Transformation of PAHs in Soil Systems

Abstract

Transformation kinetics, corrected for abiotic loss and for volatilization, of 14 polycyclic aromatic hydrocarbon (PAH) compounds were studied in two nonacclimated soils. Mean volatilization losses for naphthalene and 1-methylnaphthalene were measured as 31% and 22%, respectively, of the total masses applied. Volatilization of the other twelve PAH compounds studied was less than 0.1%. The abiotic loss (1.8–17.4%) of two- and three-ring PAH compounds in soil samples bio-inhibited by 2% HgC1\d2 was statistically significant (p<0.05). No significant loss from bio-inhibited soil was found for PAH compounds with more than three rings. Transformation half-lives corrected for volatilization and for abiotic loss were approximately 2 days for two-ring PAHs including naphthalene and 1-methylnaphthalene. Half-lives values for nonvolatile PAHs increased from 59 days for three-ring PAHs (anthracene and phenantherene) to more than 300 days for PAH compounds containing more than three rings. The PAH transformation rate was inversely proportional to molecular weight and compound ring number.