不同修复材料对稻米重金属含量的阻控效果及健康风险评价

Control Effect of Different Remediation Materials on Rice Heavy Metals and Health Risk Assessment

采用稀太太(硒肥)、猛降镉(硅肥)、修护龙(CaO≥40%)和石灰(CaO≥90%)4种修复材料,评价其对稻田土壤重金属污染修复的效果和稻米重金属含量的影响,在鹰潭市余江区某污染基地开展田间单因子试验,在水稻黄熟期采用五点取样法采集各处理的土壤和稻谷样品,并分析了样品的重金属含量,利用单因子污染指数法评价了基地各重金属元素的污染程度,通过改进层次分析法确定重金属污染因子权重的加权平均综合指数法、内梅罗综合指数法和潜在生态风险指数法,评价了试验地土壤重金属的综合污染状况;利用高危商(HQ)和高危指数(HI)法,分析了稻米重金属含量对人体造成的食用健康风险。结果表明:单因子污染指数显示基地土壤Pb的污染等级为安全,Cu、Cr的污染等级为轻微污染,Cd的污染等级为重度污染;加权平均综合指数法和潜在生态风险指数法评价结果显示研究区域总体处于轻度生态风险,内梅罗综合指数法显示该基地土壤为中度污染。虽然4种评价方法所显示的基地土壤综合污染程度有差异,但都显示Cd是研究区土壤中最主要的生态风险元素。对照稻米超标的元素为Cr、Pb,但其HQ和HI值均小于1.0,说明该基地生产的稻米无食用风险,其中猛降镉处理的稻米Cd含量下降幅度最高,达到了57%,可见猛降镉叶面肥喷施该镉污染稻田区后能取得较好的修复效果。

Field single factor experiments were carried out in a polluted area in Yujiang District of Yingtan City with four modification including one of selenium fertilizer named Xitaitai,one of silicon fertilizer named Mengjiangge,powder of Oyster named Repairing Dragon(CaO≥40%)and lime(CaO≥90%).The effects on remediation of heavy metal pollution in paddy soil and heavy metal content in rice were evaluated.The 5-point method was used to collect samples of each treatment of soil and rice at rice ripening stage,and the heavy metal content of the samples was analyzed.The pollution degree of each heavy metal element was evaluated using the single-factor pollution index method.The comprehensive pollution status of soil heavy metals were evaluated by the weighted average composite index method,the Nemero composite index method and the potential ecological risk index method,which were used to determine the propotion of heavy metal pollution factors through the improved hierarchical analysis method.Besides,the high-risk quotient(HQ)and the high-risk index(HI)methods were used to evaluate the health risks of rice heavy metal content to human.The results showed that the single-factor pollution index showed that soilPb was under standard,Cu and Cr were slight pollution,and Cd was heavy pollution.In addition,the results of the evaluation of the weighted average composite index(WACI)method and the potential ecological risk index(PRI)method showed that the study area was at a mild ecological risk in general,but the Nemero composite index(NCI)showed that the soil was moderately polluted.Although the evaluation methods showed that the field soil comprehensive pollution degree were different,they all indicated that Cd was the most ecological risk element.The elements exceeding the national standard of rice were Cr and Pb,but their HQ and HI values were less than 1.0,indicating that rice of the field had no risk of consumption.The Cd content of the rice treated with Mengjiangge decreased the most,reaching 57%,indicating that the cadmium polluted paddy can be remediated by spraying Mengjiangge foliar fertilizer.