Distribution and biodegradation of polycyclic aromatic hydrocarbons in contaminated sites of Hisar (India)

Abstract

Fifty-two soil samples were collected from various location of the Hisar city. These samples were analysed for six polycyclic aromatic hydrocarbons (naphthalene, acenaphthene, phenanthrene, anthracene, fluoranthene, and pyrene). Total mean concentration of six PAHs varied from 51.79 to 148.82 mg kg⁻¹ dry weight of the soil, PAH concentration was higher in soil samples from local auto market while lower concentration was recorded in agricultural soil. Effect of pH (5.0 to 9.0), temperature (20º to 40ºC), and concentration of PAHs (5 to 20 mg kg⁻¹) on biodegradation were optimized. Biodegradation of phenanthrene (3-ring) and pyrene (4-ring) was evaluated using two acclimatized microbial strains Pseudomonas putida and Pseudomonas paucimobilis. Biodegradation was maximum in sterilized artificial spiked soil with phenanthrene (5 mg kg⁻¹) and pyrene (5 mg kg⁻¹) at pH 7.0 and at 30ºC (optimized conditions) than the native unsterilized contaminated soil (without optimized conditions) in 42 days of incubation period with Pseudomonas putida and Pseudomonas paucimobilis. Phenanthrene was completely disappeared after 28 days with P. putida and after 35 days with P. paucimobilis. Whereas, pyrene was disappeared up to 97.40 % with P. putida and 95.5% with P. paucimobilis after 42 days incubation period at optimum conditions. Under unoptimized conditions, disappearance of phenanthrene was 65.89% with P. putida and 57.81% with P. paucimobilis after 42 days, whereas the % disappearance of pyrene was 59.80% with P. putida and 52.07% with P. paucimobilis.