黄河流域农田土壤重金属污染特征及其优先控制源分析

Characteristics and Identification Priority Source of Heavy Metals Pollution in Farmland Soils in the Yellow River Basin

农田土壤环境质量评价与污染溯源解析是保障国家粮食安全和农业可持续发展的基础,也是扎实推进国家净土保卫战的重要前提.基于2000~2023年黄河流域农田土壤重金属(As、 Cd、 Cr、 Cu、 Hg、 Ni、 Pb和Zn)含量数据,采用地累积指数法对重金属污染特征进行评价,利用正定矩阵因子分解(PMF)模型定量解析重金属的来源贡献,并通过运用蒙特卡洛(Monte Carlo)模拟和人体健康风险评价模型相耦合的方法评价重金属污染的潜在健康风险,实现优先污染源和污染元素的确定.结果表明:(1)研究区农田土壤所有重金属的含量均值均低于《土壤环境质量农用地土壤污染风险管控标准》(GB 15618-2018)(pH>7.5)的筛选值,但分别有21.69%、 5.56%和1.23%的样点Cd、 As和Zn含量超出其筛选值,Cd超标率最高.(2)Hg和Cd为偏中度污染,Cu和Pb为轻度污染,其余元素均为无污染.(3)农田土壤重金属主要来源为交通-工业源、自然-农业源、工业-自然源和农业-工业源,贡献率分别为37.04%、 26.69%、 21.72%和14.55%.(4)农田土壤重金属对成人与儿童存在致癌健康风险,但不具有非致癌风险;As和Cd为人体健康风险优先控制元素,工业-自然源和农业-工业源为研究区优先控制源.

Assessments of the soil environmental quality of farmland and pollution source apportionment are the foundation for ensuring national food security and agricultural sustainable development,as well as an important prerequisite for the pursuit to keep our lands clean.This study evaluated the characteristics of heavy metal pollution in farmland soils in the Yellow River Basin from 2000 to 2023,based on the data of heavy metal contents including As,Cd,Cr,Cu,Hg,Ni,Pb,and Zn,using the geo-accumulation index method.Source apportionment was conducted by employing a positive matrix factorization(PMF)model.The probabilistic health risks were evaluated by coupling Monte Carlo simulation with a human health risk assessment model,and priority pollution sources and elements were identified.The results showed that:①the average content of all heavy metals in farmland soils within the study area was lower than the screening values specified in the soil environment quality risk control standard for soil contamination of agriculture land(GB 15618-2018)(pH>7.5).However,the contents of Cd,As,and Zn in the samples exceeded their screening values,with percentages of 21.69%,5.56%,and 1.23%,respectively,with Cd having the highest rate of exceedance.②Hg and Cd were moderately polluted,Cu and Pb were slightly polluted,and the other elements were not polluted.③The main sources of heavy metals in farmland soil were traffic-industrial sources,natural-agricultural sources,industrial-natural sources,and agricultural-industrial sources,with contribution rates of 37.04%,26.69%,21.72%,and 14.55%,respectively.④Heavy metals in farmland soil posed carcinogenic health risks to adults and children but did not have non-carcinogenic risks;As and Cd were priority control elements for human health risks,and industrial-natural sources and agricultural-industrial sources were priority control sources in the study area.