A1 Journal article (refereed)
CH4 oxidation in a boreal lake during the development of hypolimnetic hypoxia (2020)


Saarela, Taija; Rissanen, Antti J.; Ojala, Anne; Pumpanen, Jukka; Aalto, Sanni L.; Tiirola, Marja; Vesala, Timo; Jäntti, Helena (2020). CH4 oxidation in a boreal lake during the development of hypolimnetic hypoxia. Aquatic Sciences, 82, 19. DOI: 10.1007/s00027-019-0690-8


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Publication details

All authors or editors: Saarela, Taija; Rissanen, Antti J.; Ojala, Anne; Pumpanen, Jukka; Aalto, Sanni L.; Tiirola, Marja; Vesala, Timo; Jäntti, Helena

Journal or series: Aquatic Sciences

ISSN: 1015-1621

eISSN: 1420-9055

Publication year: 2020

Volume: 82

Article number: 19

Publisher: Birkhaeuser Science

Publication country: Switzerland

Publication language: English

DOI: https://doi.org/10.1007/s00027-019-0690-8

Open Access: Open access publication published in a hybrid channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/67403


Abstract

Freshwater ecosystems represent a significant natural source of methane (CH4). CH4 produced through anaerobic decomposition of organic matter (OM) in lake sediment and water column can be either oxidized to carbon dioxide (CO2) by methanotrophic microbes or emitted to the atmosphere. While the role of CH4 oxidation as a CH4 sink is widely accepted, neither the magnitude nor the drivers behind CH4 oxidation are well constrained. In this study, we aimed to gain more specific insight into CH4 oxidation in the water column of a seasonally stratified, typical boreal lake, particularly under hypoxic conditions. We used 13CH4 incubations to determine the active CH4 oxidation sites and the potential CH4 oxidation rates in the water column, and we measured environmental variables that could explain CH4 oxidation in the water column. During hypolimnetic hypoxia, 91% of available CH4 was oxidized in the active CH4 oxidation zone, where the potential CH4 oxidation rates gradually increased from the oxycline to the hypolimnion. Our results showed that in warm springs, which become more frequent, early thermal stratification with cold well-oxygenated hypolimnion delays the period of hypolimnetic hypoxia and limits CH4 production. Thus, the delayed development of hypolimnetic hypoxia may partially counteract the expected increase in the lacustrine CH4 emissions caused by the increasing organic carbon load from forested catchments.


Keywords: boreal zone; lakes; greenhouse gases; hypoxia; methane; oxidation (active); isotopes; strata

Free keywords: boreal lake; greenhouse gases; hypoxia; methane; oxidation; stable isotopes; stratification


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Ministry reporting: Yes

Reporting Year: 2020

Preliminary JUFO rating: 1


Last updated on 2020-18-08 at 13:38