甲氰菊酯在土壤中的降解及对蚯蚓的毒性效应研究

Study on the Degradation of Fenpropathrin in Soil and Its Toxic Effect on Earthworms

拟除虫菊酯作为全球第三大杀虫剂品种,在农业生产中广泛使用,同时也带来了一系列不利的环境影响。然而,目前有关拟除虫菊酯在土壤环境中的残留行为和风险评估报道较少。以典型拟除虫菊酯类杀虫剂甲氰菊酯(FEN)为研究对象,重点探究其在不同性质土壤中的降解行为以及对典型土壤生物蚯蚓的毒性效应。结果表明,甲氰菊酯在碱性土壤中的降解速度快于酸性土壤,同时在非灭菌土壤中的降解速度为灭菌土壤的4倍。因此,土壤酸碱度和微生物是影响FEN在土壤中降解快慢的主要因素。此外,在降解过程中检测到甲氰菊酯主要代谢物3-苯氧基苯甲酸(3-PBA)的生成。蚯蚓富集结果表明,FEN在蚯蚓体内的含量先升高后降低,最大生物富集因子为0.3。亚急性毒性结果表明,高剂量(5 mg·kg^(–1))甲氰菊酯暴露14 d后,蚯蚓体内蛋白质含量显著降低(P<0.05),细胞色素P450(CYP450)、羧酸酯酶(CarE)、谷胱甘肽-S-转移酶(GST)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量均显著增加(P<0.05),同时存在剂量效应,证实土壤中残留的FEN对蚯蚓具有毒性效应。本文对甲氰菊酯在土壤环境中的降解行为研究以及生态毒性风险评估具有重要的指导意义。

【Objective】The goal of this study was to evaluate the degradation of fenpropathrin in soil and its effects on earthworms,as well as to establish a foundation for a full environmental risk assessment of fenpropathrin.【Method】High performance liquid chromatography was used to identify the bioaccumulation of fenpropathrin and the major metabolite,3-phenoxybenzoic acid,then soil exposure tests were used to assess the toxicity of fenpropathrin to earthworms.【Result】(1)Fenpropathrin decomposed four times more quickly in unsterilized soil than in sterilized soil and more quickly in alkaline soil than in acidic soil,suggesting that microorganisms and pH were the main factors affecting the degradation rate of fenpropathrin in soil.Moreover,during the decomposition process,the synthesis of its primary metabolite,3-phenoxybenzoic acid,was discovered.(2)Fenpropathrin content in earthworms increased,then dropped,with a maximum bioconcentration factor of 0.3.(3)The subacute toxicity data showed that after 14 d exposure to high doses(5 mg·kg^(–1))of fenpropathrin,the protein content in earthworms was significantly reduced(P<0.05).Also,the cytochrome P450(CYP450),carboxylesterase(CarE),glutathione-S-transferase(GST),superoxide dismutase(SOD)and catalase(CAT)activities and malondialdehyde(MDA)content were significantly increased(P<0.05)after 14 d of fenpropathrin exposure,and there was a dosage effect.【Conclusion】The rate of fenpropathrin degradation in soil was strongly linked with soil characteristics,and fenpropathrin residues in soil could cause subacute toxic effects in earthworms.These findings help in a thorough evaluation of the ecotoxicity and environmental behavior of fenpropathrin in soil,as well as a more solid foundation for pyrethroid pesticide risk assessment.