Control of climate on soil organic matter formation, sources and stabilization
EMSL Project ID
51102
Abstract
Soil organic matter (SOM) is the largest organic carbon (C) pool in terrestrial ecosystems and its formation and stability strongly affect global carbon cycling and climate change. The widely accepted Microbial Efficiency-Matrix Stabilization (MEMS) framework and the more recent Microbial Carbon Pump (MCP) theory hypothesize that the long-term storage and stability of SOM result from mineral stabilization of microbial-derived C (microbial metabolites and necromass), rather than plant-derived compounds. However, the hypothesis needs further empirical evidence and more importantly, the impacts of climate remain unclear. Therefore, in this project we propose to determine the sources and chemical composition of both SOM and dissolved OM (DOM) of soil samples across two climate gradients that span a wide range of rainfall levels (MAP: 16 – 500 cm) with relatively narrow range of MAT (16 – 23 oC). ESI-FT-ICR-MS will be used to characterize molecular composition of the DOM. The lignin concentration obtained from ESI-FT-ICR-MS indicates the contribution of plant-derived C. The SOM chemical composition at functional group level will be determined using C 1s Near edge X-ray Absorption Fine Structure spectroscopy which will provide the proportions of aromatic (plant-derived) and O-alkyl C (microbial-derived). Furthermore, biomarker analyses on selected amino sugars in SOM will be used to semi-quantify contribution of microbial derived C to SOM. We will seek correlations of the OM composition and sources with climate, clay mineral contents and other soil chemical properties. Results will provide important insights into SOM formation and stabilization at global scale.
Project Details
Project type
Limited Scope
Start Date
2019-12-17
End Date
2020-02-16
Status
Closed
Released Data Link
Team
Principal Investigator