生物活性剂淋洗对河道底泥重金属毒性和生态风险影响评价

以河道底泥为研究对象,采用Tessier五步连续提取法比较了淋洗前后底泥中重金属的形态分布变化,并采用生物活性评价法,浸出毒性法,地累积指数法和潜在生态风险指数法比较及评价了生物活性剂槐糖脂淋洗前后底泥重金属的生物活性、浸出毒性和生态风险系数的变化。研究同时还采用三维荧光对底泥中溶解性有机质进行了分析。结果表明:淋洗后底泥重金属形态分布发生变化,重金属的迁移能力降低,生物活性和危害性降低,浸出毒性减小,单一和综合潜在生态风险降低,说明淋洗是一种有效的降低底泥重金属环境危害的方法。经淋洗后的底泥中重金属稳定性提高,对生态风险小,可以进一步进行资源化利用。

Influence evaluation on toxicity and ecological risks of heavy metals in river sediment washed by bioactive agents

Tessier sequential extraction procedure was employed to analyze the heavy metal speciation of river sediment. Comparisons were made of the biological availability method, leaching characteristics method, geo-accumulation index method, and potential ecological risk method of heavy metals before and after washing by bio-surfactant sophorolipid. Dissolved organic matter in sediment was also evaluated by a three dimensional fluorescence analysis. Results showed that washing by bio-surfactant greatly changed the speciation of heavy metals in the sediment. Heavy metals became less migratory thus resulting in decreased bioavailability and decreased hazard. Washing also led to less leaching and lower potential individual or comprehensive risk to eco-environment. Our results revealed that washing by sophorolipid was effective in reducing the hazardous effect of heavy metal to environment. After washing, heavy metals were more stable and presented lower risk thus washed sediment could be considered for reuse.