Correlations between Relative Abundance of Molecular Formulae and Land Use in Watershed

Figure 3. Spearman-rank correlations between the relative abundance of assigned molecular formulae and (b) percent forest in the watershed, (c) percent agriculture in the watershed, (d) and percent urban in the watershed. Axes represent the atomic ratios of Hydrogen to Carbon (H/C) and Oxygen to Carbon (O/C) of each compound. Colors represent the correlation coefficient between the relative abundance of each formula and percent land use, with warmer color indicating positive correlations and cooler color indicating negative correlations. Meaning warmer points represent compounds that were more likely to occur in a given land use type. These resulting graphs represent the unique fingerprint of Dissolved Organic Matter types in certain land use types. Lines approximately delineate compound groups (CA = condensed aromatic compounds; HUP = highly unsaturated and phenolic compounds; PP = polyphenolic compounds). From Fig. 6 in (Vaughn et al., 2021)