1. Effects on global warming by microbial methanogenesis in alkaline lakes during the Late Paleozoic Ice Age (LPIA).
- Author
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Liuwen Xia, Jian Cao, Wenxuan Hu, Stüeken, Eva E., Xiaolin Wang, Suping Yao, Dongming Zhi, Yong Tang, Baoli Xiang, and Wenjun He
- Abstract
Methane (CH4) is an important greenhouse gas, but its behavior and influencing factors over geological time scales are not sufficiently clear. This study investigated the Late Paleozoic Ice Age (LPIA), which is thought to have experienced an interval of rapid warming at ca. 304 Ma, that may have been analogous to modern warming. To explore possible causes of this warming event, we investigated ancient alkaline lakes in the Junggar Basin, northwestern China. Results show that microbial CH4 cycling here was strong, as evidenced by carbonate d13C (d13Ccarb) values of >5‰, ~+0.6‰ offsets between pristane d13C (d13CPr) and phytane d13C (d13CPh) values, a 3ß-methylhopane index of 9.5% ± 3.0%, and highly negative d13C values of hopanes (-44‰ to -61‰). Low sulfate concentrations in the alkaline lakes made methanogenic archaea more competitive than sulfate-reducing bacteria, and the elevated levels of dissolved inorganic carbon promoted methanogenesis. Biogenic CH4 emissions from alkaline lakes, in addition to CO2, may have contributed to rapid climate warming. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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