中国农田土壤重金属污染防治现状与问题思考

土壤是农业可持续发展的基础。经过近40年的经济快速发展与农业高度集约化生产后，我国农田土壤污染与土壤环境质量下降问题逐渐凸显。当前，中国农田土壤重金属污染形势不容乐观，对农产品的安全生产和食品安全构成威胁。文章首先对我国农田土壤重金属污染现状与污染特点、农田重金属污染来源及修复技术研究现状等进行了总结。结果显示：(1)我国农田土壤重金属污染点位超标率相对较高，但以轻度污染为主；(2)污染土壤中主要以Cd、As、Hg、Pb和Cr这5种健康风险重金属元素为主，尤其以Cd风险最高，而以生态风险为主的Ni、Cu和Zn 3种重金属环境风险相对较小；(3)农田土壤污染分布总体表现为南方重于北方，东部重于西部；(4)农田土壤污染逐渐呈现由工业源向农业源、城郊向农村、土壤向食物链转移的发展趋势。基于文献计量方法对我国近30年来农田土壤污染防治研究的热点与趋势进行了分析。结果表明，我国农田土壤污染防治研究主要始于2000年前后，2009年后进入快速发展阶段，研究热点主要包括重金属污染监测、土壤环境环境质量评价、重金属污染土壤修复技术等，近10年来污染土壤修复技术表现为从单一修复技术向联合修复技术发展态势。此外，文章对我国农田重金属污染修复的一般程序、不同污染程度农田土壤的安全利用技术与高风险污染土壤的管控技术进行了评价，最后，对我国当前农田重金属污染防治过程中出现的问题进行了思考，同时针对我国今后农田重金属污染防治研究进行展望，提出了基于源头控制与风险管控措施相结合的农田重金属污染防治体系，以期为未来我国农田土壤重金属污染防治研究规划以及土壤重金属污染防治技术的创新提供参考与借鉴。

Current status of and discussion on farmland heavy metal pollution prevention in China

Soil is the foundation for sustainable agricultural development. After nearly 40 years of rapid economic expansion and intensive agricultural production, the problems of soil pollution and soil environmental quality deterioration in Chinas farmlands have gradually come into focus. At present, the heavy metal pollution in farmlands has become increasingly serious and poses a potential threat to agricultural product safety. In this paper, we first summarized the current status and characteristics of heavy metal pollution in farmland soils, and sources of heavy metal pollution in farmlands and research advances in soil remediation in China. It showed that (1) in general, the rate of heavy metal contamination exceeding safety standards in farmland soils is relatively high, but contamination is mostly light; (2) among the heavy metals, Cd, As, Hg, Pb and Cr are the five major health risk elements in contaminated farmland soils, especially Cd, while ecologically hazardous elements Ni, Cu and Zn, pose relatively low environmental risk; (3) in general, the characteristics of the pollution distribution indicates pollution is more serious in south than in north and in east than in west; and (4) the pollution trend shows gradual heavy metal transfers from industrial to agricultural sources, from suburbs to rural areas, and from soil contamination to food chain pollution. Next, we did bibliometric analysis of the hotspots and research trend of heavy metal pollution prevention and control of farmland pollution in China during the past 30 years. According to the analysis, researches of pollution prevention and control started around 2000 and entered a rapid development stage after 2009. The research hotspots mainly included heavy metal pollution monitoring, soil environmental quality assessment, heavy metal-contaminated soil remediations etc. And in the last 10 years, remediation technologies have changed from single to multi-technique applications. We then evaluated the general remediation procedures and the techniques for the safe utilization of heavy metal polluted farmland soils at different pollution levels and for the control of high-risk polluted soils. Finally, we discussed the current problems in heavy metal pollution prevention in farmlands in China and prospects for key research fields. We put forward a technical system for farmland heavy metal pollution prevention and control based on combining heavy metal source and environmental risk control measures to provide references for future research planning and technology development for the prevention of heavy metal pollution in China's farmlands.