Deconstructing methane emissions from a small Northern-European river: Hydrodynamics and temperature as key drivers.

McGinnis, Daniel F., Bilsley, Nicole, Schmidt, Mark , Fietzek, Peer, Bodmer, Pascal, Premke, Katrin, Lorke, Andreas and Flury, Sabine (2016) Deconstructing methane emissions from a small Northern-European river: Hydrodynamics and temperature as key drivers. Environmental Science & Technology, 50 (21). pp. 11680-11687. DOI 10.1021/acs.est.6b03268.

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Abstract

Methane (CH4) emissions from small rivers and streams, particularly via ebullition, are currently under-represented in the literature. Here, we quantify the methane effluxes and drivers in a small, Northern European river. Methane fluxes are comparable to those from tropical aquatic systems, with average emissions of 320 mg CH4 m-2 d-1. Two important drivers of methane flux variations were identified in the studied system: 1) temperature-driven sediment methane ebullition and 2) flow-dependent contribution suspected to be hydraulic exchange with adjacent wetlands and small side-bays. This flow-dependent contribution to river methane loading is shown to be negligible for flows less than 4 m3 s-1, and greater than 50% as flows exceed 7 m3 s-1. While the temperature - ebullition relationship is comparable to other systems, the flow rate dependency has not been previously demonstrated. In general, we found that about 80% of the total emissions were due to methane bubbles. Applying ebullition rates to global estimates for fluvial systems, which currently are not considered, could dramatically increase emission rates to ranges from lakes or wetlands. This work illustrates that small rivers can emit significant methane, and highlights the need for further studies, especially the link between hydrodynamics and connected wetlands.

Document Type: Article
Additional Information: WOS:000386991100029; PubMed ID: 27696829
Keywords: Methane emissions, wetlands, river, climate change, ebullition, water flow rate, lateral exchange
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1021/acs.est.6b03268
ISSN: 0013-936X
Date Deposited: 07 Oct 2016 07:05
Last Modified: 01 Feb 2019 15:16
URI: http://oceanrep.geomar.de/id/eprint/34203

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