水源水库沉积物中营养元素分布特征与污染评价

Distribution Characteristics and Pollution Status Evaluation of Sediments Nutrients in a Drinking Water Reservoir

为了揭示水源水库沉积物中的营养元素分布对水体富营养化的影响,以周村水库为研究对象,采用现场取样及实验室分析方法,探究了沉积物中营养元素的分布特征,并对TOC与TN、TP的相关性进行了分析,同时参考沉积物质量评价指南并采用综合污染指数对沉积物的污染状况进行了评价.结果表明,周村水库研究区域沉积物TOC含量均随深度增加而下降,而沉积物中氮负荷有增加的趋势,磷则表现出表层富集现象,表明周村水库沉积物营养盐负荷在加重;TOC与TN、TP存在较好的相关性,相关系数分别为r=0.68(P<0.01)、r=0.89(P<0.01),TOC/TN值表明,纤维束植物碎屑是水库沉积物有机质的主要来源;综合污染指数评价结果表明,3个采样点表层沉积物均达到重度污染程度,表层沉积物中TN、TP含量分别为3 273~4 870 mg·kg^(-1)、653~2 969 mg·kg^(-1),TOC含量为45.65~83.00mg·g^(-1),均超过沉积物质量评价指南规定的引发最低级别生态毒性效应的标准值,周村水库沉积物存在较大安全风险,水体面临富营养化威胁.

The main purpose of this paper is to illustrate the influence of nutrients distribution in sediments on the eutrophication of drinking water reservoir.The sediments of three representative locations were field-sampled and analyzed in laboratory in March 2015.The distribution characteristics of TOC,TN and TP were measured,and the pollution status of sediments was evaluated by the comprehensive pollution index and the manual for sediment quality assessment.The content of TOC in sediments decreased with depth,and there was an increasing trend of the nitrogen content.The TP was enriched in surface sediment,implying the nutrients load in Zhoucun Reservoir was aggravating as the result of human activities.Regression analysis indicated that the content of TOC in sediments was positively correlated with contents of TN and TP in sediments.The TOC /TN values reflected that the vascular land plants,which contain cellulose,were the main source of organic matter in sediments.The comprehensive pollution index analysis result showed that the surface sediments in all three sampling sites were heavily polluted.The contents of TN and TP of surface sediments in three sampling sites were 3 273-4870 mg·kg^-1 and 653-2 969mg·kg^-1,and the content of TOC was 45.65-83.00 mg·g^-1.According to the manual for sediment quality assessment,the TN,TP and TOC contents in sediments exceed the standard values for the lowest level of ecotoxicity,so there is a risk of eutrophication in Zhoucun Reservoir.