@article {2705, title = {Origin of Groundwater Arsenic in a Rural Pleistocene Aquifer in Bangladesh Depressurized by Distal Municipal Pumping}, journal = {Water Resources Research}, volume = {56}, year = {2020}, month = {Jan-07-2020}, abstract = {Across South Asia, millions of villagers have reduced their exposure to high-arsenic (As) groundwater by switching to low-As wells. Isotopic tracers and flow modeling are used in this study to understand the groundwater flow system of a semi-confined aquifer of Pleistocene (>10 kyr) age in Bangladesh that is generally low in As but has been perturbed by massive pumping at a distance of about 25 km for the municipal water supply of Dhaka. A 10- to 15-m-thick clay aquitard caps much of the intermediate aquifer (>40- to 90-m depth) in the 3-km2 study area, with some interruptions by younger channel sand deposits indicative of river scouring. Hydraulic heads in the intermediate aquifer below the clay-capped areas are 1{\textendash}2 m lower than in the high-As shallow aquifer above the clay layer. In contrast, similar heads in the shallow and intermediate aquifer are observed where the clay layer is missing. The head distribution suggests a pattern of downward flow through interruptions in the aquitard and lateral advection from the sandy areas to the confined portion of the aquifer. The interpreted flow system is consistent with 3H-3He ages, stable isotope data, and groundwater flow modeling. Lateral flow could explain an association of elevated As with high methane concentrations within layers of gray sand below certain clay-capped portions of the Pleistocene aquifer. An influx of dissolved organic carbon from the clay layer itself leading to a reduction of initially orange sands has also likely contributed to the rise of As.}, keywords = {Arsenic, Dhaka Bangladesh, groundwater pumping, modeling}, issn = {0043-1397}, doi = {10.1029/2020WR027178}, url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020WR027178}, author = {Mozumder, M. R. H. and Michael, H. A. and Mihajlov, I. and Khan, M. R. and Knappett, P. S. K. and Bostick, B. C. and Mailloux, B. J. and Ahmed, K. M. and Choudhury, I. and Koffman, T. and Ellis, T. and Whaley-Martin, K. and San Pedro, R. and Slater, G. and Stute, M. and Schlosser, P. and Geen, A.} } @article {966, title = {WOCE radiocarbon IV: Pacific Ocean results; P10, P13N, P14C, P18, P19 \& S4P}, journal = {Radiocarbon}, volume = {44}, year = {2002}, note = {591keTimes Cited:33Cited References Count:56}, pages = {239-392}, abstract = {The World Ocean Circulation Experiment, carried out between 1990 and 1997, provided the most comprehensive oceanic survey of radiocarbon to date. Approximately 10,000 samples were collected in the Pacific Ocean by U.S. investigators for both conventional large volume P counting and small volume accelerator mass spectrometry analysis techniques. Results from six cruises are presented. The data quality is as good or better than previous large-scale surveys. The C-14 distribution for the entire WOCE Pacific data set is graphically described using mean vertical profiles and sections, and property-property plots.}, issn = {0033-8222}, url = {https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/4097}, author = {Key, R. M. and Quay, P. D. and Schlosser, P. and McNichol, A. P. and von Reden, K. F. and Schneider, R. J. and Elder, K. L. and Stuiver, M. and Ostlund, H. G.} } @conference {1659, title = {Isotopes as tracers of the oceanic circulation: results from the world ocean circulation experiment}, booktitle = {International Conference on the Study of Environmental Change Using Isotope Techniques, I.A.E.A.}, year = {2001}, note = {id: 318}, month = {2001}, author = {Schlosser, P. and Jenkins, W. J. and Key, R. and Lupton, J.} } @inbook {1460, title = {Ocean Circulation and Climate}, booktitle = {Observing and Modelling the Global Ocean}, year = {2001}, note = {id: 309}, month = {2001}, pages = {431-452}, publisher = {Academic Press}, organization = {Academic Press}, author = {Schlosser, P. and Bullister, J. L. and Fine, R. and Jenkins, W. J. and Key, R. and Lupton, J. and Roether, W. and Smethie, W. M., Jr.}, editor = {Siedler, G.} } @article {2290, title = {The first trans-Arctic 14C section: comparison of the mean ages of the deep waters in the Eurasian and Canadian Basins of the Arctic Ocean; in Proceedings of the 7th International Conference on Accelerator Mass Spectrometry}, journal = {Nuclear Instruments and Methods}, volume = {B}, year = {1997}, note = {id: 1751}, month = {1997}, pages = {431-437}, author = {Schlosser, P. and Kromer, B. and Ekwurzel, B. and Bonisch, G. and McNichol, A. and Schneider, R. and von Reden, K. and Ostlund, H. and Swift, J.} } @conference {1604, title = {Deep water formation and exchange rates in the Arctic Ocean: Implications from the distribution of 14C}, booktitle = {7th International Conference on Accelerator Mass Spectrometry}, volume = {38}, year = {1996}, note = {id: 947; 1}, month = {1996}, pages = {106-107}, publisher = {Radiocarbon}, organization = {Radiocarbon}, address = {Tucson, AZ}, author = {Schlosser, P. and Kromer, B. and Ekwurzel, B. and Boenisch, G. and McNichol, A. and Schneider, R. and von Reden, K. and Oestlund, G.} }