Preliminary analysis and risk evaluation of heavy metals in soil from eastern slope of Gongga Mountain
Preliminary analysis and risk evaluation of heavy metals in soil from eastern slope of Gongga Mountain
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发表时间：
2012
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通讯作者：
Wang Ke-qin
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作者：
Wang Ke-qin
本论文旨在报道贡嘎山东坡土壤中Cd、Pb、Cr、Ni、Hg和As的采集和测定结果。采集和分析结果表明，表层土壤中6种重金属的平均浓度为CrNiPbAs CdHg。表层土壤中Pb、Hg和As的平均浓度均低于允许限值（按照标准1级）。 虽然铅含量与山东坡表土中的平均浓度（30.38±7.32）毫克/千克干重（dw）存在差异，非常接近容许限值。在花柏杉林表层的三个采样点，铅浓度均趋于超过容许限值（43.1毫克/千克）。 dw、41.8 mg/kg dw、35.7 mg/kg dw）、Cd、Cr、Ni的平均浓度（按国家规定的一级标准）也是如此。Cd的变异系数最大为0.91，Pb的变异系数最小为0.24。三种不同森林类型中，Cd、Pb、Hg、As在森林表层的平均浓度 花伯冷杉/白杨混交林和花伯中龄冷杉林的含量均高于花伯冷杉/白杨混交林。因此,我们发现Pb、Hg、As浓度存在显着变化,而Cd则不存在显着变化。同时,花伯冷杉/白杨混交林表层Cr、Ni平均浓度显着高于其他林区。 二、由此可见，随着Cd、Cr、As、Hg在土层中从表层到深层的迁移，三点测点土层中重金属的分布均呈现多样化，但变化程度不是很明显。此外，我们还通过分析各点表土信息，得出了单因素污染物指数数据。 各重金属中表土污染程度最高，最严重的是镉。单因素指数污染程度按PCdPCrPNiPPbPHgPAs顺序递减，这有助于证明东坡表土污染程度随着Cd、Cr、Ni的升高而累积。因此，综合评价 通过对六种重金属表土质量的分析表明，三个站点的污染指数PN均在0.92～4.89之间，受重金属污染程度较小。
The present paper is aimed at reporting our collection and determining the concentrations of Cd,Pb,Cr,Ni,Hg and As in soils of the eastern slope of Gongga Mountain.The results of our collection and analysis show that the mean concentrations of six heavy metals in top soil are CrNiPbAs CdHg in degraded order.The mean concentrations of Pb,Hg and As in the top soil prove to be below the tolerance limit(grade-1 in accordance with the state standard established for testing the uncontaminated soils),though lead was found different from the mean concentrations about(30.38±7.32) mg/kg dw in the topsoil from the eastern slope of the Mountain,that is,very close to the tolerance limit.At the three sampling points of the surface layer in the Faber's matured-fir forest, lead concentrations tends to be over the tolerance limit(43.1 mg/kg dw,41.8 mg/kg dw,35.7 mg/kg dw),and so are the mean concentrations of Cd,Cr and Ni(grade-1 in accordance with the standard set up by the state).The variation coefficient of Cd is maximal at 0.91,whereas that of Pb—minimal at 0.24.Of all the three different forest types,mean concentrations of Cd,Pb,Hg and As in the surface layer of the Faber's matured-fir forest turns to be higher than the Faber's Fir/Purdom Poplar(Populus purdomii) mixed forest and the Faber's middleaged fir forest.Thus,we have found that there were significant variations with Pb,Hg and As concentrations,but not with Cd.In the mean time,the average concentrations of Cr and Ni in surface layer of the Faber's Fir/Purdom Poplar mixed forest were significantly higher than those in the other two.Thus,it can be concluded that the distribution of heavy metals determined in soil layers at each of the three points surveyed proves to be diversified,though the degree of variation turns to be not very obvious with the mobility of Cd,Cr,As,and Hg in the soil horizon from the top-layer to deep-layer.Besides,we have also worked out the single-factor contaminant index data by analyzing the information obtained from the topsoil at each sampling point.The highest degree of topsoil contamination among all the heavy metals the most serious one comes from cadmium.The order of contamination degree due to single-factor index is found decreasing in the order of PCdPCrPNiPPbPHgPAs,which helps to prove that the topsoil contamination on the eastern slope of the Mountain were supposed to be accumulated with the elevation of Cd and Cr and Ni.Therefore,the integrated assessment of the topsoil quality for six heavy metals through analysis indicates that the contamination index PN for all the three sites vary between 0.92 and 4.89 and the contamination degree affected by heavy metals being little and slight.