针对农业型村落地表水体长期遭受混合农药污染,生态环境受损严重的情况,于2015年8月在广州市近郊建立了黑藻(Hydrilla verticillata)和苦草(Vallisneria natans)混种修复示范区,开展了沉水植物的构建对示范区7种农药(4种有机磷农药、2种有机氯农药和1种拟除虫菊酯类农药)污染控制、底栖动物恢复效果及常规水质指标浓度削减的研究,并采用风险商(RQ)法对水体中的农药进行生态风险评估.结果表明,示范区重建的半年内,水体中毒死蜱、氰戊菊酯、腐霉利、甲拌磷和乙草胺5种农药的平均去除率均大于75％,马拉硫磷和乐果的去除率约为50％.构建后,腐霉利由中等风险降为低风险,毒死蜱、乙草胺和乐果由高风险降为中等风险,其他3种农药的RQ值均显著下降(P＜0.05).综合质量浓度和生态风险控制效果,将甲拌磷和马拉硫磷列为重点控制农药品种.底栖动物的物种数、生物量及多样性较修复前均呈明显增加趋势,并与沉水植物生物量呈显著正相关(P＜0.05).水体各项常规水质指标质量浓度显著下降(P＜0.01),水质基本上从地表水标准的劣V类提高到Ⅲ～ⅣV类.综上所述,沉水植物的构建可有效控制水体中混合农药的质量浓度,降低其对水体的生态风险,恢复底栖动物多样性,是修复广东农村地区混合农药污染水体的有效方法.%With the aim of ecological restoration for surface water that suffered from pesticides and domestic waste water pollution in a agricultural village,this study established a Vallisneria natans and Hydrilla verticillata demonstration area in August 2015,and evaluated the effect of submerged vegetation restoration on the control of seven pesticides (four organophosphates pesticides,two organochlorine pesticides and one pyrethroid pesticides),the recovery of macrozoobenthos and the reduction of conventional water quality indicators.Risk quotient (RQ) method was applied to evaluate ecological risk.The results indicated that the average removal efficiencies of chlorpyrifos,fenvalerate,procymidone,phorate and acetochlor in water were over 75％,the removal efficiencies of malathion and dimethoate were around 50％.The ecological risk of procymidone varied from medium risk to low risk,chlorpyrifos,acetochlor and dimethoate varied from high risk to medium risk,and the risk quotient value of the other three pesticides were significantly decreased (P＜0.05).Considered the concentration control and ecological risk of the pesticides,phorate and malathion were screened as the key factors.The species,biomass and diversity of macrozoobenthos increased significantly,and they were positively correlated with the biomass of submerged macrophytes (P＜0.05).All conventional water quality indicators were decreased significantly,and the water quality was improved from worse than grades V to grades Ⅲ or IV according to state water quality standards for surface water.Over all,the construction of vegetation could effectively control the concentration of mixed pesticides in water,reduce the ecological risk,and recover the macrozoobenthos diversity.Hence it could be recognized as an effective and available method to repair the pesticide-polluted water body in Guangdong rural areas.
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