赣南某钨矿区土壤重金属污染状况研究

Mixed heavy metals contamination of tungsten mine area soil in south of Jiangxi Province

为研究钨矿区土壤重金属的污染现状,采集尾矿堆积区土壤样品,用ICP-MS测定土壤重金属（Cr、As、Mn和Pb）含量,采用Kriging插值法分析土壤重金属的空间分布特征,并分析测定土壤脲酶、过氧化氢酶、蔗糖酶的活性.结果表明土壤重金属的浓度均值高于背景值,Cr、As、Mn、Pb的均值分别是土壤背景值的2.26,3.06,1.85和2.59倍.空间分析表明Mn和Pb间两种元素具有较为相似的分布,Cr、As、Mn和Pb 4种重金属的空间分布相关性强,且呈条带状分布.土壤酶活性结果进一步验证重金属的污染状况,土壤酶活性低于对照样,土壤脲酶、过氧化氢酶、蔗糖酶分别是对照的7%～93%和5%～86%、11%～90%.逐步多元回归法分析表明,在Cr、As、Mn、Pb复合污染条件下,矿区土壤不同酶活性表现出抑制或者激活作用,但各重金属元素对不同的酶活性的影响系数是不一样的,蔗糖酶对复合重金属污染最为敏感.主成分分析表明土壤酶活性的指标能较好地反映钨矿矿区土壤重金属复合污染状况。

To investigate the current status of soil pollution of Cr, As, Mn and Pb in tungsten mining area, a total of nine surface soil samples were collected in the tailings accumulation areas. Concentrations of Cr, As, Mn and Pb in the nine samples were measured by the inductively coupled plasma mass spectrometry （ICP-MS） and the spatial distribution of the heavy metal concentrations in this area was estimated by Kriging interpolation model. The activities of urease, catalase and invertase in these nine samples were also assessed. It was demonstrated that the average values of all the heavy metal concentrations were much higher than the background values and the mean concentrations of Cr, As, Mn and Pb were as 2.26, 3.06, 1.85 and 2.59 times high as their background values. The spatial distribution analysis of heavy metals revealed that the distribution of Mn and Pb was relatively similar, the distribution of these heavy metals in soil was banded and strong spatial correlations were observed for Cr, As, Mn, and Pb distributions, indicating that they were likely originated from the same source. Soil enzyme activities were estimated to be as low as 7% ～93%, 5%～86% and 11%～90% of their background values for the urease, catalase and invertase, respectively, which further confirmed the existence of heavy metals soil pollution. Multivariate stepwise regression analysis between heavy metal contents and soil enzyme activities displayed that the coefficient between the heavy metal and the enzyme activity was different. Among them, the invertase was the most sensitive. In addition, principle component analysis pointed out that enzyme activities in mining soils were feasible indicators to assess changes in soil environmental quality caused by heavy metals pollution.