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

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。该项目将采用多学科方法，以内华达州卡森河为试验场，研究控制土壤中汞甲基化及其进入水生系统的因素。现场和实验室调查将包括分析汞的形态，测量甲基化、去甲基化和汞的还原，负责汞转化的细菌基因的分布和表达，以及应用汞生物传感器来调查汞的生物利用度。将进行操作实验，以确定干湿循环和氧气可得性对汞循环途径的影响。生物地球化学/分子结果将用于极大地改进汞运输模型，该模型将在低流量和高流量条件下进行经验测试。这些结果将描述对甲基汞的净形成和最终在污染场地的运输的控制，并将有助于了解土壤在控制甲基汞污染中的作用。该提案是响应环境地球化学和生物地球化学招标NSF 99-9而提交的，由化学、地球科学和海洋科学部联合资助。

Lyons9975414The 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, and Ocean Sciences.