Department of Earth Sciences─Geochemistry, Utrecht University, Princetonlaan 8a, 3584 CB Utrecht, The Netherlands.
Department of Microbiology, Radboud Institute for Biological and Environmental Sciences, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
Environ Sci Technol. 2023 Aug 29;57(34):12722-12731. doi: 10.1021/acs.est.3c02023. Epub 2023 Aug 16.
Methane is a powerful greenhouse gas that is produced in large quantities in marine sediments. Microbially mediated oxidation of methane in sediments, when in balance with methane production, prevents the release of methane to the overlying water. Here, we present a gene-based reactive transport model that includes both microbial and geochemical dynamics and use it to investigate whether the rate of growth of methane oxidizers in sediments impacts the efficiency of the microbial methane filter. We focus on iron- and methane-rich coastal sediments and, with the model, show that at our site, up to 10% of all methane removed is oxidized by iron and manganese oxides, with the remainder accounted for by oxygen and sulfate. We demonstrate that the slow growth rate of anaerobic methane-oxidizing microbes limits their ability to respond to transient perturbations, resulting in periodic benthic release of methane. Eutrophication and deoxygenation decrease the efficiency of the microbial methane filter further, thereby enhancing the role of coastal environments as a source of methane to the atmosphere.
甲烷是一种强效温室气体，大量产生于海洋沉积物中。沉积物中微生物介导的甲烷氧化作用与甲烷生成作用保持平衡时，可以防止甲烷释放到上覆水中。在这里，我们提出了一个基于基因的反应传输模型，其中包括微生物和地球化学动态，并利用该模型来研究沉积物中甲烷氧化菌的生长速度是否会影响微生物甲烷过滤的效率。我们专注于富含铁和甲烷的沿海沉积物，并通过该模型表明，在我们的研究地点，高达 10%的甲烷去除量是由铁和锰氧化物氧化的，其余部分则由氧气和硫酸盐负责。我们证明，厌氧甲烷氧化微生物的缓慢生长速度限制了它们对瞬态扰动的响应能力，导致甲烷在海底周期性释放。富营养化和缺氧进一步降低了微生物甲烷过滤的效率，从而增强了沿海环境作为大气甲烷源的作用。
