渝东南山区乡镇尺度土壤合理采样数估算及重金属污染评价

为了研究乡镇尺度土壤重金属污染状况及土壤合理采样数的确定方法，选择在重庆市黔江区舟白镇采集表层（0~20 cm）土壤样品320件，分析了土壤中各重金属元素（Cd、Cr、Pb、Hg、As、Cu、Zn、Ni）含量和pH，基于经典统计学方法和地统计法研究不同土壤指标的空间变异特征及土壤合理采样数，利用内梅罗指数法进行土壤重金属污染评价.结果表明:研究区土壤中Cd、Cr、Pb、Ni含量及pH的空间分布主要受到成土母质的影响，土壤中Hg、As、Cu、Zn含量同时受到地质背景和人为活动的影响.对于研究区土壤各重金属含量和pH而言，250个土壤样点即可反映其基本信息.研究区中部土壤污染程度较低，北部和南部污染程度较高，中度和重度污染区主要分布在研究区南部.原始土壤点位和合理土壤点位重金属污染评价结果差别较小，说明所得的合理采样数结果较可靠.与地层分布对比发现，土壤中度、重度污染主要与二叠系地层有关. 

Estimation of Reasonable Soil Sampling Number and Evaluation of Heavy Metal Pollution in Mountainous Area of Southeast Chongqing

In order to study the status of soil heavy metal pollution and the method for determining the reasonable number of soil samples at the township scale, 320 topsoil samples(0-20 cm) were collected in Zhoubai Town, Qianjiang District, Chongqing City, and soil heavy metals (Cd, Cr, Pb, Hg, As, Cu, Zn and Ni) content and pH were tested. Based on classical statistical methods and geostatistical methods, the spatial variability of different soil indicators and reasonable soil sampling numbers were studied, and the Nemerow index method was used to evaluate soil heavy metal pollution. The results show that the spatial distribution of soil Cd, Cr, Pb, Ni contents and pH were mainly affected by the soil-forming parent material, and soil Hg, As, Cu and Zn were affected by geological background and human activities. For soil heavy metals and pH, 250 soil samples could reflect the basic information of various soil indicators. The central part of the study area had low degree of soil pollution, while the northern and southern areas had high levels of soil pollution. The moderately and heavily polluted areas were mainly distributed in the southern part of the study area. The difference between the original soil site and the reasonable soil site heavy metal pollution evaluation results were small, indicating that the reasonable sampling number results obtained are more reliable. Compared with the stratum distribution, it is found that the moderate and severe soil pollution is mainly related to the Permian stratum.