Fig. 2: Two distinct signatures of the composition of dissolved organic matter (DOM) in grassland soils.
From: Spatial patterns and environmental functions of dissolved organic matter in grassland soils of China
a, b Fluorescence spectra of the DOM with a high humic-like and b high protein-like fractions. Region I, tyrosine protein-like; Region II, tryptophan protein-like; Region III, fulvic acid-like; Region IV, soluble microbial byproduct-like; and Region V, humic acid-like. c, d Apparent molecular weight distribution of the DOM with c high HMW and d high LMW fractions. e, f Significant Spearman’s rank correlations (P < 0.05) between the relative abundance of individual molecules vs e humic-like (C1 + C2 + C3) and f 3.4–25 kDa fractions. The green and purple colors of the circles indicate negative and positive correlation coefficients, respectively. The dashed lines in van Krevelen diagrams separate the molecules into different compound categories. HMW, 3.4–25 kDa; LMW, <1.2 kDa.
