Zhan Peng-Fei, Tong Chuan
School of Geographical Sciences/School of Carbon Neutrality Future Technology, Fujian Normal University, Fuzhou 350117, China.
Key Laboratory of Humid Subtropical Eco-geography Process of Ministry of Education, Fujian Normal University, Fuzhou 350117, China.
Ying Yong Sheng Tai Xue Bao. 2023 Nov;34(11):2958-2968. doi: 10.13287/j.1001-9332.202311.006.
Wetlands serve as atmospheric carbon dioxide (CO) sinks, as well as atmospheric methane (CH) source due to the anaerobic soil environment. Although some studies report that the CH emission from wetlands partially offset their net CO uptake, there is no global data analysis on the offset of net ecosystem exchange of CO (NEE) by CH emission in wetland ecosystems. In this study, we collected the data sets of NEE and CH flux which were simultaneously measured in the inland wetlands (peatland and non-peatland wetland) and coastal wetlands (seagrass beds, salt marshes and mangroves) around the world. The results showed that all types of wetlands were atmospheric CO sink, with the NEE values ranking as follows: mangrove (-2011.0 g CO·m·a) < salt marsh (-1636.6 g CO·m·a) < non-peatland wetland (-870.8 g CO·m·a) < peatland (-510.7 g CO·m·a) < seagrass bed (-61.6 g CO·m·a). When CH flux being converted into CO-equivalent flux (CO-eq flux) based on the 100-year scale global warming potentials, we found that the CH emissions partially offset 19.4%, 14.0%, 36.1%, 64.9% and 60.1% of the net CO uptake in seagrass beds, salt marshes, mangroves, non-peatland wetland and peatland, respectively. Over the 20-year scale, CH emissions partially offset 57.3%, 41.4%, 107.0%, 192.0% and 177.3% of the net CO uptake, respectively. Some mangroves, peatlands, and non-peatland wetlands acted as net CO equivalent source. Over the 100-year scale, the net greenhouse gas balance of each wetland ecosystem was negative value, which indicated that even accounting CH emission, wetland ecosystem was still an atmospheric carbon sink. Our results indicated that clarifying the main regulation mechanism of CH emission from wetland ecosystems and proposing reasonable CH reduction measures are crucial to maintain the carbon sink function in wetland ecosystems, and to mitigate the trend of climate warming.
由于土壤厌氧环境，湿地既是大气二氧化碳（CO）汇，也是大气甲烷（CH）源。尽管一些研究报告称湿地的CH排放部分抵消了其净CO吸收量，但尚无关于湿地生态系统中CH排放对CO净生态系统交换量（NEE）抵消情况的全球数据分析。在本研究中，我们收集了全球内陆湿地（泥炭地和非泥炭地湿地）以及沿海湿地（海草床、盐沼和红树林）同步测量的NEE和CH通量数据集。结果表明，所有类型的湿地都是大气CO汇，NEE值排序如下：红树林（-2011.0 g CO·m·²·a）＜盐沼（-1636.6 g CO·m·²·a）＜非泥炭地湿地（-870.8 g CO·m·²·a）＜泥炭地（-510.7 g CO·m·²·a）＜海草床（-61.6 g CO·m·²·a）。当基于100年尺度的全球变暖潜能值将CH通量转换为CO当量通量（CO-eq通量）时，我们发现CH排放在海草床、盐沼、红树林、非泥炭地湿地和泥炭地中分别部分抵消了净CO吸收量的19.4%、14.0%、36.1%、64.9%和60.1%。在20年尺度上，CH排放分别部分抵消了净CO吸收量的57.3%、41.4%、107.0%、192.0%和177.3%。一些红树林、泥炭地和非泥炭地湿地充当了净CO当量源。在100年尺度上，每个湿地生态系统的净温室气体平衡为负值，这表明即使计入CH排放，湿地生态系统仍是大气碳汇。我们的结果表明，阐明湿地生态系统CH排放的主要调控机制并提出合理的CH减排措施，对于维持湿地生态系统的碳汇功能以及缓解气候变暖趋势至关重要。
