Assessment of summer trends of tropospheric radon isotopes in a coastal Antarctic station (Terra Nova Bay)

This work reports the first results of atmospheric radon measurements performed at the Italian Antarctic station located at Terra Nova Bay (74.69°S; 164.12°E) during summer campaigns of 1995-96, 1996-97 and 1997-98. Mean 222Rn concentrations was 0.51±0.43 Bq m-3(median = 0.37 Bq m-3), and ranged from 0.01 to 2.74 Bq m-3. On the average, these values were considered high, in comparison to results reported for other sites in Antarctica at equivalent latitudes. This could be explained by two causes: radon data for Terra Nova Bay were only for the summer period, when the ice-free area is at its maximum and thus the radon emission to the atmosphere; and by the larger ice-free area at Terra Nova Bay compared, for example, to measurements taken at another Antarctic site by the same technique (Ferraz station-62°05′S; 058°23.5′W). The mean 222Rn to 220Rn activitty ratio was 4.4±4.2, ranging between 0.1 and 45.3. The highest ratios indicated that some of observed surges of concentration of222Rn could be attributed to not local sources. Lower radon concentrations were observed during katabatic wind events. The diurnal radon variation followed the general trend observed for continental areas located at lower latitudes.