Abstract

Extensive pesticide use for agriculture can diffusely pollute aquatic ecosystems through leaching and runoff events and has the potential to negatively affect non-target organisms. Atrazine and S-metolachlor are two widely used herbicides often detected in high concentrations in rivers that drain nearby agricultural lands. Previous studies focused on concentration-response exposure of algal monospecific cultures, over a short exposure period, with classical descriptors such as cell density, mortality or photosynthetic efficiency as response variables. In this study, we exposed algal biofilms (periphyton) to a concentration gradient of atrazine and S-metolachlor for 14 days. We focused on fatty acid composition as the main concentration-response descriptor, and we also measured chlorophyll a fluorescence. Results showed that atrazine increased cyanobacteria and diatom chlorophyll a fluorescence. Both herbicides caused dissimilarities in fatty acid profiles between control and high exposure concentrations, but S-metolachlor had a stronger effect than atrazine on the observed increase or reduction in saturated fatty acids (SFAs) and very long-chain fatty acids (VLCFAs), respectively. Our study demonstrates that two commonly used herbicides, atrazine and S-metolachlor, can negatively affect the taxonomic composition and fatty acid profiles of stream periphyton, thereby altering the nutritional quality of this resource for primary consumers.

中文翻译：

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阿特拉津和精异丙甲草胺对河流附生生物分类和脂肪酸组成的影响

摘要

农业中大量使用农药会通过淋滤和径流事件广泛污染水生生态系统，并有可能对非目标生物体产生负面影响。阿特拉津和精异丙甲草胺是两种广泛使用的除草剂，经常在流经附近农田的河流中检测到高浓度的除草剂。先前的研究重点是藻类单特异性培养物在短时间内的浓度响应暴露，以细胞密度、死亡率或光合效率等经典描述符作为响应变量。在这项研究中，我们将藻类生物膜（附生生物）暴露于阿特拉津和精异丙甲草浓度梯度中 14 天。我们重点关注脂肪酸组成作为主要的浓度响应描述符，并且我们还测量了叶绿素 a 荧光。结果表明，莠去津增加了蓝藻和硅藻叶绿素 a 的荧光。两种除草剂均导致对照浓度和高暴露浓度之间的脂肪酸谱存在差异，但精异丙甲草胺对观察到的饱和脂肪酸 (SFA) 和极长链脂肪酸 (VLCFA) 的增加或减少的影响分别比莠去津更强。 。我们的研究表明，两种常用的除草剂莠去津和精异丙甲草胺会对溪流附生生物的分类组成和脂肪酸谱产生负面影响，从而改变该资源对初级消费者的营养质量。