Distribution and Ecological Risk Assessment of Mercury in Water, Sediments and Typical Aquatic Organisms from Northern Taihu Lake

Taihu Lake, the second largest freshwater lake in China, has become polluted in recent years. However, there is little information about mercury pollution. In this study, mercury contents in water, sediments and typical aquatic organisms in Northern Taihu Lake were determined using a NIC MA-800 Mercury Analyzer. Single Pollution Index and Index of Geoaccumulation were used to assess ecological risks of mercury. The results showed that mercury concentrations in aqueous phase in three bays of Northern Taihu Lake were lower than the secondary-level standard of the National Surface Water Environment Quality Standard(≤50 ng·L-1). The average mercury concentration in sediments from Gonghu Bay and Meiliang Bay was below the primary standard of the National Soil Environmental Quality Standard(≤150ng·g-1), whereas higher from Zhushan Bay. Mercury ecological risks was in order of Zhushan Bay(moderate pollution)Gonghu Bay(partial moderate pollution)Meiliang Bay(mild pollution). Mercury contents in typical aquatic organisms(snail, corbicula and fish)were all lower than the criteria for Agricultural Product-Safety Standards for Non-Pollution Aquatic Products of China(≤300 ng·g-1). Mercury concentrations in typical aquatic organisms were fish(mild pollution)corbicula(normal background)snail(normal background level), with Zhushan BayGonghu BayMeiliang Bay. Compared with the results from previous studies, mercury concentrations in Northern Taihu Lake were elevated. Greater efforts should be made to monitor mercury pollution in Northern Taihu Lake.