Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradation
<p>The Qinghai–Tibet Plateau (QTP) accounts for approximately 70 % of global alpine permafrost and is an area sensitive to climate change. The thawing and mobilization of ice-rich and organic-carbon-rich permafrost impact hydrologic conditions and biogeochemical processes on the...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2018-11-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/15/6637/2018/bg-15-6637-2018.pdf |
| _version_ | 1811281354175807488 |
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| author | Y. Wang Y. Wang R. G. M. Spencer D. C. Podgorski A. M. Kellerman H. Rashid P. Zito W. Xiao D. Wei Y. Yang Y. Xu |
| author_facet | Y. Wang Y. Wang R. G. M. Spencer D. C. Podgorski A. M. Kellerman H. Rashid P. Zito W. Xiao D. Wei Y. Yang Y. Xu |
| author_sort | Y. Wang |
| collection | DOAJ |
| description | <p>The Qinghai–Tibet Plateau (QTP) accounts for approximately
70 % of global alpine permafrost and is an area sensitive to climate
change. The thawing and mobilization of ice-rich and organic-carbon-rich
permafrost impact hydrologic conditions and biogeochemical processes on the
QTP. Despite numerous studies of Arctic permafrost, there are no reports to
date for the molecular-level in-stream processing of permafrost-derived
dissolved organic matter (DOM) on the QTP. In this study, we examine temporal
and spatial changes of DOM along an alpine stream (3850–3207 m above sea
level) by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR
MS), accelerator mass spectrometry (AMS) and UV–visible spectroscopy.
Compared to downstream sites, dissolved organic matter (DOM) at the
headstream site exhibited older radiocarbon age, higher mean molecular
weight, higher aromaticity and fewer highly unsaturated compounds. At the
molecular level, 6409 and 1345 formulas were identified as unique to the
active layer (AL) leachate and permafrost layer (PL) leachate, respectively.
Comparing permafrost leachates to the downstream site, 59 % of
AL-specific formulas and 90 % of PL-specific formulas were degraded,
likely a result of rapid in-stream degradation of permafrost-derived DOM. From
peak discharge in the summer to low flow in late autumn, the DOC
concentration at the headstream site decreased from 13.9 to
10.2 mg L<sup>−1</sup>, while the <sup>14</sup>C age
increased from 745 to 1560 years before present (BP), reflecting an increase
in the relative contribution of deep permafrost carbon due to the effect of
changing hydrological conditions over the course of the summer on the DOM source
(AL vs. PL). Our study thus demonstrates that hydrological conditions impact
the mobilization of permafrost carbon in an alpine fluvial network, the
signature of which is quickly lost through in-stream mineralization and
transformation.</p> |
| first_indexed | 2024-04-13T01:32:01Z |
| format | Article |
| id | doaj.art-6e9d72fb7c7344168081cfb53941d999 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-04-13T01:32:01Z |
| publishDate | 2018-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-6e9d72fb7c7344168081cfb53941d9992022-12-22T03:08:29ZengCopernicus PublicationsBiogeosciences1726-41701726-41892018-11-01156637664810.5194/bg-15-6637-2018Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradationY. Wang0Y. Wang1R. G. M. Spencer2D. C. Podgorski3A. M. Kellerman4H. Rashid5P. Zito6W. Xiao7D. Wei8Y. Yang9Y. Xu10Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, ChinaKey Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing 100871, ChinaNational High Magnetic Field Laboratory Geochemistry Group and Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USAPontchartrain Institute for Environmental Sciences, Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USANational High Magnetic Field Laboratory Geochemistry Group and Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USAShanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, ChinaPontchartrain Institute for Environmental Sciences, Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USAKey Laboratory for Earth Surface Processes of the Ministry of Education, College of Urban and Environmental Sciences, Peking University, Beijing 100871, ChinaShanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, ChinaState Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, ChinaShanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China<p>The Qinghai–Tibet Plateau (QTP) accounts for approximately 70 % of global alpine permafrost and is an area sensitive to climate change. The thawing and mobilization of ice-rich and organic-carbon-rich permafrost impact hydrologic conditions and biogeochemical processes on the QTP. Despite numerous studies of Arctic permafrost, there are no reports to date for the molecular-level in-stream processing of permafrost-derived dissolved organic matter (DOM) on the QTP. In this study, we examine temporal and spatial changes of DOM along an alpine stream (3850–3207 m above sea level) by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), accelerator mass spectrometry (AMS) and UV–visible spectroscopy. Compared to downstream sites, dissolved organic matter (DOM) at the headstream site exhibited older radiocarbon age, higher mean molecular weight, higher aromaticity and fewer highly unsaturated compounds. At the molecular level, 6409 and 1345 formulas were identified as unique to the active layer (AL) leachate and permafrost layer (PL) leachate, respectively. Comparing permafrost leachates to the downstream site, 59 % of AL-specific formulas and 90 % of PL-specific formulas were degraded, likely a result of rapid in-stream degradation of permafrost-derived DOM. From peak discharge in the summer to low flow in late autumn, the DOC concentration at the headstream site decreased from 13.9 to 10.2 mg L<sup>−1</sup>, while the <sup>14</sup>C age increased from 745 to 1560 years before present (BP), reflecting an increase in the relative contribution of deep permafrost carbon due to the effect of changing hydrological conditions over the course of the summer on the DOM source (AL vs. PL). Our study thus demonstrates that hydrological conditions impact the mobilization of permafrost carbon in an alpine fluvial network, the signature of which is quickly lost through in-stream mineralization and transformation.</p>https://www.biogeosciences.net/15/6637/2018/bg-15-6637-2018.pdf |
| spellingShingle | Y. Wang Y. Wang R. G. M. Spencer D. C. Podgorski A. M. Kellerman H. Rashid P. Zito W. Xiao D. Wei Y. Yang Y. Xu Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradation Biogeosciences |
| title | Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradation |
| title_full | Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradation |
| title_fullStr | Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradation |
| title_full_unstemmed | Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradation |
| title_short | Spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the Qinghai–Tibet Plateau: importance of source and permafrost degradation |
| title_sort | spatiotemporal transformation of dissolved organic matter along an alpine stream flow path on the qinghai tibet plateau importance of source and permafrost degradation |
| url | https://www.biogeosciences.net/15/6637/2018/bg-15-6637-2018.pdf |
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