School of Environment, Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing Normal University, Nanjing, 210023, China; Department of Transdisciplinary Science and Engineering, Tokyo Institute of Technology, Tokyo, 152-8550, Japan.
School of Environment, Jiangsu Engineering Lab of Water and Soil Eco-remediation, Nanjing Normal University, Nanjing, 210023, China; Department of Applied Physics and Chemical Engineering, Tokyo University of Agriculture and Technology, Tokyo, 184-8588, Japan.
Water Res. 2024 Sep 1;261:122018. doi: 10.1016/j.watres.2024.122018. Epub 2024 Jun 28.
The continuous increase in sulfate (SO) concentrations discharged by anthropogenic activities lacks insights into their dynamics and potential impact on CH budgets in freshwater lakes. Here we conducted a field investigation in the lakes along the highly developed Yangtze River basin, China, additionally, we analyzed long-term data (1950-2020) from Lake Taihu, a typical eutrophic lake worldwide. We observed a gradual increase in SO concentrations up to 100 mg/L, which showed a positive correlation with the trophic state of the lakes. The annual variations indicated that eutrophication intensified the fluctuation of SO concentrations. A random forest model was applied to assess the impact of SO concentrations on CH emissions, revealing a significant negative effect. Synchronously, a series of microcosms with added SO were established to simulate cyanobacteria decomposition processes and explore the coupling mechanism between sulfate reduction and CH production. The results showed a strong negative correlation between CH concentrations and initial SO levels (R = 0.83), indicating that higher initial SO concentrations led to lower final CH concentrations. This was attributed to the competition for cyanobacteria-supplied substrates between sulfate reduction bacteria (SRB) and methane production archaea (MPA). Our study highlights the importance of considering the unexpectedly increasing SO concentrations in eutrophic lakes when estimating global CH emission budgets.
人为活动排放的硫酸盐（SO）浓度持续增加，但人们对其动态及其对淡水湖泊 CH 收支的潜在影响缺乏了解。在这里，我们在中国高度发达的长江流域的湖泊中进行了实地调查，此外，我们还分析了全球典型富营养化湖泊太湖的长期数据（1950-2020 年）。我们观察到 SO 浓度逐渐增加到 100mg/L，这与湖泊的营养状态呈正相关。年度变化表明，富营养化加剧了 SO 浓度的波动。我们应用随机森林模型来评估 SO 浓度对 CH 排放的影响，结果表明其具有显著的负向影响。同时，我们建立了一系列添加 SO 的微宇宙来模拟蓝藻分解过程，并探索硫酸盐还原和 CH 产生之间的耦合机制。结果表明，CH 浓度与初始 SO 水平之间存在强烈的负相关关系（R = 0.83），这表明较高的初始 SO 浓度会导致最终 CH 浓度降低。这归因于硫酸盐还原菌（SRB）和甲烷产生古菌（MPA）对蓝藻供应底物的竞争。我们的研究强调了在估算全球 CH 排放预算时，需要考虑富营养化湖泊中 SO 浓度的意外增加。
