南四湖及主要入湖河流沉积物金属空间分布特征与污染评价

Spatial Distribution and Contamination Evaluation of Metals in Sediments from Nansihu Lake and Its Main Inflow Rivers

对南四湖湖区及其主要人湖河流表层沉积物中金属元素质量分数进行了测试分析．结果表明，14种金属元素可分为3类组合：Ca和Sr为第1组元素；Al，Fe，Na，K，Mg，Ni，V和Ti为第Ⅱ组元素；第Ⅲ组元素包括Zn，Cr，Cu和Pb．其中，第1组元素在独山湖区及微山湖区质量分数较高，与第Ⅱ组元素变化趋势相反，这2组元素主要为流域自然来源；第Ⅲ组元素在老运河、白马河上游、洗府河下游及人湖口沉积物中质量分数较高，可能受到人为污染的影响．此外，其他表层沉积物中第Ⅱ组元素与第Ⅲ组元素质量分数具有相似的变化规律．选取流域非耕作土壤样品作为背景，采用参比元素校正及沉积物富集系数法，对Zn，Cr，Cu和Pb等重金属元素的人为污染特征进行了定量评价．结果显示：老运河沉积物中Cr和Pb的富集系数为3．7和3．9，具有中等程度的人为污染特征．Cu和Zn的富集系数达到16．6和22．0，具备重或严重的人为污染特征．Zn和Cu在洗府河下游及入湖口、白马河上游沉积物中的富集系数为2．0～7．1，具有中等或较重的人为污染特征．其余表层沉积物中Zn，Cr，Cu和Pb的富集系数均低于2．0，基本未受到人为污染的影响．

The concentrations of 14 metals in surface sediments from Nansihu Lake and its main inflow rivers were determined. The metals could be classified into three groups according to their spatial variation. The first group, including Ca and St, showed high concentrations in the sediments from Dushan Lake and Weishan Lake area. The second group, including Al, Fe, Na, K, Mg, Ni, V and Ti, which are mainly from the natural source of the river basin, showed opposite spatial variation in concentration as compared with elements in the first group. The third group was composed of Zn, Cr, Cu and Pb, which had high concentrations in the sediments from the Laoyun River, upstream of the Baima River, downstream of the Guangfu River and the estuary, indicating anthropogenic input influence. Moreover, the concentrations of the metals in the third group had similar variation with the elements in the second group in the other sediments. The anthropogenic enrichment factors （EF） for Zn, Cr, Cu and Pb could be quantified with the local noncultivated soil samples using the background values and Al as the reference element. In the Laoyun River, the EFs of Cr and Pb were3.7 and 3.9, indicating moderate human contamination, while the EFs of Cu and Zn were 16.6 and 22. 0, showing significant to very high human contamination. Downstream of the Guangfu River and in its estuary, and upstream of the Baima River, the EFs of Cu and Zn were 2.0-7.1, indicating moderate to significant human contamination. Nevertheless, the EFs of Zn, Cr, Cu and Pb in the other sediments were all below 2.0, indicating minimal contamination.