Estimation Of Amorphous Organic Carbon/water Partition Coefficients, Subcooled Liquid Aqueous Solubilities, And N-octanol/water Partition Coefficients Of Nonpolar Chlorinated Aromatic Compounds From Chlorine Fragment Constants

摘要

This study aims to derive the relation between the number of chlorine atoms in chlorobenzenes, poly-chlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), and dibenzofurans (PCDFs) and logK_(oc) for linear partitioning between water and average amorphous organic carbon in soils or sediments. Because reliable determinations of logK_(oc) are relatively sparse for chlorobenzenes and PCBs, and are even absent for PCDDs and PCDFs, a work-around solution was developed: First, the relation of n-octanol/water partitioning (K_(ow)) and (subcooled) liquid solubility (S_1) to the number of chlorines was investigated. Slopes for the linear correlation of logK_(ow) with the number of chlorines (corrected for the number of ortho-chlorines in the case of PCBs) appeared identical for chlorobenzenes, PCBs, PCDDs, and PCDFs. Such was also the case for logS_1. Slopes for the linear relation of chlorobenzenes and PCB logK_(oc) values with the number of chlorines were similar for the various soils and sediments, though intercepts were different. The ortho-chlorine correction factor for PCB logK_(oc) was equal to the ortho-chlorine correction factor for PCB logK_(ow) and logS_1. For PCDDs and PCDFs, a relation between logK_(oc) and the number of chlorine atoms was derived by combining the chlorobenzenes/PCB logK_(oc) - logK_(ow) and logK_(oc) - logS_1, relationships with logK_(ow) (or S_1)-chlorine number relations for PCDDs and PCDFs.