Yale-NUIST Center on Atmospheric Environment, International Joint Laboratory on Climate and Environment Change (ILCEC), Nanjing University of Information Science and Technology, Nanjing 210044, China; NUIST-Wuxi Research Institute, Wuxi 214105, China.
Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
Sci Total Environ. 2019 Jul 1;672:400-409. doi: 10.1016/j.scitotenv.2019.03.466. Epub 2019 Apr 1.
Submerged macrophytes are important primary producers for shallow lake systems. So far, their overall role in regulating lake methane flux is a subject of debate because the oxygen produced by their roots can promote methane oxidation in the sediment but they can also enhance methanogenesis through organic substrate production. In this study, we used the eddy covariance method to investigate the temporal dynamics of the CH flux in a habitat of submerged macrophytes in Lake Taihu. The results show that the nighttime CH flux is on average 33% higher than the daytime flux, although a clear diurnal pattern is evident only in the spring. At the daily to the seasonal time scale, the sediment temperature is the main driver of the CH flux variations, implying higher methane production in the sediment at higher temperatures. The annual CH emission (6.12 g C m yr) is much higher than the published whole-lake mean flux (1.12 g C m yr) and that reported previously in the eutrophic phytoplankton zone of the lake (1.35 g C m yr), indicating that the net effect of the submerged macrophytes is to enhance methane emission. At the annual time scale, 3.5% of the carbon gained by the net ecosystem production is lost to the atmosphere in the form of CH.
沉水植物是浅水湖泊系统中重要的初级生产者。到目前为止，它们在调节湖泊甲烷通量方面的总体作用仍存在争议，因为它们的根产生的氧气可以促进沉积物中的甲烷氧化，但它们也可以通过有机底物的产生来增强甲烷生成。在这项研究中，我们使用涡度相关法来调查太湖沉水植物生境中 CH 通量的时间动态。结果表明，夜间 CH 通量平均比白天通量高 33%，尽管只有在春季才明显存在昼夜模式。在日到季节时间尺度上，沉积物温度是 CH 通量变化的主要驱动因素，这意味着在较高温度下，沉积物中的甲烷生成量更高。年 CH 排放量（6.12 g C m yr）远高于已发表的全湖平均通量（1.12 g C m yr）和先前在富营养化浮游植物区报告的通量（1.35 g C m yr），这表明沉水植物的净效应是增强甲烷排放。在年时间尺度上，净生态系统生产力获得的碳有 3.5%以 CH 的形式损失到大气中。
