Biased sampling of methane release from northern lakes: A problem for extrapolation

• Published in: Geophysical Research Letters
• Main Authors: Wik, Martin, Thornton, Brett F., Bastviken, David, Uhlbaeck, Jo, Crill, Patrick M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Linköpings universitet, Tema Miljöförändring 2016
• Subjects: northern lakes; methane; sampling bias; ebullition; diffusion; subarctic; Earth and Related Environmental Sciences; Geovetenskap och miljövetenskap; Subarctic
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-127058; https://doi.org/10.1002/2015GL066501

Methane emissions from lakes are widely thought to be highly irregular and difficult to quantify with anything other than numerous distributed measurement stations and long-term sampling campaigns. In spite of this, a large majority of the study sites north of 50 degrees N have been measured over surprisingly short time periods of only one to a few days. Using long-term data from three intensively studied small subarctic lakes, we recommend that measurements of diffusive methane flux and ebullition should be made over at least 11 and 39days scattered throughout the ice-free season using depth-stratified sampling at 3 and 11 or more locations, respectively. We further show that low temporal and spatial resolutions are unlikely to cause overestimates. Therefore, we argue that most sites measured previously are likely underestimated in terms of emission potential. Avoiding these biases seen in much of the contemporary data is crucial to further constrain large-scale methane emissions from northern lakes and ponds. Funding Agencies|Swedish Research Council [2007-4547]; Nordic Center of Excellence DEFROST under Nordic Top-Level Research Initiative