燃煤火电厂周边土壤重金属污染状况及绿化树种对重金属的积累特性

以上海市某火力发电厂周边地区土壤及木本植物为研究对象,利用湿法消解和电感耦合等离子体发射光谱仪(ICP-AES)测定了其中Cd、Cr、Pb、Cu、Zn、As等6种重金属的含量。通过单因子污染指数法、内梅罗污染指数法和潜在生态危害指数法分析了该地区土壤重金属污染状况和潜在生态危害。同时研究了当地木本植物积累和转运重金属的能力。结果表明,土壤中Cd达到了中度或重度污染水平,其潜在生态危害指数也达到了严重级别;而其余5种重金属均处于清洁水平。但是该区的内梅罗综合污染指数均达到了轻度污染或中度污染的水平。对植物重金属含量的分析表明,样地中15种优势树种对重金属的吸收能力普遍较弱。综合分析植物对6种重金属的积累能力,黄杨(Buxus sinica)、金钟花(Forsythia viridissima)、红花檵木(Loropetalum chinense)和苦楝(Melia azedarach)积累重金属的能力较强;而水杉(Metasequoia glyptostroboides)、黄山栾树(Koelreuteria bipinnata)、构树(Broussonetia papyrifera)转移重金属的能力较高。并且这几种植物在样地中的生长状况良好,适于作为此类重金属污染厂区的生态防护绿化树种。

Heavy Metal Contamination of Soil and Accumulation in Greening Trees Surrounding Coal-Fired Power Plant

Concentrations of Cd,Cr,Pb,Cu,Zn and As in the soil and plant samples taken from the area surrounding a coal-fired power plant in Shanghai were assayed with ICP-AES after being wet-digested.Heavy metal contamination status and potential pollution risk of this area were evaluated through single factor pollution index method,Nemerow comprehensive pollution index method and potential ecological risk index method.Heavy metal accumulation and transport capacities of the greening trees were assessed.The results indicated that Cd in the soil reached moderate or serious pollution,its potential ecological risk index reached serious level,while the other 5 heavy metals were at cleaning level.The Nemerow comprehensive pollution index of the area reached light or moderate pollution.Heavy metal accumulation capacities of the 15 dominant trees in this area were generally weak.This study comprehensively analyzed the accumulation capacity of plants to the 6 heavy metals.Buxus sinica,Forsythia viridissima,Loropetalum chinense and Melia azedarach had stronger ability to accumulate heavy metal comparing with the other species.Metasequoia glyptostroboides,Koelreuteria bipinnata and Broussonetia papyrifera had higher capacity to transfer heavy metal.These trees grew well in the area surrounding power plant,so they are suitable for ecological protection greening trees around coal-fired power plants.