Fate of Crude Oil in the Environment and Remediation of Oil Spills

Abstract

The world consumes approximately 5.1 billion tons of crude oil per year, with the United States and Saudi Arabia producing the largest shares [1]. Countries rely on various means for transporting crude oil [1, 2]. Large vessel/tankers transport oil at sea, while oil is transported inland via pipelines, railroads, trucks, and barges [2]. Unfortunately, some of the oil gets spilled into the ocean, freshwater bodies, and terrestrial ecosystems during its production, transportation, and use [3]. Usually, oil spills are caused by accidents involving tankers, barges, pipelines, refineries, drilling rigs, and storage facilities [3]. Small spills are frequent, but are handled by local responders. However, in the case of relatively large spills, known as spills of national significance, a national effort is needed to respond. Examples of large spills include the running aground of the Exxon Valdez in Alaska and the Deepwater Horizon blowout in the Gulf of Mexico. These spills triggered the application of the Oil Pollution Act of 1990 and ensuing regulations [4-9]. When an oil spill reaches the shoreline, efforts are taken to remove as much of the oil as possible using physical means, such as water flushing [3]. When the oil content within sediments becomes too low, physical removal becomes inefficient and/or can lead to further damage [3]. In this situation, oil biodegradation, that is the degradation of oil mediated by microorganisms, becomes an important process to consider [10]. Beaches are bioremediated by monitoring and enhancing the biodegradation of oil. Critically understanding and analyzing oil biodegradation and remediation techniques allows for a better response by decision-makers. This paper first addresses the general chemical composition of oils and then covers the different physical and natural processes that can remove crude oil from beaches, with a focus on bioremediation.