东洞庭湖湿地土壤重金属污染特征及潜在生态风险评价

摘要

Soilsin three typicalbottom lands(X iaoxihu,Lium enzha and M atang)around EastD ongting w ere sam pled and the contents of heavy m etals in the soils w ere analyzed. T he characteristics of heavy m etal pollution and potential ecological risks w ere evaluated using the single factor pollution index m ethod, N em erow com posite index m ethod and Hakansonpotentialecologicalrisksindexmethod.Theresultsshowed that the contentsofCd,Cr,Ni,Pb,Hg,andAsin soils from the three bottom lands w ere 0.59-2.40 m g/kg, 114.52-119.94 m g/kg, 53.49-66.59 m g/kg, 42.88-83.46 m g/kg, 0.09-0.21 m g/kg and 11.65-24.04 m g/kg respectively. A nd the values of six indexes of heavy m etals in the M atang bottom lands w ere higher than those in the X iaoxihu and L ium enzha bottom lands. O f the six kinds of heavy m etals, C d pollution w as the m ostsevere one,as the contentofC d in M atang w as 7 tim es m ore than the background value,and 3.8 tim esand 4.1 tim esm ore than the contentsofX iaoxihu and Lium enzha respectively.The single factorpollution index of different heavy m etals w ere as follow s, C d > N i> H g > A s> Pb > C r, w hich also show ed that the heaviest polluted bottomlandswasinM atang,andtheninXiaoxihu,andthelightestpollutedbottomlandswasinLiumenzha.Thepotential ecologicalrisksindex ofheavy m etalsand pollution grading evaluation show ed thatthe soilsin Lium enzha and X iaoxihu w ere at low ecological risk, w hile the soils in M atang w as at m oderate ecological risk. T herefore, the heavy m etal pollution in the bottom lands around D ongting Lake,especially in the area w hich connected to X iangjiang R iver,should be attracted m ore and m ore attention and effective m easures should be take to handle the heavy m etal pollution in this district.%选择东洞庭湖3个典型洲滩（小西湖、六门闸和麻塘）进行土壤取样，分析其土壤重金属含量，并应用单项污染指数法、内梅罗综合污染指数法以及Hakanson潜在生态危害指数法对土壤中重金属污染特征和潜在生态危害进行了评价。结果表明，东洞庭三个洲滩区域（小西湖、六门闸和麻塘）土壤重金属Cd、Cr、Ni、Pb、Hg、As的含量分别为0.59-2.40 mg/kg,114.52-119.94 mg/kg,53.49-66.59 mg/kg,42.88-83.46 mg/kg,0.09-0.21 mg/kg and 11.65-24.04 mg/kg，麻塘洲滩中的6种土壤重金属指标均高于小西湖和六门闸两个洲滩，其中Cd问题突出，Cd含量是背景值的7倍，是小西湖和六门闸的3.8和4.1倍。单项污染分级评价表明，研究区重金属污染程度依次为Cd>Ni>Hg>As>Pb>Cr，以麻塘最为严重，小西湖次之，六门闸基本不存在污染。潜在生态危害系数和污染分级评价表明，麻塘达到中度生态危害，小西湖和六门闸则为低度生态危害。因此，东洞庭湖洲滩湿地土壤，尤其是与湘江航道相连的地区，土壤重金属污染问题值得高度关注，需采取合理措施进行治理。