“…This is also where WRT and the adsorption treatment diverge in their effect on DOM composition: Whereas unsaturated compounds are generally lost from solution in both processes, even fairly saturated compounds can be adsorbed as long as they have a high O/C (Figures 3c and S3). The observed adsorption of oxygen-rich compounds is in agreement with various other studies, where both highly oxidized aromatics (Coward et al, 2018;Fleury et al, 2017;Galindo & Del Nero, 2014;Lv et al, 2016), and in some cases also oxidized saturated, aliphatic compounds (Galindo & Del Nero, 2014;Avneri-Katz et al, 2017) were preferentially adsorbed. The preferential adsorption of oxygen-rich compounds indicates that the presence of carboxyl and hydroxyl functional groups may be important for adsorptive processes, as these groups allow for ligand exchange with oxide and hydroxide groups at the sorbent's surface (Chassé et al, 2015;Gu et al, 1995;Kaiser, 2003;Kaiser et al, 1997;Kothawala et al, 2012;Lv et al, 2016;Meier et al, 1999;Tipping, 1981b).…”