NAPHTHALENE MINERALIZATION COUPLED TO SULFATE REDUCTION IN AQUIFER-DERIVED ENRICHMENTS

Naphthalene was microbially transformed in sulfate-reducing laboratory microcosms established under strictly anaerobic conditions using sedi ment from two sulfate-rich, coal tar-contaminated aquifers and enriche d over a 3-year period. As much as 66% of [C-14]naphthalene was minera lized to CO2 over 13 days. Addition of sodium molybdate inhibited sulf idogenesis and resulted in a 44% reduction in total [C-14]naphthalene mineralized. Methane was never detected in active naphthalene-degradin g microcosms, and formation of sulfide during naphthalene degradation was confirmed using a (SO42-)-S-35 radiotracer technique. GC/MS analys es of stabilized naphthalene-degrading consortia indicated the formati on of naphthalenol as a potential metabolic intermediate. These result s demonstrate that naphthalene oxidation may be coupled to sulfate red uction in aquifer-derived sediments.