What, exactly, inhibits decomposition at low temperature?
EMSL Project ID
50209
Abstract
Arctic soils contain large carbon (C) stores, and the balance of C fluxes is likely to shift because Arctic temperatures are rising at twice the global rate. However, predicting soil responses is uncertain due to complex warming effects on decomposition. The response of carbon dioxide release depends on multiple feedbacks on microbial activities for which we lack key information. Understanding biochemical mechanisms controlling temperature responses, particularly the interactions between organic matter chemistry, enzyme activities, and product composition will enable models that better constrain C cycling in response to warming, especially at low temperatures relevant to the C rich Arctic and boreal biomes.
We propose to answer the question: What are the rate limiting steps for organic matter decomposition at low temperatures? Our goal is to determine the biochemical mechanisms controlling temperature responses of decomposition in tundra soil, particularly the interactions between substrate chemistry and degradative enzyme activities. We will leverage an existing Arctic project, from which we will incubate organic horizon soil and determine the temperature responses of the key biochemical steps of lignocellulose degradation at different temperatures in collaboration with EMSL. We will then use the results to develop a mechanistic model of decomposition temperature responses. Access to EMSL is critical to the success of this research because EMSL's advanced analytical capabilities are required to directly and independently measure changes in individual enzyme substrates and reaction products.
This research closely fits PNNL's Environmental Sciences focus on understanding biogeochemical processes governing terrestrial C and nutrient cycling, including microbial processes that drive nutrient cycling, and plant-microbe-soil-atmosphere interactions. This study also addresses the Biological Sciences focus on integrated modeling and structural biology studies to understand the enzymatic systems involved in biomass deconstruction, as well as experimental and modeling approaches with biological systems (e.g., bacteria, fungi) to enable predictive understanding of C and nutrient fluxes.
This work will generate: 1) mechanistic insight to the rate limiting steps to decomposition at low temperatures, which is critical in C rich northern soils, and relevant to the DOE's ongoing research in boreal (ABoVE) and Arctic (NGEE) systems; 2), quantitative tools to model changes in soil C dynamics and carbon dioxide fluxes with temperature variations across these limitations, both seasonally and over longer terms associated with global climate change; and 3) additional insight to the biochemical controls on enzymatic deconstruction of lignocellulose polymers.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2018-10-01
End Date
2021-03-31
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members