Assessment of the bioremediation of crude oil spills on the Lebanese shoreline.

Abstract

With the planned oil and gas exploration activities off the coast of Lebanon, the risk of shoreline contamination with crude oil spills has become a major concern. This study aims at assessing the crude oil bioremediation potential of the Lebanese shoreline and the efficiency of bioremediation enhancement by biostimulation, during the dry and the wet seasons. Laboratory scale biodegradation experiments were conducted using crude oil-spiked sediments and seawater over a 42-day period. It was postulated that, since untreated raw sewage is discharged continuously along the shoreline of Lebanon, nitrogen and phosphorous nutrients may be found in the seawater at high enough concentrations to stimulate microbial activity without the need for additional nutrients enhancement. The experiments were conducted during the wet (18⁰C) and dry (28⁰C) seasons to account for temperature and nutrients variability during these periods. The biodegradability of oil constituents – namely alkanes and polycyclic aromatic hydrocarbons (PAHs), was monitored and quantified periodically using gas chromatography-mass spectrometry (GC-MS). Little to no enhancement to the overall biodegradation rates of alkanes and PAHs was observed under the biostimulation treatment in sediments at 18⁰C and 28⁰C. Significant enhancement in the biodegradation rates however was observed in seawater at both temperatures. Under both natural attenuation and biostimulation treatments, the increase in temperature increased the oil biodegradation rates in the sediment and seawater microcosms. The results obtained from this study would guide policy makers and spill responders in developing sound environmental planning for the bioremediation of potential crude oil spills on the Lebanese shoreline.