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National Geographic : 1993 May
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EarthAlmanac More Ships May Crowd Glacier Bay's Whales The sight of a humpback whale rewarded many of the record 216,000 visitors to Alaska's Glacier Bay National Park last year. The vast majority came by cruise ship, and cruise operators now are seeking from the National Park Ser vice a 72 percent jump in the number of vessel visits allowed each season, from 107 to 184. "The noise from the ships and its effect on the whales and Steller sea lions is a concern," says Kevin Apgar of the Park Service. "But we also worry about air pollution from ship stacks. At a glacier's face there is often an air inver sion, and pollution can linger for hours. It detracts from a visitor's pristine experience." The Park Service is also weighing restrictions on commercial fishing and a ban on the subsistence nets of Tlingit Indians, who have caught sockeye salmon in Glacier Bay for centuries. Commercial fishing, an old tradition there, has long been tolerated, contrary to regulations. But a lawsuit by conservationists may halt all such fishing in the park. ANNIE GRIFFITHSBELT AL GIDDINGS, IMAGES UNLIMITED Are British Cavers at Risk From Radon Gas? T he joys of "potholing"-as Britons call messing about in caves like Gaping Gill Hole may mean hazardous exposure to radon for cavers who spend a great deal of time at their hobby. Radon, a gas created by the radioactive decay of radium, seeps naturally from rocks and soil and has been found to accumulate in basements. Long-term exposure to high concen trations can cause lung cancer. A year-long survey of 40 British caves by University of Huddersfield geographers found an average radon level nearly 15 times higher than the maximum safe exposure recom mended for homes by the British government. Ventilating fans have been installed in some caverns to disperse radon, and potholers are warned by caving associations to limit their time in certain caves. In the U. S ., Jeanne Gurnee, president of the National Speleolog ical Society, says, "We have con ducted radon studies, as has the National Park Service. The studies have found no problem in caves with natural ventilation, unless a person spends extended periods of time down under." NationalGeographic, May 1993 I
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