CONTINUOUS DOSIMETRY OF THE BIOLOGICALLY HARMFUL UV-RADIATION IN ANTARCTICA WITH THE BIOFILM TECHNIQUE

For the first time, a continuous biological dosimetry experiment for c ytotoxic solar UV-radiation has been performed in Antarctica. The biol ogically harmful UV-radiation on the ground was measured at the German Antarctic Georg von Neumayer Station (70-degrees-37' S, 80-degrees-22 ' W) from December 1990 to March 1992 using the biofilm technique. The UV-sensitive targets were dried spores of Bacillus subtilis which wer e immobilized on the film surface. The UV-induced inhibition of biolog ical activity, determined photometrically from the protein synthesized after incubation and staining, was taken as a measure for the absorbe d UV-dose. Films were exposed in horizontal position for time interval s ranging from 4 days during summer up to 51 and 41 days before and af ter the polar night respectively. The use of different cut-off filters allowed the calculation of the biologically effective UVA, UVB and th e complete UV-radiation (UVA+B). The data were compared with the globa l radiation and the ozone column thickness indicating an increase of b iologically harmful UVB radiation during austral spring at reduced ozo ne concentrations yielding a radiation amplification factor (RAF) of 1 .4, whereas for the total UV(A+B) range the RAF amounted to 0.3.