Title: Abundant carbon substrates drive extremely high sulfate reduction rates and methane fluxes in Prairie Pothole Wetlands

Abstract

Inland waters are increasingly recognized as critical sites of methane emissions to the atmosphere, but the biogeochemical reactions driving such fluxes are less well understood. The Prairie Pothole Region (PPR) of North America is one of the largest wetland complexes in the world, containing millions of small, shallow wetlands. The sediment pore waters of PPR wetlands contain some of the highest concentrations of dissolved organic carbon (DOC) and sulfur species ever recorded in terrestrial aquatic environments. Using a suite of geochemical and microbiological analyses we measured the impact of sedimentary carbon and sulfur transformations in these wetlands on methane fluxes to the atmosphere. This research represents the first study of coupled geochemistry and microbiology within the PPR, and demonstrates how the conversion of abundant labile DOC pools into methane results in some of the highest fluxes of this greenhouse gas to the atmosphere ever reported. Abundant DOC and sulfate additionally supported some of the highest sulfate reduction rates ever measured in terrestrial aquatic environments, which we infer to account for a large fraction of carbon mineralization in this system. Methane accumulations in zones of active sulfate reduction may be due to either the transport of free methane gas from deepermore » locations, or the co-occurrence of methanogenesis and sulfate reduction. If both respiratory processes are concurrent, any competitive inhibition of methanogenesis by sulfate-reducing bacteria may be lessened by the presence of large labile DOC pools that yield non-competitive substrates such as methanol. Our results reveal some of the underlying mechanisms that make PPR wetlands biogeochemical hotspots, which ultimately leads to their critical, but poorly recognized role in regional greenhouse gas emissions.« less

Authors:

Dalcin Martins, Paula ^[1]; Hoyt, David W. ^[2]; Bansal, Sheel ^[3]; Mills, Christopher T. ^[4]; Tfaily, Malak ^[2]; Tangen, Brian A. ^[3]; Finocchiaro, Raymond G. ^[3]; Johnston, Michael D. ^[5]; McAdams, Brandon C. ^[5]; Solensky, Matthew J. ^[3]; Smith, Garrett J. ^[1]; Chin, Yu-Ping ^[5]; Wilkins, Michael J.  ^[6]

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+ Show Author Affiliations

1. Microbiology Department, The Ohio State University, Columbus OH 43210 USA
2. Environmental Molecular Sciences Laboratory, Richland WA 99350 USA
3. United States Geological Survey - Northern Prairie Wildlife Research Center, Jamestown ND 58401 USA
4. United States Geological Survey, Crustal Geophysics and Geochemistry Science Center, Building 20, Denver Federal Center Denver CO 80225 USA
5. School of Earth Sciences, The Ohio State University, Columbus OH 43210 USA
6. Microbiology Department, The Ohio State University, Columbus OH 43210 USA; School of Earth Sciences, The Ohio State University, Columbus OH 43210 USA

Publication Date:

2017-02-23

Research Org.:

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

Sponsoring Org.:

USDOE

OSTI Identifier:

1406680

Report Number(s):

PNNL-SA-120033
Journal ID: ISSN 1354-1013; 48837; KP1704020

DOE Contract Number:  

AC05-76RL01830

Resource Type:

Journal Article

Journal Name:

Global Change Biology

Additional Journal Information:

Journal Volume: 23; Journal Issue: 8; Journal ID: ISSN 1354-1013

Publisher:

Wiley

Country of Publication:

United States

Language:

English

Subject:

Environmental Molecular Sciences Laboratory