LONDON, July 26 (Xinhua) -- British scientists have discovered large quantities of ozone-depleting chemicals in the Antarctic atmosphere.

    Researchers from the University of Leeds, the University of East Anglia, and the British Antarctic Survey carried out an 18-month study of the make-up of the lowest part of the earth's atmosphere on the Brunt Ice Shelf, about 20 kilometers from the Weddell Sea, and found high concentrations of halogens -- bromine and iodine oxides -- which persist throughout the period when there is sunlight in Antarctica (August through May), according to a report Thursday on the science news website of Alpha-Galileo.

    The study was carried out in a new atmospheric observatory at Halley Station, operated by the British Antarctic Survey. Using high-tech measuring equipment, the scientists projected a beam of light across the ice shelf, analyzed the spectrum of the reflected light and measured chemical levels.

    The scientists said the source of the halogens is natural -- sea-salt in the case of bromine, and in the case of iodine, almost certainly bright orange algae that coat the underside of the sea ice around the continent.

    Halogens in the lowest part of the atmosphere have important impacts on ozone depletion, the ability of the atmosphere to remove potentially harmful compounds, and aerosol formation, John Plane, professor of atmospheric chemistry at the University of Leeds, said.

    The halogens cause a substantial depletion in ozone above the ice surface, affecting the so-called oxidizing capacity of the atmosphere, its ability to "clean itself" by removing certain often man-made chemical compounds.

    The iodine oxides that have not been detected in the Arctic also form tiny particles (a few nanometers in size), which can grow to form ice clouds, with a consequent impact on the local climate, according to the scientists who now plan to carry out further research to assess what impact this may be having on the local environment.