Survey on Physical, Chemical and Microbiological Characteristics of PAH-Contaminated Soils in Iran

Polycyclic aromatic hydrocarbons (PAHs) are one of the important groups of organic micro pollutants (Xenobiotics) due to their widespread distribution and low degradability in the environment (atmosphere, water and soil). Some PAHs exhibit carcinogenic and/or mutagenic properties and are listed by the United States Environmental Protection Agency (USEPA) and European Commission (EC) as priority pollutants. In this research three petroleum contaminated sites in Iran were selected in order to separate and classify PAH-degrading microorganisms. Samples were analysed for: soil physico-chemical properties, soil particle size distribution, Ultrasonic extraction of PAH (phenanthrene) and microbial analysis. Ultrasonic extraction method was shown to be a reliable procedure to extract a wide range of PAH concentrations from different soils, e.g. clay, silt, and clay-silt mixtures. Results showed that the extraction rate of phenanthreen in mentioned different soils was in the range of 85 – 100 percent. Results showed that two of three selected sites were contaminated with phenanthrene in the range of 10 – 100 mg/kg of soil, and had a reasonable population of PAH-degrading bacteria, which were enable to adaptate and degradate a concentration range of phenanthrene between 10 and 1000 mg/kg of soil. According to results, it can conclude that, the bioremediation of contaminated soils in Iran may be considered as a feasible practice.