Paper No. 103-1
Presentation Time: 5:35 PM
DOES PLATE TECTONICS GENERATE PRIMARY SOURCE FOR WORLDWIDE GROUNDWATER ARSENIC? (Invited Presentation)
MUKHERJEE, Abhijit1, GUPTA, Saibal1, COOMAR, Poulomee1, FRYAR, Alan E.2, BHATTACHARYA, Prosun3, GUILLOT, Stéphane4, VERMA, Swati5 and CHARLET, Laurent6, (1)Department of Geology and Geophysics, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India, (2)Department of Earth and Environmental Sciences, University of Kentucky, 101 Slone Building, Lexington, KY 40506-0053, (3)KTH-International Groundwater Arsenic Research Group, Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Teknikringen 10B, Stockholm, 100 44, Sweden, (4)ISTerre CNRS, Université de Grenoble, Grenoble, 38041, France, (5)Geological Oceanography Division, CSIR - National Institute of Oceanography, Dona Paula, Goa, 403004, India, (6)Earth and Planetary Science Department (LGIT-OSUG), Universite Joseph Fourier, BP 53, 38041 Grenoble, Grenoble, 38041, France
Arsenic (As) enrichment in groundwater, which potentially affects the health of more than 200 million inhabitants worldwide, has been one of the most well researched environmental and geoscience topics for more than last three decades. Consequently, a large scientific knowledge-base has developed on the 3-dimensional distribution of As at local to global-scales, based mostly on geochemical surveys and statistical analyses. Several models have been proposed with a general consensus on the mechanisms of fate, mobilization and transport of As on the earth’s surface. However, the ultimate, primary source of the bulk As in the polluted aquifer sediments is yet-unknown, and we still need to answer the questions of
where, why and how on the sources and processes that lead to the eventual enrichment of groundwater by As.
Since, globally, most of the major polluted aquifers are preferentially located in orogenic foreland basins of present or ancient convergent margins, we propose a hypothetical model, advocating the primary source of groundwater As to be related to convergent tectonism, from where it is eventually transported to foreland sedimentary basins that subsequently act as the groundwater As-enriched aquifers. We suggest that the primary source of groundwater As is arc magmas in active continental margins. These rising arc magmas scavenge the As from the thick continental crust. The continental arcs that collide to form “hot” orogens continue to be As sources by promoting As-rich fluid hydrothermal circulation. Erosion of such orogens eventually enriches the bulk sediment As concentration in the adjoining foreland basins, subsequently leading to As enrichment in the groundwater of downstream aquifers, which is later ingested by human through drinking water through groundwater wells. Thus, these processes form bridge between tectonics-scale operating over millions of years with groundwater pollution happening and observed in human time-scales.
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