衡水湖底泥重金属污染特征及生态风险评价

Pollution characteristics and ecological risk assessment of heavy metals in the sediment of Hengshui Lake

在衡水湖设置了11个采样点,分析底泥中重金属Cr、Ni、Cu、Zn、As、Cd、Pb、Mn、Co、Sb、Tl的浓度,运用地累积指数法、潜在生态风险指数法对重金属污染程度进行评价,采用SPSS软件进行Pearson相关性分析。结果表明:除Cd和Co外,衡水湖底泥中其他重金属浓度平均值均低于河北省A层土壤背景值,其中Cr、Ni、Cu、Zn、As和Pb浓度在各采样点均低于GB 15618—2018《土壤环境质量农用地土壤污染风险管控标准(试行)》中农用地土壤风险筛选值,Sb、Co浓度在各采样点均低于GB 36600—2018《土壤环境质量建设用地土壤污染风险管控标准(试行)》中建设用地土壤风险管制值,Cd浓度有8个采样点超过GB 15618—2018的农用地土壤风险筛选值,1个采样点高于GB 36600—2018的建设用地土壤风险管制值;地累积指数法评价结果表明,底泥中Cd总体为偏中度污染,Co总体为轻度污染,而Cr、Ni、Cu、Zn、As、Pb、Mn、Sb和Tl可视为无污染;潜在生态风险指数评价结果表明,衡水湖底泥中重金属RI平均值为270.79,属于中等生态危害,底泥中各重金属对衡水湖生态风险贡献率为Cd>>Co>As>Sb≈Pb>Cu>Ni>Cr>Mn≈Zn,其中Cd对RI的贡献率高达91%,是主要的污染因子,Cd污染可能是引黄河水入湖和人类活动等原因造成的。

Eleven sampling points were set in Hengshui Lake to analyze the concentration distribution of heavy metals including Cr,Ni,Cu,Zn,As,Cd,Pb,Mn,Co,Sb and Tl in sediment.The degree of heavy metal pollution was evaluated by the method of geo-accumulation index and potential ecological risk assessment index.Pearson correlation analysis was conducted by SPSS.The results showed that the average concentrations of other heavy metals in the sediment of Hengshui Lake were lower than the background value of Layer A soil in Hebei Province except for Cd and Co.The concentrations of Cr,Ni,Cu,Zn,As and Pb at each sampling point were lower than the soil risk screening values of agricultural land in Soil Environmental Quality,Agricultural Land Risk Control Standards for Soil Contamination(Trial)(GB 15618-2018).Sb and Co were lower than the soil risk control values of construction land in Soil Environmental Quality,Construction Land Risk Control Standards for Soil Contamination(Trial)(GB 36600-2018).There were 8 sampling points of Cd whose concentration exceeded the agricultural land risk screening value of GB 15618-2018,and 1 point was higher than the construction land risk control value of GB 36600-2018.The evaluation results of the geo-accumulation index method showed that Cd was generally moderately polluted,Co was generally mildly polluted,and the nine heavy metals of Cr,Ni,Cu,Zn,As,Pb,Mn,Sb and Tl could be regarded as non-polluted.The results of potential ecological risk index evaluation indicated that the impact degree of each pollutant on the ecological risk of Hengshui Lake was Cd>>Co>As>Sb≈Pb>Cu>Ni>Cr>Mn≈Zn.The RI average value was 270.79,which was a medium ecological hazard.However,the contribution rate of Cd to RI was as high as 91%,which was the main pollution factor.Cd pollution was possibly caused by Yellow River water diversion into the lake and other human activities.