富含人为输入营养物质的沉积物对汞转化与鱼汞富集的影响

我国大量水域都曾进行过各种形式的水产养殖活动，由于大量投放饲料，导致部分饲料沉降进入沉积物中，致使养殖区域沉积物营养物质异常丰富。饲料中的有机质、氮、磷、硫等营养物质，会影响到沉积物的氧化还原电位等理化性质、以及微生物活动等对汞转化（特别是甲基化）起决定性作用的因素。由此可见，由水产养殖活动带来的大量营养物质输入势必会影响汞在水生生态系统中的迁移转化。为探明其影响机制，本申请拟选择曾进行过高密度网箱养殖的重庆市长寿湖为研究对象，通过现场定点采样分析，摸清长寿湖不同区域（原养殖区和非养殖区）沉积物中汞形态以及微生物区系、理化性质等相关因素的季节变化特征；采集原状沉积物柱，利用稳定同位素示踪技术，研究不同营养物质输入对沉积物中汞甲基化/去甲基化作用机制；利用微宇宙模拟装置，探讨不同营养沉积物对水生食物链汞富集过程的影响。目的为预测渔业生产过程中人为营养物质输入可能引起的汞问题提供科学依据。

Various forms of aquaculture activities have been carried out in a large number ofwaterbodies in China. Due to intensive feeding, portions of fish food settle intosediments, resulting in abnormally rich nutrients in certain culture areas.Nutrients in fish food, including organic matter, nitrogen, phosphorus, sulfur,…etc., could affect the physical and chemical properties, such as the redoxpotential, of the sediment as well as the factors that play a critical role inmercury (Hg) transformation (especially methylation). Therefore, the input oflarge amounts of nutrients by aquaculture activities will inevitably affect themigration and transformation of Hg in aquatic ecosystems. In order to study itsimpact mechanism, this study selected Changshou Lake in Chongqing, which has been engaged in high-density cage culture, as the research site. Through field sampling, specific seasonal characteristics of Hg species, microflora, physicochemical properties and other related factors in sediments from both cultured areas and non-cultured areas of Changshou Lake will be examined. The undisturbed sediment column will be collected, and the mechanism of Hg methylation/demethylation in sediments by different levels of nutrient inputs will be studied using a stable isotope tracer technique. The effects of different nutrient sediments on the Hg bioaccumulation process of aquatic food chains will be investigated using a microcosm simulation device. The aim of this study is to provide a scientific basis for predicting potential Hg-associated concerns caused by the input of anthropogenic nutrients by the fishery industry.