Cleaning Up after the Exxon Valdez Was A Mistake Through many hours of research I have determined that the spill cleaning techniques used to clean the Prince William Sound area of Alaska did more harm than leaving the oil where it was. The Alaskan oil spill has become the most studied and managed event of its kind. Although there is not much that can be done about the marine life that came into direct contact with the crude oil, the geologic effects that the oil introduced into the area should have been left to nature to repair. To understand the effects of the oil to the area, it is best that you know a little bit about the oil itself.
There are many types of crude oil, but in general they contain hundreds, even thousands of different compounds. Some are straight-chain hydrocarbons with carbon numbers ranging from 4 or 5 to 35 or more. Other hydrocarbons have branched chains with a wide range of carbon numbers. Aromatic compounds such as benzene, toluene, and polynuclear hydrocarbons are substantially present. Other constituents include waxes and complex, high molecular weight asphaltenes. (Abelson) All of these substances and more are present in Prudhoe Bay crude oil. When ingested, most of the compounds are nontoxic. Notable exceptions are some of the aromatic compounds, including benzene and toluene.
After a crude oil is spilled in a marine environment, many processes follow.
Typical crude has a density of about 0.85, more or less, and this factor combined with winds, wave action, and currents leads to spreading, which is very rapid during the first 24 hours. During that period most of the components having boiling points below 200[deg.]C volatilize. As a result some of the toxic chemicals such as benzene are removed. (The composition of the floating mixture is further changed immediately and later by photooxidation, biodegradation, dispersion, and dissolution. About a day after the spill, depending on temperature and wave action, an emulsification of oil and sea water occurs, leading to formation of a highly viscous material that contains about 70% water.
This material is very sticky, and it adheres to almost all objects that it encounters, including birds and sea otters. Abelson) There has been one report of a minor fish kill in Prince William Sound. Observations at other oil spills indicate that dispersed oil is not toxic to zooplankton when ingested. It is eliminated in the feces. In general, oil chemicals are not concentrated in the food chain.
There are many ways that nature fights oil in the environment, when it gets put where its not suppose to be. After all crude oil is a natural part of our environment. In one study designed to simulate the effects of waves and tides, contact with seawater gave the black, sticky oil "the fluffy appearance of a flocculated emulsion" that no longer strongly adheres well to sediment, Bragg reports. Seawater made up about 80 percent of these cloud-like aggregates. The rest consisted largely of mineral grains stably bound to oil droplets 1 to 10 microns in diameter.
(Beached) For instance, the Exxon scientists found that flocculation can increase the area of the oil-water interface -- sometimes by up to 1,000 times. This increases the likelihood that the more toxic, water-soluble aromatic chemicals will leach from the oil, Bragg says. Moreover, it expands the area available for hydrocarbonhungry bacteria to latch on to, thereby facilitating the oil's breakdown. Indeed, water taken from oiled beach sediment revealed that active bacteria usually make up part of any naturally produced oil-clay floc.
Flocculation also helps explain another formerly puzzling observation: the relatively rapid disappearance of oil from even quiet, sheltered bays. Most researchers expected oil to persist in these areas, where abrading waves and sediment movement seldom occur, even during storms. But experiments by Bragg and his co-workers showed that waves too weak to move sediment sands could still drive the flocculation-fostered removal of oil, initially at rates of 3 percent per hour. Bragg says it now appears that every ebb tide may remove some oil - even after heavy weathering has rendered oil tarry and very insoluble in water.
The unusually high levels of "mineral fines" -- clay "flours" produced by local glaciers -- along the southern Alaskan shoreline contributed to the unusually efficient emulsification of beached Valdez oil, the Exxon studies indicate. (Beached) They also suggest that adding such flours to shores with low clay contents might augment the natural cleanup of oil spills in the future.
The Alaska Current enters the Sound on the east and exits on the west. This flow has protected some of the Sound from major contamination and has carried part of the spill out of the Sound. As a result of various physical, biological, and chemical processes, the inventory of oil in Prince William Sound (originally 10 million gallons) dropped about 70% during the first 4 weeks after the spill. The U.S.
Forest Service, one agency active at the site, quotes an Exxon estimate as follows: evaporated, 35%; recovered, 17%; burned, 8%; biodegraded, 5%; dispersed, 5%. The total in the form of oil slicks on Prince William Sound amounted to 10% of the original spill; that on the shoreline, 18%. A large fleet of vessels was mopping up the slicks, and in good weather was capturing about 120,000 gallons a day.
Previous experience has shown that once the slicks become thin (some micrometers) they are fairly rapidly destroyed by photooxidation and microbial action. (Abelson) One of the main cosmetic problems was the shoreline. The shorelines were blackened by the first 24-hours of the spill. To the clean up crews this was more of a public relations problem than a geologic problem since the news media made a big deal of it. This outraged the public and the first thing that the clean up crews wanted to do was clean it and clean it fast. They made a big mistake by using high-pressure hot water cleaners.
The frequently used high-pressure, hot water washing also "annihilates a lot of marine life that otherwise survive the spill," observes Alan J. Mearns of NOAA's ecological recovery monitoring program in Seattle. Rockweed, a brown alga, proved its most prominent victim. Formerly constituting up to 90 percent of the intertidal plant mass in some areas of Prince William Sound, it virtually disappeared in many areas subjected to hot water, scientists reported. And especially in higher tidal zones, rockweed's recovery remains slow. (Raloff)
The National Oceanic and Atmospheric Administration (NOAA) announced that, contrary to the best advice then available, washing the oil off 400 miles of beach with powerful streams of hot seawater--the first time this has been used as the primary cleanup mode for a spill--was more destructive than leaving the oil where it was. In terms of the abundance and diversity of life, oiled beaches that were left untreated are now similar in most instances to sites where no oil had come ashore, say NOAA's chief scientist, marine biologist Sylvia E
arle. Treated beaches are clearly in the worst shape.(Kerr) In conclusion there will most likely be no long-term effects of the oil spill. The efforts to clean it will add to the time of recovery, but Mother Nature will catch up and before to long you will not be able to tell that an oil spill even occurred, both cosmetically and ecologically. The money used to clean the spill was mostly for the public's approval.
They cleaned for the press and the media. Pressure washing only killed the organisms and plants on the shorelines. Sylvia Earle says: "Sometimes the best, and ironically the most difficult, thing to do in the face of an ecological disaster is to do nothing." References 1. Abelson, Philip H., Oil Spills, American Association for the Advancement of Science, May 12,1989 v244 n4905 p629(1).
2. Kerr, Richard A., A lesson learned, again, at Valdez., American Association for the Advancement of Science, April 19, 1991 v252 n5004 p371(1).
3. Beached Valdez oil fled in floc., Science News, May 8, 1993 v143 n19 p302(1) 4. Raloff, Janet, Valdez spill leaves lasting oil impacts., Science News, Feb 13, 1993 v143 n7 p102(2)