Source Apportionment of Polycyclic Aromatic Hydrocarbons (PAHs) in a Tropical Estuarine Epipelic Sediment and Its Associated Bacterial Degrading Potentials
Nsikak A. Abraham *
Department of Microbiology, University of Uyo, Uyo, Nigeria and International Centre for Energy and Environmental Sustainability Research (ICEESR), University of Uyo, Uyo, Nigeria.
Nnanake-Abasi O. Offiong
International Centre for Energy and Environmental Sustainability Research (ICEESR), University of Uyo, Uyo, Nigeria and Department of Chemistry, University of Uyo, Uyo, Nigeria.
Owen P. Ukafia
Department of Chemistry, University of Uyo, Uyo, Nigeria and Department of Science Education, University of Calabar, Calabar, Nigeria.
Patrick E. Akpan
Department of Science and Technology, Akwa Ibom State Polytechnic, Ikot Osurua, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
The present study was designed to evaluate the distribution and sources of polycyclic aromatic hydrocarbons (PAHs) and the degradation potentials of bacteria associated with the Iko River estuarial epipelic sediment using standard analytical and microbiological techniques. The results of the analysis revealed that the mudflat of the ecosystem contained varying levels of PAHs with lower molecular weight (2-3 rings), with concentrations ranging from 4.9 – 5.2 mg/kg. The levels of 4-ringed, 5- ringed and 6-ringed PAHs ranged from 1.30 to 1.44, 2.14 – 2.47 and 0.20 – 1.53 mg/kg, respectively. The molecular diagnostic ratios of relevant PAH congeners revealed that the ecosystem is contaminated with PAH from multiple (petrogenic and/or pyrogenic) sources. Among the bacterial strains isolated from the sediment samples, Pseudomonas aeruginosa, Bacillus subtilis and Micrococcus luteus were found to possess strong PAHs degrading capabilities. The isolation of bacteria with PAH degradability from the mudflat is an indication that the ecosystems have the capability to recover through natural attenuation over time.
Keywords: Bacteria, degradation, PAHs, source apportionment.