Degradation of PAHs by indigenous microbes in contaminated river sediment /

Abstract

Sediment from a polycyclic aromatic hydrocarbon (PAH) contaminated site on the Mahoning River was incubated for 0 and 4 days with the addition ofPAHs in 0,3,6, and 12 Ilg/ml concentrations. PAH concentrations, microbial activity, and viable heterotrophic counts were performed at Day 0 and Day 4. PAHs were extracted and analyzed using GC/MS. Samples with PAH concentrations of 0, 3, and 6 Ilg/ml decreased after incubating 4 days while samples with 12 Ilg/ml concentrations were found to inhibit degradation after incubating 4 days. Microbial activity, measured using 2-(p-iodophenyl)3( p-nitrophenyl)-5-phenyl tetrazolium chloride (INT) reduction, showed similar activity in all samples initially and a decrease in activity after 4 days. Viable heterotrophic counts were higher for Day 4 incubations suggesting that microorganisms in sediment were able to grow and reproduce, but eventually became carbon limited due to lowered activity measurements. Results suggest that microorganisms in sediment are able to degrade PAHs up to a 6 Ilg/m1 concentration, but may eventually become carbon limited.