Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms
Soil organic carbon turnover to CO 2 and CH 4 is sensitive to soil redox potential and pH conditions. However, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubation...
Published in: | Biogeosciences |
---|---|
Main Authors: | , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2016
|
Subjects: | |
Online Access: | https://doi.org/10.5194/bg-13-5021-2016 https://doaj.org/article/706ec24b83b8461999d291b01ec2e1a3 |
id |
ftdoajarticles:oai:doaj.org/article:706ec24b83b8461999d291b01ec2e1a3 |
---|---|
record_format |
openpolar |
spelling |
ftdoajarticles:oai:doaj.org/article:706ec24b83b8461999d291b01ec2e1a3 2023-05-15T14:59:56+02:00 Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms G. Tang J. Zheng X. Xu Z. Yang D. E. Graham B. Gu S. L. Painter P. E. Thornton 2016-09-01T00:00:00Z https://doi.org/10.5194/bg-13-5021-2016 https://doaj.org/article/706ec24b83b8461999d291b01ec2e1a3 EN eng Copernicus Publications http://www.biogeosciences.net/13/5021/2016/bg-13-5021-2016.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-13-5021-2016 https://doaj.org/article/706ec24b83b8461999d291b01ec2e1a3 Biogeosciences, Vol 13, Iss 17, Pp 5021-5041 (2016) Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 article 2016 ftdoajarticles https://doi.org/10.5194/bg-13-5021-2016 2022-12-31T02:46:03Z Soil organic carbon turnover to CO 2 and CH 4 is sensitive to soil redox potential and pH conditions. However, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximately describe the observed pH evolution without additional parameterization. Although Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. The equilibrium speciation predicts a substantial increase in CO 2 solubility as pH increases, and taking into account CO 2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO 2 production from closed microcosms can be substantially underestimated based on headspace CO 2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions. Article in Journal/Newspaper Arctic Directory of Open Access Journals: DOAJ Articles Arctic Biogeosciences 13 17 5021 5041 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
spellingShingle |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 G. Tang J. Zheng X. Xu Z. Yang D. E. Graham B. Gu S. L. Painter P. E. Thornton Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms |
topic_facet |
Ecology QH540-549.5 Life QH501-531 Geology QE1-996.5 |
description |
Soil organic carbon turnover to CO 2 and CH 4 is sensitive to soil redox potential and pH conditions. However, land surface models do not consider redox and pH in the aqueous phase explicitly, thereby limiting their use for making predictions in anoxic environments. Using recent data from incubations of Arctic soils, we extend the Community Land Model with coupled carbon and nitrogen (CLM-CN) decomposition cascade to include simple organic substrate turnover, fermentation, Fe(III) reduction, and methanogenesis reactions, and assess the efficacy of various temperature and pH response functions. Incorporating the Windermere Humic Aqueous Model (WHAM) enables us to approximately describe the observed pH evolution without additional parameterization. Although Fe(III) reduction is normally assumed to compete with methanogenesis, the model predicts that Fe(III) reduction raises the pH from acidic to neutral, thereby reducing environmental stress to methanogens and accelerating methane production when substrates are not limiting. The equilibrium speciation predicts a substantial increase in CO 2 solubility as pH increases, and taking into account CO 2 adsorption to surface sites of metal oxides further decreases the predicted headspace gas-phase fraction at low pH. Without adequate representation of these speciation reactions, as well as the impacts of pH, temperature, and pressure, the CO 2 production from closed microcosms can be substantially underestimated based on headspace CO 2 measurements only. Our results demonstrate the efficacy of geochemical models for simulating soil biogeochemistry and provide predictive understanding and mechanistic representations that can be incorporated into land surface models to improve climate predictions. |
format |
Article in Journal/Newspaper |
author |
G. Tang J. Zheng X. Xu Z. Yang D. E. Graham B. Gu S. L. Painter P. E. Thornton |
author_facet |
G. Tang J. Zheng X. Xu Z. Yang D. E. Graham B. Gu S. L. Painter P. E. Thornton |
author_sort |
G. Tang |
title |
Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms |
title_short |
Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms |
title_full |
Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms |
title_fullStr |
Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms |
title_full_unstemmed |
Biogeochemical modeling of CO 2 and CH 4 production in anoxic Arctic soil microcosms |
title_sort |
biogeochemical modeling of co 2 and ch 4 production in anoxic arctic soil microcosms |
publisher |
Copernicus Publications |
publishDate |
2016 |
url |
https://doi.org/10.5194/bg-13-5021-2016 https://doaj.org/article/706ec24b83b8461999d291b01ec2e1a3 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
Biogeosciences, Vol 13, Iss 17, Pp 5021-5041 (2016) |
op_relation |
http://www.biogeosciences.net/13/5021/2016/bg-13-5021-2016.pdf https://doaj.org/toc/1726-4170 https://doaj.org/toc/1726-4189 1726-4170 1726-4189 doi:10.5194/bg-13-5021-2016 https://doaj.org/article/706ec24b83b8461999d291b01ec2e1a3 |
op_doi |
https://doi.org/10.5194/bg-13-5021-2016 |
container_title |
Biogeosciences |
container_volume |
13 |
container_issue |
17 |
container_start_page |
5021 |
op_container_end_page |
5041 |
_version_ |
1766332051029491712 |