Microbial lipid signatures and substrate potential of organic matter in permafrost deposits: Implications for future greenhouse gas production. Issue 10 (22nd October 2016)

• Record Type: Journal Article
• Authors: Stapel, J. G.; Schirrmeister, L.; Overduin, P. P.; Wetterich, S.; Strauss, J.; Horsfield, B.; Mangelsdorf, K.
• Is Part Of: Journal of geophysical research. Volume 121:Issue 10(2016:Oct.)
• Page Start: 2652
• Page End: 2666
• Publication Date: 2016-10-22
• Subjects: phospholipids -- phospholipid fatty acids -- GDGTs -- carbon quality -- Arctic permafrost -- greenhouse gas potential; Geobiology -- Periodicals; Biogeochemistry -- Periodicals; Biotic communities -- Periodicals; Geophysics -- Periodicals; 577.14
• DOI: 10.1002/2016JG003483
• Languages: English
• ISSNs: 2169-8953

Abstract

Abstract: A terrestrial permafrost core from Buor Khaya in northern Siberia comprising deposits of Late Pleistocene to Early Holocene age has been investigated to characterize living and past microbial communities with respect to modern and paleoclimate environmental conditions and to evaluate the potential of the organic matter (OM) for greenhouse gas generation. Microbial life markers—intact phospholipids and phospholipid fatty acids—are found throughout the entire core and indicate the presence of living microorganisms also in older permafrost deposits. Biomarkers for past microbial communities (branched and isoprenoid glycerol dialkyl glycerol tetraether as well as archaeol) reveal links between increased past microbial activity and intervals of high OM accumulation accompanied by increased OM quality presumably caused by local periods of moister and warmer environmental conditions. Concentrations of acetate as an excellent substrate for methanogenesis are used to assess the OM quality with respect to microbial degradability for greenhouse gas production. For this purpose two acetate pools are determined: the pore water acetate and OM bound acetate. Both depth profiles reveal similarities to the OM content and quality indicating a link between the amount of the stored OM and the potential to provide substrates for microbial greenhouse gas production. The data suggest that OM stored in the permafrost deposits is not much different in terms of OM quality than the fresh surface organic material. Considering the expected increase of permafrost thaw due to climate warming, this implies a potentially strong impact on greenhouse gas generation from permafrost areas in future with positive feedback on climate variation. Key Points: Abundant microbial life in the active layer but living microorganisms are also identified in the permafrost deposits Increased past microbial activity is indicated in intervals of high organic matter accumulation with increased organic matter quality Future potential for greenhouse gas generation from permafrost deposits depend on the quality and amount of the organic matter