Biocomplexity IDEA: Portable Devices To Map The Distribution of Arsenic In Bangladesh Groundwater & The Relation To Sediment Structure

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0119933Van GeenArsenic concentrations in groundwater of Bangladesh can vary by three orders magnitude within lateral and vertical spatial scales of tens of meters. This extreme variability is the result of a poorly understood set of hydrological, microbial, and geochemical interactions that reflect the complex evolution of the Ganges-Brahmaputra delta over the past 10,000 years. There may also be a temporal dimension to these complex pattems on shorter time scales with, potentially, a response of groundwater arsenic to the monsoon and to increased groundwater usage for irrigation. Understanding these pattems has immediate societal relevance because at least 25 million people are currently poisoned by drinking groundwater from millions of tube wells containing 50 ug/L arsenic, the Bangladesh and (until very recently) US drinking water standard.T'his proposal for exploratory work under the topical area "Instrumentation Development for Environmental Activities (IDEA)" is centered around the notion that the principles underlying the distribution of arsenic in Bangladesh groundwater can be understood only through the collection of geophysical, geochemical, and eventually microbiological, data representative of in situ conditions on spatial scales ranging from meters to kilometers. With this objective in mind, and as a complement to its current work in Bangladesh supported by the NIEHS/Superfund Basic Research Program, this interdisciplinary team of scientists seeks to develop and test two portable devices that measure key properties of the subsurface by taking advantage of the enonnous ar-ray of existing tube wells: (1) groundwater arsenic concentrations with a high-precision, double-beam calorimeter, (2) the vertical sediment structure by electromagnetic conductivity. In parallel, we will start to develop the statistical tools needed to interpret and integrate the complex data sets that can be generated with these instruments. Our intention is to set the stage for a full-scale Biocomplexity proposal aimed at improving our ftindamental understanding of the complex set of interactions, including microbial and societal factors, that resulted in a human tragedy of staggering dimension.0119933