Despite the globally significant role that soil organic carbon (SOC) has on the climate, significant knowledge gaps persist regarding SOC decomposition and preservation. We seek to leverage released datasets from EMSL (Environmental Molecular Science Laboratory)'s 1000 Soils Research Campaign (a pilot program of the Molecular Observation Network, MONet) to identify relationships between SOC vs. (i) biogeochemical indicators (biogeochemistry dataset) and (ii) compound class diversity in dissolved organic matter (FTICR-MS dataset). We utilize a gridded SOC product to extract surface (0-30 cm) SOC values for each site according to their geographic coordinates. Our preliminary results suggest that several geochemical indicators—including cation exchange capacity, soil pH, and abundance of nitrogen, iron, and sulfur—correlate significantly with SOC (with each individually accounting for >20% of observed variability in SOC content). The diversity of lipid compounds inversely correlates with SOC content—a relationship that was statistically significant and accounts for ~16% of observed variability. None of the diversity metrics for the remaining compound classes— amino sugars, carbohydrates, condensed hydrocarbons, lignin, proteins, tannins, and unsaturated hydrocarbons—correlate significantly with SOC content. There are, however, consistently significant and positive correlations between compound class intercomparisons. These preliminary results suggest that (i) increasing compound class diversity is generally reflected in all major dissolved organic compound class categories and (ii) compound class diversity is a generally poor predictor of SOC content. To gain further insights into the dynamics of SOC stabilization or turnover, we intend to conduct more detailed analyses of the relationship between dissolved organic compound distribution/diversity vs. SOC content.
