龙岩市不同利用类型土壤及农作物Pb、 Cd和As污染风险与贡献分析

Pollution Risk and Contribution Analysis of Pb, Cd, and As in Soils and Crops Under Different Land Use Types in Longyan City

以龙岩市2个典型地块为研究对象,采集了土壤样品174件及谷物类样品87件,利用污染指数法、 Hakanson潜在生态风险指数法和美国EPA人体暴露风险评价模型开展不同利用类型土壤及农作物Pb、 Cd和As的污染评价、生态风险评价和不同暴露途径下的健康风险评估,并对比分析Pb、 Cd和As对土壤及农作物污染风险的贡献.结果表明,Ⅰ区不同利用类型土壤及农作物Pb、 Cd和As的污染等级较低,Cd是主要土壤污染和生态风险因子,对土壤综合污染和综合潜在生态风险的贡献率分别为55.3%和60.2%.Ⅱ区土壤及农作物Pb、 Cd和As的污染等级较高,Pb和Cd是主要土壤污染和生态风险因子,对综合污染的贡献率分别为44.2%和51.6%,对综合潜在生态风险的贡献率分别为23.7%和67.3%.Pb是主要农作物污染因子,对薏米和水稻综合污染的贡献率分别为60.6%和51.7%.经口-土壤暴露途径下,2个典型地块土壤Cd和As对成人和儿童的致癌风险均在可接受范围内,Ⅰ区土壤Pb、 Cd和As的非致癌风险较小,Ⅱ区3种污染物对总非致癌风险的贡献率为:Pb(68.1%)>As(30.5%)>Cd(1.38%).经口-水稻摄入途径下,2个典型地块水稻Pb均无致癌风险,Cd和As对成人和儿童的致癌风险贡献率分别为:As(76.8%)>Cd(22.7%)和Cd(69.1%)>As(30.3%).Ⅰ区和Ⅱ区3种污染物具有较高非致癌风险,均以As的贡献最为显著,贡献率分别为84.0%和52.0%,其次为Cd,最后为Pb.

A total of 174 soil samples and 87 grain samples were collected in two typical fields in Longyan City.The pollution index method,Hakanson potential ecological risk index method,and EPA human exposure risk assessment model were used to evaluate the pollution status,ecological risk,and health risks of heavy metals Pb,Cd,and As in soil of different land use types.The contributions of Pb,Cd,and As to soil and crop pollution risk were also analyzed.The results indicated that the pollution levels of Pb,Cd,and As in soils and crops of different utilization types in regionⅠwere low.Cd was the main soil pollutant and ecological risk factor,contributing 55.3%to comprehensive soil pollution and 60.2%to comprehensive potential ecological risk,respectively.The pollution levels of Pb,Cd,and As in soils and crops in regionⅡwere high.Pb and Cd were the main soil pollutants and ecological risk factors,contributing 44.2%and 51.6%to comprehensive pollution and 23.7%and 67.3%to comprehensive potential ecological risk,respectively.Pb was the main pollution factor of crops,contributing 60.6%and 51.7%to the comprehensive pollution of coix and rice,respectively.The carcinogenic risks of Cd and As in soil of the two typical regions for adults and children were all within the acceptable range under the oral-soil exposure pathway.The contribution of Pb,Cd,and As to the total non-carcinogenic risk in regionⅠwas Pb(68.1%)>As(30.5%)>Cd(1.38%).There was no carcinogenic risk of Pb in rice in the two typical regions under the oral-rice intake pathway.The contribution of Cd and As to carcinogenic risk in adults and children were As(76.8%)>Cd(22.7%)and Cd(69.1%)>As(30.3%),respectively.Three pollutants in regionⅠandⅡhad high non-carcinogenic risk,and As was the most significant contributor(84.0%and 52.0%,respectively),followed by Cd and Pb.