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镉和扑草净联合暴露对蚯蚓的生态毒性效应研究
Ecotoxicological Effects of combined Pollution between Cadmium and Prometryn on Earthworms
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摘要: 为探究重金属镉和农药扑草净单一及联合作用对土壤动物的生化毒性和细胞毒性,以赤子爱胜蚓为受试生物,研究了镉、扑草净单一及联合暴露对其乙酰胆碱酯酶(AchE)、超氧化物歧化酶(SOD)活性、丙二醛(MDA)的含量的影响,以及蚯蚓生长、繁殖、回避行为和体腔细胞DNA损伤的情况。结果表明:滤纸法得到扑草净对蚯蚓24 h和48 h的半致死浓度(LC50)分别为66.72 mg/kg和29.41 mg/kg是镉的11.03倍和12.67倍;镉与扑草净联合暴露下随染毒时间延长蚯蚓体内AchE、SOD活性均受到显著抑制;复合污染导致蚯蚓的氧化损伤程度加强,MDA含量均高于单一处理组;联合暴露21d内蚯蚓体重没有显著抑制,但繁殖能力显著降低,回避反应较为显著;镉-扑草净联合暴露会引起蚯蚓体腔细胞DNA损伤,且与二者复合污染浓度存在剂量-效应关系。镉-扑草净联合暴露对蚯蚓产生更为严重的毒害,加重了机体的氧化应激效应,受到的环境胁迫作用增强。Abstract: In order to investigate the biochemical toxicity and cytotoxicity of the heavy metal cadmium and the pesticide prometryn, single and combined effects on soil animals, the effects of single and combined exposure to cadmium and prometryn on the levels of acetylcholinesterase(AchE), superoxide dismutase(SOD) activity, malondialdehyde(MDA), and the growth of the earthworms were studied with the ruddy love winsome earthworm, Eisenia fetida, as the test organism, reproduction, avoidance behavior and DNA damage in coelomocyte.The results showed that: The LC50 of prometryn for earthworms at 24 and 48 h were 66.72 mg/kg and 29.41 mg/kg, respectively, which were 11.03 and 12.67 times higher than those of cadmium, obtained by the filter paper method; AchE and SOD activities in earthworms were significantly inhibited(p < 0.05) with the extension of the dyeing time under the combined exposure of cadmium and prometryn; Compound pollution resulted in enhanced oxidative damage in earthworms, with all MDA levels higher than those in the single treatment group; earthworm body weight was not significantly suppressed(p > 0.05) within 21 d of combined exposure, but reproduction was significantly reduced(p < 0.05), and avoidance responses were more significant(p < 0.05);Combined exposure to cadmium and prometryn induced DNA damage in the coelomocyte of earthworms, and there was a dose-effect relationship with the concentration of the two composite pollutants.The combined exposure of cadmium-prometryn resulted in more severe toxicity to earthworms, aggravated the oxidative stress effect of the organism, and enhanced the environmental stress.