Methane cycling dynamics in sediments of Alaskan Arctic Foothill lakes

Autor:	Stephen C. Whalen, Kristen Alexandra Bretz
Rok vydání:	2014
Předmět:	Hydrology Methanogenesis Phytodetritus Sediment Aquatic Science Methane chemistry.chemical_compound chemistry Arctic Environmental chemistry Anaerobic oxidation of methane Environmental science Dominance (ecology) Cycling Water Science and Technology
Zdroj:	Inland Waters. 4:65-78
ISSN:	2044-205X 2044-2041
Popis:	We measured aspects of sediment methane (CH 4 ) cycling dynamics in 3 shallow (mean depth, z = 2.1 m) and 3 deep (z = 6.5 m) Alaskan Arctic Foothill lakes to establish reference data to evaluate future climate-mediated changes in these systems and to identify lake-size-dependent differences in rates and controls on CH 4 production and consumption or sensitivity to changing climate. The mean sedimentation rate and sediment oxygen (O 2 ) penetration depth were significantly higher and lower, respectively, in shallow versus deep lakes. The molar carbon to nitrogen (C:N) ratio of 12 for sedimenting material across lakes indicated a dominance by phytodetritus. Pore water dissolved organic C and CH 4 concentrations were higher in shallow than in deep lakes at comparable depths below the sediment surface. The average area-based rate of methanogenesis was significantly higher in shallow lakes, exceeding the mean of deep lakes by a factor of 4; however, the mean potential area-based rate of CH 4 oxidation was comparable between lake classes due to the reduced sediment O 2 penetration depth in shallow lakes. All lake sediments responded similarly to chemical amendments. Hydrogen addition significantly stimulated rates of methanogenesis relative to unamended controls, while rates were unchanged by alternate electron acceptors (SO 4 2− , Fe 3+ , NO 3 − , Mn 4+ ), suggesting that other microbial groups did not compete with methanogens for common substrates or produce toxic intermediates. Across all lakes, 30% of assimilated CH 4 was converted to methanotophic biomass, and methanotrophic C production could be as much as 23% of epipelic primary production, pointing to the potential importance of CH 4 -derived C in Arctic lacustrine food webs.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::6d02f487511e126b180f0363239e50f7 https://doi.org/10.5268/iw-4.1.637 Zobrazit plný text záznamu