Abstract
AbstractConfining clay layers typically protect groundwater aquifers against downward intrusion of contaminants. In the context of groundwater arsenic in Bangladesh, we challenge this notion here by showing that organic carbon drawn from a clay layer into a low-arsenic pre-Holocene (>12 kyr-old) aquifer promotes the reductive dissolution of iron oxides and the release of arsenic. The finding explains a steady rise in arsenic concentrations in a pre-Holocene aquifer below such a clay layer and the repeated failure of a structurally sound community well. Tritium measurements indicate that groundwater from the affected depth interval (40–50 m) was recharged >60 years ago. Deeper (55–65 m) groundwater in the same pre-Holocene aquifer was recharged only 10–50 years ago but is still low in arsenic. Proximity to a confining clay layer that expels organic carbon as an indirect response to groundwater pumping, rather than directly accelerated recharge, caused arsenic contamination of this pre-Holocene aquifer.
Funder
U.S. Department of Health & Human Services | NIH | National Institute of Environmental Health Sciences
National Science Foundation
Publisher
Springer Science and Business Media LLC
Subject
General Physics and Astronomy,General Biochemistry, Genetics and Molecular Biology,General Chemistry
Reference70 articles.
1. Argos, M. et al. Arsenic exposure from drinking water, and all-cause and chronic-disease mortalities in Bangladesh (HEALS): a prospective cohort study. Lancet 376, 252–258 (2010).
2. Quansah, R. et al. Association of arsenic with adverse pregnancy outcomes/infant mortality: a systematic review and meta-analysis. Environ. Health Perspect. 123, 412–421 (2015).
3. Rosenzweig, M., Pitt, M. & Nazmul Hassan, N. Identifying the costs of a public health success: arsenic well water contamination and productivity in Bangladesh. Rev. Econ. Studies http://ibread.org/bread/system/files/bread_wpapers/546.pdf (2020).
4. Wasserman, G. A. et al. Water arsenic exposure and children’s intellectual function in Araihazar, Bangladesh. Environ. Health Perspect. 112, 1329–1333 (2004).
5. Aggarwal, P. K. et al. Isotope hydrology of groundwater in Bangladesh: Implications for characterization and mitigation of arsenic in groundwater, IAEA-TC Project (BGD/8/016). Report No. IAEA-TC Project (BGD/8/016), (International Atomic Energy Agency, 2000).
Cited by
80 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献