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Environ Sci Technol. 2018 Feb 6;52(3):1244-1252. doi: 10.1021/acs.est.7b04979. Epub 2018 Jan 12.

Changes in Methane Flux along a Permafrost Thaw Sequence on the Tibetan Plateau.

Yang G1,2, Peng Y1, Olefeldt D3, Chen Y1, Wang G1,2, Li F1,2, Zhang D1,2, Wang J1,2, Yu J1,2, Liu L1,2, Qin S1,2, Sun T1,2, Yang Y1,2.

Author information

1
State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences , Beijing 100093, China.
2
University of Chinese Academy of Sciences , Beijing 100049, China.
3
Department of Renewable Resources, University of Alberta , Edmonton, Alberta Canada , T6G 2H1.

Abstract

Permafrost thaw alters the physical and environmental conditions of soil and may thus cause a positive feedback to climate warming through increased methane emissions. However, the current knowledge of methane emissions following thermokarst development is primarily based on expanding lakes and wetlands, with upland thermokarst being studied less often. In this study, we monitored the methane emissions during the peak growing seasons of two consecutive years along a thaw sequence within a thermo-erosion gully in a Tibetan swamp meadow. Both years had consistent results, with the early and midthaw stages (3 to 12 years since thaw) exhibiting low methane emissions that were similar to those in the undisturbed meadow, while the emissions from the late thaw stage (20 years since thaw) were 3.5 times higher. Our results also showed that the soil water-filled pore space, rather than the soil moisture per se, in combination with the sand content, were the main factors that caused increased methane emissions. These findings differ from the traditional view that upland thermokarst could reduce methane emissions owing to the improvement of drainage conditions, suggesting that upland thermokarst development does not always result in a decrease in methane emissions.

PMID:
29276825
DOI:
10.1021/acs.est.7b04979

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