重庆汞矿区耕地土壤和农作物重金属污染状况及健康风险评价

Heavy metal pollution and human health risks assessment of soil and crops near the mercury ore in Chongqing

为了解重庆汞矿区耕地土壤-农作物重金属污染状况,在研究区采集水稻45件、玉米32件、红薯18件及其种植土壤样品90件,分析测定As、Cd、Cr、Cu、Hg、Ni、Pb、Zn等8种重金属含量,采用地累积指数法、潜在生态危害指数法和健康风险评估模型,对该区土壤重金属污染程度、生态风险和食用农作物的健康风险进行评估.结果表明,研究区水稻田、玉米地和红薯地土壤重金属平均含量均高于重庆市土壤背景值,呈现不同程度的积累;Cd、Hg、As超出国家农用地土壤污染风险筛选值,水稻田土壤超标率分别为88.9%、62.2%、11.1%,玉米地土壤超标率分别为81.3%、43.8%、18.8%,红薯地土壤超标率分别为100%、44.4%、16.7%.与食品安全国家标准相比,部分水稻和玉米中Cd超标,超标率分别为20%、15.6%;部分红薯中Cd、Cr和Pb超标,超标率分别为22.2%、5.56%和27.8%.地累积指数法评价显示土壤Hg污染严重,以中污染和极重污染为主,As、Cd总体处于轻污染水平,Cr、Cu、Ni、Pb、Zn总体呈无-轻污染状态.潜在生态风险评价显示,Hg、Cd、As为研究区土壤主要生态危害元素,Hg以极强风险为主,Cd以中等风险和强等风险为主,As以轻微风险为主,单一重金属健康风险指数表明研究区居民食用水稻存在较高的As风险.多种重金属总健康风险指数显示成人食用玉米没有明显的健康影响,但食用水稻、红薯存在明显的复合健康风险;同时儿童更易受到重金属污染威胁,食用水稻、玉米和红薯的THQ均大于1.

In order to understand the heavy metal pollution of agriculture soil-crops in mercury ore of Chongqing,45 rice samples,32 corn samples,18 sweet potato samples and 90 corresponding soil samples were collected,and the concentrations of As,Cd,Cr,Cu,Hg,Ni,Pb and Zn were analyzed.The soil heavy metal pollution level,the ecological risk and health risk were evaluated by the geological accumulation index,potential ecological hazard index and health risk assessment model.Results showed that the average values of 8 heavy metals in the surrounding soil of mercury mining area were higher than the soil background values of Chongqing,showing different degree of accumulation effect.The concentrations of Cd,Hg and As significantly exceeded the risk screening values for soil contamination of agricultural land,with the over-standard rates of 88.9%,62.2% and11.1% in rice soil.with the over-standard rates of 81.3%,43.8% and 18.8% in corn soil,with the over-standard rates of 100%,44.4% and 16.7% in sweet potato soil.Compared with the national food safety standard,Cd exceeded the standard in some rice and corn,with the exceeding rate of 20% and15.6% respectively.Cd,Cr and Pb exceeded the standard in some sweet potatoes,and the exceeding rates were 22.2%,5.56% and 27.8%,respectively.Evaluation of the soil by geological accumulation index,Hg pollution was relatively serious,and its pollution level was medium pollution or very heavy pollution,As and Cd were generally light pollution,and the remaining heavy metals were basically pollution-free.The potential ecological hazard index showed that Hg,Cd and As were the main ecological hazard elements,Hg ecological risk was mainly extremely strong,Cd ecological risk was mainly medium and strong,and As ecological risk was mainly slight risk.The heavy metal health risk assessment results showed adults and children had a higher risk of As by rice ingestion.The heavy metal health risk assessment of multiple heavy metals showed that adult had no significant health effects by corn ingestion.However,there were significant health effects by rice and sweet potato ingestion.Meanwhile,The heavy metal health risk assessment results showed children were more susceptible to the heavy metal pollution,the THQ of rice,corn and sweet potatoes are all greater than 1.