U.S. Geological Survey, California Water Science Center, Placer Hall, 6000 J St., Sacramento, CA 95819, United States of America.
U.S. Geological Survey, Washington Water Science Center, 934 Broadway, Suite 300, Tacoma, WA 98402, United States of America.
Sci Total Environ. 2021 Nov 1;793:148453. doi: 10.1016/j.scitotenv.2021.148453. Epub 2021 Jun 15.
Pesticides occur in urban streams globally, but the relation of occurrence to urbanization can be obscured by regional differences. In studies of five regions of the United States, we investigated the effect of region and urbanization on the occurrence and potential toxicity of dissolved pesticide mixtures. We analyzed 225 pesticide compounds in weekly discrete water samples collected during 6-12 weeks from 271 wadable streams; development in these basins ranged from undeveloped to highly urbanized. Sixteen pesticides were consistently detected in 16 urban centers across the five regions-we propose that these pesticides comprise a suite of urban signature pesticides (USP) that are all common in small U.S. urban streams. These USPs accounted for the majority of summed maximum pesticide concentrations at urban sites within each urban center. USP concentrations, mixture complexity, and potential toxicity increased with the degree of urbanization in the basin. Basin urbanization explained the most variability in multivariate distance-based models of pesticide profiles, with region always secondary in importance. The USPs accounted for 83% of pesticides in the 20 most frequently occurring 2-compound unique mixtures at urban sites, with carbendazim+prometon the most common. Although USPs were consistently detected in all regions, detection frequencies and concentrations varied by region, conferring differences in potential aquatic toxicity. Potential toxicity was highest for invertebrates (benchmarks exceeded in 51% of urban streams), due most often to the neonicotinoid insecticide imidacloprid and secondarily to organophosphate insecticides and fipronil. Benchmarks were rarely exceeded in urban streams for plants (at 3% of sites) or fish (<1%). We propose that the USPs identified here would make logical core (nonexclusive) constituents for monitoring dissolved pesticides in U.S. urban streams, and that unique mixtures containing imidacloprid, fipronil, and carbendazim are priority candidates for mixtures toxicity testing.
农药在全球城市溪流中普遍存在，但由于地域差异，农药的出现与城市化之间的关系可能会被掩盖。在美国五个地区的研究中，我们调查了地区和城市化对溶解农药混合物出现和潜在毒性的影响。我们分析了从 271 个可涉水溪流中每周采集的 6-12 周离散水样中的 225 种农药化合物；这些流域的发展从未开发到高度城市化不等。在五个地区的 16 个城市中心，我们一致检测到了 16 种农药——我们提出，这些农药构成了一套城市特征农药 (USP)，在美国小型城市溪流中都很常见。这些 USP 占每个城市中心城市站点中最大农药浓度总和的大部分。USP 浓度、混合物复杂性和潜在毒性随流域城市化程度的增加而增加。流域城市化在基于距离的多变量农药分布模型中解释了最大的变异性，而区域始终是次要因素。USP 占城市站点 20 种最常出现的 2 种独特混合物中农药的 83%，其中多菌灵+丙溴磷最为常见。尽管所有地区都一致检测到了 USP，但检测频率和浓度因地区而异，导致潜在水生毒性存在差异。无脊椎动物的潜在毒性最高（51%的城市溪流中超过基准），主要是由于新烟碱类杀虫剂噻虫啉，其次是有机磷杀虫剂和氟虫腈。在城市溪流中，植物（在 3%的地点）或鱼类（<1%）很少超过基准。我们提出，这里确定的 USP 将成为监测美国城市溪流中溶解农药的合理核心（非排他性）成分，并且含有噻虫啉、氟虫腈和多菌灵的独特混合物是混合物毒性测试的优先候选物。
