Systems-level insights into carbon transformations in thawing permafrost by parallel high-resolution organic matter and microbial community characterizations
EMSL Project ID
48467
Abstract
A fundamental challenge of modern environmental science is to understand how earth systems will respond to climate change. A parallel challenge in biology is to understand how information encoded in organismal genes manifests as biogeochemical processes at ecosystem-to-global scales. 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 in the coming century. 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 this permafrost "old" C with "new" extant plant-derived C, specifically how do microbial communities interact with these chemical structures 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. Complementary microbial metagenome sequencing at the Joint Genome Institute, targeted to increase coverage for current population genomes, will greatly strengthen the population-specific analytical inferences for which microbial groups are actively performing which C transformations. Together, these efforts will improve our understanding of the fate of Arctic and Subarctic C on a changing planet. In this study, we focus on a well-instrumented and highly-studied "model ecosystem" of permafrost thaw and C mobilization, spanning a natural thaw chronosequence. We will characterize in parallel (1) the detailed changes in input C and 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
FICUS Research
Start Date
2014-10-01
End Date
2016-03-31
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
Martinez M.A., B.J. Woodcroft, J.C. Ignacio-Espinozaa, A.A. Zayed, C.M. Singleton, J. Boyd, and Y. Li, et al. 2019. "Discovery and ecogenomic context of a global Caldiserica-related phylum active in thawing permafrost, Candidatus Cryosericota phylum nov, Ca. Cryosericia class nov, Ca. Cryosericales ord. nov., Ca. Cryosericaceae fam. nov., comprising the four species Cryosericum septentrionale gen. nov. sp. nov., Ca. C. hinesii sp. nov., Ca. C. odellii sp. nov., Ca. C. terrychapinii sp. nov." Systematic and Applied Microbiology 42, no. 1:54-66. PNNL-SA-135223. doi:10.1016/j.syapm.2018.12.003
Wilson RM, MM Tfaily, V Rich, JK Keller, SD Bridgham, C Medvedeff, L Meredith, PJ Hanson, ME Hines, L Pfeifer-Meister, S Saleska, PM Crill, WT Cooper, J Chanton, and JE Kostka. 2017. "Hydrogenation of Organic Matter as a Terminal Electron Sink Sustains High CO2:CH4 Production Ratios During Anaerobic Decomposition." Organic Geochemistry 10. 1016/j. orggeochem. 2017. 06. 0(112):22-32.
Wilson R.M., R.B. Neumann, K.B. Crossen, N.M. Raab, S.B. Hodgkins, S. Saleska, and B. Bolduc, et al. 2019. "Microbial Community Analyses Inform Geochemical Reaction Network Models for Predicting Pathways of Greenhouse Gas Production." Frontiers in Earth Science 7, no. 59. doi:10.3389/feart.2019.00059
Wilson RM, Zayed AA, Crossen KB, Woodcroft B, Tfaily MM, et al. (2021) Functional capacities of microbial communities to carry out large scale geochemical processes are maintained during ex situ anaerobic incubation. PLOS ONE 16(2): e0245857. https://doi.org/10.1371/journal.pone.0245857