四川花椒主产地土壤Pb的化学形态分析及生物有效性评价
The Lead Chemical Speciation Analysis and Bioavailability Assessment about Main Locality Soils of Chinese Prickly Ash in Sichuan
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摘要: 以四川主要花椒产地的18个试验点土壤为研究对象,进行了总铅的内梅罗指数污染评价,分析了各样本铅的5种形态,比较了各主产区样本铅的生物有效性和迁移性,以及pH值对铅化学形态和生物有效性的影响。结果表明,各花椒产地土壤中残渣态铅含量均显著高于各样地土壤中的其他四种形态,铁锰态铅含量均显著高于有机态铅、碳酸盐态铅和交换态铅。pH值>7的土壤样本中生物有效性和迁移性都显著低于其他样本。18个花椒供试地土壤样品中B主产区土样铅的生物有效性和迁移性显著高于A主产区,也显著高于其他主产区。按现行四川森林食品产地环境和产品限量标准,花椒产地土壤总铅含量有一定的超标风险,仍然需要适时监测,但四川森林食品产地环境和产品限量标准以及内梅罗污染评估结果所反映的产地土壤铅污染超标都比较片面,建议加入有效铅含量测定做辅助分析。Abstract: In this study,we took 18 experimental points' soils from Chinese prickly ash main production areas in Sichuan as research objects to evaluate the total lead pollution with Nemerow Index Method,analyzed 5 forms of lead in each sample,compared the lead bioavailability and mobility of samples in main production areas,and studied the effect of pH value on lead chemical forms and bioavailability.The results showed that the residual lead contents in locality soils were significantly higher than those of other 4 forms; the lead contents of Fe/Mn oxide were significantly higher than those of organic forms,carbonate forms,and exchangeable forms; the soil samples' bioavailability and mobility were much lower than others when pH>7; the bioavailability and mobility of soil samples in main production area B were much higher than those in area A and other areas.According to the current limit standard for Sichuan forest food production environment and product,the total lead contents in locality soils of Chinese prickly ash had certain overproof risk which needed timely monitoring.However,the locality soils' lead pollution reflected by the limit standard and Nemerow assessment result was a little one-sided,so we recommended adding the determination of available lead contents to serve as auxiliary analysis.