Fig. 3. The sorption onto goethite of 60 mg C L^–1 solutions of the hydrophilic and hydrophobic DOM fractions of the plant biomass- and animal manure-derived DOM before and after decomposition. Error bars indicate standard deviation of the mean of three replicates. *, **, and *** designate significant difference at the p = 0.05, 0.01, and 0.001 levels using the student's t test between the fresh and decomposed means. NS indicates that the mean difference is not significant.