|Exxon Valdez Oil Spill
In March 1989, the Exxon Valdez went aground on Bligh Reef, Alaska. It’s punctured hull emptied between 40 and 136 million Li of crude oil into Prince William Sound. The spill’s severity was compounded by the heavy, persistent properties of North Slope crude, heavy storm conditions and a three-day lag in Exxon’s response.
Prior to the Exxon Valdez spill, it was assumed that impacts to species from oil spills were almost exclusively from acute mortality.ii The Exxon spill demonstrated that unexpected persistence of toxic, subsurface oil could hinder species recovery for decades. Because of vast amount of research completed after the spill, there has been a shift in oil toxicity paradigms in relation to impacts on fish and other aquatic animals.
The immediate impacts included 2000 km of oiled shorelineiii, deaths of 250,000 seabirds, up to 2800 sea otters, unknown numbers of porpoises and dolphins, countless intertidal shellfish and smothered kelp and eel grass habitats over a 3400 sq. km area. In time, other impacts surfaced; 22 killer whales died (devastating two pods), the herring population has not recovered (though possibly confounded by other factors); subsistence gathering of intertidal resources has only partially returned; and more than 80,000 L of oil still remains buried just beneath the surface, much of it nearly as toxic as the first few weeks after the spill.iv As many as 3,000 clean-up workers have now suffered from spill related illnesses.v Estimates of economic, social, and ecological damages are $9.5 billion, of which Exxon paid $3.4 billion with US taxpayers covering the shortfall.vi
Two and a half years after the Exxon Valdez spill (1991) an estimated 13 percent of the oil remained in sub-tidal sediments, and two percent remained in intertidal (shorezone) areas, mostly as highly weathered residuals.vii By 2007, roughly 80,000 L of oil still remained in subsurface sediments and was degrading at 0-4 percent per year.viii Some oil pockets were still relatively unchanged since the spill.ix At this rate, the remaining oil will take decades and possibly centuries to disappear entirely.
Although researchers initially thought that the weathered oil was inert, they now believe otherwise.x Weathered oil (which concentrates PAHs) is more toxic on a weight per weight basis than non-weathered oil.xi There are concerns that weathered oil will remain toxic to some species for decades.xii
Exxon’s estimate is 40 million litres. Others are higher i.e., AK Department of Law. 1991. Files on ‘ACE’ investigation, 1989–1991. ARLIS, Anchorage
ii Peterson et al. 2003.
iii 2000 km estimate from Peterson et al. 2003
iv Exxon Valdez Oil Spill Trustees Council. 2009. 2009 Status Report.
v Based on the findings from a Yale graduate study in 2003 that Dr. Riki Ott relayed to US Congress according to Anchorage Daily News June 29, 2010. According to ProPublica (Marian Wang, June 4 2010) Exxon's internal medical reports revealed that an unspecified number of the 11,000 Exxon Valdez workers made 5,600 clinic visits for upper respiratory illnesses in the summer of 1989.
vi Vanem et al. 2007
vii Wolfe et al. 2008.
viii Short et al. 2007.
ix Short et al. 2007.
xBiologically inert; meaning it wouldn’t affect the health of biological organisms.
xi Carls and Meador 2009.
xii Esler et al. 2010.