Characterization of terrestrial dissolved organic matter fractionated by pH and polarity and their biological effects on plant growth

Chemical and Biological Technologies in Agriculture

Table 4 Mass spectral characteristics of the formulae responsible for the variance in the FTICR-MS PCA dataset

Parameter	General characteristics of molecular formulae from PCA
	Purple (enriched in filtrate-dominated samples)		Green (enriched in retentate-dominated samples)		Red (enriched in acid insoluble)
	range	average	range	average	range	average
O/C	0.40-1.18	0.74	0.18-0.63	0.40	0.06-0.63	0.29
H/C	0.32-1.50	0.90	0.43-1.70	1.10	0.32-2.00	0.99
DBE	4-20	11.2	4-26	14.1	1-26	13.1
DBE/C	0.31-0.89	0.61	0.20-0.82	0.49	0.03-0.89	0.55
m/z	233-683	451	277-699	559	227-665	429

The PCA scores and loadings are given in Figure 6d and 6e, respectively, with the corresponding color-coded van Krevelen plot shown in Figure 6 f.