Logo image
Back
Clumped Isotopes Link Older Carbon Substrates With Slower Rates of Methanogenesis in Northern Lakes
Journal article   Open access   Peer reviewed

Clumped Isotopes Link Older Carbon Substrates With Slower Rates of Methanogenesis in Northern Lakes

Peter M. J. Douglas, Regina Gonzalez Moguel, Katey M. Walter Anthony, Martin Wik, Patrick M. Crill, Katherine S. Dawson, Derek A. Smith, Ella Yanay, Max K. Lloyd, Daniel A. Stolper, …
Geophysical research letters, v 47(6), 2019
28 Mar 2020
DOI: https://doi.org/10.1029/2019GL086756
Featured in Collection :   UN Sustainable Development Goals @ Drexel
url
https://doi.org/10.1029/2019GL086756View
Published, Version of Record (VoR) Open

Abstract

Geosciences, Multidisciplinary Science & Technology Geology Physical Sciences
The release of long-stored carbon from thawed permafrost could fuel increased methanogenesis in northern lakes, but it remains unclear whether old carbon substrates released from permafrost are metabolized as rapidly by methanogenic microbial communities as recently produced organic carbon. Here, we apply methane (CH4) clumped isotope (Delta(18)) and C-14 measurements to test whether rates of methanogenesis are related to carbon substrate age. Results from culture experiments indicate that Delta(18) values are negatively correlated with CH4 production rate. Measurements of ebullition samples from thermokarst lakes in Alaska and glacial lakes in Sweden indicate strong negative correlations between CH4 Delta(18) and the fraction modern carbon. These correlations imply that CH4 derived from older carbon substrates is produced relatively slowly. Relative rates of methanogenesis, as inferred from Delta(18) values, are not positively correlated with CH4 flux estimates, highlighting the likely importance of environmental variables other than CH4 production rates in controlling ebullition fluxes. Plain Language Summary There is concern that carbon from thawed permafrost will be emitted to the atmosphere as methane (CH4). It is currently uncertain whether old organic carbon from thawed permafrost can be converted to CH4 as rapidly as organic carbon recently fixed by primary producers. We address this question by combining radiocarbon and clumped isotope measurements of CH4 from lakes in permafrost landscapes. Radiocarbon (C-14) measurements indicate the age of CH4 carbon sources. We present data from culture experiments that support the hypothesis that clumped isotope values are dependent on microbial CH4 production rate. In lake bubble samples, we observe a strong correlation between these two measurements, which implies that CH4 formed from older carbon is produced relatively slowly. We also find that higher rates of CH4 production, as inferred from clumped isotopes, are not linked to higher rates of CH4 emissions, implying that variables other than CH4 production rate strongly influence emission rates.

Metrics

1 Record Views
44 citations in Web of Science

Details

UN Sustainable Development Goals (SDGs)

This publication has contributed to the advancement of the following goals:

#15 Life on Land
#13 Climate Action
#14 Life Below Water

Source: SDGs in the Output

InCites Highlights

Data related to this publication, from InCites Benchmarking & Analytics tool:

Collaboration types
Domestic collaboration
International collaboration
Web of Science research areas
Geosciences, Multidisciplinary
Logo image