崇明东滩湿地沉积物中汞累积特征及其影响因素研究

湿地是汞的活性库,研究湿地汞的累积特征对揭示湿地汞生物地球化学过程及其生态效应等均具有重要意义. 通过分析崇明东滩沉积物汞累积特征,为进一步深入研究湿地汞的地球化学循环和湿地环境保护提供依据. 采集了崇明东滩湿地高潮滩、中潮滩、中潮滩植被带前缘3个柱状沉积物样品,测得沉积物中w(Hg)为0.015～0.315 mg/kg. 利用地累积指数法对潮滩沉积物中汞的污染状况进行了评价,结果表明:崇明东滩沉积物存在轻度的汞污染. 同时对w(Fe),w(Mn),w(有机质)及粒度等理化参数进行了测定. 采用相关性分析,探讨沉积物中w(有机质),w(Fe),w(Mn)和粒度对沉积物汞累积的影响,指出有机质和铁、锰循环是影响沉积物中汞累积的主导因素,而粒度不是控制因素.

Cumulation Characteristics and Influencing Factors of Mercury in Sediments from Chongming Wetland

Wetlands are active storage places of mercury. It is of great significance to research the accumulation of mercury in wetlands to understand the biogeochemical cycle of mercury and the ecological impacts on the wetlands. Investigating the mercury accumulation in sediments of Chongming Wetland can provide a foundation for future research on the biogeochemical cycle of mercury in wetlands and environmental protection of wetlands. The contents of mercury, iron, manganese, and organic matter, as well as the grain sizes of three cores from the high, medium flat and the front of medium tidal flat vegetation zones in Chongming Wetland were investigated. The distribution characteristics of mercury in the sediments were analyzed. The mercury content in the sediments of Chongming Wetland ranged from 0.015-0.315 mg/kg. The index of geoaccumulation I_(geo) was used to evaluate the enrichment and pollution of mercury in the sediments. The analytical results show that the mercury accumulation in Chongming Wetland reached the slightly-polluted level. To some extent, there is an enrichment of mercury. By means of correlation analysis, environmental factors such as organic matter content, iron, manganese and grain size affecting Hg concentration variation in the sediments were explored, suggesting that organic matter, iron and manganese play an important role in mercury accumulation in tidal flat sediments. The grain size of sediment is not the main factor in the geochemical cycle of mercury in tidal flat sediments.