铬(Ⅵ)老化对赤子爱胜蚓抗氧化酶活性的影响

Effects of Aged Chromium( Ⅵ) on Activities of Antioxidant Enzymes of Eisenia fetida

为评估土壤Cr（Ⅵ）老化的生态风险,设计未老化和老化人工土壤组,研究Cr（Ⅵ）对赤子爱胜蚓体内SOD（超氧化物歧化酶）、CAT（过氧化氢酶）和POD（过氧化物酶）活性的影响.结果表明：在未老化土壤中,30 mg/kg（低浓度）、60 mg/kg（中浓度）和90 mg/kg（高浓度）Cr（Ⅵ）对赤子爱胜蚓抗氧化酶系统产生了显著的影响,在暴露的前14 d,赤子爱胜蚓体内SOD和CAT活性均随土壤中w〔Cr（Ⅵ）〕的升高而降低（暴露第3天,低浓度组除外）,高浓度组与对照组相比降低了约60%;在暴露的第14天~第21天,SOD和CAT活性均显著升高,但POD的活性一直处于抑制状态.在老化28 d的人工土壤中,暴露第1天,CAT和POD活性均显著升高,随着暴露时间的延长,其酶活性均受到显著抑制;但蚯蚓体内SOD活性在整个试验过程中均未受显著影响.Cr（Ⅵ）对赤子爱胜蚓体内3种抗氧化酶活性的影响在未老化和老化土壤中有很大差异,这种差异影响到对土壤Cr（Ⅵ）污染的毒性评估.因此,进行Cr（Ⅵ）毒性试验时应考虑其在土壤中的老化作用.

The effects of chromium（ Cr（ Ⅵ）） on activities of three antioxidant enzymes-superoxide dismutase（ SOD）,catalase（ CAT）and peroxidase（ POD）-in the earthworm Eisenia fetida were investigated with both freshly spiked and aged soils. The results showed that Cr（ Ⅵ） caused significant effects on activities of three antioxidant enzymes at the low（ 30 mg/kg）,medium（ 60 mg/kg） and high（ 90mg/kg） concentrations on freshly spiked soils. The SOD and CAT activities（ except the low concentration group in the 3rdday of exposure） decreased with the exposed dose of Cr（ Ⅵ） in the first 14 d of exposure. The inhibition rates were about 60% with the treatments with high concentrations. The SOD and CAT activities were significantly enhanced,while POD activity was inhibited in the14-21 d of exposure. In the early days,CAT and POD activities were markedly elevated. However,after a longer exposure period,the activities were inhibited. On the other hand,the activity of SOD was not affected by the test on aged soils. The results indicated that soil aging leads to effects on the toxicity of Cr（ Ⅵ）,and it should be taken into consideration when toxicity tests of Cr（ Ⅵ） are carried out.