区域农田镉含量空间变异与综合风险的不确定性评估

Spatial variation of cadmium concentration in regional wheat fields and uncertainty-enabled comprehensive risk assessment

我国小麦镉(Cd)污染格局多样,从不确定性角度评估区域小麦田Cd累积风险有助于提升污染防治决策的准确性。本研究基于不确定性理论,将蒙特卡洛(Monte-Carlo)随机模拟方法引入到区域土壤-小麦系统Cd污染综合风险评估中,结合多元统计和空间分析开展实例研究。结果表明河南省某小麦主产区92.8%的土壤样品Cd含量超过农田土壤风险筛选值(0.6 mg·kg^(−1)),84.0%的小麦籽粒样品Cd含量超过国家食品安全限量标准(0.1 mg·kg^(−1))。区域土壤-小麦系统Cd累积水平整体上呈现西北高东南低的空间分布格局。区域Cd生态风险以中度污染为主。区域人群Cd摄入量超过WHO推荐安全值的风险概率为31.6%,控制土壤Cd累积趋势可将该超标风险下降至7.3%。不确定性模拟、空间分析和场景分析的综合应用可准确识别农田Cd污染风险等级和相应概率,为区域Cd污染防治提供决策建议。

China faces great challenges in protecting its wheat soil from spatial heterogeneity of cadmium(Cd)accumulation.The uncertainty analysis helps improve the accuracy in the risk assessment for Cd in soil-wheat system.Based on the stochastic theory,the Monte-Carlo simulation approach was introduced in the ecological risk assessment and health risk assessment.Together with the multi-statistical technique and spatial analysis,proposed models were used for risk analysis in a certain area of Henan Province.Results showed that about 92.8%of the soil samples had Cd exceeding the national soil threshold value(0.6 mg·kg^(−1)),and 84.0%of the wheat samples had Cd concentrations exceeding the national foodstuff threshold value(0.1 mg·kg^(−1)).The concentration of Cd in the soils in the spatial distribution decreased from northwest to southeast,and the ecological risk of regional Cd is mainly moderate pollution.The ecological risk of Cd in the investigated wheat fields fall into the moderate contamination level.About 31.6%of the adult populations consumed wheat cropping in affected areas risk a daily Cd intake above the WHO limit.This risk was significantly decreased to 7.3%,when the accumulation trend of Cd has been controlled.The integrated application of uncertainty simulation,spatial analysis,and scenario analysis can accurately identify the risk levels and probability of Cd contamination from regional agricultural field,provide decision-making recommendations for the prevention and control of local Cd contamination.