Predicting dissolved organic carbon partition and distribution coefficients of neutral and ionizable organic chemicals

Estimating K-DOC (dissolved organic carbon/water partition coefficient) and D-DOC (diSSOIVCCI organic carbon/water distribution coefficient) of neutral and ionizable organic chemicals is a crucial task for assessing mobility, modelling transport, environmental fate of a variety of chemicals and for evaluating their bioavailability in terrestrial and aquatic environments. A critical literature search of reliability-selected K-DOC and D-DOC values was performed to setup novel predictive relationships for K-DOC and D-DOC of neutral and ionizable organic chemicals. This goal was pursued by using: 1) LSER (linear solvation energy relationship) models to predict Kpoc for neutral chemicals using Abraham solute parameters calculated for different DOC sources (all DOC sources together, soil porewater, surface water, wastewater and Aldrich humic acid (HA)); 2) linear regressions for predicting K-DOC of organic acids from the octanol/water partition coefficient (Log K-OW or Log P) and the dissociation constant (pKa), accounting separately for the contribution of the neutral and ionic fraction. The proposed models predicted Log K-DOC and D-DOC values within a root mean square deviation (RMSD) generally smaller than 0.3 log units. (C) 2018 Elsevier B.V. All rights reserved.