蠡湖沉积物现状调查及表层沉积物污染评价

Investigation on the current situation of sediment and pollution assessment of surface sediment in Lihu Lake

将蠡湖分成5个区域,于2019年10月对蠡湖沉积物的淤积深度和淤积特点进行调查,测定沉积物中有机质(OM)、总氮(TN)、总磷(TP)的含量,并通过有机污染指数法和综合污染指数法对蠡湖污染程度进行了评价。结果表明:1)蠡湖底泥平均淤积深度为0.35 m,越向湖心越浅,平均淤积深度A区最浅,B区最深;2)蠡湖沉积物中TP含量属于二级,OM含量和TN含量属于三级;D区与A、B区的TP含量差异较大:3)蠡湖表层沉积物中有机物为中度污染,氮、磷为重度污染,D区磷的污染最严重,B区氮和有机物的污染较轻;4)污染评价中,以1960年太湖沉积物中的氮磷背景值和加拿大1992年发布的引起最低级别生态风险效应的总氮、总磷阈值为基准的氮污染指数S_(TN)和综合污染指数FF评价结果一致;以美国沉积物基准值和1960年太湖沉积物中的氮磷背景值为基准的磷污染指数S_(TP)评价结果一致。

The Lihu Lake was divided into 5 areas,and the deposition depth and characteristics of Lihu Lake sediment were investigated in October 2019.The content of organic matter(OM),total nitrogen(TN)and total phosphorus(TP)in the sediment were determined,and the pollution degree of Lihu Lake was evaluated by organic pollution index method and comprehensive pollution index method.The results showed that:1)The average depth of sediment deposition in Lihu Lake was 0.35 m,the shallower the lake center was,the average deposition depth of area A was the shallowest and that of area B was the deepest.2)TP content in Lihu Lake sediment belonged to the second level,OM content and TN content belonged to the third level.There was significant difference in TP content between D area and A,B area.3)The organic matter in the surface sediment of Lihu Lake was moderately polluted,while the pollution of nitrogen and phosphorus was serious.The phosphorus pollution in area D was the most serious,while the pollution of nitrogen and organic matter in area B was light.4)In the pollution assessment,the assessment results of nitrogen pollution index STN and comprehensive pollution index FF based on the background value of nitrogen and phosphorus in the sediment of Taihu Lake in 1960 and the thresholds of total nitrogen and total phosphorus for the lowest level of ecological risk effect issued by Canada in 1992 were consistent.The assessment results of phosphorus pollution index STP based on the U.S.sediment baseline and the background value of nitrogen and phosphorus in Taihu Lake sediment in 1960 were consistent.