PNNL

Abstract

Natural organic matter is comprised of a highly complex mixture of thousands of organic compounds which, historically, proved difficult to characterize. However, a molecular-level characterization of the organic matter coupled with microbial community analyses is necessary for understanding the thermodynamic and kinetic controls on greenhouse gas (carbon dioxide CO2 and methane, CH4) production. Climate and environmental changes are expected to perturbate the system potentially upsetting complex interactions that influence both the supply of organic matter substrates and the microorganisms performing the transformations. To predict the direction and magnitude of the effects of environmental changes however, a detailed molecular characterization of the organic matter, microbial community, and the pathways and transformations by which organic matter is decomposed is required. Herein we describe a methodological throughput for comprehensive metabolite characterization in a single sample by direct injection Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS), gas chromatography mass spectrometry (GCMS), nuclear magnetic resonance (NMR), and liquid chromatography mass spectrometry (LCMS). This approach results in a fully-paired dataset which improves statistical confidence for inferring pathways of organic matter decomposition, the resulting CO2 and CH4 production rates, and their responses to environmental perturbation.