Freshwater microbes play a crucial role in the global carbon cycle. Anthropogenic stressors that lead to changes in these microbial communities are likely to have profound consequences for freshwater ecosystems. Using field data from the coordinated sampling of 617 lakes, ponds, rivers, and streams by citizen scientists, we observed linkages between microbial community composition, light and chemical pollution, and greenhouse gas concentration. All sampled water bodies were net emitters of CO₂, with higher concentrations in running waters, and increasing concentrations at higher latitudes. Light pollution occurred at 75% of sites, was higher in urban areas and along rivers, and had a measurable effect on the microbial alpha diversity. Genetic elements suggestive of chemical stress and antimicrobial resistances (IntI1, blaOX₅₈) were found in 85% of sites, and were also more prevalent in urban streams and rivers. Light pollution and CO₂ were significantly related to microbial community composition, with CO₂ inversely related to microbial phototrophy. Results of synchronous nationwide sampling indicate that pollution-driven alterations to the freshwater microbiome lead to changes in CO₂ production in natural waters and highlight the vulnerability of running waters to anthropogenic stressors.

淡水微生物在全球碳循环中发挥着至关重要的作用。导致这些微生物群落变化的人为压力源可能会对淡水生态系统产生深远的影响。利用公民科学家对 617 个湖泊、池塘、河流和溪流的协调采样的现场数据，我们观察了微生物群落组成、光和化学污染以及温室气体浓度之间的联系。所有采样的水体都是 CO _{2的净排放者}，在流水中浓度更高，在高纬度地区浓度增加。光污染发生在 75% 的地点，城市地区和河流沿岸的光污染较高，对微生物 α 多样性有可测量的影响。在 85% 的地点发现了暗示化学应激和抗菌素耐药性的遗传元素（IntI1，blaOX ₅₈），并且在城市溪流和河流中也更为普遍。光污染和CO ₂与微生物群落组成显着相关，而CO ₂与微生物光养成反比。全国同步采样的结果表明，污染驱动的淡水微生物组变化导致 CO _2的变化在天然水域生产，并强调流水对人为压力源的脆弱性。