近日，中国地质大学（武汉）谢树成团队研究了古新世-始新世极热期间湖泊环境中盐度限制的甲烷循环。2025年10月23日出版的《地质学》杂志发表了这项成果。

内陆水生生态系统是向大气释放温室气体甲烷（CH₄）的最大自然环境。尽管淡水系统中CH₄动态的温度依赖性已被充分记录，但人们对富盐内陆水域的CH₄循环及其对快速全球变暖的响应仍然知之甚少，特别是在过去的温室气候期间。

研究组采用脂质生物标志物的碳同位素组成，重建了古新世-始新世极热事件（PETM，约56百万年前）期间一个咸水湖的甲烷循环过程。该地质时期可作为研究未来气候变暖的天然类比案例。研究结果表明，与当代淡水湿地的高温敏感性相反，江汉盆地（中部）咸水湖泊系统中的微生物CH₄循环对PETM期间温室气体的快速变暖表现出微弱的响应。高盐度和硫酸盐浓度，加上有限的可利用底物，可能抑制了生态系统水平的甲烷生成和随后的CH₄排放。该研究结果表明，广泛的盐碱化可能限制内陆水生生态系统中CH₄的动态，并影响大规模的温室气体对气候变暖的反馈。

附：英文原文

Title: Salinity limited methane cycling in lacustrine settings during the Paleocene-Eocene Thermal Maximum

Author: Funing Sun, Jiajie Zhang, Xiaohua Teng, Genming Luo, Chunlian Wang, Zuwei Feng, Richard D. Pancost, Shucheng Xie

Issue&Volume: 2025-10-23

Abstract: Inland aquatic ecosystems are the largest natural source of greenhouse gas methane (CH4) release to the atmosphere. Although the temperature dependence of CH4 dynamics in freshwater systems is well documented, CH4 cycling in salt-rich inland waters and its response to rapid global warming remain poorly understood, particularly during past greenhouse climates. Here, we use the carbon isotopic composition of lipid biomarkers to reconstruct CH4 cycling in a saline lake during the PaleoceneEocene Thermal Maximum (PETM; ca. 56 Ma), a geological analog for future warming. Our results suggest that, in contrast to the high temperature sensitivity reported for contemporaneous freshwater wetlands, microbial CH4 cycling in the saline lacustrine system of the Jianghan Basin (central China) showed a muted response to rapid greenhouse warming during the PETM. The high salinity and sulfate concentrations, combined with limited available substrates, may have inhibited methanogenesis and subsequent CH4 emissions at the ecosystem level. Our findings suggest that widespread salinization could restrict CH4 dynamics in inland aquatic ecosystems and affect large-scale greenhouse gas feedbacks to climate warming.

DOI: 10.1130/G53790.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G53790.1/662107/Salinity-limited-methane-cycling-in-lacustrineredirectedFrom=fulltext