Decomposability and chemical composition of soil organic matter in a Canadian High Arctic polar semi-desert environment
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Authors
Watson, Danika
Date
2024-05-08
Type
thesis
Language
eng
Keyword
soil organic matter , permafrost , Arctic , permafrost carbon feedback , x-ray photoelectron spectroscopy , XPS , molecular diversity , SOM , decomposability , recalcitrance , composition , spectroscopy , Cape Bounty Arctic Watershed Observatory , Nunavut , polar semi-desert , quality , incubation , soil , active layer , CO2 , mineralization , carbon
Alternative Title
Abstract
Arctic warming is driving widespread permafrost thaw, which could generate a positive
feedback leading to further warming and release of vast amounts of carbon dioxide (CO2) into
the atmosphere. The rate at which CO2 is released from the active layer of permafrost depends in
part on the decomposability of active layer soil organic matter (SOM), which is poorly
understood, particularly for polar semi-desert environments. A better understanding of active
layer SOM decomposability is needed to inform models and project future climate warming. In
this study, the decomposability of SOM in polar semi-desert soils collected at the Cape Bounty
Arctic Watershed Observatory (CBAWO) on Melville Island, NU, Canada, was assessed with a
100-day soil incubation experiment. The potential influences of vegetation, soil texture, and
molecular diversity (determined using X-ray photoelectron spectroscopy (XPS) characterization)
on SOM decomposability were investigated. This is the first study to date that reports molecular
diversity for polar semi-desert soils. In sandy soils, organic carbon (OC) concentration, CO2
production (g/g OC), fast-decomposing carbon (C) pool size (C1) and slow C pool decomposition
rate (kr) were all higher in vegetated areas than unvegetated areas (as was molecular diversity,
although this result was non-significant). However, OC concentration and CO2 production did
not differ between vegetated and unvegetated soils in more clay-rich polar semi-desert sites. This
suggests that the amount of soil mixing may vary between sites, possibly in relation to the
influence of soil texture on cryoturbation. So, vegetation cover alone should not be used to map
SOM properties in the polar semi-desert. Soils with high molecular diversity produced more CO2
and had larger fast-decomposing C pools than soils with lower molecular diversity. Thus,
molecular diversity could be a valuable tool for predicting future CO2 production from the active
layer of permafrost.
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This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial 4.0 International
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
Attribution-NonCommercial 4.0 International