New tips on coal from the murky swamp
Just ahead of our canoe a white ibis stands on some floating peat and probes with its long, curving beak for its next meal. Around the bend, an alligator sleeps atop some muck. Cypress trees, their hoop skirt-like bases half-submerged in the reflective, still, brown water, line the quite channel.
This is part of the face Okefenokee, the nation's largest fresh water swamp, reveals to the canoeist or boater who ventures beyond the boardwalks.
But the "land of trembling earth," as the Indians called the swamp (because the peat is unstable in the water), has a deeper character -- one revealing secrets that could make coal mining more efficient.
For years researchers have assumed that peat -- the decayed plant matter from which coal is formed over millions of years -- would unlock secrets of the nature of coal. Now some of the continuing study of peat swamps, especially the Okefenokee, is providing data applicable to existing coalfields.
By studying the geological formations of the Okefenokee and other coastal swamps, Arthur D. Cohen, a University of South Carolina geologist, has set up a model for predicting the direction, width, and thickness of coal seams in similar formations.
And Daniel Casagrande, an organic geochemist now working for Exxon in Houston , has developed models to predict the sulfur content of prospective coalfields. He bases his models on data from the Okefenokee and the Florida Everglades.
"Given enough time, the Okefenokee would probably end up as low-sulfur coal," he says. By comparing samples of vegetation dug up from the swamps with what is found in existing coalfields, one can better estimate which coal deposits are likely to have a low- sulfur content (and thus be less environmentally objectionable), he said.
But predicting metal and ash content of coalfields, based on data from the swamps, is still "5 to 10 years" and away, said Dr. Casagrande.
"The work is slow and tedious," he says. "Every day we're generating new information."
The data, he says, could eventually amount to millions of dollars in savings in mining costs. Exxon, which has coalfields in several states, was interested enough to hire him away from a university.
Already, a graduate student working under Dr. Cohen has saved a West Virginia coal company (which he declined to name) considerable cost.
The company had just opened a mine in a formation geologically similar to a coastal swamp. In such swamps, the coal eventually formed would parallel the old beach features. With this data in hand, the company -- which had missed the main part of the coal seam -- changed directions and hit it, said Dr. Cohen.
Coal mining engineers are showing increasing interest in swamp-derived data on peat, he says.
University of Georgia researchers are studying the ecology of the Okefenokee. Among other things, they want to know the effect on the swamp of timber companies draining some nearby land.
Okefenokee gets most of its water from rainfall in and around the swamp and losses most of it due to evaporation and transpiration.
Wildlife refuge manager John R. Eadie welcomes the research as a way to know more about how to maintain the swamp in its natural condition and "begin to know what Okefenokee is all about."
Nearly 270,000 people, including some 4,200 overnight canoeists, visited the swamp last year. On one- to six-day trips along watery trails through the prairie and forests, canoeists sleep on platforms or islands.
Visitors information is available from the Okefenokee National Wildlife Refuge; Box 117; Waycross, Ga. 3 1501.