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Characterization of mercury cycling in a coastal wetland

Characterization of mercury cycling in a coastal wetland. In wetlands, mercury is transformed to a more toxic form by anaerobic bacteria. The rate of this reaction is determined by the availability of mercury to these bacteria, as well as their activity in the environment. Overall hypothesis:

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Characterization of mercury cycling in a coastal wetland

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  1. Characterization of mercury cycling in a coastal wetland In wetlands, mercury is transformed to a more toxic form by anaerobic bacteria. The rate of this reaction is determined by the availability of mercury to these bacteria, as well as their activity in the environment. Overall hypothesis: Microbial communities attached to wetland plants play an important role in mercury cycling • Specific questions: • How deep does oxygen penetrate the sediment while the tide is out? • After inundation, how long do surface sediments remain oxic? • What controls the rate of mercury transformation by bacteria on plants and in soils? (such as oxygen level, pH, and general water chemistry)

  2. Effects of irrigation well pumping on arsenic contamination of groundwater in Bangladesh Overall hypothesis: Irrigation-return flow mobilizes arsenic (As) as it passes through an arsenic-enriched iron oxide band in the sediment. • Specific questions: • During irrigation, is rice-paddy return flow the main water infiltrating through the Fe band? • Does anoxic irrigation water cause changes in the redox environment of the Fe band? • How is arsenic mobilized as the recharge flows through the Fe band? • Do sensor measurements of calcium and ammonium correlate with the arsenic concentration in well water, and can they be used to trigger manual arsenic sampling?

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