锰矿区雨水径流中重金属含量及污染水平的空间结构特征

运用地统计学方法对湘潭市锰矿红旗矿区雨水径流中重金属含量及污染水平的空间结构特征进行了分析研究.结果表明,锰矿区雨水径流中Mn、Ni、Cu、Zn、Cd、Pb含量的最大值与最小值之间差异较大,Ni、Cu、Cd、Pb的变异系数在0.7~1.0之间,表现出中等变异性,Mn和Zn的变异系数大于1.0,表现出强变异性.空间结构分析表明,除Cd外,Mn、Ni、Cu、Zn、Pb的拟合效果均比较理想,6种元素的拟合模型的决定系数R2介于0.540~0.895之间,块金值与基台值的比值C0/(C0+C)均小于0.4,具有较强的空间相关性.空间分布图表明,元素Mn、Ni、Cd、Pb的分布较相似,元素Cu和Zn的分布很相似且以某块区域为中心向四周逐步递减.污染指数及其空间分析表明,矿区内大部分区域的雨水径流中存在中度重金属污染,东部沿线区域的存在着严重的重金属污染,仅少量地方不存在重金属污染,重金属污染从低到高的顺序为Zn、Ni、Cu、Pb、Mn、Cd.从环境风险和人体健康的角度来看,应将Cd元素作为需要优先治理和控制的重金属.

Spatial structure characteristics of heavy metal content and pollution levels of rainfall runoff in manganese ore zone

Heavy metal pollution of rainfall runoff in manganese ore zone has been increasingly recognized as a threat to the environment in recent years due to the mining of manganese. The spatial structure characteristics of heavy metal content and pollution levels of rainfall runoff in manganese ore zone from Xiangtan were studied using geostatisitc method. Results showed that there was a significant difference between the maximum and minimum value of Mn, Ni, Cu, Zn, Cd and Pb levels collected from the rainfall runoff. The variation coefficients of Ni, Cu, Cd and Pb were between 0.7 and 1.0, indicated a moderate variability while those of Mn and Zn were more than 1.0, showing a strong variability. Results of spatial structure analysis indicated that the fittings for the investigated heavy metals were relatively ideal except for Cd. It was found that the correlation coefficients (R²) of fittings ranged from 0.540 to 0.895, and the nugget-sill ratio of C₀ to (C₀+C) was less than 0.4. This implied the heavy metal distribution was largely affected by the spatial structure. The spatial distribution of Mn, Ni, Cd and Pb were relatively similar and a similar spatial distribution found between Cu and Zn gradually decreased from the center to the surrounding. Spatial distribution and pollution index showed that the majority of the regions investigated in this study had a moderately heavy metal pollution in the rainfall runoff with a small portion of manganese region without any pollution. There was a serious pollution along the eastern region. Heavy metal contamination degree in ascendent order was Zn,Ni,Cu,Pb,Mn and,Cd. It was obvious that Cd had a significant threat to environment risk and human health and should be treated with priority.