典型城郊湖泊沉积物重金属生态风险评价

POTENTIAL ENVIRONMENT RISK ASSESSMENT OF SEDIMENT HEAVY METALS IN A TYPICAL SUBURBAN SHALLOW LAKE

城郊浅水湖泊沉积物通常受到不同程度的污染,并面临重金属污染积累和生态风险增加的问题。以典型城郊浅水湖泊北麻漾近岸表层沉积物为研究对象,分析各重金属的分布特征,并利用地积累指数法(Igeo)和潜在生态风险指数法(RI)评价重金属生态风险。结果表明:表层沉积物中Cr、Ni、Cu、Zn、Cd、Pb含量均不同程度超过环境背景值,体现出一定的污染积累特征;地积累指数法评价所得风险顺序为Cu>Cd>Zn>Ni>Pb>Cr>Hg,潜在生态风险指数法获得单一重金属潜在生态风险顺序为Cd>Hg>Cu>Pb>Ni>Cr>Zn,两种评价结果均显示出以Cd为主,多种重金属复合污染的特征。综合潜在生态风险指数表明入湖河口区风险等级较高,外源输入对沉积物重金属污染影响显著。

Sediments in suburban shallow lakes are usually polluted in different levels and facing problems such as accumulation of heavy metal pollution and increasing of ecological risk. This research focused on heavy metals in surface sediments of near shore area of Lake Beimayang,a typical suburban shallow lake. Distributions and pollution characteristics of different heavy metals were studied. Geoaccumulation index( Igeo) assessment and potential ecological risk index( RI)assessment were employed to evaluate the ecological risk of heavy metals. The results showed that the concentrations of Cr,Ni,Cu,Zn,Cd,Pb in sediments were higher than environmental baselines in most sites and reflected certain degrees of enrichment. Based on the geoaccumulation index,the risk order of heavy metals was Cu > Cd > Zn > Ni > Pb > Cr > Hg.However,according to single heavy metal ecological risk index,the risk levels arranged in Cd > Hg > Cu > Pb > Ni > Cr > Zn.Thus,the results of both assessments indicated that sediments were mainly polluted by Cd accompanied with other heavy metals. Potential ecological risk index indicated that the risk levels were higher in estuary areas than other sites,which reflected that inputs from rivers showed significant influence on heavy metal pollution.