The Effects of Freeze–Thaw Cycles on Methane Emissions From Peat Soils of a High-Altitude Peatland

The Qinghai– Tibet Plateau (QTP), which embodies the largest area of permafrost at mid–low altitudes of the world, has been experiencing rapid permafrost degradation and changes in freeze–thaw processes for the past decades. However, the responses and potential feedbacks of the methane flux from pea...

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Main Authors: Zao Yang, Dan Zhu, Liangfeng Liu, Xinwei Liu, Huai Chen
Format: Article
Language:English
Published: Frontiers Media S.A. 2022-03-01
Series:Frontiers in Earth Science
Subjects:
Online Access:https://www.frontiersin.org/articles/10.3389/feart.2022.850220/full
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author Zao Yang
Zao Yang
Dan Zhu
Dan Zhu
Liangfeng Liu
Liangfeng Liu
Xinwei Liu
Xinwei Liu
Huai Chen
Huai Chen
author_facet Zao Yang
Zao Yang
Dan Zhu
Dan Zhu
Liangfeng Liu
Liangfeng Liu
Xinwei Liu
Xinwei Liu
Huai Chen
Huai Chen
author_sort Zao Yang
collection DOAJ
description The Qinghai– Tibet Plateau (QTP), which embodies the largest area of permafrost at mid–low altitudes of the world, has been experiencing rapid permafrost degradation and changes in freeze–thaw processes for the past decades. However, the responses and potential feedbacks of the methane flux from peatlands on the QTP to changing freeze–thaw cycles (FTCs) remain unknown. In this study, we collected peat soils from the Zoîgé peatlands, the largest peatland complex on the QTP, to examine methane emissions under simulated diurnal FTC scenarios. In incubation experiments of 15 days, two freeze–thaw temperature ranges of −5 to 4°C (mild) and −15 to 4°C (intense) were applied to two sets of peat soil samples, and each of them was characterized by 100% or 80% maximum water holding capacity (MWHC). The results showed that the peak of methane emission from the peat soil occurred after the first freeze–thaw cycle (FTC1), with the highest reaching a value of 0.103 mg kg soil−1·h−1. Generally, the cumulative methane emissions were elevated by FTCs, and relative higher rates of methane emissions were found for the 2nd FTC to the 15th FTC, compared with those from low-altitude peatlands. Methane emissions were significantly correlated to the export of dissolved organic carbon (DOC) and the activities of β-D-cellobiosidase and phenol oxidase in various freeze–thaw conditions. This study highlights the importance of FTCs in stimulating methane emissions and implies that methane emissions during FTCs from high-altitude peatlands would increase under a warmer climate in the future.
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spelling doaj.art-7a18221b91db4c30b7b4aae92999d6ca2022-12-21T23:55:47ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632022-03-011010.3389/feart.2022.850220850220The Effects of Freeze–Thaw Cycles on Methane Emissions From Peat Soils of a High-Altitude PeatlandZao Yang0Zao Yang1Dan Zhu2Dan Zhu3Liangfeng Liu4Liangfeng Liu5Xinwei Liu6Xinwei Liu7Huai Chen8Huai Chen9Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, ChinaZoîgé Wetland Ecosystem Research Station, Chinese Academy of Sciences, Aba, ChinaChengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, ChinaZoîgé Wetland Ecosystem Research Station, Chinese Academy of Sciences, Aba, ChinaChengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, ChinaZoîgé Wetland Ecosystem Research Station, Chinese Academy of Sciences, Aba, ChinaChengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, ChinaZoîgé Wetland Ecosystem Research Station, Chinese Academy of Sciences, Aba, ChinaChengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, ChinaZoîgé Wetland Ecosystem Research Station, Chinese Academy of Sciences, Aba, ChinaThe Qinghai– Tibet Plateau (QTP), which embodies the largest area of permafrost at mid–low altitudes of the world, has been experiencing rapid permafrost degradation and changes in freeze–thaw processes for the past decades. However, the responses and potential feedbacks of the methane flux from peatlands on the QTP to changing freeze–thaw cycles (FTCs) remain unknown. In this study, we collected peat soils from the Zoîgé peatlands, the largest peatland complex on the QTP, to examine methane emissions under simulated diurnal FTC scenarios. In incubation experiments of 15 days, two freeze–thaw temperature ranges of −5 to 4°C (mild) and −15 to 4°C (intense) were applied to two sets of peat soil samples, and each of them was characterized by 100% or 80% maximum water holding capacity (MWHC). The results showed that the peak of methane emission from the peat soil occurred after the first freeze–thaw cycle (FTC1), with the highest reaching a value of 0.103 mg kg soil−1·h−1. Generally, the cumulative methane emissions were elevated by FTCs, and relative higher rates of methane emissions were found for the 2nd FTC to the 15th FTC, compared with those from low-altitude peatlands. Methane emissions were significantly correlated to the export of dissolved organic carbon (DOC) and the activities of β-D-cellobiosidase and phenol oxidase in various freeze–thaw conditions. This study highlights the importance of FTCs in stimulating methane emissions and implies that methane emissions during FTCs from high-altitude peatlands would increase under a warmer climate in the future.https://www.frontiersin.org/articles/10.3389/feart.2022.850220/fullmethane emissionshigh-altitude peatlandsfreeze–thaw cyclesdissolved organic carbonenzyme activity
spellingShingle Zao Yang
Zao Yang
Dan Zhu
Dan Zhu
Liangfeng Liu
Liangfeng Liu
Xinwei Liu
Xinwei Liu
Huai Chen
Huai Chen
The Effects of Freeze–Thaw Cycles on Methane Emissions From Peat Soils of a High-Altitude Peatland
Frontiers in Earth Science
methane emissions
high-altitude peatlands
freeze–thaw cycles
dissolved organic carbon
enzyme activity
title The Effects of Freeze–Thaw Cycles on Methane Emissions From Peat Soils of a High-Altitude Peatland
title_full The Effects of Freeze–Thaw Cycles on Methane Emissions From Peat Soils of a High-Altitude Peatland
title_fullStr The Effects of Freeze–Thaw Cycles on Methane Emissions From Peat Soils of a High-Altitude Peatland
title_full_unstemmed The Effects of Freeze–Thaw Cycles on Methane Emissions From Peat Soils of a High-Altitude Peatland
title_short The Effects of Freeze–Thaw Cycles on Methane Emissions From Peat Soils of a High-Altitude Peatland
title_sort effects of freeze thaw cycles on methane emissions from peat soils of a high altitude peatland
topic methane emissions
high-altitude peatlands
freeze–thaw cycles
dissolved organic carbon
enzyme activity
url https://www.frontiersin.org/articles/10.3389/feart.2022.850220/full
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