中国农田土壤重金属空间分布特征及污染评价

土壤是农业生产过程中不可或缺的自然资源,掌握农田土壤重金属的空间分布特征及污染水平,对于农田生态系统安全及人类健康具有重要意义.基于2002年来中国各行政区农田土壤重金属实测数据,探讨了农田土壤Cr、Cd、Pb、Zn、Cu、As和Hg等7种重金属的空间分布特征,并采用地累积指数法对污染状况展开评价.结果表明中国农田土壤重金属的空间分布特征差异较为明显,南方农田土壤重金属含量明显高于北方;平均值统计结果表明,湖南、云南、贵州、四川、福建、广西以及上海的农田土壤重金属含量较高;污染评价结果显示7种重金属的污染程度大小依次为CdHgPbCuZnAsCr,其中福建、广东、海南、浙江、湖南、陕西、甘肃、河南、重庆、山西、天津、内蒙古和安徽的富集程度较高.

Spatial Distribution Characteristics and Pollution Evaluation of Heavy Metals in Arable Land Soil of China

Soil is an important component of the terrestrial ecosystem and an indispensable natural resource in agricultural production. Understanding the spatial distribution characteristics and pollution levels of heavy metals in arable land soil is important to safeguard the agriculture ecosystem and human health. Based on the collected data of heavy metal concentrations in arable land soil in various administrative regions of China since 2002, first, we selected and removed the abnormal values, then obtained the spatial distribution of the provinces by the Kriging method, and discussed the spatial distribution characteristics of seven heavy metals (Cr, Cd, Pb, Zn, Cu, As, and Hg) in arable land soil. Finally, we adopted the geo-accumulation index to evaluate the pollution status of arable land soil. The results showed that the spatial distribution of heavy metals Cr, Pb, Cu, Zn, and As in arable land soil of China was obvious, while the spatial distribution of soil Cd and Hg was very similar. Furthermore, the concentration of arable land soil in south China was obviously higher than that in the north. The mean value of the results showed that heavy metals are enriched to different degrees in arable land soil of China, and the average soil heavy metal concentrations of arable land are higher in Hunan, Yunnan, Guizhou, Sichuan, Fujian, Guangxi, and Shanghai. The results of geo-accumulation index pollution evaluations showed that the pollution degree of the seven heavy metals was in the order Cd > Hg > Pb > Cu > Zn > As > Cr, among which the soil heavy metals in arable land soil had a higher enrichment degree in Fujian, Guangdong, Hainan, Zhejiang, Hunan, Shaanxi, Gansu, Henan, Chongqing, Shanxi, Tianjin, Inner Mongolia, and Anhui. In general, the geo-accumulation indexes of Cd and Hg in each administrative region are higher, whereas the average land accumulation indexes also indicate that Cd and Hg in arable land shows greater pollution specially. Results from this study provide valuable scientific basis for formulating effective arable land pollution control strategies in the future.