高氟地区电解铝厂场地氟污染特征及其风险评估
Fluorine pollution characteristics and risk assessment of electrolytic aluminum plant site in high fluoride area
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摘要: 针对位于我国典型高氟地区的氟污染场地开展环境调查,分析氟化物污染水平分布特征,并探析场地重污染区不同深度土层氟化物的地下迁移特征,评估该场地基于不同用地功能的氟化物环境风险效应。结果表明:场地表层土壤中氟化物浓度为3 340~38 400 mg/kg,与当地土壤氟化物背景值相比超标率为96%,土壤浸出液中氟化物浓度为0.06~25.40 mg/L;土壤中氟化物赋存形态以残渣态为主(占比93.88%),水溶态占比为0.85%;污染场地土壤类型影响氟化物地下迁移行为,黏土层对氟化物有很强的吸附和滞留能力。该污染场地若用作第一类用地(以住宅用地为代表),场地风险超过可接受风险水平;若用作第二类用地(以工业用地为代表),场地风险未超过可接受风险水平。Abstract: Based on the environmental investigation of the fluorine-contaminated site located at a typical fluorine rich region in China, the distribution characteristics of fluoride pollution level were analyzed, the underground migration characteristics of fluoride in different depth soil layers in the heavily polluted areas investigated, and the environmental risk effect of fluoride of the sites evaluated based on different landuse functions. The results showed that the concentrations of fluoride in surface soil ranged from 3 340 to 38 400 mg/kg, while the water-soluble fluoride content ranged from 0.06 to 25.40 mg/L. The over-standard rate was as high as 96% compared with the local soil fluoride background value. The occurrence forms of fluoride in soil were mainly residual state with percentage of 93.88% and the water-soluble percentage was 0.85%. The underground migration behaviours of fluoride were affected by soil types of the contaminated site, where the fluorine was strongly adsorbed and detained by the clay layer. The healthy risk was over the acceptable level when the contaminated site was used as the Classification Ⅰ lands, represented by residential land. If it was used as Classification Ⅱ lands, represented by industrial land, its hazard did not exceed the acceptable risk level.