洪泽湖围栏养殖对表层沉积物重金属含量影响与生态风险评价

为探讨洪泽湖全湖沉积物重金属分布特征及围栏养殖对其影响，于2018年洪泽湖部分围栏拆除后，对洪泽湖不同区域（河口、湖心、围栏区、拆除区和外围区）表层沉积物中重金属含量、来源和空间分布特征进行分析，评估其生态风险.结果表明，洪泽湖表层沉积物中Cr、Ni、Cu、Zn、As、Cd和Pb含量均值分别为66.78、33.89、25.35、74.77、16.55、0.23和27.20mg ·kg^-1.采用地累积指数和Hakanson潜在生态风险指数对沉积物重金属污染现状和潜在生态风险程度的评价表明，除了As和Cd元素处于较轻污染程度，其余元素Cr、Ni、Cu、Zn和Pb均处于无污染；除Cd存在严重的潜在生态风险，其余元素均只有低水平潜在生态风险.结果表明围栏区、拆除区和外围区之间的重金属含量呈现递增趋势，并向湖心蓄积，拆除围栏并未在短时间内明显降低重金属含量.洪泽湖整体呈现低生态风险的状态，今后治理重点应是北部及东北部的表层沉积物堆积区和养殖区.

Impact of Enclosure Culture on Heavy Metal Content in Surface Sediments of Hongze Lake and Ecological Risk Assessment

In order to explore the concentrations of heavy metals and the influence of fencing on Hongze lake, the content, source, and spatial distribution characteristics of heavy metals in surface sediments and ecological risks were analyzed in 2018 after part of the fence around Hongze Lake was removed. The results showed that the average contents of Cr, Ni, Cu, Zn, As, Cd, and Pb in the surface sediments in Hongze Lake were 66.78, 33.89, 25.35, 74.77, 16.55, 0.23, and 27.20 mg·kg^-1, respectively. Cr, Ni, Cu, Zn, and Pb contents were at non-polluting levels, with As and Cd at the lowest level, based on the accumulation index evaluation. Except for Cd, all the elements showed low potential ecological risk. The results showed that the heavy metal content in the fenced, dismantled, and peripheral areas increased and accumulated towards the center of the lake. The removal of the fence did not significantly reduce the heavy metal content in the short-term. Overall, Hongze Lake presented a state of low ecological risk. In the future, environmental policies should include surface sediment accumulation areas and fencing culture in the north and northeast of Hongze Lake.