上海市养殖池塘沉积物中重金属分布及生态风险评价

为了解养殖池塘沉积物中重金属分布概况评估其生态风险，2018年采集上海市范围内17个鱼虾蟹养殖池塘沉积物样品，检测样品中重金属（Cu、Zn、Pb、Cd、Cr、Hg、As）含量并进行多元统计分析以探究其分布和来源特点，利用3种不同评价方法评估其重金属生态风险。研究结果表明，池塘表层沉积物中Zn、Cr、Cu、Pb、As、Cd和Hg年均含量分别为（58.36±23.41） mg/kg、（41.96±11.92） mg/kg、（20.61±7.76） mg/kg、（10.87±5.83） mg/kg、（7.81±2.12） mg/kg、（0.13±0.05） mg/kg和（0.055±0.03） mg/kg，Cu、Zn、Pb、Cr、As的年均含量在不同养殖品种之间无显著差异（P>0.05），虾塘和蟹塘沉积物中Cd和Hg年均含量均显著高于鱼塘。池塘沉积物中重金属地质累积指数（I_geo）由高至低分别为Cd、As、Cu、Zn、Cr、Hg、Pb，属清洁等级的样品占比均高于95%。鱼、虾、蟹塘沉积物中重金属潜在生态危害指数（RI）平均值分别为56.94、76.51和69.65，均属低风险等级。一致性沉积物质量基准（CBSQGs）评价结果显示池塘沉积物样品中重金属的平均可能效应浓度商（M_PEC-Q）均低于0.5，即重金属整体上不会产生生物毒性效应。

Distribution and ecological risk assessment of heavy metals in the sediment of aquaculture ponds in Shanghai

The concentrations of heavy metals (Cu, Zn, Pb, Cd, Cr, Hg, and As) in the sediment which were collected from 17 ponds were determined to clarify their distribution characteristicsand evaluate their ecological risk in aquaculture ponds in Shanghai.Their distribution and sources were analyzed using multivariate statistics, and the ecological risk of heavy metal was assessed by three different methods.The results showed that the average concentrations of heavy metals in the surface sediment were as follows,Zn(58.36±23.41)mg/kg, Cr(41.96±11.92)mg/kg, Cu(20.61±7.76)mg/kg, Pb(10.87±5.83)mg/kg,As(7.81±2.12)mg/kg, Cd(0.13±0.05)mg/kg, Hg(0.055±0.03)mg/kg. There were no significant difference of the annual values of Cu,Zn,Pb,Cr, and As among the sediment from different aquaculture species(P>0.05),while the values of Cd and Hg in the sediment of shrimp and crab ponds were higher than fish ponds obviously (P<0.05). The order of geo-accumulation index (I_geo) of the heavy metals in the sediment were as follows, Cd > As > Cu > Zn > Cr > Hg > Pb, and more than 95%of the samples belong to unpolluted class. The potential ecological risk index (RI) of the heavy metals were 56.94, 76.51, and 69.65 in the sediment of fish, shrimp and crab ponds, respectively. They were all ranged to the low ecological risk grade.Evaluations of consensus-based sediment quality guidelines (CBSQGs) showed that the mean probable effect concentration quotients (M_PEC-Q) of samples were all lower than 0.5, which means that the combined effects of heavy metals in the sediment were not toxic.