苏南太湖流域农田土壤重金属输入输出清单构建及风险预警

Input-output inventory and risk early warning of heavy metal in farmland soil in Taihu Lake Basin, southern Jiangsu

为指导产地环境管理策略、巩固污染防治成果,以公开数据为基础构建了苏南太湖流域农田土壤重金属的输入输出清单,探究了土壤中八大重金属元素(As、Cd、Cr、Cu、Hg、Ni、Pb和Zn)的累积现状并预测了未来发展趋势.其中,输入途径主要包括大气沉降、畜禽粪便、灌溉水和化肥农药施用,输出途径主要包括作物收获和土壤渗流.结果表明,As、Cd、Cu、Cr和Hg元素主要通过灌溉用水输入农田,Ni主要通过大气沉降、化肥施用和灌溉水输入农田,Pb和Zn主要通过大气沉降进入农田;As、Cr、Cu、Hg和Pb主要通过土壤渗流输出农田,Cd和Zn主要通过作物收获输出农田.Cd是苏南太湖流域农田土壤中最需关注的重金属元素,在短期内其可能达到风险阈值,其余重金属元素均存在不同程度累积但远未达到风险阈值.

In this study, a thorough inventory of heavy metal inflows and outflows in the agricultural soils of the Taihu Lake Basin in southern Jiangsu Province was meticulously compiled using publicly available data. The objective was to evaluate the current accumulation status of eight key heavy metals—arsenic(As), cadmium(Cd), chromium(Cr), copper(Cu), mercury(Hg), nickel(Ni),lead(Pb), and zinc(Zn)-and forecast their future trends. The primary routes of heavy metal entry into the soil included atmospheric deposition, livestock manure application, irrigation water, and the use of chemical fertilizers and pesticides, while the main pathways for metals to migrate out of soil were crop removal during harvest and soil leaching processes. The findings revealed that As, Cd, Cu,Cr, and Hg mainly infiltrated the agricultural soils via irrigation water, while Ni entered through atmospheric deposition and the use of chemical fertilizers and irrigation water. Lead and Zn predominantly infiltrated through atmospheric deposition. With regard to the removal of these metals from the soil, As, Cr, Cu, Hg, and Pb were chiefly lost through leaching, whereas Cd and Zn were primarily removed via crop harvesting. Notably, Cd has emerged as the most critical heavy metal requiring attention in the agricultural soil of the Taihu Lake Basin, with the potential to exceed the threshold in the near future. The other heavy metals showed varying levels of accumulation, all remaining well below the established risk thresholds.