土壤中结合残留态农药的生态环境效应

Eco-environmental impacts of bound pesticide residues in soil: a review

土壤中农药结合残留态的形成,导致其活性暂时降低,但并未从土壤中消失,在特定的环境条件下又重新释放到环境中并表现出较高的生物有效性,从而威胁农产品质量安全与环境质量。文章论述了土壤中结合残留态农药的定义、形成过程及影响因素、老化和释放过程及机制。土壤中结合残留态农药主要通过吸附过程、化学反应及物理镶嵌等作用而形成,其形成过程受农药的结构和化学特性、土壤理化性质、环境条件和农艺措施的影响。老化是化合物和土壤组分紧密结合,减少被普通提取方法提取出来的数量,降低了化合物的生物有效性。同时老化的物质在土壤环境条件改变的情况下又重新释放到土壤溶液中或进行矿化,此过程可以通过物理-化学机制或生物化学作用而发生。重新释放到环境中的结合残留态农药又表现出较高的生物有效性,可能被植物、动物或微生物所吸收,并沿食物链富集和放大或进入水体污染水产品和造成水质恶化,从而威胁人体健康。文章还分析了土壤结合残留态农药可能带来的环境问题,提出了此问题今后研究的方向。

Nearly 90% pesticides applied in agricultural field became bound residues in soil when they entered into environment. Although bound pesticide residues existed in soil became less toxicity temporarily, under special condition they may be released into soil, just as chemical time bombs, will bring profound impacts on quality of agricultural products and environment, and bring threaten to peoples health. Thus the effects of bound pesticide residues on agricultural productions and eco-environment have be-come hot topic in the world. This paper gives an overview on the conception, process and influencing factors of bound pesticide residues when they formed; mechanism of aging and release of bound pesticide residues; eco-environmental impacts of bound pesti-cide residues. In general, during the formation of bound pesticide residues, there are three actions occurred, which are adsorption, chemical reaction and physical mosaic. Structure and chemical attributes of pesticide, physic-chemical property of soil and environmental condition are the main factors to influence the forming process of bound pesticide residues in soil. Ageing is thought to be the result of either a redistribution of the chemicals from weaker to stronger adsorption sites, slow chemisorption, or covalent bond formation between the compounds and soil components. In nature, bound pesticide residues may be released to ambient environment by phys-ico-chemical and biochemical processes. Although toxicity of bound pesticide residues was decreased compared with original pesti-cide, they may produce eco-toxical effects on plant, animal and microorganism in soil when they were released again. Released bound pesticide residues may be leached into water, the quality of water and its products will be deteriorated. Furthermore, the perspectives in bound pesticide residues research in the future were suggested.