Highest methane concentrations in an Arctic river linked to local terrestrial inputs

Author:

Castro-Morales KarelORCID,Canning Anna,Arzberger Sophie,Overholt Will A.,Küsel Kirsten,Kolle Olaf,Göckede MathiasORCID,Zimov Nikita,Körtzinger ArneORCID

Abstract

Abstract. Large amounts of methane (CH4) could be released as a result of the gradual or abrupt thawing of Arctic permafrost due to global warming. Once available, this potent greenhouse gas is emitted into the atmosphere or transported laterally into aquatic ecosystems via hydrologic connectivity at the surface or via groundwaters. While high northern latitudes contribute up to 5 % of total global CH4 emissions, the specific contribution of Arctic rivers and streams is largely unknown. We analyzed high-resolution continuous CH4 concentrations measured between 15 and 17 June 2019 (late freshet) in a ∼120 km transect of the Kolyma River in northeast Siberia. The average partial pressure of CH4 (pCH4) in tributaries (66.8–206.8 µatm) was 2–7 times higher than in the main river channel (28.3 µatm). In the main channel, CH4 was up to 1600 % supersaturated with respect to atmospheric equilibrium. Key sites along the riverbank and at tributary confluences accounted for 10 % of the navigated transect and had the highest pCH4 (41 ± 7 µatm) and CH4 emissions (0.03 ± 0.004 mmolm-2d-1) compared to other sites in the main channel, contributing between 14 % to 17 % of the total CH4 flux in the transect. These key sites were characterized by warm waters (T>14.5 ∘C) and low specific conductivities (κ<88 µS cm−1). The distribution of CH4 in the river could be linked statistically to T and κ of the water and to their proximity to the shore z, and these parameters served as predictors of CH4 concentrations in unsampled river areas. The abundance of CH4-consuming bacteria and CH4-producing archaea in the river was similar to those previously detected in nearby soils and was also strongly correlated to T and κ. These findings imply that the source of riverine CH4 is closely related with sites near land. The average total CH4 flux density in the river section was 0.02 ± 0.006 mmolm-2d-1, equivalent to an annual CH4 flux of 1.24×107 g CH4 yr−1 emitted during a 146 d open water season. Our study highlights the importance of high-resolution continuous CH4 measurements in Arctic rivers for identifying spatial and temporal variations, as well as providing a glimpse of the magnitude of riverine CH4 emissions in the Arctic and their potential relevance to regional CH4 budgets.

Funder

Deutsche Forschungsgemeinschaft

Horizon 2020 Framework Programme

Publisher

Copernicus GmbH

Subject

Earth-Surface Processes,Ecology, Evolution, Behavior and Systematics

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3