Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China; College of Water Conservancy Engineering, Zhengzhou University, Zhengzhou, Henan 450001, China.
Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Sci Total Environ. 2022 Feb 10;807(Pt 2):150898. doi: 10.1016/j.scitotenv.2021.150898. Epub 2021 Oct 12.
Methane (CH) is the second most important greenhouse gas, contributing approximately 17% of radiative forcing, and CH emissions from river networks due to intensified human activities have become a worldwide issue. However, there is a dearth of information on the CH emission potentials of different rivers, especially those draining contrasting watershed landscapes. Here, we examined the spatial variability of diffusive CH emissions and discerned the roles of environmental factors in influencing CH production in different river reaches (agricultural, urban, forested and mixed-landscape rivers) from the Chaohu Lake Basin in eastern China. According to our results, the urban rivers most frequently exhibited extremely high CH concentrations, with a mean concentration of 5.46 μmol L, equivalent to 4.1, 9.7, and 7.2 times those measured in the agricultural, forested, and mixed-landscape rivers, respectively. The availability of carbon sources and total phosphorus were commonly identified as the most important factors for CH production in agricultural and urban rivers. Dissolved oxygen and oxidation-reduction potential were separately discerned as important factors for the forested and mixed-landscape rivers, respectively. Monte Carlo flux estimations demonstrated that rivers draining contrasting landscapes exhibit distinct potentials to emit CH. The urban rivers had the highest CH emissions, with a flux of 9.44 mmol m d, which was 5.1-10.4 times higher than those of the other river reaches. Overall, our study highlighted that management actions should be specifically targeted at the river reaches with the highest emission potentials and should carefully consider the influences of different riverine environmental conditions as projected by their watershed landscapes.
甲烷（CH）是第二大重要的温室气体，对辐射强迫的贡献率约为 17%，并且由于人类活动的加剧，河网系统中的 CH 排放已成为全球性问题。然而，关于不同河流的 CH 排放潜力的信息却很少，特别是那些排水系统截然不同的流域。在这里，我们研究了中国东部巢湖水系不同河流（农业、城市、森林和混合景观河流）中扩散 CH 排放的空间变异性，并探讨了环境因素在影响不同河流段 CH 产生中的作用。结果表明，城市河流最常表现出极高的 CH 浓度，平均浓度为 5.46 μmol L，分别是农业、森林和混合景观河流的 4.1、9.7 和 7.2 倍。碳源的可用性和总磷通常被认为是农业和城市河流中 CH 产生的最重要因素。溶解氧和氧化还原电位分别被认为是森林和混合景观河流的重要因素。蒙特卡罗通量估算表明，排水系统截然不同的流域具有不同的 CH 排放潜力。城市河流的 CH 排放量最高，通量为 9.44 mmol m d，比其他河流段高 5.1-10.4 倍。总体而言，本研究强调应针对具有最高排放潜力的河流段采取管理措施，并应根据流域景观预测的不同河流水环境条件的影响进行谨慎考虑。
