Premium
Spatial and Temporal Variation in Methane Concentrations, Fluxes, and Sources in Lakes in Arctic Alaska
Author(s) -
TownsendSmall Amy,
Åkerström Frida,
Arp Christopher D.,
Hinkel Kenneth M.
Publication year - 2017
Publication title -
journal of geophysical research: biogeosciences
Language(s) - English
Resource type - Journals
eISSN - 2169-8961
pISSN - 2169-8953
DOI - 10.1002/2017jg004002
Subject(s) - arctic , environmental science , transect , oceanography , latitude , atmospheric sciences , permafrost , spatial variability , physical geography , hydrology (agriculture) , geology , geography , statistics , mathematics , geotechnical engineering , geodesy
Abstract Climate warming may lead to a positive feedback of increased emissions of CH 4 from sediments beneath Arctic lakes, but the contribution of these lakes to the global CH 4 budget is poorly quantified. Here we present results of a study of CH 4 concentrations and sources from a series of 50 lakes in Arctic Alaska across an 80,000 km 2 spatial gradient and a 2 year time period. We measured dissolved CH 4 concentrations and stable isotopes of CH 4 in lakes in the North Slope of Alaska in August 2014 and 2015 and April 2015 (under ice). Stable isotopes indicated that biogenic CH 4 dominated versus thermogenic sources, with both acetate fermentation and carbonate reduction sources. Dissolved CH 4 was about 100 times higher under the ice than during the summer, indicating that the spring ice off period is a large source of atmospheric CH 4 . Open‐water dissolved CH 4 concentrations had a negative relationship with latitude in both years of our study, although CH 4 fluxes were consistent among a subset of lakes measured along a ~150 km north to south transect in both years (14 lakes in 2014 and 12 in 2015). Dissolved CH 4 concentrations and fluxes were significantly higher in August 2015 versus August 2014, concurrent with a 3°C higher mean water temperature in 2015 versus 2014. Much longer‐term monitoring is needed, however, to conclude that CH 4 emissions from Arctic lakes mirror observed warming trends. This study provides valuable baseline data and can inform methods for future studies investigating carbon cycle‐climate change feedbacks in Alaskan Arctic lakes.