Influence of electron acceptor availability and microbial community structure on sedimentary methane oxidation in a boreal estuary

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http://hdl.handle.net/10138/327684

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Myllykangas , J-P , Rissanen , A J , Hietanen , S & Jilbert , T 2020 , ' Influence of electron acceptor availability and microbial community structure on sedimentary methane oxidation in a boreal estuary ' , Biogeochemistry , vol. 148 , no. 3 , pp. 291-309 . https://doi.org/10.1007/s10533-020-00660-z

Title: Influence of electron acceptor availability and microbial community structure on sedimentary methane oxidation in a boreal estuary
Author: Myllykangas, Jukka-Pekka; Rissanen, Antti J.; Hietanen, Susanna; Jilbert, Tom
Other contributor: University of Helsinki, Marine Ecosystems Research Group
University of Helsinki, University Management
University of Helsinki, Ecosystems and Environment Research Programme




Date: 2020-04
Language: eng
Number of pages: 19
Belongs to series: Biogeochemistry
ISSN: 0168-2563
DOI: https://doi.org/10.1007/s10533-020-00660-z
URI: http://hdl.handle.net/10138/327684
Abstract: Methane is produced microbially in vast quantities in sediments throughout the world's oceans. However, anaerobic oxidation of methane (AOM) provides a near-quantitative sink for the produced methane and is primarily responsible for preventing methane emissions from the oceans to the atmosphere. AOM is a complex microbial process that involves several different microbial groups and metabolic pathways. The role of different electron acceptors in AOM has been studied for decades, yet large uncertainties remain, especially in terms of understanding the processes in natural settings. This study reports whole-core incubation methane oxidation rates along an estuarine gradient ranging from near fresh water to brackish conditions, and investigates the potential role of different electron acceptors in AOM. Microbial community structure involved in different methane processes is also studied in the same estuarine system using high throughput sequencing tools. Methane oxidation in the sediments was active in three distinct depth layers throughout the studied transect, with total oxidation rates increasing seawards. We find extensive evidence of non-sulphate AOM throughout the transect. The highest absolute AOM rates were observed below the sulphate-methane transition zone (SMTZ), strongly implicating the role of alternative electron acceptors (most likely iron and manganese oxides). However, oxidation rates were ultimately limited by methane availability. ANME-2a/b were the most abundant microbial phyla associated with AOM throughout the study sites, followed by ANME-2d in much lower abundances. Similarly to oxidation rates, highest abundances of microbial groups commonly associated with AOM were found well below the SMTZ, further reinforcing the importance of non-sulphate AOM in this system.
Subject: Baltic sea
Methanotrophy
Radiotracer incubation
High throughput sequencing
16S rRNA gene
MEDIATED ANAEROBIC OXIDATION
ARCHAEAL COMMUNITY
MARINE-SEDIMENTS
IRON
REDUCTION
DEEP
MANGANESE
HYPOXIA
LAKE
RNA
1172 Environmental sciences
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