October 5, 1993

THE major flaw in the $150 million Biosphere 2 project has been discovered by a leading geochemist and his student, raising questions of whether the venture in the Arizona desert will be corrected in the interest of serious science or will be doomed to repeated cycles of failure in the years ahead. In theory, the experiment is to last 100 years. A mysterious decline in oxygen during the two-year trial run of the project endangered the lives of crew members and forced its leaders to inject huge amounts of oxygen, spoiling the idea of a self-contained ecosystem that was supposedly a way to learn about living in space.

Richard L. Scott's idea of fun is fixing up rundown hospitals, closing some institutions and seeking to please doctors. Riding a nationwide wave of health-care consolidations, the 40-year-old lawyer has gone to the top of the world's largest for-profit hospital empire in eight years of nonstop wheeling and dealing. His eight-year-old Columbia Healthcare Corporation has agreed to merge with the HCA-Hospital Corporation of America to create a 190-hospital colossus stretching across 26 states and two foreign countries. On Sept. 1, Columbia completed a merger with Galen Healthcare, the big chain of former Humana hospitals.

BECAUSE of the sheer immensity of the task, botanists have long been thwarted in their attempt to compile a full listing of North America's floral riches. But a start has at last been made with the publication this week of the first two volumes of a work that aims to describe all of the 20,000 wild plant species in the United States and Canada. The work, "Flora of North America North of Mexico," describes the startling inroads made by foreign invaders, which now comprise one-fifth to one-third of all North American plant species. Many of these "exotic" plants spread so easily that along with native weeds, which account for 5 to 10 percent of species, their physical extent is proportionally greater than their species numbers. And because exotics and native weeds include some of the showiest and most conspicuous species, their visual impact eclipses that of other plants in many parts of the region.

Companies Viacom said the Nynex Corporation had agreed to invest $1.2 billion in it, giving Viacom new ammunition for its $7.4 billion bid for Paramount Communications. [ Page D1. ] Behind the war between Viacom and QVC Network for Paramount lies the wisdom that bigger is better in the media business. But earlier media mergers have yet to demonstrate the magic of synergy. [ D1. ] The planned merger of Keycorp and the Society Corporation, which would create the country's 10th-largest banking company, was set in motion by a spirited horse in Wyoming. [ D1. ]

Four weeks before Election Day, the race between Mayor David N. Dinkins and Rudolph W. Giuliani remains a tossup. Fewer than half of voters trust either candidate to deal with New York City's problems and nearly half are concerned that each might make serious mistakes, according to the latest New York Times / WCBS-TV News poll. In a bitter rematch between two well-known contenders, the electorate is strikingly unenthusiastic about both. Just 38 percent of voters expressed a favorable opinion of the Democratic Mayor, while a scant 31 percent had a favorable view of his Republican-Liberal challenger. About as many voters viewed each candidate unfavorably as viewed him favorably.