iES Landau, Institute for Environmental Sciences, University of Koblenz-Landau, Fortstrasse 7, 76829, Landau, Germany.
Chemosphere. 2020 Nov;259:127459. doi: 10.1016/j.chemosphere.2020.127459. Epub 2020 Jun 20.
To assess potential aquatic pesticide risks, environmental monitoring strategies often focus on water and sediment. However, knowledge gaps with regard to the pollution status of organic matrices important for the structure and functioning of aquatic ecosystems do exist. The present study assessed the dissipation of the triazole fungicide tebuconazole (TEB; K = 5.01 × 10) and the pyrethroid insecticide etofenprox (ETO; K = 7.94 × 10) as model hydrophobic pesticide compounds among aquatic plants, vertical layers of allochthonous leaf litter, and detritus within flow-through outdoor stream mesocosms. During a 3-h pesticide exposure and a subsequent 24-h post-exposure period, retention was higher for ETO (max concentration: Myriophyllum spicatum > Elodea nuttallii > Ranunculus fluitans > Potamogeton perfoliatus ≫ leaf litter > detritus) and depended amongst other factors on surface area, while in the water compartment the pesticides reached concentration levels < LOQ 2 h after exposure. Desorption was observed for both pesticides in plants, and for TEB in detritus, while in leaves the ETO levels even increased over time, suggesting leaf litter to be a suitable additional sampling matrix for transient hydrophobic pesticide peaks, yet also a potential source of contamination for invertebrate shredders. The upper layer of leaf material contained higher ETO levels than those situated further in the sediment, which implies short-term positive effects for species inhabiting the deeper leaf layers, yet again pinpoints to a potential pesticide exposure pathway via organic matter in aquatic systems.
为了评估潜在的水生农药风险，环境监测策略通常侧重于水和沉积物。然而，对于对于水生生态系统的结构和功能很重要的有机基质的污染状况，仍存在知识空白。本研究评估了三唑类杀菌剂戊唑醇（TEB；K=5.01×10）和拟除虫菊酯类杀虫剂乙氰菊酯（ETO；K=7.94×10）作为模型疏水性农药化合物在水生植物、异源叶凋落物的垂直层和流水室外溪流中体中物质的消解情况。在 3 小时的农药暴露和随后的 24 小时暴露后，ETO 的保留率更高（最大浓度：狐尾藻>伊乐藻>浮萍>菹草>叶凋落物>底泥），除其他因素外，还取决于表面积，而在水相中，暴露 2 小时后，农药的浓度水平<LOQ。两种农药在植物中均观察到解吸，TEB 在底泥中也观察到解吸，而在叶片中，ETO 的水平甚至随时间增加，表明叶凋落物是暂态疏水性农药峰的合适附加采样基质，但也是水生无脊椎动物碎屑分解者的潜在污染源。叶材料的上层比沉积中更深的位置含有更高的 ETO 水平，这意味着栖息在更深叶层的物种短期内会受到积极影响，但再次指出了通过水生系统中的有机物进行农药暴露的潜在途径。
