School of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023, China; State Environmental Protection Key Laboratory of Soil Health and Green Remediation, College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China.
School of Chemical and Environmental Engineering, Wuhan Polytechnic University, Wuhan 430023, China.
J Hazard Mater. 2024 Jan 15;462:132757. doi: 10.1016/j.jhazmat.2023.132757. Epub 2023 Oct 10.
Accelerated eutrophication in lakes reduces the number of submerged macrophytes and alters the residues of glyphosate and its degradation products. However, the effects of submerged macrophytes on the fate of glyphosate remain unclear. We investigated eight lakes with varying trophic levels along the middle and lower reaches of the Yangtze River in China, of which five lakes contained either glyphosate or aminomethylphosphate (AMPA). Glyphosate and AMPA residues were significantly positively correlated with the trophic levels of lakes (P < 0.01). In lakes, glyphosate is degraded through the AMPA and sarcosine pathways. Eight shared glyphosate-degrading enzymes and genes were observed in different lake sediments, corresponding to 44 degrading microorganisms. Glyphosate concentrations in sediments were significantly higher in lakes with lower abundances of soxA (sarcosine oxidase) and soxB (sarcosine oxidase) (P < 0.05). In the presence of submerged macrophytes, oxalic and malonic acids secreted by the roots of submerged macrophytes increased the abundance of glyphosate-degrading microorganisms containing soxA or soxB (P < 0.05). These results revealed that a decrease in the number of submerged macrophytes in eutrophic lakes may inhibit glyphosate degradation via the sarcosine pathway, leading to a decrease in glyphosate degradation and an increase in glyphosate residues.
湖泊富营养化加速会减少沉水植物的数量，并改变草甘膦及其降解产物的残留。然而，沉水植物对草甘膦命运的影响仍不清楚。我们调查了中国长江中下游地区 8 个不同营养水平的湖泊，其中 5 个湖泊中含有草甘膦或氨甲基膦酸 (AMPA)。草甘膦和 AMPA 残留与湖泊的营养水平呈显著正相关 (P < 0.01)。在湖泊中，草甘膦通过 AMPA 和肌氨酸途径降解。在不同的湖泊沉积物中观察到 8 种共享的草甘膦降解酶和基因，对应于 44 种降解微生物。在 soxA（肌氨酸氧化酶）和 soxB（肌氨酸氧化酶）丰度较低的湖泊中，沉积物中的草甘膦浓度显著更高 (P < 0.05)。在有沉水植物存在的情况下，沉水植物根部分泌的草酸和丙二酸增加了含有 soxA 或 soxB 的草甘膦降解微生物的丰度 (P < 0.05)。这些结果表明，富营养化湖泊中沉水植物数量的减少可能会通过肌氨酸途径抑制草甘膦的降解，导致草甘膦降解减少和残留增加。
