Sediment Characteristics and Methane Ebullition in Three Subarctic Lakes. Issue 8 (20th August 2018)

• Record Type: Journal Article
• Authors: Wik, Martin; Johnson, Joel E.; Crill, Patrick M.; DeStasio, Joel P.; Erickson, Lance; Halloran, Madison J.; Fahnestock, M. Florencia; Crawford, Maurice K.; Phillips, Stephen C.; Varner, Ruth K.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 8(2018)
• Page Start: 2399
• Page End: 2411
• Publication Date: 2018-08-20
• Subjects: methane -- northern lakes -- carbon -- sediment -- Arctic -- climate; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1029/2017JG004298
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: Ebullition (bubbling) from climate‐sensitive northern lakes remains an unconstrained source of atmospheric methane (CH4 ). Although the focus of many recent studies, ebullition is rarely linked to the physical characteristics of lakes. In this study we analyze the sediments of subarctic postglacial lakes and investigate how sediment properties relate to the large spatial variation in CH4 bubble flux, quantified over multiple years using bubble traps. The results show that the sediments from our lakes are rich in total organic carbon, containing 37 kg/m 3 on average. This number is roughly 40% higher than the average for yedoma deposits, which have been identified as high CH4 emitters. However, the quantity of total organic carbon is not a useful indicator of high emissions from the study lakes. Neither is the amount of CH4 in the sediment a reliable measure of ebullition potential. Instead, our data point to coarse detritus, partly from buried submerged aquatic vegetation and redeposited peat as spatial controls on fluxes, often in combination with previously established effects of incoming solar radiation and water depth. The results once again highlight the climate sensitivity of northern lakes, indicating that biological responses to warmer waters and increased energy input and heating of organic sediments during longer ice‐free seasons can substantially alter future CH4 emissions. Key Points: The quality of organic carbon appears more important than quantity in regulating methane flux Autochthonous carbon from submerged aquatic plants fuels ebullition in postglacial lakes Climate sensitive postglacial lake sediments can be a sustained methane source with Arctic warming