Center for Fisheries, Aquaculture and Aquatic Sciences and Department of Zoology, Southern Illinois University, Carbondale, IL 62901, USA.
U.S. Geological Survey, Washington Water Science Center, Tacoma, WA 98402, USA.
Environ Pollut. 2019 Nov;254(Pt A):112931. doi: 10.1016/j.envpol.2019.07.099. Epub 2019 Jul 22.
Pyrethroids are a class of widely-used insecticides that can be transported from terrestrial applications to aquatic systems via runoff and tend to sorb to organic carbon in sediments. Pyrethroid occurrence is detrimental to stream ecosystems due to toxicity to sediment-dwelling invertebrates which are particularly at risk of pyrethroid exposure in urban streams. In this work, 49 streams located in watersheds in the northeastern United States were surveyed for nine current-use pyrethroids using two extraction methods. Total sediment concentrations were determined by exhaustive chemical extraction, while bioaccessible concentrations were determined by single-point Tenax extraction. Total and bioaccessible pyrethroid concentrations were detected in 76% and 67% of the sites, and the average sum of pyrethroids was 232 ng/g organic carbon (OC) for total and 43.8 ng/g OC for bioaccessible pyrethroids. Bifenthrin was the most commonly detected pyrethroid in streambed sediments. Sediment toxicity was assessed using 10-d Hyalella azteca bioassays, and 28% and 15% of sediments caused a decrease in H. azteca biomass and survival, respectively. A temperature-based focused toxicity identification evaluation was used to assess pyrethroids as the causal factor for toxicity. The concentrations of pyrethroids was only weakly correlated with the degree of urban land use. Sediment toxicity was predicted by total and bioaccessible pyrethroid concentrations expressed as toxic units. This work suggests that bioaccessibility-based methods, such as Tenax extraction, can be a valuable tool in assessing sediment toxicity.
拟除虫菊酯是一类广泛使用的杀虫剂，可通过径流从陆地应用转移到水生系统，并倾向于吸附到沉积物中的有机碳上。由于对栖息在沉积物中的无脊椎动物具有毒性，拟除虫菊酯的存在对溪流生态系统有害，而这些无脊椎动物在城市溪流中特别容易受到拟除虫菊酯的暴露。在这项工作中，使用两种提取方法对美国东北部流域的 49 条溪流进行了 9 种当前使用的拟除虫菊酯的调查。通过彻底的化学提取法测定总沉积物浓度，而通过单点 Tenax 提取法测定生物可利用浓度。在 76%和 67%的地点检测到总和生物可利用的拟除虫菊酯浓度，总拟除虫菊酯和生物可利用拟除虫菊酯的平均总和分别为 232ng/g 有机碳（OC）和 43.8ng/g OC。在底泥沉积物中，联苯菊酯是最常见的拟除虫菊酯。使用 10 天的大型蚤（Hyalella azteca）生物测定法评估了沉积物毒性，分别有 28%和 15%的沉积物导致大型蚤生物量和存活率降低。基于温度的集中毒性鉴定评估用于评估拟除虫菊酯是否为毒性的因果因素。拟除虫菊酯的浓度与城市土地利用程度的相关性较弱。以毒性单位表示的总拟除虫菊酯和生物可利用拟除虫菊酯浓度可预测沉积物毒性。这项工作表明，基于生物可利用性的方法，如 Tenax 提取，可能是评估沉积物毒性的有用工具。
