中国七大水系沉积物中典型重金属生态风险评估

摘要

为评价国内水系重金属生态风险,根据2000-2015年国内外文献报道,选择中国七大水系——长江水系、黄河水系、辽河水系、松花江水系、海河水系、淮河水系和珠江水系的沉积物,以Cu、Cd、Pb、Zn、Ni等5种典型重金属为研究目标,对其质量分数及分布特征进行了系统分析;并利用生物效应数据库法对5种重金属的淡水水体沉积物质量基准值——TEL(临界效应浓度)和PEL(可能效应浓度)进行了更新.结果表明:Cu、Cd、Pb、Zn、Ni的新TEL分别为56.2、2.58、47.3、79.9和35.4 mg/kg,新PEL分别为141、19.6、200、461和78.6 mg/kg.七大水系以珠江水系沉积物中Cu、Cd、Pb、Zn、Ni的浓度最高,海河水系和黄河水系次之,而长江水系、辽河水系、松花江水系和淮河水系沉积物中重金属浓度较低.通过比较生物效应数据库法更新的沉积物质量基准值与实际沉积物重金属浓度,评价中国重点水系沉积物生态风险所得结论与国内外研究结果基本一致.研究显示,重金属对中国七大水系沉积物的污染大多处于生态风险较小或风险不确定的水平,其中仅有1.15％ ～7.60％的采样点重金属生态风险较高;七大水系以珠江水系沉积物生态风险最高,其5种重金属质量分数最高,并且超过各自PEL的采样点占比在4.41％～26.8％之间;其次,海河水系沉积物也存在一定的重金属生态风险,其Cu、Zn和Ni的质量分数较高,超过各自PEL的采样点分别占14.1％、15.2％和14.8％.%In order to evaluate the ecological risks of heavy metals in freshwater sediments,according to the data reported in the literatures over the past 16 years (2000 to 2015),the concentrations and distributions of five typical heavy metals (i.e.,Cd,C u,Ni,Pb and Zn)in the sediments of seven major watersheds in China,including Yangtze River,Yellow River,Liaohe River,Songhua River,Haihe River,Huaihe River and Pearl River,were systematically analyzed.The sediment quality guidelines,including the threshold effect levels (TEL) and probable effect levels (PEL),for the five heavy metals were updated based on the biological effect database.TELs and PELs of Cu,Cd,Pb,Zn and Ni were 56.2,2.58,47.3,79.9,35.4 mg/kg and 141,19.6,200,461,78.6 mg/kg respectively.The concentrations of Cu,Cd,Pb,Zn and Ni in the sediments of the Pearl River were the highest among the seven rivers,followed by the Haihe and Yellow Rivers.The concentrations of heavy metals in the Yangtze River,Liaohe River,Songhua River and Huaihe River were relatively low.Comparing the heavy metal concentrations with the corresponding sediment quality guidelines,the ecological risks of the five heavy metals in the river sediments were evaluated,and the results were basically identical with the domestic and foreign research.The results indicated that the ecological risks of heavy metals in most of the river sediments were relatively low or not clear.Among all of the investigated river sediments,1.15％-7.60％ displayed relatively high risk of heavy metals.The sediments of the Pearl River displayed the highest ecological risks,given that the concentrations of the five heavy metals were the highest and 4.41％-26.8％ of the sampling sites exceeded the PELs,which was followed by Haihe River.The concentrations of Cu,Zn and Ni in the sediments of Haihe River were relatively high,and 14.1％,15.2％ and 14.8％ of the sampling sites exceeded their corresponding PELs.