安徽庐江尾矿区河流重金属分布及污染评价

Heavy metal distribution and pollution evaluation of rivers along mining area in Lujiang County, Anhui Province

利用BCR法提取、分析安徽省庐江县失曹河与黄屯河沉积物重金属形态及含量,并开展污染程度和生态风险评价,分析了该地区受铁矿酸性矿山废水影响的河流重金属污染状况.结果表明,两条河流沉积物重金属Zn、Cu、Pb和Cd含量均值超过长江水系沉积物背景值.两条河流沉积物中Ni、Zn和Pb以残渣态为主,对环境危害较小;Cu以可氧化态为主,Mn和Cd以可还原态和残渣态为主,有潜在环境危害.相关分析表明,Cu的弱酸提取态含量受粒度影响较大.地累积指数(Igeo)评价结果表明,失曹河重金属Igeo顺序为Cu>Cd>Zn>Pb>Mn>Ni,Cu和Cd的Igeo均值分别为2.05和1.19,属中度和偏中污染;黄屯河重金属Igeo顺序为Cu>Cd>Pb>Zn>Ni>Mn,Cu的Igeo均值为2.25,属中度污染.潜在生态风险指数评价结果表明,两条河流沉积物重金属潜在生态风险强度为Cd>Cu>Pb>Ni>Zn>Mn.失曹河Cd和Cu的潜在生态风险系数(Eir)均值分别为162.81和57.03,属很强和中等级别;黄屯河Cd和Cu的Eir均值分别为80.62和46.97,属强和中等级别,表明Cd和Cu为主要风险因子.与铜陵受硫铁矿影响的河流对比表明,庐江受酸性矿山废水影响河流沉积物的金属含量相对较低,污染相对较轻.

The heavy metal distribution and pollution of two rivers affected by acid mine drainage(AMD)in Lujiang County were reported in this study.The results showed that the average concentrations of Zn,Cu,Pb and Cd in these two rivers exceeded the baseline of sediments in the Yangtze River.For the speciation of heavy metals,residual species was the main form of Ni,Zn and Pb,which was stable with less harmful to the environment;Oxidizable species was the main form of Cu,and the reducible and residual species of Mn and Cd.Correlation analyses indicated that the weak acid-extraction of Cu in river sediments was affected by grain size greatly.The Igeo of heavy metals in Shicao river was Cu>Cd>Zn>Pb>Mn>Ni,with a mean of 2.05 for Cu and 1.19 for Cd,respectively,corresponding to moderate and partial moderate pollution level.The Igeo of Huangtun river was Cu>Cd>Pb>Zn>Ni>Mn,with an average of 2.25 for Cu,corresponding to moderate pollution level.The potential ecological risk of heavy metals in these two rivers was Cd>Cu>Pb>Ni>Zn>Mn.The Eir of Cd and Cu in Shicao river were 162.81 and 57.03,respectively,indicated very strong and medium ecological risk,respectively;The Eir of Cd and Cu in Huangtun river were 80.62 and 46.97,indicated strong and medium ecological risk,respectively.It indicated that Cd and Cu were the main risk factors.Both of Shicao and Huangtun rivers affected by AMD at Lujiang County showed a low level of heavy metal pollution in contrast to those at Tongling City.