太湖营养状态对沉积物中总汞和甲基汞分布特征的影响

为探讨营养状态对太湖沉积物汞的分布及其甲基化的影响,以太湖不同营养水平的湖区为研究对象,采用PSA和GC-CVAFS方法,分别测定了沉积物总汞(THg)、甲基汞(MeHg)含量;另测定了沉积物有机质含量和水体总氮、总磷浓度.结果显示,太湖表层沉积物THg含量为32.30~150.28ng/g,均值为62.94ng/g,含量高低与营养化程度一致,其垂向分布主要受到人为活动和有机质的影响;MeHg含量为0.32~1.01ng/g,均值为0.51ng/g,不同营养水平的湖湾区MeHg含量差别不大,其分布受有机质的影响,高含量富集在表层,随深度的增加逐渐降低并趋于稳定;甲基化比率比较低主要是太湖水体溶解氧含量高抑制了甲基化过程.

The Effect of nutrition status on sediments distribution characteristics of total mercury and methylmercury in Lake Taihu

In order to investigate the effects of nutritional status on the mercury (Hg) distribution and methylation of mercury (Hg) in the sediment in Lake Taihu, total mercury (THg) and methylmercury (MeHg) were determined by PSA and GC-CVAFS for sediment samples collected from areas with different levels of trophic level. The organic matter content in sediment, total nitrogen (TN) and total phosphorus (TP) in overlying water were also measured. The results showed that the average concentration of THg in surface sediment was 62.94ng/g with a range from 32.30 to 150.28ng/g, correlating well with trophic levels. The vertical profile of THg was influenced by anthropogenic activities and organic matter. MeHg concentrations in the sediment ranged from 0.32 to 1.01ng/g with an average of 0.51ng/g. There were no significant differences among MeHg levels in the bay areas with different trophic status. The concerntration of MeHg was affected by organic matter content, with higher levels of MeHg being observed in surface sediment and decreasing with increasing depth until reaching a stable level. The methylation ratio of Hg was low in Lake Taihu, probably due to high dissolved oxygen in water that inhibits methylation process.