Bacteria fed for eons by hydrocarbons dripping from the rain forests of southeast Alaska may be the salvation of some beaches coated with crude oil from the Exxon Valdez.
Scientists with the Environmental Protection Agency and Exxon say that if these or other naturally occuring bacteria are fortified with fertilizer, they can urge them into an oil eating frenzy.
The idea seems to be working.
At Snug Harbor on Knight Island in Prince William Sound, EPAfed bacteria have gone at the North Slope oil like a bunch of singlecell PacMan characters. Their success in consuming oil has offered the first hope of getting any of Alaska's oiled beaches truly clean this summer.
Experiments done on oil left stranded on the beaches at Snug Harbor have cleansed portions of those beaches, said Chuck Costa, program manager for the EPA.
Experimental plots that were treated with a nitrogenphosphorous fertilizer stand out in marked contrast to the lightly to moderately oiled beach that surrounds them, said Parmely "Hap" Prichard, the EPA's scientific coordinator for the project.
Videotapes of the plots show onceoily rocks glowing white in the midst of a glistening, oily beach.
"There is an observable difference," Costa said. "There is a dramatic difference, and that's what caught the eyes of a lot of people.
"Within two weeks, it really cleaned the oil off the rock," he said. "It looked like someone brought in new rock."
Most other cleaning methods now being used including beachsterilizing sprays of hot water leave rocks coated with an even layer of oil that causes water to bead. Water doesn't bead on the bacteria cleansed rocks, Costa said.
Closer examinations only reveal more encouraging news. Bacteria populations on the fertilized rocks have mushroomed, and bacteria appear to be working themselves down a foot deep into gravel and cobble beaches to get at oil.
Prichard said he has been surprised by the effectiveness of the bacteria. He didn't expect to find so many oil hungry microbes in the Sound. When microbiologists and other scientists first met in April to discuss bacteriological warfare against the 11milliongallon Exxon spill, they didn't know what to expect in Alaska's waters.
They didn't know if there would be any oileating bacteria available, although these microorganisms are common in most marine environments.
Scientists worried that even if Alaska had oileating bacteria, it might take a long time for sufficient populations to become North Slope crude eaters. Many sorts of bacteria have the ability to become oil eaters, but making the shift from eating other complex organic molecules to eating hydrocarbons can take considerable time.
But Alaska, as it turned out, had a treasure chest of hydrocarbon munchers.
Scientists Don Button of the Institute of Marine Science at the University of Alaska Fairbanks and Ron Atlas of the University of Louisville, in Kentucky, said the most probable reason is a regular diet of naturally occurring hydrocarbons, most notably terpenes.
Terpenes are the chemicals removed from evergreen trees to make turpentine. Conifers regularly release them into the air. Terpene emissions are what cause the haze over some mountain forests in warm weather, Button said.
The chemical is among the kinds of volatile, organic hydrocarbons Georgia Tech scientists have implicated in air pollution problems in Atlanta.
Computer models and other research there have concluded the city's trees emit more hydrocarbons than automobiles, factories and other manmade sources, according to Dr. William L. Chameides, a Tech geophysicist. He has suggested that on a typical summer day in the southern city the trees emit nearly 11|2 times more hydrocarbons than manmade sources.
No one knows the volume of hydrocarbons emitted from the forests of southeast Alaska, but Button said the evergreens there obviously pump a vast supply of terpenes into the environment. He first detected these hydrocarbons while studying bacteria in Port Valdez years ago.
The sheer volume of hydrocarboneating bacteria discovered there, and later in Resurrection Bay, led to a search for a source of natural hydrocarbons. Button traced the food supply back to the terpenes draining off the vast forests of Southeast.
Because of that region's wet climate, he said, few terpenes evaporate into the air. Instead, they are washed off the trees by rain and enter the ocean.
The terpenes slip into the Alaska Coast Jet, a swift current moving northward from southeast Alaska toward the mouth of Cook Inlet, and move north. Along the way, they provide food for zillions of bacteria that provide the base for a huge food chain.
The bacteria attack the hydrocarbons to get at the carbon tied up in their complex molecules. In the process of consuming that carbon, the bacteria break down toxic hydrocarbon molecules into water and carbon dioxide.
Cages of mussels located along the beaches of Snug Harbor, for instance, indicate that process is happening to the oil on the beaches there, Atlas said. Mussels are extremely efficient at trapping hydrocarbons, but those along the fertilized beaches have stayed clean, Costa said.
Meanwhile, bacteria populations on those beaches have reached levels 100 times higher than on nonfertilized beaches, Atlas said. Atlas is employed as a consultant for Exxon. He has been working with Pritchard at Snug Harbor. He is a former consultant to the EPA and National Oceanic and Atmospheric Administration and is well respected in his field. He has studied pollution in Alaska waters since the early 1970s.
Atlas and Button said bacteria almost immediately began attacking the 11 million gallons of crude that leaked from Exxon Valdez on March 24. The scientists believe these bacteria simply switched from a diet of terpenes to the new, larger source of carbon.
"There's an awful lot of bacteria out there," Button said. "There's almost a million per milliliter."
These bacteria will attack the oil even without man's help, but the EPA thinks they can do a lot better with assistance.
"They were there even before we applied the fertilizer," Costa said. "We've just kind of juiced it up a little bit."
Bacteria gorging themselves on hydrocarbons run short of the phosphorous and nitrogen needed to synthesize lifegiving proteins, Prichard said.
These bacteria are something like growing children on a diet high in nutrition but low in vitamins. They need to be given the vitamins to help them grow big and strong.
Enter the fertilizer. The EPA is so enthusiastic about its possibilities that Exxon has been given permission to begin fertilizing miles of beach with two different kinds of fertilizer.
One is a longlasting, watersoluble fertilizer that sinks down into gravels and cobbles to help bacteria there. The other bonds to surface oil.
"We recommended to Exxon that they use both," Costa said.
The only major restriction on the use of these fertilizers is a ban on spraying in protected bays. Adding nitrogen and phosphorous nutrients to poorly flushed bays could lead to algae blooms that would choke off other marine life, said Erich Bretthauer, acting assistant administrator for research and development at EPA.
That is the only potential environmental problem so far associated with fertilization, he added. Bretthauer has directed Exxon to limit its fertilizer to beaches that are regularly flushed by tides or surf, although he said the company can try the technique in questionable areas if it is willing to maintain ecological monitoring programs there to watch for signs of environmental damage.
"If monitoring results demonstrate any adverse environmental effect, the application of the fertilizer should be terminated immediately," Bretthauer warned.
Scientists don't expect significant problems.
"We have a well flushed Sound out there, so we really don't expect to see any changes," Coast said.
There are, however, some lingering questions about whether the fertilization process will work as well on other beaches as it has at Snug Harbor.
"It's an extremely conditioned phenomenon," Button said. "It isn't just a single question. It's an awfully complicated issue."
Biodegradation is dependent on more than just available food and fertilizer. It also requires agitation to make sure the bacteria, the fertilizer and the food are thoroughly mixed.
Where bacteria is used commercially, such as in the making of beer, vats are stirred. In Alaska waters, scientists are counting on winds and tides to do the same. That has worked in Snug Harbor.
Whether other beaches have enough agitation remains to be seen. Bacteria can't break down the oil unless they can get at it. Atlas has suggested rototilling old beach oil in some places to expose it to bacteriological degradation. Coast Gaurd Vice Adm. Clyde Robbins, the federal onscene coordinator for the oil spill, has also raised that possibility.
Both men also agree that while bacteria can help, some types of oil thick oil, foamy oil, tar balls or asphalt are immune to carbonhungry microorganisms.
"Some kinds of oil will resist all degradation, and there's some residue," Atlas said.
Weathered oil that has hardened to asphalt could persist for decades. Is that a concern?
"Obviously, there is an aesthetics question there, but otherwise I don't know what it means. If it's hard, it's like a rock," he said, comparing the asphalt to peat or coal deposits now found on beaches in various parts of the state.
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