唐山南部稻田土壤和稻米中重金属状况调查及风险评价

Investigation and Risk Assessment of Heavy Metals in Paddy Soil and Rice in Southern Tangshan

以唐山南部稻田土壤和稻米为研究对象,测定土壤和稻米中Cr、Cd、Pb、As和Hg含量,采用单因子污染指数法、内梅罗综合污染指数法及潜在生态风险指数法对研究区稻田土壤的污染状况及生态风险进行评估。结果表明:稻田土壤中Cr、Cd、Pb、As和Hg的平均值均超过河北省土壤重金属背景值,主要以Cd和Hg污染问题最为突出。稻米中Cr、Cd、Pb、As和Hg的含量均低于食品安全国家标准限定值,说明当地居民食用的稻米对健康没有威胁。研究区土壤总体上处于轻度污染状态,且有25.63%处于警戒限。稻田土壤Cr、Pb、As和Hg均处于轻微潜在生态危害,Cd有2.74%处于中等潜在生态危害。5种重金属的综合潜在生态危害指数的均值为23.42,为轻微生态风险水平。Cd对综合潜在生态危害的贡献率最大,是该稻田土壤生态风险的主要来源。

The paddy soil and rice in the south of Tangshan were studied to determine the contents of Cr,Cd,Pb,As and Hg,and the methods of the single factor index,the Nemerow comprehensive index and the potential risk index were used to the evaluate pollution status and ecological risk of paddy soil in the study area.Results show these as follows the average value of the contents of Cr,Cd,Pb,As and Hg in paddy soil is higher than the background value of heavy metals in soil of Hebei Province,and Cd and Hg pollution are the most prominent problems.The contents of Cr,Cd,Pb,As and Hg in rice is lower than the national standard limit value of food safety,indicating the rice eaten by the local people is not a threat to their health.On the general,the soil in the study area is slightly polluted,and 25.63%is in the alert limit.Cr,Pb,As and Hg in paddy soil are at low potential ecological risk,though 2.74%of cadmium is in moderate potential ecological hazard.The average value of comprehensive potential ecological harm index of five heavy metals is 23.42,which is the level of slight ecological risk.The contribution rate of Cd to the potential ecological harm is the highest,so it is the main source of soil ecological risk in the paddy field.