Department of Civil, Architectural and Environmental Engineering, University of Miami, Coral Gables, FL, United States of America.
Department of Chemistry, Ball State University, Muncie, IN 47306, United States of America.
Sci Total Environ. 2020 Jul 10;725:138391. doi: 10.1016/j.scitotenv.2020.138391. Epub 2020 Apr 2.
Naled, an organophosphate pesticide, received considerable attention during 2016 as it was applied aerially to control the first mosquito-borne Zika virus outbreak in the continental United States. Stakeholders living in affected areas raised concerns about its environmental impacts. One factor influencing environmental impacts is the persistence of the chemical applied. The objective of this study was to evaluate the persistence of naled - and its degradation bi-product, dichlorvos - in natural waters. Initial naled concentrations were measured at ground level after full-scale aerial spray activities. Laboratory experiments were designed to evaluate factors (fresh versus marine water chemistry, temperature, and sunlight) that may promote the degradation of naled and dichlorvos in the environment. Results show that natural fresh and marine water chemistry promoted naled degradation as experiments with de-ionized water resulted in half-lives greater than 6 days. The half-life in natural waters without light ranged from 5 to 20 h with lower half lives at higher temperatures. Under light exposure, degradation was accelerated and yielded more dichlorvos. Detectable levels (0.05 μM for naled and 0.10 μM for dichlorvos) were measured in water samples collected from the field during aerial spray events. Results can be used in risk assessments that consider both naled and dichlorvos to better understand ecological impacts and to develop improved public health recommendations.
纳乐，一种有机磷农药，在 2016 年受到了广泛关注，因为它被用于空中喷洒，以控制美国大陆首例蚊媒寨卡病毒爆发。生活在受影响地区的利益相关者对其环境影响表示担忧。影响环境影响的一个因素是所应用化学物质的持久性。本研究的目的是评估纳乐及其降解副产物敌敌畏在天然水中的持久性。在全面空中喷洒活动后，在地面水平测量初始纳乐浓度。实验室实验旨在评估可能促进纳乐和敌敌畏在环境中降解的因素（淡水与海水化学、温度和阳光）。结果表明，天然淡水和海水化学促进了纳乐的降解，因为去离子水实验导致半衰期超过 6 天。在没有光照的天然水中，半衰期范围为 5 至 20 小时，温度较高时半衰期较短。在光照下，降解速度加快，并产生更多的敌敌畏。在喷洒空中喷洒事件期间从现场采集的水样中检测到可检测水平（纳乐为 0.05 μM，敌敌畏为 0.10 μM）。结果可用于风险评估，同时考虑纳乐和敌敌畏，以更好地了解生态影响，并制定改进的公共卫生建议。
