School of Civil and Environmental Engineering, Yonsei University, Seoul03722, South Korea.
Korea Polar Research Institute, Incheon21990, South Korea.
Environ Sci Technol. 2023 Feb 14;57(6):2647-2659. doi: 10.1021/acs.est.2c05228. Epub 2023 Jan 31.
CH emission in the Arctic has large uncertainty due to the lack of mechanistic understanding of the processes. CH oxidation in Arctic soil plays a critical role in the process, whereby removal of up to 90% of CH produced in soils by methanotrophs can occur before it reaches the atmosphere. Previous studies have reported on the importance of rising temperatures in CH oxidation, but because the Arctic is typically an N-limited system, fewer studies on the effects of inorganic nitrogen (N) have been reported. However, climate change and an increase of available N caused by anthropogenic activities have recently been reported, which may cause a drastic change in CH oxidation in Arctic soils. In this study, we demonstrate that excessive levels of available N in soil cause an increase in net CH emissions via the reduction of CH oxidation in surface soil in the Arctic tundra. In vitro experiments suggested that N in the form of NO is responsible for the decrease in CH oxidation via influencing soil bacterial and methanotrophic communities. The findings of our meta-analysis suggest that CH oxidation in the boreal biome is more susceptible to the addition of N than in other biomes. We provide evidence that CH emissions in Arctic tundra can be enhanced by an increase of available N, with profound implications for modeling CH dynamics in Arctic regions.
由于缺乏对过程的机理理解，北极的 CH 排放存在很大的不确定性。北极土壤中的 CH 氧化在这一过程中起着关键作用，高达 90%的土壤中产生的 CH 可以在到达大气之前被甲烷氧化菌去除。先前的研究报告了气温升高对 CH 氧化的重要性，但由于北极通常是一个氮限制系统，因此关于无机氮（N）影响的研究较少。然而，气候变化和人为活动导致的可利用氮的增加最近已经被报道，这可能会导致北极土壤中 CH 氧化的剧烈变化。在这项研究中，我们证明了土壤中过量的可利用氮通过减少北极苔原表土中的 CH 氧化，导致净 CH 排放增加。体外实验表明，以 NO 形式存在的氮通过影响土壤细菌和甲烷氧化菌群落，导致 CH 氧化减少。我们的荟萃分析结果表明，北方生物群落中的 CH 氧化比其他生物群落更容易受到氮的添加的影响。我们提供的证据表明，北极苔原的 CH 排放可以通过增加可利用氮来增强，这对北极地区 CH 动态模型的建立具有深远的影响。
