基于Monte-Carlo模拟的湖南省典型工厂周边农田土壤重金属区域潜在生态风险特征及来源解析

Potential Ecological Risk Characteristics and Source Apportionment of Heavy Metals in Farmland Soils around Typical Factories in Hunan Province Based on Monte-Carlo Simulation

为探究湖南省典型工厂周边农田土壤重金属的污染特征、生态风险和来源,以氟化工厂、皮革工厂和电镀工厂为研究对象,分析其周边农田土壤中8种重金属的污染特征,利用地累积指数和潜在生态风险指数对重金属污染进行评估和风险评价,利用相关性分析、聚类分析和主成分分析对重金属污染来源进行解析,利用Monte-Carlo模型对于区域生态风险进行概率风险评估.结果表明,土壤中主要污染元素为Cd和Zn,其均值为背景值的4.46和2.73倍;3个典型工厂周边土壤中Zn处于轻度污染水平,氟化厂周边土壤中Cd处于偏中度污染水平;典型工厂周边土壤中重金属主要来自自然源、工业活动源(“三废”排放、矿产挖掘、金属冶炼等活动)和交通源.潜在生态风险评价结果表明,氟化厂周边土壤中重金属污染的生态风险处于高风险等级,皮革厂和电镀厂生态风险处于较高风险等级,Cd是主要贡献元素.Monte-Carlo概率生态风险评价结果降低了确定性评价的不确定性,可为区域实现精准风险管控提供科学依据.

In order to explore the pollution characteristics,ecological risks,and pollution sources of heavy metals in farmland soils around typical factories in Hunan Province,the content characteristics of eight heavy metals in farmland soils around fluoride factories,leather factories,and plating plants were analyzed.The geo-accumulation index and potential ecological risk index were used to evaluate the pollution and environmental risk of heavy metals.The correlation analysis,hierarchical cluster analysis,and principal component analysis were used to analyze the sources of heavy metals.The Monte-Carlo model was used to evaluate the probability risk of regional ecological risk.The results showed that the main pollution elements in the soil were Cd and Zn,and their mean values were 4.46 and 2.73 times the background values,respectively.Zn was at a mild pollution level in the soil of the three typical factories,and Cd was at a moderate pollution level in the whole fluoride factory.The pollution sources of heavy metals in the typical factories were mainly natural sources,industrial activity sources(industrial waste discharge,mineral mining,and smelting activities),traffic sources,etc.The results of potential ecological risk assessment showed that the ecological risk of the fluoride factory was at a high risk level,and the ecological risk of the leather factory and plating plants was at a high risk level.Cd was the main contributing element.The results of Monte-Carlo probabilistic ecological risk assessment reduced the uncertainty of deterministic assessment,which could provide scientific basis for accurate risk management and control in the regions.