巢湖沉积物氮磷分布及污染评价

Distribution of Nitrogen and Phosphorus in Lake Chaohu Sediments and Pollution Evaluation

以巢湖为研究对象,分析了沉积物中氮磷等营养盐的分布特征及储量信息,并对巢湖沉积物氮磷污染指数进行评价.结果表明,巢湖表层沉积物总氮(TN)和总磷(TP)平均含量为1088 mg·kg^(-1)和585 mg·kg^(-1),底层为666 mg·kg^(-1)和509mg·kg^(-1),表层总氮含量显著高于底层(P<0.01);总氮、总磷与沉积物厚度空间分布特征为:西湖区>东湖区>中湖区,中湖区表层沉积物总氮和总磷含量与东湖区存在差异显著(P<0.05,P<0.01);全湖沉积物总氮和总磷储量分别为1.58×10^(5)t和0.98×10^(5)t.TN与TP在西湖区和中湖区均表现出极显著正相关(P<0.01),其中中湖区表层沉积物TN与沉积物厚度也呈显著相关,表明沉积物氮磷可能有相同的污染源,沉积物厚度影响了TN含量.全湖总氮污染指数(STN)、总磷污染指数(STP)和综合污染指数(FF)值分别为1.09、1.39和1.32,为轻度-中度污染,其中,西湖区表层沉积物TP为重度污染,东湖区为中度污染,中湖区为轻度污染,表明巢湖不同湖区污染差异较大,西湖区沉积物存在较大的安全风险,水体面临富营养化威胁.

We investigated the spatial distribution and storage of nitrogen and phosphorus in Lake Chaohu sediments and evaluated the sediment nitrogen and phosphorus pollution index.Results show that the average total nitrogen(TN)and total phosphorus(TP)content in the surface-layer sediments of Lake Chaohu were 1088 mg·kg^(-1) and 585 mg·kg^(-1),respectively,and 666 mg·kg^(-1) and 509 mg·kg^(-1) in the bottom-layer sediments,respectively.TN content in the surface layer was significantly higher than in the bottom layer(P<0.01).Spatially,TN,TP,and sediment thickness were ranked in the order western lake area>eastern lake area>middle lake area,and the TN and TP contents were significantly different in the surface sediments from the middle and eastern areas of the lake(P<0.05,P<0.01).TN and TP storage in the lake sediments was 1.58×10^(5) t and 0.98×10^(5) t,respectively.TN and TP were significantly correlated in both the western and middle parts of the lake(P<0.01).In addition,TN was significantly correlated with sediment thickness in middle area of the lake,which indicated that TN may have the same pollution sources as TP and both were affected by sediment thickness.TN pollution index(STN),TP pollution index(STP),and comprehensive pollution index(FF)values were 1.09,1.39,and 1.32,respectively,indicating light-to-moderate levels of pollution.Specifically,the western lake surface sediments were heavily polluted with respect to TP,the eastern lake surface sediments were moderately polluted,and the middle lake surface sediments were slightly polluted.Nutrient pollution varied widely between different areas of the lake,with sediments in the western part of the lake presenting a higher safety risk.Overall,these observations indicate that Lake Chaohu is threatened by internal nutrient loading.