滆湖表层沉积物营养盐和重金属分布及污染评价

Distribution and Pollution Assessment of Nutrient and Heavy Metals in Surface Sediments from Lake Gehu in Southern Jiangsu Province,China

为了揭示滆湖表层沉积物营养盐及重金属分布和污染特征,2014年1月采集了滆湖湖北区、湖中区和湖南区共20个沉积物样品.分析了沉积物营养盐和重金属的水平分布特征,并对营养盐及重金属的污染特征和来源进行了研究.结果表明,滆湖沉积物总氮(TN)和总磷(TP)的平均含量分别为2 207.94 mg·kg^(-1)和708.62 mg·kg^(-1),其中湖中区(N=20,P=0.027)和湖南区(N=20,P=0.005)TN及湖中区(N=20,P=0.005)TP含量显著大于湖北区;重金属(Zn、As、Cr、Cu、Ni、Pb、Cd、Hg)的平均含量分别为766.59、350.66、307.98、59.54、122.67、168.97、2.34和0.41 mg·kg^(-1),其中湖中区的Cu含量显著(N=20,P=0.013)大于湖北区,湖中区的Zn含量显著(N=20,P=0.024)大于湖南区,其它重金属元素含量在3个湖区的差异性不显著(P<0.05).除TP、Cu和Hg与粒径之间有一定的相关性,其它元素与粒径的相关性不明显.营养盐污染评价中,综合污染指数(PI)表明滆湖处于严重污染,且湖中区和湖南区比湖北区污染更为严重.潜在生态风险评价中,重金属Cd、As和Hg均已达到很强到极强污染程度,其余重金属则处于轻微到中等污染水平,重金属潜在生态风险指数(RI)表明滆湖沉积物存在很强到极强的潜在生态风险,其中Cd、As和Hg对RI的贡献最大.

This study investigated the horizontal distribution characteristics of nutrients and heavy metals（ Zn,As,Cr,Cu,Ni,Pb,Cd and Hg） in January,2014,and assessed the potential ecological risk of Lake Gehu. It was found that the average contents of TN and TP were 2 207. 94 and 708. 62 mg·kg^（-1）,respectively. TN and TP contents of the sediments at the centre were significantly higher than those in the north,while the TN content in the south was also significantly higher than that in the north of Lake Gehu. The average contents of Zn,As,Cr,Cu,Ni,Pb,Cd,Hg were 766. 59,350. 66,307. 98,59. 54,122. 67,168. 97,2. 34,0. 41 mg·kg^（-1）,respectively. The content of Cu at the centre was significantly higher than that in the north,and the Zn content at the centre was significantly greater than that in the south of Lake Gehu,however the difference in the content of other heavy metals at these three areas was not significant. Furthermore,the obvious correlation between elements and granularity was only found in the aspect of TP,Cu and Hg. The comprehensive pollution index（ PI） indicated that the Lake Gehu was heavily polluted,especially the centre and south areas.The potential ecological risk index（ RI） showed that Cd,As and Hg had caused serious pollution in Lake Gehu while the other heavy metals only induced slight or medium pollution. According to the contribution of Cd,As and Hg to RI,it was concluded that the sediments in Lake Gehu were at a serious potential ecological risk.