金属矿产资源开发活动通常会导致矿区土壤重金属含量的累积，选用科学的评价标准及方法成为评判、区分矿业活动农田土壤重金属累积影响和风险的关键问题。在简述土壤背景值和土壤环境质量标准含义的基础上，提出采用与矿区其他环境条件基本相同或相近的邻区耕作层土壤重金属元素的平均含量作为评判矿业活动重金属对耕作层土壤的累积影响的对照值。以2011年小秦岭金矿区80件耕作层土壤重金属含量为例，金矿开发活动区耕作层土壤重金属的累积风险研究表明，土壤重金属低风险以上样品数占总样品数百分比的排序为Hg>Cd>Pb>Cu，矿业活动对土壤重金属累积的贡献率排序为Hg>Cu>Pb>Cd>Zn。土壤中的Cr、As、Zn元素有轻度累积但无风险。土壤中Hg元素的累积风险面积达到了187.77km2，占到研究区总面积的47.08%。其中，中、高风险的面积为99.55km2，土壤重金属累积风险极其严重。研究结果科学地评判了矿业活动对耕作层土壤重金属的累积影响及其贡献，为土壤污染防治指明了方向。%The accumulation of heavy metals in soil is generally sourced from metal mineral exploitation activities in the mining area, and hence the key to assessing the cumulative effect and risk of heavy metal accumulation in soil is to choose scientific evaluation stan-dards and methods. In this paper, the background of heavy metals and the meaning of the soil environmental quality standards were briefly explained, and the average heavy metal concentrations in adjacent areas with the same or similar conditions were taken as the background of heavy metal accumulation. In 2011, case study was performed in the Xiaoqinling gold mining area. 80 groups of heavy metal samples were collected in the agricultural soil. The experimental results showed that the proportion of lower risk samples of heavy metals to total samples was in order of Hg>Cd>Pb>Cu, whereas the contribution rate of mining activities on the soil heavy metal accumulation was in order of Hg>Cu>Pb>Cd>Zn. There existed no risk of Cr, As and Zn in soil in spite of slight accumula-tion of these elements. The risk area of Hg reached 187.77km2, accounting for 47.08%of the total survey area. And the area of mid-dle and high risk possessed 99.55km2, suggesting an extremely serious situation. The research results provide the scientific evaluation of the cumulative effects and contribution of mining activities on the heavy metal accumulation in soil and point out the way forward in the aspect of the soil pollution prevention.
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