甲烷排放部分抵消湿地生态系统碳汇功能:全球数据分析

doi:10.13287/j.1001-9332.202311.006

摘要/Abstract

摘要： 湿地生态系统是吸收全球大气二氧化碳(CO₂)的汇,同时土壤厌氧环境造成其是大气甲烷(CH₄)的源。尽管有证据表明,湿地生态系统CH₄排放部分抵消其对大气CO₂的净吸收,但目前未见全球尺度湿地CH₄排放对其净生态系统CO₂交换(NEE)抵消效应的研究。本研究分析了全球内陆湿地(泥炭湿地和非泥炭湿地)以及滨海湿地(海草床、盐沼和红树林)中同时测定湿地NEE和CH₄排放通量的数据。结果表明: 各类型湿地生态系统均为大气CO₂的汇,NEE值排序为红树林(-2011.0 g CO₂·m^-2·a^-1)<盐沼(-1636.6 g CO₂·m^-2·a^-1)<非泥炭地(-870.8 g CO₂·m^-2·a^-1)<泥炭地(-510.7 g CO₂·m^-2·a^-1)<海草床(-61.6 g CO₂·m^-2·a^-1)。基于100年尺度CH₄全球变暖潜势将CH₄排放通量转换成CO₂当量通量(CO₂-eq flux)发现,CH₄排放分别抵消海草床、盐沼、红树林、非泥炭地和泥炭地生态系统净CO₂吸收的19.4%、14.0%、36.1%、64.9%和60.1%,而在未来20年尺度上,它们分别抵消CO₂吸收的57.3%、41.4%、107.0%、192.0%和177.3%,部分红树林、泥炭地和非泥炭地是净CO₂当量源。100年尺度各类湿地生态系统净温室气体平衡仍为负值,说明即使考虑CH₄排放,在100年尺度各类湿地生态系统仍为碳汇。明晰湿地生态系统CH₄排放主要调控机制并提出合理的减排对策,对于维系湿地生态系统碳汇功能,减缓气候变暖至关重要。

关键词: 净生态系统CO₂交换, CH₄排放, 抵消, 净温室气体平衡, 滨海湿地, 内陆湿地

Abstract: Wetlands serve as atmospheric carbon dioxide (CO₂) sinks, as well as atmospheric methane (CH₄) source due to the anaerobic soil environment. Although some studies report that the CH₄ emission from wetlands partially offset their net CO₂ uptake, there is no global data analysis on the offset of net ecosystem exchange of CO₂ (NEE) by CH₄ emission in wetland ecosystems. In this study, we collected the data sets of NEE and CH₄ 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 CO₂ sink, with the NEE values ranking as follows: mangrove (-2011.0 g CO₂·m^-2·a^-1) < salt marsh (-1636.6 g CO₂·m^-2·a^-1) < non-peatland wetland (-870.8 g CO₂·m^-2·a^-1) < peatland (-510.7 g CO₂·m^-2·a^-1) < seagrass bed (-61.6 g CO₂·m^-2·a^-1). When CH₄ flux being converted into CO₂-equivalent flux (CO₂-eq flux) based on the 100-year scale global warming potentials, we found that the CH₄ emissions partially offset 19.4%, 14.0%, 36.1%, 64.9% and 60.1% of the net CO₂ uptake in seagrass beds, salt marshes, mangroves, non-peatland wetland and peatland, respectively. Over the 20-year scale, CH₄ emissions partially offset 57.3%, 41.4%, 107.0%, 192.0% and 177.3% of the net CO₂ uptake, respectively. Some mangroves, peatlands, and non-peatland wetlands acted as net CO₂ equivalent source. Over the 100-year scale, the net greenhouse gas balance of each wetland ecosystem was negative value, which indicated that even accounting CH₄ emission, wetland ecosystem was still an atmospheric carbon sink. Our results indicated that clarifying the main regulation mechanism of CH₄ emission from wetland ecosystems and proposing reasonable CH₄ reduction measures are crucial to maintain the carbon sink function in wetland ecosystems, and to mitigate the trend of climate warming.

Key words: net ecosystem exchange of CO₂, CH₄ emission, offset, net greenhouse gas balance, coastal wetland, inland wetland

展鹏飞, 仝川. 甲烷排放部分抵消湿地生态系统碳汇功能:全球数据分析[J]. 应用生态学报, 2023, 34(11): 2958-2968.

ZHAN Pengfei, TONG Chuan. Methane emissions partially offset carbon sink function in global wetlands: An analysis based on global data.[J]. Chinese Journal of Applied Ecology, 2023, 34(11): 2958-2968.

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