Dissolved organic matter (DOM) is a complex mixture of
organic
compounds with chemical heterogeneity in natural soils, sediments,
and waters. Predicting the dissolved organic carbon (DOC)–water
partition coefficients (K
DOC) of organic
pollutants to DOMs from various sources is important for assessing
their fate and bioavailability. However, the accuracy of the recently
developed polyparameter linear free energy relationship (pp-LFER) K
DOC models is generally restricted by the small
data set, inclusion of experimental data from unreliable measurement
methods, or undefined selection standards. The aim of this study was
to establish pp-LFER models for predicting the K
DOC of nonionic organic chemicals to a variety of sources of
DOMs and to get an understanding of DOM chemodiversity. A reliable
and expanded experimental K
DOC data set
was compiled. Improved pp-LFER models were developed and assessed
for All DOM (DOM from all sources), Aldrich humic acid (HA), Roth
HA, soil porewater DOM, sediment porewater DOM, natural aquatic DOM,
natural terrestrial DOM, natural DOM, and commercial DOM. The models
developed in this study were reasonably robust and accurate with a
root mean square error (RMSE) of 0.538 for the All DOM model and RMSE
from 0.196 to 0.860 for the specific DOMs. Also, the models generally
performed better than previously published ones. Moreover, the system
parameters of the models well described the chemical variabilities
between soil porewater DOM and sediment porewater DOM, between natural
aquatic DOM and natural terrestrial DOM, and between natural DOM and
commercial DOM regarding polarizability, dipolarity, H-bond-accepting
and -donating ability, and cavity formation energy. This study provides
effective tools to assess the tendencies of organic chemicals to DOMs
and improves our understanding of the chemical heterogeneity of DOMs
from different sources.