Collaborative Research: Mercury Cycling in Soils: Dynamic Sources for Aquatic Environments

Hines 9975407由于甲基汞的毒性和生物放大作用，水生系统中汞的生物地球化学受到了相当大的关注。然而，进入水体的甲基汞大部分来自土壤。该项目将利用多学科方法，以内华达州的卡森河为试验地点，调查控制土壤中汞甲基化及其向水生系统迁移的因素。实地和实验室调查将包括汞形态分析、汞的甲基化、去甲基化和还原的测量、负责汞转化的细菌基因的分布和表达，以及汞生物传感器在调查汞生物利用度中的应用。将进行操纵实验，以确定润湿和干燥循环以及氧气供应对汞循环途径的影响。地球化学/分子结果将用于大大改善汞迁移模型，该模型将在低流量和高流量条件下进行经验测试。研究结果将描述对净甲基汞形成和污染场地最终迁移的控制，并将有助于理解土壤在控制甲基汞污染中的作用。MPS多学科活动办公室

Hines9975407The biogeochemistry of mercury in aquatic systems has received considerable attention because of the toxicity and biomagnification of methylmercury. However, much of the methylmercury entering water bodies is derived from soils. This program will utilize a multidisciplinary approach to investigate factors controlling mercury methylation in soils and its transport into aquatic systems using the Carson River, Nevada as the test site. Field and laboratory investigations will include analysis of mercury speciation, measurements of methylation, demethylation, and reduction of mercury, the distribution and expression of bacterial genes responsible for mercury transformations, and application of a mercury biosensor for investigating mercury bioavailability. Manipulative experiments will be conducted to determine effects of wetting and drying cycles and oxygen availability on pathways of mercury cycling. The biogeochemical/molecular results will be used to greatly improve a mercury transport model, which will be tested empirically during low and high flow conditions. The results will delineate controls on net methylmercury formation and eventual transport in a contaminated site, and will be useful for understanding the role of soils in controlling methylmercury pollution in general.This proposal was submitted in response to the Environmental Geochemistry and Biogeochemistry solicitation NSF 99-9, and is being funded jointly by the Divisions of Chemistry, Earth Sciences, Ocean Sciences, and MPS Office of Multidisciplinary Activities.