山东省典型金矿区土壤重金属空间特征分析与环境风险评估

以山东省典型金矿区——焦家式金矿带为研究区,系统采集了77个表层土壤样品并对Cu、Pb、Zn和Cr的含量进行了测定;采用空间统计分析方法对重金属的空间变异结构、分布规律及潜在污染风险进行了研究.Cu、Pb、Zn和Cr的平均含量分别为19.41、27.32、49.81和39.27 mg·kg-1.半方差函数拟合表明Cu和Pb属于中等空间自相关,空间分布呈岛状;而Zn和Cr为结构性空间变异,受自然因素的控制,空间分布呈带状和岛状.热点分析与指示克里金插值结果表明,金城镇、辛庄镇与蚕庄镇的交界地带重金属环境风险较高,南部则为安全区,其中Pb的超标概率最大且中高风险区分布范围广泛.研究结果可为研究区土壤重金属污染评价和调控提供参考和依据.

Spatial Characteristics and Environmental Risk of Heavy Metals in Typical Gold Mining Area of Shandong Province

In order to reveal the influence of anthropogenic factors on soil environment quality, a total of seventy-seven samples in topsoils were collected from Jiaojia gold mining area in Shandong province and were determined for Cu, Pb, Zn, Cr contents. Spatial structure, spatial distributions of concentrations and risk probability of heavy metals were analyzed using spatial statistic analysis. The average concentrations of Cu, Pb, Zn and Cr were 19.41 mg·kg^-1, 27.32 mg·kg^-1, 49.81 mg·kg^-1 and 39.27 mg·kg^-1, respectively. Pb, Zn and Cr were distributed normally and Cu was distributed normally after logarithm transformation. Semivariance analysis demostrated that Pb could be fitted to exponential model, and Cu, Zn and Cr were fit for spherical model. Nugget coefficents of Cu and Pb were between 0.25 and 0.75, which illustrated middle spatial autocorrelation; Zn and Cr showed the structural variation with nugget values below 0.25. Cu and Pb in the topsoils were distributed dispersedly due to effects of some human factors, whereas contents of Zn and Cr indicated relatively regular distributions and were mainly affected by natural factors. Spatial distributions of the 4 heavy metals were approximately consisitent and the high value areas appeared in the gold mines band. The result of hot spot analysis and indicator kriging interpolation revealed that the relatively high risk areas were located in Jincheng town, the boundary zone of Xinzhuang town and Canzhuang town, while the safe zone was situated in south part of the study area. Pb had higher probability exceeding the threshold and the middle or high environmental risk areas of Pb were distributed widely, which should be paid more attentions.