QSARs for predicting reductive transformation rate constants of halogenated aromatic hydrocarbons in anoxic sediment systems

Abstract

Abstract Quantitative structure-activity relationships (QSARs) are developed relating initial and final pseudo-first-order disappearance rate constants of 45 halogenated aromatic hydrocarbons in anoxic sediments to four readily available molecular descriptors: the carbon-halogen bond strength, the summation of the Hammett sigma constants of the additional substituents, the summation of the inductive constants of these substituents, and the steric factors of the additional substituents. Comparison of the “initial” and “final” QSARs suggests that the same agent is involved as the reductant in both processes. The rate constants for reduction of seven haloaromatics obtained in 10 different sediment samples are correlated with the organic carbon content of the samples. The correlations are enhanced by taking into account the fraction of the compounds sorbed to the solid phase. Biotransformation