Systems-level insights into carbon transformations in thawing permafrost by parallel high-resolution organic matter and microbial community characterization.
EMSL Project ID
48361
Abstract
A fundamental challenge of modern biology is to understand how information encoded in the genes of organisms translates into physiological and biogeochemical processes manifested at ecosystem to global scales. A parallel challenge of earth sciences is to understand how earth systems will respond to climate change. These grand challenges intersect in the need to understand the global carbon (C) cycle, which is both mediated by biological processes and a key driver of climate through the greenhouse gases carbon dioxide (CO2) and methane (CH4). A key aspect of these challenges is the C cycle implications of the predicted dramatic shrinkage in northern permafrost. Large releases of C from thawing permafrost to the atmosphere are plausible, and a strong potential positive feedback to global warming, but little is known about the controls on such release. What is the interplay of microbial communities and organic matter chemical structure in the decomposition/preservation of organic C across a thaw gradient? This proposed work linking microbial dynamics, organic geochemistry and trace gas production will improve models of C cycling in thawing permafrost systems, and clarify the fate of C under future climates. Recent technical advances at EMSL in high-resolution characterization of organic matter chemistry, and high-throughput proteomic analysis, now permit a uniquely detailed combined approach that will reveal biogeochemical consequences of microbial community dynamics to improve our understanding of the fate of permafrost C on a changing planet. In this study, we focus on understanding microbial dynamics and co-evolving geochemistry along a chronsequence of permafrost thaw and C mobilization. We will characterize in parallel (1) the detailed changes in soil and pore water C chemical structure as it is metabolized and mobilized post-thaw, and (2) the microbial community expression that mediates these C transformations and release to the atmosphere. This approach will address key outstanding questions about the pathways for C loss under permafrost thaw: is previously-frozen old C or new C predominating C gas emissions? How are microbial community systems interacting with these C substrates to control the ratio of CH4 to CO2 released, a key parameter in simulations of CH4 biogeochemistry used to estimate global emissions? Who are the key microbial lineages performing C transformations in these systems?.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2014-10-01
End Date
2016-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Hodgkins S, MM Tfaily, DC Podgorski, C McCalley, S Saleska, PM Crill, V Rich, J Chanton, and WT Cooper. 2016. "Elemental composition and optical properties reveal changes in dissolved organic matter along a permafrost thaw chronosequence in a subarctic peatland." Geochimica et Cosmochimica Acta 187:123-140. doi:10. 1016/j. gca. 2016. 05. 015
Rue G, N Rock, RS Gabor, J Pitlick, MM Tfaily, and DM Mcknight. 2017. "Concentration-discharge relationships during the recession of an extreme flood in the Boulder Creek Watershed: stability of major base cation concentrations contrasts with decreases in concentration and changes in chemical quality of dissolved organic material." Water Resources Research 53(7):5276-5297. doi:10.1002/2016WR019708
Wilson RM, AM Hopple, MM Tfaily, S Sebestyen, CW Schadt, L Pfeifer-Meister, C Medvedeff, K McFarlane, JE Kostka, M Kolton, R Kolka, LA Kluber, JK Keller, TP Guilderson, N Griffiths, J Chanton, SD Bridgham, and PJ Hanson. 2016. "Stability of a peatland carbon to rising temperatures." Nature Communications 7:Article No. 13723. doi:10.1038/ncomms13723