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Potential role of submerged macrophytes for oxic methane production in aquatic ecosystems
Limnology and Oceanography ( IF 4.5 ) Pub Date : 2022-05-10 , DOI: 10.1002/lno.12095
Sabine Hilt 1 , Hans‐Peter Grossart 2, 3 , Daniel F. McGinnis 4 , Frank Keppler 5, 6
Affiliation  

Methane (CH4) from aquatic ecosystems contributes to about half of total global CH4 emissions to the atmosphere. Until recently, aquatic biogenic CH4 production was exclusively attributed to methanogenic archaea living under anoxic or suboxic conditions in sediments, bottom waters, and wetlands. However, evidence for oxic CH4 production (OMP) in freshwater, brackish, and marine habitats is increasing. Possible sources were found to be driven by various planktonic organisms supporting different OMP mechanisms. Surprisingly, submerged macrophytes have been fully ignored in studies on OMP, yet they are key components of littoral zones of ponds, lakes, and coastal systems. High CH4 concentrations in these zones have been attributed to organic substrate production promoting classic methanogenesis in the absence of oxygen. Here, we review existing studies and argue that, similar to terrestrial plants and phytoplankton, macroalgae and submerged macrophytes may directly or indirectly contribute to CH4 formation in oxic waters. We propose several potential direct and indirect mechanisms: (1) direct production of CH4; (2) production of CH4 precursors and facilitation of their bacterial breakdown or chemical conversion; (3) facilitation of classic methanogenesis; and (4) facilitation of CH4 ebullition. As submerged macrophytes occur in many freshwater and marine habitats, they are important in global carbon budgets and can strongly vary in their abundance due to seasonal and boom-bust dynamics. Knowledge on their contribution to OMP is therefore essential to gain a better understanding of spatial and temporal dynamics of CH4 emissions and thus to substantially reduce current uncertainties when estimating global CH4 emissions from aquatic ecosystems.

中文翻译:

沉水植物对水生生态系统中产氧甲烷的潜在作用

来自水生生态系统的甲烷 (CH 4 ) 约占全球大气 CH 4排放总量的一半。直到最近,水生生物 CH 4的产生还完全归因于生活在沉积物、底水和湿地中缺氧或低氧条件下的产甲烷古菌。然而,淡水、微咸水和海洋生境中产氧 CH 4 (OMP) 的证据正在增加。发现可能的来源是由支持不同 OMP 机制的各种浮游生物驱动的。令人惊讶的是,沉水植物在 OMP 研究中被完全忽略,但它们是池塘、湖泊和沿海系统沿岸带的关键组成部分。高 CH 4这些区域的浓度归因于有机底物的产生,在没有氧气的情况下促进了经典的产甲烷作用。在这里,我们回顾了现有的研究并认为,与陆生植物和浮游植物类似,大型藻类和沉水大型植物可能直接或间接促成有氧水中 CH 4的形成。我们提出了几种潜在的直接和间接机制:(1)直接生产 CH 4;(2) CH 4前体的产生和促进其细菌分解或化学转化;(3) 促进经典的产甲烷作用;(4) 促进 CH 4沸腾。由于淹没的大型植物出现在许多淡水和海洋生境中,它们在全球碳预算中很重要,并且由于季节性和繁荣-萧条动态,它们的丰度可能会有很大差异。因此,了解它们对 OMP 的贡献对于更好地了解 CH 4排放的空间和时间动态至关重要,从而在估算来自水生生态系统的全球 CH 4排放时大幅减少当前的不确定性。
更新日期:2022-05-11
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