Genetic and molecular basis of organic-arsenic-microbe interactions in arsenic prone aquifers (GOAM)

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Contamination of groundwater from naturally occurring arsenic (As) in the subsurface poses a global public health crisis in countries including Mexico, China, Hungary, Argentina, Chile, Cambodia, India (West Bengal), and Bangladesh and has been termed "the largest mass poisoning" in human history. The mechanism of arsenic release from these sediments has been a topic of intense international debate. However, microbially-mediated reduction of assemblages comprising arsenic (most likely as arsenate) sorbed to ferric oxyhydroxides has gained consensus as the most likely method of mobilization of arsenic into these groundwaters, although the precise mechanism of release remains to be identified. Critical questions that remain include (i) the identity of the organisms that catalyse the process; (ii) the physiological mechanism that leads to electron transfer to the extracellular Fe/As mineralogical assemblage; (iii) the nature (and delivery route) of the organic material that activates metal reduction and release; and (iv) the interplay between other competing processes such as oxidation, sulfidation and sorption that can attenuate the process in situ. By focusing the combination of cutting edge microbiological, high throughput molecular ecology (meta-omics), geochemical and mineralogical techniques against samples obtained directly from two contrasting field sites with high arsenic groundwaters, GOAM is a hypothesis driven research programme that aims to identify the critical molecular scale factors causing this environmental disaster, while informing strategies to minimise their impact. A mature network of international collaborations will underpin our field related activities, transfer of molecular scale data to inform hydrogeochemical models and subsequent knowledge exchange with key stakeholders in countries including Bangladesh and Cambodia.