Wetlands impact global warming by regulating the atmospheric exchange of greenhouse gases (GHGs), including carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O). We investigated GHG emissions in the Great Lakes coastal wetlands across various hydrologic, temperature, and nitrogen (N) inflow regimes using a process-based simulation model. We found the emission of CH₄, N₂O, and sequestration of C (i.e., negative net ecosystem exchange, NEE) in our simulations were all positively related to water residence time and N inflow, primarily due to greater plant productivity and N uptake, which facilitated greater C and N cycling rates in the model. Water level scenarios also had an effect on GHG exchanges by moderating the transitions between aerobic and anaerobic conditions. Temperature effects on GHGs were minimal compared with other factors. The net sustained-flux global warming potential (SGWP; i.e., sum SGWP of CH₄, N₂O, and NEE) of wetlands on 20-year and 100-year time horizons were both primarily driven by CH₄ emissions and strongly controlled by the tradeoffs between CH₄ emission and CO₂ sequestration, with a negligible amount of simulated N₂O emissions. Future research could include model enhancements to provide increased process-level details on the aerobic-anaerobic transitions or the direct effects of plants on mediating GHG exchanges. Field studies addressing the interaction of N inflows and water residence time at appropriately large scales are needed to test the complex interactions revealed by our modeling study. Our results highlight the previously under-appreciated role of nitrogen and water residence time in modulating SGWP in coastal wetlands.

中文翻译：

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大湖沿岸湿地模型中氮流入和水周期驱动的持续通量全球变暖潜势

湿地通过调节包括二氧化碳 (CO ₂ )、甲烷 (CH ₄ ) 和一氧化二氮 (N ₂ O)在内的温室气体 (GHG) 的大气交换来影响全球变暖。我们使用基于过程的模拟模型调查了五大湖沿岸湿地在各种水文、温度和氮 (N) 流入情况下的温室气体排放。我们发现 CH ₄ , N ₂的排放在我们的模拟中，O 和 C 的封存（即负净生态系统交换，NEE）都与水停留时间和 N 流入呈正相关，主要是由于更高的植物生产力和 N 吸收，这促进了更高的 C 和 N 循环率模型。水位情景还通过调节好氧和厌氧条件之间的转变对温室气体交换产生影响。与其他因素相比，温度对温室气体的影响很小。20 年和 100 年时间范围内湿地的净持续通量全球变暖潜势（SGWP；即 CH ₄、N ₂ O 和 NEE 的总 SGWP ）均主要由 CH ₄排放驱动，并受以下因素的强烈控制CH ₄排放和 CO之间的权衡₂封存，模拟 N ₂ O 排放量可忽略不计。未来的研究可能包括模型增强，以提供有关好氧-厌氧转变或植物对调节温室气体交换的直接影响的更多过程级细节。需要在适当的大规模范围内解决 N 流入和水停留时间的相互作用的实地研究，以测试我们的建模研究揭示的复杂相互作用。我们的研究结果强调了以前被低估的氮和水停留时间在调节沿海湿地 SGWP 中的作用。