ROANOKE TIMES

                         Roanoke Times
                 Copyright (c) 1995, Landmark Communications, Inc.

DATE: THURSDAY, May 20, 1993                   TAG: 9305200230
SECTION: NATIONAL/INTERNATIONAL                    PAGE: A-13   EDITION: METRO 
SOURCE: 
DATELINE: NEW YORK                                LENGTH: Short


MT. PINATUBO ERUPTION LINKED TO `OZONE HOLE'

Scientists have found chemical evidence that the 1991 eruption of Mount Pinatubo contributed to a record "ozone hole" over Antarctica late last year.

The hole is an annual period of ozone depletion over the South Pole, which scientists blame on man-made, chlorine-bearing compounds.

A study in today's issue of the journal Nature suggests that liquid droplets of sulfuric acid and water from the volcano acted with the chlorine compounds to promote last year's ozone destruction.

Normally, ozone-destroying species of chlorine form over Antarctica in chemical reactions on the surface of icy particles found in polar stratospheric clouds. Those clouds occur at high altitudes at very cold temperatures.

One product of those reactions is chlorine dioxide. The new study found a dramatic buildup of chlorine dioxide in April and May 1992, when the air was too warm for the polar stratospheric clouds to form, the researchers wrote.

Apparently, the critical chemical reactions took place on the surface of the droplets from Mount Pinatubo, they said. The droplets were abundant over Antarctica when the chlorine dioxide was observed, they said.

In contrast, no chlorine dioxide buildup was found over Antarctica during March to May 1991, before the eruption in June 1991, researchers said. - Associated Press



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