Bioremediation of marine oil spills: when and when not – theExxon Valdezexperience

Abstract

SummaryIn this article we consider what we have learned from the Exxon Valdez oil spill (EVOS) in terms of when bioremediation should be considered and what it can accomplish. We present data on the state of oiling of Prince William Sound shorelines 18 years after the spill, including the concentration and composition of subsurface oil residues (SSOR) sampled by systematic shoreline surveys conducted between 2002 and 2007. Over this period, 346 sediment samples were analysed by GC‐MS and extents of hydrocarbon depletion were quantified. In 2007 alone, 744 sediment samples were collected and extracted, and 222 were analysed. Most sediment samples from sites that were heavily oiled by the spill and physically cleaned and bioremediated between 1989 and 1991 show no remaining SSOR. Where SSOR does remain, it is for the most part highly weathered, with 82% of 2007 samples indicating depletion of total polycyclic aromatic hydrocarbon (Total PAH) of > 70% relative to EVOS oil. This SSOR is sequestered in patchy deposits under boulder/cobble armour, generally in the mid‐to‐upper intertidal zone. The relatively high nutrient concentrations measured at these sites, the patchy distribution and the weathering state of the SSOR suggest that it is in a form and location where bioremediation likely would be ineffective at increasing the rate of hydrocarbon removal.

Marine Oil-Degrading Microorganisms and Biodegradation Process of Petroleum Hydrocarbon in Marine Environments: A Review

“…Different microorganisms have different tendencies to attack various types of petroleum hydrocarbons. Generally, the susceptibilities of hydrocarbons that can be degraded by microorganisms are as follows: n-alkane [branched alkane [small aromatics hydrocarbon[polycyclic aromatic hydrocarbon (PAHs) [7,20]. Temperature is another important parameter that determines the biodegradation rate of hydrocarbons by affecting the metabolic activity and the diversity of the microorganisms [57].…”

Hydrocarbon biodegradation by Arctic sea-ice and sub-ice microbial communities during microcosm experiments, Northwest Passage (Nunavut, Canada)

“…Sub-ice seawater bacteria depleted almost all the resolvable alkanes (C 9 to C 40 , pristane and phytane; sensu Atlas & Bragg 2009) within 11 days at -1.7°C (Fig. 5B).…”

Aerobic Degradation of Petroleum Components by Microbial Consortia

“…Numerous works have been done on the use of fungi for biodegradation of petroleum hydrocarbons [38,44,78,116,145]. Most filamentous fungi is unable to totally mineralize aromatic hydrocarbons; but only transform them into indirect products of lowered toxicity and increased susceptibility to decomposition with the use of bactetria.…”

“…Although many of these compounds can be relatively easily degraded under soil and fresh water environments [3,12] and low salinity marine habitats [13][14][15][16]. Biodegradation rates have been shown to be highest for the saturates, followed by the light aromatics, with high-molecular-weight PAHs and polar compounds (resins and asphaltenes) exhibiting extremely low rates of degradation or may not be degraded at all [38][39][40].…”