太湖流域重金属湿沉降特征

为研究太湖流域湿沉降中重金属含量特征及污染现状,采用ICP-MS对2009年8月—2010年4月期间太湖周边10个采样点湿沉降中的ρ(Cr),ρ(Cd),ρ(Pb),ρ(Ni),ρ(Mn)和ρ(Zn)进行监测,结果表明:湿沉降中ρ(Zn)最高(年均值为79.54μg/L),超过《地表水环境质量标准》(GB 3838—2002),占重金属总量的66.3%;其他依次为ρ(Mn),ρ(Pd),ρ(Ni),ρ(Cr)和ρ(Cd),分别为26.90,6.36,5.12,1.74和0.26μg/L.湿沉降中重金属含量季节变化和空间分布存在显著差异,ρ(Cr)和ρ(Mn)以西北部湖区较高,ρ(Cd)和ρ(Zn)以南部湖区较高,ρ(Ni)以西部湖区较高,ρ(Pb)以东部和西部湖区较高.Cr,Cd,Pb,Ni,Zn及Mn的湿沉降率分别为2.14,0.34,7.57,6.18,101和33.1 mg/(m2.a),通过湖面湿沉降年入湖量分别为5.00,0.79,17.7,14.5,236及77.4 t.

Wet Deposition Characteristics of Heavy Metals in Taihu Lake Watershed

Ten atmospheric precipitation samples were collected around Taihu Lake from August 2009 to April 2010 to assess the wet deposition pollution status and characteristics of heavy metals.The mass concentrations of heavy metals(Cr,Cd,Pb,Ni,Mn and Zn) in the samples were analyzed by Inductively Coupled Plasma-Mass Spectrometry(ICP-MS).The mass concentration of Zn was the highest with an average of 79.54 μg/L,which exceeded the standard level of the National Environmental Quality Standards of Surface Waters(GB 3838-2002),and accounted for 66.3% of the total heavy metal contents.The other heavy metals’ mass concentrations were much lower than that of Zn,with average mass concentrations for Mn,Pb,Ni,Cr,and Cd of 26.90,6.36,5.12,1.74,and 0.26 μg/L,respectively.The mass concentrations of most heavy metals in the precipitation showed seasonal and spatial variations.The mass concentrations of Cr and Mn were higher in the western and northern lake regions;Cd and Zn were higher in the southern lake region;Ni was higher in the western lake region;and,Pb was higher in the eastern and western lake regions.Annual wet deposition fluxes of Cr,Cd,Pb,Ni,Zn and Mn were 2.14,0.34,7.57,6.18,101 and 33.1 mg/(m2·a),respectively.The annual atmospheric wet deposition amounts of Cr,Cd,Pb,Ni,Zn and Mn directly into the lake were 5.00,0.79,17.7,14.5,236 and 77.4 t,respectively.