ATTENUATION AND BIODEGRADATION OF CHLOROPHENOLS IN-GROUND WATER AT A FORMER WOOD TREATING FACILITY

This communication describes novel methods to measure site-specific sorption data, and to determine if biodegradation of pentachlorophenol (PCP) in complex technical-grade formulations occurs at industrial facilities. Ground-water slurry samples containing between 0.012 and 230 mg/l PCP were collected from a former wood treating site, the liquid and solid fractions separated, and both fractions analyzed for PCP using selective ion monitoring to determine sorption coefficients (K(d(PCP))). Although field sorption coefficients could not be represented by simple Freundlich and Langmuir isotherms, an empirical hyperbolic function (K(d(PCP)) 0.054 + 0.086/C(aq)) fit the isotherm (r > 0.99), demonstrating that for PCP > 10 mg/l, no measurable retardation occurred in the aquifer. Biodegradation of PCP in ground water was apparent when PCP concentrations were < 20 mg/l, while at higher concentrations, PCP in the technical-grade formulation appeared to break down less readily. The results imply that, at the plume periphery, PCP in the subsurface will be attenuated and degrade, while at higher concentrations (i.e., at the source), PCP is mobile, and more recalcitrant to degradation.