Wu Fu-Lin, Chen Li, Yi Ting-Hui, Yang Zhi-Min, Chen Yu-Cheng
Chongqing Engineering Research Center of Rural Cleaning, College of Resources and Environment, Southwest University, Chongqing 400716, China.
Chongqing Station of Agricultural Ecology & Resources Protect, Chongqing 401120, China.
Huan Jing Ke Xue. 2018 Nov 8;39(11):5116-5126. doi: 10.13227/j.hjkx.201803205.
In order to understand the accumulation of heavy metals of agricultural land in Chongqing and make clear priority control elements, the soil heavy metal baseline values need to be determined. Based on geochemical baselines, a total of 214 surface soil samples of six soil types were collected according to stratified sampling. Under strict quality control, the As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn content in each sample was measured. The baseline values of eight heavy metals were determined using mathematical statistics, iterative culling, and cumulative frequency curve methods. The accumulation of heavy metals in agricultural soils in Chongqing was evaluated using the geochemical baseline pollution and geological accumulation index methods. The mean baseline values of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn in agricultural land in Chongqing were 5.83, 0.25, 66.78, 25.45, 0.069, 29.90, 26.18, and 78.44 mg·kg, respectively, which agreed with the historical findings. Evaluation of the geochemical baseline pollution index method showed that the accumulation of As, Hg, and Zn in soil was the most prominent, with 14.65%, 11.82%, and 3.88% of the samples reaching severe accumulation, respectively. The proportions of moderate accumulation of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were 12.12%, 6.50%, 3.79%, 6.50%, 15.27%, 5.29%, 5.45%, and 17.96%, respectively, of which As, Hg, and Zn were relatively large. The geological accumulation index indicated that more than 93% of the samples of Cd, Cr, Cu, Ni, and Pb were in a state of no accumulation. The proportions of mild accumulation of Hg, Zn, and As were 26.60%, 21.84%, and 21.21%, respectively. Only 5.56% and 0.49% of the samples had moderate accumulation of As and Zn. Different soil types have different properties. All soil types in the sample had different degrees of accumulation of the eight kinds of heavy metals. The accumulation of heavy metals in paddy and purple soils was lower than that in other soil types. For the soils of different geological and geomorphic types, the values of As in the limestone middle and low mountain area of Daba Mountain in Northeast Chongqing and the low mountain area of the limestone of Wuling Mountain in Southeast Chongqing were relatively large; the rest were not significantly different, and all belonged to the non-accumulation and mild accumulation ranges. Both evaluation methods showed that the main accumulated heavy metals in agricultural land soil in Chongqing was As, followed by Hg and Zn, and management and prevention of the accumulation of these elements should be strengthened.
为了解重庆市农用地土壤重金属积累状况并明确优先控制元素，需确定土壤重金属基线值。基于地球化学基线，按照分层抽样方法共采集了6种土壤类型的214个表层土壤样品。在严格的质量控制下，测定了每个样品中砷（As）、镉（Cd）、铬（Cr）、铜（Cu）、汞（Hg）、镍（Ni）、铅（Pb）和锌（Zn）的含量。采用数理统计、迭代剔除和累积频率曲线法确定了8种重金属的基线值。运用地球化学基线污染指数法和地质累积指数法对重庆市农用地土壤重金属积累状况进行了评价。重庆市农用地土壤中As、Cd、Cr、Cu、Hg、Ni、Pb和Zn的平均基线值分别为5.83、0.25、66.78、25.45、0.069、29.90、26.18和78.44mg·kg，与历史研究结果相符。地球化学基线污染指数法评价表明，土壤中As、Hg和Zn的积累最为突出，分别有14.65%、11.82%和3.88%的样品达到重度积累。As、Cd、Cr、Cu、Hg、Ni、Pb和Zn中度积累的比例分别为12.12%、6.50%、3.79%、6.50%、15.27%、5.29%、5.45%和17.96%，其中As、Hg和Zn的比例相对较大。地质累积指数表明，Cd、Cr、Cu、Ni和Pb超过93%的样品处于无积累状态。Hg、Zn和As轻度积累的比例分别为26.60%、21.84%和21.21%。只有5.56%和0.49%的样品As和Zn呈中度积累。不同土壤类型性质不同。样品中的所有土壤类型对8种重金属均有不同程度的积累。水稻土和紫色土中重金属的积累低于其他土壤类型。对于不同地质地貌类型的土壤，重庆东北部大巴山石灰岩中低山区和重庆东南部武陵山石灰岩低山区土壤中As含量相对较高；其余差异不显著，均属于非积累和轻度积累范围。两种评价方法均表明，重庆市农用地土壤中主要积累的重金属为As，其次是Hg和Zn，应加强对这些元素积累的管控与防治。
