLANET CHANGE, V48, P165, DOI 10.1016/j.gloplacha.2004.12.011 Benner R, 2004, GEOPHYS RES LETT, V31, DOI 10.1029/2003GL019251 Bidleman TF, 2007, ENVIRON SCI TECHNOL, V41, P2688, DOI 10.1021/es062375b BYRNE RH, 1987, ANAL CHEM, V59, P1479, DOI 10.1021/ac00137a025 Cai WJ, 2010, SCIENCE, V329, P556, DOI 10.1126/science.1189338 CARMACK EC, 1989, J GEOPHYS RES-OCEANS, V94, P18043, DOI 10.1029/JC094iC12p18043 Carmack EC, 2004, MAR ECOL PROG SER, V277, P37, DOI 10.3354/meps277037 Carmack EC, 2002, ARCTIC, V55, P29 CLAYTON TD, 1993, DEEP-SEA RES PT I, V40, P2115, DOI 10.1016/0967-0637(93)90048-8 Cooper LW, 1997, J GEOPHYS RES-OCEANS, V102, P12563, DOI 10.1029/97JC00015 Cooper LW, 2008, GEOPHYS RES LETT, V35, DOI 10.1029/2008GL035007 Cooper LW, 2005, J GEOPHYS RES-BIOGEO, V110, DOI 10.1029/2005JG000031 Delille B, 2007, LIMNOL OCEANOGR, V52, P1367, DOI 10.4319/lo.2007.52.4.1367 Dickson A. G., 1994, ORNLCDIAC74 DEP EN DICKSON AG, 1990, J CHEM THERMODYN, V22, P113, DOI 10.1016/0021-9614(90)90074-Z DICKSON AG, 1987, DEEP-SEA RES, V34, P1733, DOI 10.1016/0198-0149(87)90021-5 Eicken H, 2002, J GEOPHYS RES-OCEANS, V107, DOI 10.1029/2000JC000583 Ekwurzel B, 2001, J GEOPHYS RES-OCEANS, V106, P9075, DOI 10.1029/1999JC000024 Else BGT, 2011, J GEOPHYS RES-OCEANS, V116, DOI 10.1029/2010JC006760 EPSTEIN S, 1953, GEOCHIM COSMOCHIM AC, V4, P213, DOI 10.1016/0016-7037(53)90051-9 Fransson A, 2009, CONT SHELF RES, V29, P1317, DOI 10.1016/j.csr.2009.03.008 Gibson JAE, 1999, MAR CHEM, V66, P187, DOI 10.1016/S0304-4203(99)00040-7 Grasshoff K., 1983, METHODS SEAWATER ANA Gratton Y., 2006, 2006 GEN M CAN ARCT Guay CK, 1997, DEEP-SEA RES PT II, V44, P1543, DOI 10.1016/S0967-0645(97)00066-0 Guay CKH, 2009, J GEOPHYS RES-OCEANS, V114, DOI 10.1029/2008JC005099 Guo LD, 2007, GEOPHYS RES LETT, V34, DOI 10.1029/2007GL030689 Howell SEL, 2009, GEOPHYS RES LETT, V36, DOI 10.1029/2009GL037681 Jeansson E, 2008, PROG OCEANOGR, V78, P12, DOI 10.1016/j.pocean.2007.08.031 JOHNSON KM, 1993, MAR CHEM, V44, P167, DOI 10.1016/0304-4203(93)90201-X JONES EP, 1981, J GEOPHYS RES-OC ATM, V86, P1041, DOI 10.1029/JC086iC11p11041 JONES EP, 1986, J GEOPHYS RES-OCEANS, V91, P759, DOI 10.1029/JC091iC09p10759 Jones EP, 2003, J GEOPHYS RES-OCEANS, V108, DOI 10.1029/2001JC001141 Jones EP, 2008, J GEOPHYS RES-OCEANS, V113, DOI 10.1029/2007JC004124 Jones EP, 1998, GEOPHYS RES LETT, V25, P765, DOI 10.1029/98GL00464 Karcher MJ, 2002, J GEOPHYS RES-OCEANS, V107, DOI 10.1029/2000JC000530 Karstensen J., 2005, Journal of Geophsical Research-Part C-Oceans, V110, DOI 10.1029/2004JC002510 Karstensen J., 2006, OMP OPTIMUM MULTIPAR Keeling RF, 2008, ATMOSPHERIC CO2 RECO KROUSE HR, 1971, CAN J EARTH SCI, V8, P1107 Leffanue H, 2004, J MARINE SYST, V48, P3, DOI 10.1016/j.jmarsys.2003.07.004 LEHMANN M, 1991, J GLACIOL, V37, P23 Lewis E., 1998, ORNLCDIAC105 US DEP Macdonald R. W., 2006, HDB ENV CHEM, P91 Macdonald RW, 2002, DEEP-SEA RES PT I, V49, P1769, DOI 10.1016/S0967-0637(02)00097-3 Macdonald RW, 1999, GEOPHYS RES LETT, V26, P2223, DOI 10.1029/1999GL900508 MACDONALD RW, 1995, J GEOPHYS RES-OCEANS, V100, P895, DOI 10.1029/94JC02700 MACDONALD RW, 1989, J GEOPHYS RES-OCEANS, V94, P18057, DOI 10.1029/JC094iC12p18057 Macdonald RW, 1999, MAR CHEM, V65, P3, DOI 10.1016/S0304-4203(99)00007-9 MACDONALD RW, 1987, J GEOPHYS RES-OCEANS, V92, P2939, DOI 10.1029/JC092iC03p02939 MACKAS DL, 1987, J GEOPHYS RES-OCEANS, V92, P2907, DOI 10.1029/JC092iC03p02907 Mathis JT, 2007, J GEOPHYS RES-OCEANS, V112, DOI 10.1029/2006JC003899 McGuire AD, 2009, ECOL MONOGR, V79, P523, DOI 10.1890/08-2025.1 McLaughlin FA, 2004, DEEP-SEA RES PT I, V51, P107, DOI 10.1016/j.dsr.2003.09.010 McLaughlin FA, 1996, J GEOPHYS RES-OCEANS, V101, P1183, DOI 10.1029/95JC02634 MEHRBACH C, 1973, LIMNOL OCEANOGR, V18, P897 MELLING H, 1993, CONT SHELF RES, V13, P1123, DOI 10.1016/0278-4343(93)90045-Y MELLING H, 1995, CONT SHELF RES, V15, P89, DOI 10.1016/0278-4343(94)P1814-R Miller LA, 2011, J GEOPHYS RES-OCEANS, V116, DOI 10.1029/2009JC006058 MILLERO FJ, 1993, MAR CHEM, V44, P143, DOI 10.1016/0304-4203(93)90199-X Millot R, 2003, GEOCHIM COSMOCHIM AC, V67, P1305, DOI 10.1016/S0016-7037(02)01207-3 Mucci A, 2010, J GEOPHYS RES-OCEANS, V115, DOI 10.1029/2009JC005330 Mundy CJ, 2009, GEOPHYS RES LETT, V36, DOI 10.1029/2009GL038837 Newton R, 2008, J GEOPHYS RES-OCEANS, V113, DOI 10.1029/2007JC004111 Nilsen F, 2008, CONT SHELF RES, V28, P1838, DOI 10.1016/j.csr.2008.04.015 Nomura D, 2006, TELLUS B, V58, P418, DOI 10.1111/j.1600-0889.2006.00204.x OSTLUND HG, 1984, J GEOPHYS RES-OCEANS, V89, P6373, DOI 10.1029/JC089iC04p06373 Overpeck J., 2005, EOS, V86, P312, DOI DOI 10.1029/2005EO340001 Overpeck JT, 2005, EOS, V86, P309, DOI [10.1029/2005EO340001, DOI 10.1029/2005E0340001, DOI 10.1029/2005EO340001] Papadimitriou S, 2004, GEOCHIM COSMOCHIM AC, V68, P1749, DOI 10.1016/j.gca.2003.07.004 Pickart RS, 2004, J GEOPHYS RES-OCEANS, V109, DOI 10.1029/2003JC001912 Pickart RS, 2009, J GEOPHYS RES-OCEANS, V114, DOI 10.1029/2008JC005009 Pipko II, 2002, PROG OCEANOGR, V55, P77, DOI 10.1016/S0079-6611(02)00071-X Retamal L, 2008, POLAR BIOL, V31, P363, DOI 10.1007/s00300-007-0365-0 ROBERTBALDO GL, 1985, ANAL CHEM, V57, P2564, DOI 10.1021/ac00290a030 Rudels B, 1996, J GEOPHYS RES-OCEANS, V101, P8807, DOI 10.1029/96JC00143 Rudels B, 2004, POLAR RES, V23, P181, DOI 10.1111/j.1751-8369.2004.tb00007.x Rysgaard S, 2007, J GEOPHYS RES-OCEANS, V112, DOI 10.1029/2006JC003572 Schlitzer R., 2009, OCEAN DATA VIEW Schlosser P, 2002, GEOPHYS RES LETT, V29, DOI 10.1029/2001GL013135 Semiletov IP, 2007, J MARINE SYST, V66, P204, DOI 10.1016/j.jmarsys.2006.05.012 Serreze MC, 2006, J GEOPHYS RES-OCEANS, V111, DOI 10.1029/2005JC003424 Serreze MC, 2007, SCIENCE, V315, P1533, DOI 10.1126/science.1139426 Shadwick E. H., 2009, BIOGEOSCI DISCUSS, V6, P971, DOI [10.5194/bgd-6-971-2009, DOI 10.5194/BGD-6-971-2009] Shadwick EH, 2011, LIMNOL OCEANOGR, V56, P303, DOI 10.4319/lo.2011.56.1.0303 Shadwick EH, 2011, CONT SHELF RES, V31, P806, DOI 10.1016/j.csr.2011.01.014 Shaw WJ, 2009, J GEOPHYS RES-OCEANS, V114, DOI 10.1029/2008JC004991 Shcherbina AY, 2003, SCIENCE, V302, P1952, DOI 10.1126/science.1088692 Sherr BF, 2003, DEEP-SEA RES PT I, V50, P529, DOI 10.1016/S0967-0637(03)00030-X Shimada K, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2005GL025624 Skogseth R, 2008, J GEOPHYS RES-OCEANS, V113, DOI 10.1029/2007JC004452 Spall MA, 2008, J PHYS OCEANOGR, V38, P1644, DOI 10.1175/2007JPO3829.1 Stroeve JC, 2005, GEOPHYS RES LETT, V32, DOI 10.1029/2004GL021810 Symon C., 2005, ARCTIC CLIMATE IMPAC Taylor JR, 2003, J GEOPHYS RES-OCEANS, V108, DOI 10.1029/2002JC001635 Telang S. A., 1991, BIOGEOCHEMISTRY MAJO, P75 Thomas H, 2011, J GEOPHYS RES-OCEANS, V116, DOI 10.1029/2011JC007120 Timmermans ML, 2008, J PHYS OCEANOGR, V38, P133, DOI 10.1175/2007JPO3782.1 TOMCZAK M, 1989, J GEOPHYS RES-OCEANS, V94, P16141, DOI 10.1029/JC094iC11p16141 Tremblay JE, 2008, J GEOPHYS RES-OCEANS, V113, DOI 10.1029/2007JC004547 Vallieres C, 2008, J MARINE SYST, V74, P756, DOI 10.1016/j.jmarsys.2007.12.002 White D, 2007, J GEOPHYS RES-BIOGEO, V112, DOI 10.1029/2006JG000353 Williams WJ, 2006, CONT SHELF RES, V26, P2352, DOI 10.1016/j.csr.2006.06.012 Williams WJ, 2008, J GEOPHYS RES-OCEANS, V113, DOI 10.1029/2006JC003591 Williams WJ, 2008, J MAR RES, V66, P645 Woodgate RA, 2006, GEOPHYS RES LETT, V33, DOI 10.1029/2006GL026931 Yamamoto-Kawai M, 2008, J GEOPHYS RES-OCEANS, V113, DOI 10.1029/2006JC003858 Yamamoto-Kawai M, 2009, J GEOPHYS RES-OCEANS, V114, DOI 10.1029/2008JC005000 Yamamoto-Kawai M, 2005, J GEOPHYS RES-OCEANS, V110, DOI 10.1029/2004JC002793 Yi Y, 2010, J HYDROL, V383, P223, DOI 10.1016/j.jhydrol.2009.12.038 Lansard, Bruno Mucci, Alfonso Miller, Lisa A. Macdonald, Robie W. Gratton, Yves Macdonald, Robie/A-7896-2012 Macdonald, Robie/0000-0002-1141-8520 CCGS Amundsen; CASES (Canadian Arctic Shelf Exchange Study) NSERC network (Natural Sciences and Engineering Research Council of Canada); Canadian Fund for Innovation; Canadian Coast Guard; Department of Fisheries and Oceans Canada; NSERC Discovery We thank the officers and crew of the CCGS Amundsen for their support and dedication to the CASES expedition. We are indebted to Constance Guignard, Nes Sutherland, Pascale Collin, Simon Belanger, Jens Ehn, Mike Arychuk and Owen Owens for their care and perseverance in collecting and analyzing the TA, TIC and pH samples at sea. Thanks must go to the CTD data acquisition group for these basic but critical measurements and the calibration of the various probes. Most of the plots and maps in this study were created with the ODV Software [Schlitzer, 2009]. We also thank A. Proshutinsky and two anonymous reviewers who provided constructive comments that helped to improve our manuscript. This study was funded through the CASES (Canadian Arctic Shelf Exchange Study) NSERC network (Natural Sciences and Engineering Research Council of Canada) and a Canadian Fund for Innovation grant to support the upgrade and operation of the CCGS Amundsen. Additional financial contributions were provided by the Canadian Coast Guard, the Strategic Science Fund of the Department of Fisheries and Oceans Canada, and NSERC Discovery grants to A. Mucci and Y. Gratton. 10 AMER GEOPHYSICAL UNION WASHINGTON J GEOPHYS RES-OCEANS; We examined the seasonal variability of water mass distributions in the southeastern Beaufort Sea from data collected between September 2003 and August 2004. Salinity, total alkalinity (TA) and isotopic composition (delta O-18) of seawater were used together as tracers of freshwater input, i.e., meteoric water and sea ice meltwater. We used an optimum multiparameter analysis to identify the different water masses, including the Mackenzie River, sea ice melt (SIM), winter polar mixed layer (PML), upper halocline water (UHW) with core salinity of 33.1 psu (Pacific origin) and Atlantic Water. Computed values of CO2 fugacity in seawater (fCO(2)-sw) show that the surface mixed layer (SML) remains mostly undersaturated (328 +/- 55 mu atm, n = 552) with respect to the average atmospheric CO2 concentration (380 +/- 5 mu atm) over the study period. The influence of the Mackenzie River (fCO(2-SW) > 500 mu atm) was relatively small in the southeastern Beaufort Sea, and significant fractions were only observed on the inner Mackenzie Shelf. The contribution of sea ice melt (fCO(2-SW) < 300 mu atm) to the SML could reach 30% beyond the shelf break and close to the ice pack in autumn. The density of the PML increased through the winter due to cooling and brine rejection. The winter PML reached a maximum depth of 70 m in late April. The UHW (fCO(2-SW) > 600 mu atm) was usually located between 120 and 180 m depth, but could contribute to the SML during wind-driven upwelling events, in summer and autumn, and during brine-driven eddies, in winter.