土壤基本理化性质对外源镉蚯蚓慢性毒性的影响

Effects of soil physico-chemical properties on chronic toxicity of cadmium to earthworm Eisenia fetida

为了给污染土壤生态风险评价和构建土壤生态筛选基准提供基础参考数据,参考经济合作与发展组织(OECD)颁布的蚯蚓慢性毒性试验方法,研究了镉在我国18种典型土壤中对赤子爱胜蚓(Eisenia fetida)的慢性毒性。结果表明,镉在不同类型土壤中对蚯蚓产茧量最大无影响浓度NOEC变化范围为10~100 mg·kg^(-1),半数有效抑制浓度EC_(50)变化范围为66.5~263.5 mg·kg^(-1)。土壤基本性质显著影响着镉的生物毒性,通过对EC_(50)与土壤的主要理化性质逐步多元回归分析,发现土壤pH值和有机质含量与EC_(50)呈显著正相关关系,黏粒与EC_(50)呈显著负相关关系,三种因子共同控制了EC_(50)预测回归模型变异的89.1%。同时分析不同类型土壤中蚯蚓体内镉积累量变化可知,土壤pH越高,有机质含量越高,土壤中镉生物有效性就越低。

The effects of soil physico-chemical properties on the chronic toxicity of cadmium（Cd） to earthworm were investigated in 18 soils spiked with Cd by employing the methods of Organization for Economic Co-operation and Development（OECD）. Results showed that Cd toxicity to E. fetida differed in different soils. No observed effect concentrations（NOEC） of Cd varied from 10 to 100 mg·kg^-1. The Cd concentration for 50% of maximal inhibition effect（EC50） of cocoon production ranged from 66.5 to 263.5 mg·kg^-1. Significant positive correlations were observed between soil pH, organic matter content and cadmium EC50, while significant negative correlation was present between clay content and cadmium EC50. These three factors accounted for 89.1% of variance for cadmium EC50. The bioavailability of Cd was lower in soil with higher pH and more soil organic matter, which was in accordance with the results of the inhibition of cocoon production experiments. The Cd ecotoxicity data generated in the current study may provide useful reference information for the environmental risk assessment of Cd contaminated soils and the development of soil screening values.