沉积物是水环境中汞甲基化的主要场所。水环境中有机质的增加会改变汞的赋存状态、生物有效性、微生物群落、pH值、氧化还原电位及硫的存在形态，并最终影响汞的净甲基化率和迁移转化。水体富营养化导致沉积物中有机质逐年增加，使甲基化风险日益严峻，但其具体影响的机理和影响程度并不清楚。.本研究拟采用单一汞同位素加入法，对贵州省境内4个不同有机质输入来源的水体沉积物进行甲基化/去甲基化机理研究，测定其沉积物的甲基化速率、微生物活度、汞的赋存状态和含量、有机质的组成和结构等相关参数，以了解和掌握水体富营养化过程对沉积物中汞的甲基化/去甲基化机理,评估和预测水体富营养化带来的甲基化风险。

Sediment is a main site for mercury methylation in aquatic system. Organic matter input would effect on mercury species, bioavailability, microbes, pH, redox potential and sulfur species in sediment, finally change net methylation rate and mercury transformation and transportation. Eutrophicaiton of aquatic system leads to the increasing of organic matter and mercury methylation risk in sediment, gradually. The mechanism and degree of risk are not well known. .In this study, according to the difference of organic matter sources, the methylaion/demethylation rate, metabolic activity of microbes, mercury species and organic matter will be researched in sediment of 4 eutrophic aquatic systems using single mercury isotope spike technology. This project aims to understand well and master the mercury methylation/demethylation mechanism in sediment of eutrophic aquatic systems, and estimate and predict mercury methylation risk in eutrophic aquatic systems.