典型抗寄生虫药在环境中的分布和光降解研究

Anthelmintics are widely used for prevention and treatment of parasitic infections in agriculture and aquaculture, as well as for human. Some anthelmintics have also found applications as pre- or post-harvest fungicides for control of a wide range of fungi affecting field crops, stored fruit and vegetables. Recently, anthelmintics were found ubiquitously occurrence in various environmental mediums around the world. However, little is known regarding on the seasonal variation, fate, and ecological risk of anthelmintics. According to the characteristics of the water resource and environment in China, wastewater, ground water, surface water, soil, and sediments in typical city of Sichuan province were collected to study the distribution and the fate of the anthelmintics. Based on the development of the analytical and pretreatment methods of 19 widely used anthelmintics, the aim of this study was 1) to investigate the occurrence and seasonal variation of the target chemicals in wastewater treatment plants and aquatic environment; 2) to estimate the effect of agricultural activities for releasing the pollutants into the environment based on the investigation of the contaminants in the soil, ground water, surface water, and sediments around the typical farm in Sichuan province, and 3) to evaluate the photochemical mechanisms of typical pollutants in aquatic environment. The results expand knowledge concerning the distribution and fate of anthelmintics in the municipal environment, and could provide the basic data for evaluation the ecological risk of the anthelmintics, as well as for their scientific management.

抗寄生虫药被广泛应用于人、农牧动物和水产养殖中寄生虫病的防治，某些药品甚至用做农作物、水果和蔬菜等收获前后的杀菌剂。虽然研究有限，抗寄生虫药已在世界多个地区多种环境介质中被广泛检出。目前，环境中抗寄生虫药的时空分布、迁移等环境行为和生态风险性尚未搞清楚。本项目根据我国城市水资源与环境特点，选择四川典型城市，以水处理系统（如污水处理厂）相连的水源地、污水、地下水、地表水、沉积物和土壤为研究对象，以19种常用的抗寄生虫药为目标物质。在建立前处理和分析方法基础上，分别研究：1）目标物在四川省水处理系统和水环境中的时空分布；2）对四川省典型大型养殖场废弃物和周边土壤、地下水、地表水和沉积物进行调查研究，明确人类农业活动对目标物释放进入环境的影响；3）典型目标物在水环境中的光化学转化。本项目将阐明目标污染物在城市环境中的分布及归趋机制等科学问题，同时为我国评价其生态风险、实施正确管理措施提供依据。

本研究在建立19种抗寄生虫药在各环境介质中的前处理和分析方法基础上，研究目标物在城市典型污水处理厂中的归趋；调查其在锦江中的时空变化和生态风险；阐述其在农田土壤中的污染和风险；通过室内外光降解实验，研究目标物在自然环境中的降解途径、产物和路径。研究发现，目标物在城市典型污水处理系统进出水中均被检出，每种目标物的人均每日排放负荷为0.2-153 μg，说明污水厂出水可能是受纳水体中目标物的重要来源。在锦江河水和沉积物中，所有目标物均有检出，平均浓度为0.3-24.7 ng/L和<0.01-107.7 ng/kg，目标物在夏季锦江河水和沉积物中的平均浓度显著高于冬季。伊维菌素、依普菌素、非班太尔和阿苯达唑在水环境中的生态风险较高，其余目标物处于可接受范围。所有目标物在农田土样中均被检出，总浓度为0.3-23.5 ng/g，施用粪肥的农田土壤目标物浓度较高。苯并咪唑类和大环内酯类是土壤中的主要污染物，合计占比>80%。成都市果蔬中芬苯达唑与噻苯咪唑的检出率为100%，且有健康风险。所有抗寄生虫药在养殖场周边土壤，养殖场内土壤和粪便中均被检出，总平均浓度为8.1-121.2 ng/g，排泄物能污染周围土壤。吸附解析和柱淋滤实验发现硫双二氯酚和左旋咪唑很难发生纵向迁移而影响地下水。光降解研究发现，直接光降解是阿苯达唑和硫双二氯酚在环境水体中的主要去除途径，其在夏季水体半衰期分别为16.9和9.1分钟。受光照形成激发态是他们降解的关键。左旋咪唑的降解是由多途径导致的，最主要的途径为直接光降解（50%），随后依次是间接光降解（29%），水解（13%）和光催化生物降解、颗粒物催化光降解等导致的降解（8%），微生物降解的作用可忽略不计。其在夏季水体中的半衰期为11.4天。最后鉴定出6种阿苯达唑的、2种硫双二氯酚的和24种左旋咪唑的降解产物，发现他们都是发生转化，并未矿化，并推导了他们的降解路径。

内容获取失败，请点击重试