Department of Chemical & Environmental Engineering, University of Arizona, 1133 E James E Rogers Way, Harshbarger 108, Tucson, AZ 85721-0011, USA; Nanyang Technological University, Nanyang Environment & Water Research Institute (NEWRI), 1 Cleantech Loop, CleanTech One, #06-08, Singapore 637141, Singapore.
Department of Chemical & Environmental Engineering, University of Arizona, 1133 E James E Rogers Way, Harshbarger 108, Tucson, AZ 85721-0011, USA.
Environ Int. 2019 Nov;132:105038. doi: 10.1016/j.envint.2019.105038. Epub 2019 Aug 14.
DEET (N, N-diethyl-m-toluamide) is one of the most frequently detected trace organic contaminants (TOrC) in wastewaters and is used primarily as an insect repellent. It was introduced for use in the general public in 1957. It is ubiquitously present in the environment and DEET concentrations are usually among the highest reported for TOrCs. Due to recent concerns about possible analytical interferences in detection methods being reported, this study focused on possible artifacts caused by seasonal, spatial, and diurnal variations in wastewater influent concentration of DEET. We also compared usage data to observed wastewater concentrations of seven wastewater treatment plants (WWTPs) in four different regions in the US monitored from November 2014 to November 2016. Consumption data obtained reveal patterns of consumption according to climatic regions and season. During the summer DEET usage accounts for almost 60% of all usage during a year, while during the winter months DEET usage accounts for <5%. Concerning spatial distribution, while per capita consumption of DEET in Florida is three times higher than the one observed in Arizona (44 g vs 14 g), DEET concentrations in wastewater tend to be much higher in Arizona. Regardless of WWTPs or monitoring period, concentrations as high as 15,200 ng/L were observed during the month of October 2016. While DEET has a diurnal variation in the wastewater influent, with a maximum at 18:00, the diurnal variability is not enough to explain the great discrepancies between consumption of DEET versus occurrence in wastewaters. Although LC-MS/MS analysis of isobaric and structural mimics suggests some possibility of interferences, NMR spectroscopy analysis of environmental samples does not support the presence of such mimics in real samples.
避蚊胺（N，N-二乙基-间-甲苯酰胺）是废水中最常检测到的痕量有机污染物（TOrC）之一，主要用作驱虫剂。它于 1957 年开始在公众中使用。它广泛存在于环境中，避蚊胺的浓度通常是报告的 TOrC 中最高的之一。由于最近人们担心可能会在检测方法中报告分析干扰，因此本研究侧重于废水进水浓度中避蚊胺的季节性、空间和昼夜变化可能引起的人为因素。我们还将使用数据与 2014 年 11 月至 2016 年 11 月期间在美国四个不同地区的七个废水处理厂（WWTP）监测的废水浓度进行了比较。获得的消费数据揭示了根据气候区和季节的消费模式。在夏季，避蚊胺的使用量占全年使用量的近 60%，而在冬季，避蚊胺的使用量占不到 5%。就空间分布而言，虽然佛罗里达州的人均避蚊胺消费量是亚利桑那州的三倍（44 克比 14 克），但废水中的避蚊胺浓度在亚利桑那州要高得多。无论 WWTP 或监测期如何，在 2016 年 10 月，都观察到高达 15200ng/L 的浓度。尽管废水进水存在昼夜变化，最大值出现在 18:00，但昼夜变化不足以解释避蚊胺的消耗与废水中出现的情况之间的巨大差异。尽管 LC-MS/MS 对等摩尔和结构类似物的分析表明存在一些干扰的可能性，但环境样品的 NMR 光谱分析不支持实际样品中存在此类类似物。
