土壤B[a]P叠加污染对蚯蚓体腔细胞SOD、POD和MDA的毒性效应

采用累积试验方法,研究土壤苯并a]芘（Ba]P）多次叠加污染对赤子爱胜蚓（Eisenia foetida）体腔细胞超氧化物歧化酶（SOD）、过氧化物酶（POD）和丙二醛（MDA）的毒性效应.结果表明,随着土壤中Ba]P暴露时间的延长,蚯蚓体腔细胞的SOD、POD活力和MDA含量呈初期（1～14 d）下降速率较快,尔后（14～56 d）下降速率减小的变化趋势.在叠加污染条件下,0～ 20 cm深度土壤中蚯蚓体腔细胞SOD活力和MDA含量在14d时分别比一次污染低20.97％和15.96％,POD活力比一次污染高20.44％;而在＞20～40 cm深度土壤中蚯蚓体腔细胞SOD、POD活力和MDA含量在14d时分别比一次污染低52.89％、18.00％和70.60％.表明Ba]P叠加污染土壤中蚯蚓体腔细胞的毒性效应低于一次污染.

Toxic Effects of Repeated Superimposed B[a] P Pollution of Soil on SOD,POD and MDA in Coelomocytes of Eisenia foetida

As a persistent organic pollutant （POP）,benzo （a） pyrene （B a] P） is gradually accumulating in the soil,posing a serious threat to the soil environment quality.The routine approach to environmental risk assessment of Ba] P is only based on one-time pollution,i.e.mixing the soil with Ba] P only once,which deviates from the step-by-step procedure of B a] P entering the soil.In this paper,a toxic bioassay was conducted to investigate toxic effects of B a] P on superoxide dismutase （SOD） and peroxidase （POD） activities and malondialdehyde （MDA） levels in coelomocytes of earthworm （Eiseniafoetida）,using the multiple-time superimposed and one-time pollution methods.Results show that with the exposure to Ba]P going on,SOD and POD activities and MDA content in coelomocytes of earthworm dropped rapidly in the first 14 days （1-14 d）,and then declined slowly in the 42 days to follow （14-56 d） under both the multiple-time superimposed and one-time pollution methods.In the first 14 days,the SOD activity and MDA content in earthworms found in the 0-20 cm soil layer under superimposed pollution was 20.97% and 15.96% lower,respectively,while POD activity was 20.44% higher than that under one-time pollution.However,the SOD and POD activities,as well as the MDA content in earthworms found in the 〉20-40 cm soil layer under superimposed pollution was 52.89%,18.00% and 70.60% lower than that under one-time pollution,respectively.All the above findings suggest that toxicity of multiple-time superimposed Ba] P pollution to earthworms was lower than that of one-time pollution.The study provides crucial data for evaluating ecological toxicity of cumulative B a] P pollution in the soil.