太湖北部小流域沉积物重金属污染特征与评价

近几十年来重金属的沉积记录、来源及污染水平受到了广泛关注.为探明太湖北部小流域重金属的污染来源和环境质量状况，本研究分析了柱状沉积物中8种重金属（Mn、Cr、Zn、Cu、As、Pb、Ni和Co）含量.运用主成分分析法判定污染源，富集因子法表征重金属富集特征，通过熵权模糊模型对沉积物中重金属污染状况进行评价.结果显示，所有重金属含量均较高，高低依次为Mn > Cr > Zn > Cu > As > Pb > Ni > Co.其中Mn含量最高，为380.06~767.69μg/g.沉积物重金属污染的主要贡献因子为交通排放、农业污染和煤炭燃烧.As的富集指数最大（2.89~15.61）.其中77.59%的沉积层属于显著富集，受人类活动影响最为显著.熵权模糊综合评价结果表明，Cu（0.483）和As（0.352）的权重值最大，是沉积物中的首要污染物，且65.52%的沉积层重金属含量处于中度污染水平.

Characteristics and assessment of heavy metals pollution in the sediments from a small catchment in northern Taihu Basin

In recent decades, more attention has been focused on the sedimentary record, sources and pollution level of heavy metals. In order to identify the sources of heavy metals and assess the environmental quality of the small catchment in northern Taihu Basin, the concentrations of eight heavy metals including Mn, Cr, Zn, Cu, As, Pb, Ni and Co in the profile of sediments were analyzed. A series of methods e.g. principal component analysis, the enrichment factor method and the entropy weight fuzzy model were used to determine the pollution sources, define the heavy metal enrichment degree and evaluate the pollution level of heavy metals in the sediments. Results showed that all of the heavy metals concentrations were high, and the order was Mn > Cr > Zn > Cu > As > Pb > Ni > Co. Among them, the concentration of Mn was the highest (380.06~767.69 μg/g).Traffic emissions, agricultural pollution and coal combustion were the main contributors to heavy metal pollution in the sediments. The enrichment index of As was the largest(2.89~15.61), of which 77.59% of the sedimentary layers were significantly enriched and greatly influenced by human activities. The synthetic fuzzy comprehensive evaluation indicated that Cu (0.483) and As (0.352) had the largest weight value, being the primary pollutant in the sediments. Besides, 65.52% of the sedimentary heavy metals in the profile were in moderate pollution level.