Predicting organic carbon-water partitioning of hydrophobic organic chemicals in soils and sediments based on water solubility

摘要

For predicting organic carbon-water partitioning of organic pollutants in soils and sediments, a simple empirical relationship is derived from Raoult's law and fitted to data sets of experimental organic carbon normalized partition coefficients (K_(oc)) and aqueous solubilities (S_i) of 64 hydrophobic organic chemicals (HOCs) from literature including mono- and polycyclic aromatic hydrocarbons, halogenated monoaromatic and alkyl hydrocarbons, and polychlorinated biphenyls. Although over 5 orders of magnitude are covered in sorptivity (log K_(oc)), the new relationship (log K_(oc) = - 0.85 log S_i - 0.55) predicts K_(oc) with an average absolute deviation of only .0.23 log units. The relationship between K_(oc) and S_i is inverse and slightly nonlinear. The product of K_(oc) times S_i (= K_(oc)~*, which indicates the theoretical maximum contaminant loading at its solubility limit per unit mass of organic carbon) is 0.098 kg kg~(-1) and 0.012 kg kg~(-1) for compounds with water solubilities of 1 g L~(-1) and 1 μg L~(-1), respectively.