Title: Temporal dynamics of CO₂ and CH₄ loss potentials in response to rapid hydrological shifts in tidal freshwater wetland soils

Abstract

Earth System Models predict climate extremes that will impact regional and global hydrology. Aquatic-terrestrial transition zones like wetlands are subjected to the immediate consequence of climate change with shifts in the magnitude and dynamics of hydrologic flow. Such fluctuating hydrology can alter the nature and rate of biogeochemical transformations and significantly impact the carbon balance of the ecosystem. We tested the impacts of fluctuating hydrology and, specifically, the role of antecedent moisture conditions in determining the dominant carbon loss mechanisms in soils sampled from a tidal freshwater wetland system in the lower Columbia River, WA, USA. The objective was to understand shifts in biogeochemical processes in response to changing soil moisture, based on soil respiration and methane production rates, and to elucidate such responses based on the observed electron acceptor and metabolite profiles under laboratory conditions. Metabolomics and biogeochemical process rates provided evidence that soil redox was the principal factor driving metabolic function. Fluctuating redox conditions altered terminal electron acceptor and donor availability and recovery strengths of their concentrations in soil such that a disproportionate release of carbon dioxide stemmed from alternative anaerobic degradation processes like sulfate and iron reduction compared to carbon loss due to methanogenesis. These results showmore » that extended and short-term saturation created conditions conducive to increasing metabolite availability for anaerobic decomposition processes, with a significant lag in methanogenesis. In contrast, extended drying caused a cellular-level stress response and rapid recycling of alternate electron acceptors.« less

Authors:

RoyChowdhury, Taniya ^[1]; Bramer, Lisa ^[2]; Hoyt, David W. ^[1]; Kim, Young-Mo ^[1]; Metz, Thomas O. ^[1]; McCue, Lee Ann ^[1]; Diefenderfer, Heida L. ^[3]; Jansson, Janet K. ^[1]; Bailey, Vanessa ^[1]

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+ Show Author Affiliations

1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Earth and Biological Sciences Directorate
2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). National Security Directorate
3. Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Energy and Environment Directorate

Publication Date:

Tue Jun 27 00:00:00 EDT 2017

Research Org.:

Pacific Northwest National Laboratory (PNNL), Richland, WA (United States). Environmental Molecular Sciences Laboratory (EMSL)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1439016

Alternate Identifier(s):

OSTI ID: 1390570; OSTI ID: 1698174

Report Number(s):

PNNL-SA-123359
Journal ID: ISSN 0925-8574; 50052

Grant/Contract Number:  

AC05-76RL01830; 1619948

Resource Type:

Accepted Manuscript

Journal Name:

Ecological Engineering

Additional Journal Information:

Journal Volume: 114; Journal Issue: C; Journal ID: ISSN 0925-8574

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; anaerobic respiration; tidal wetlands; methane production; sulfate reduction; iron reduction; soil metabolites; Environmental Molecular Sciences Laboratory