Assessment of Summer Trends of Tropospheric Radon Isotopes in a Coastal Antarctic Station (Terra Nova Bay)

Abstract

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 ), and ranged from 0.01 to 2.74 Bq m À3 . 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 0 S; 058 23.5 0 W). The mean 222 Rn to 220 Rn activity ratio was 4.4 AE 4.2, ranging between 0.1 and 45.3. The highest ratios indicated that some of observed surges of concentration of 222 Rn 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.

Characterising terrestrial influences on Antarctic air masses using Radon-222 measurements at King George Island

“…Pereira, 1990;Pereira et al, 2004Pereira et al, , 2006Ui et al, 1998;Tositti et al, 2002), little information on seasonal cycles has been published. Pereira (1990) reports on two years of observations (1986-1987; excluding summers) at Ferraz Station, 30 km NE of KSG.…”

“…Local thoron levels can sometimes be significant at Antarctic stations (e.g. Tositti et al, 2002). We corrected the Mawson radon record by first removing a linear trend in the instrumental background signal and then shifting the net hourly counts such that the monthly third percentile value was not less than −2σ BG (see Sect.…”

“…In later publications, however, Pereira et al (2004Pereira et al ( , 2006 refer to Ferraz radonic storms in June and October of 1997 reaching concentrations of 1300-2900 mBq m −3 . Furthermore, in Table III of Tositti et al (2002), mean annual Ferraz radon concentrations of 160 ± 140 mBq m −3 and 156 ± 144 mBq m −3 are reported for 1997 and 1998, respectively, and in Table IV a longer-term annual mean value of 110 mBq m −3 is stated. These results are an order of magnitude higher than the autumn-through-spring means of Pereira (1990), which may therefore be erroneous.…”

“…Reported radonic storms reached concentrations of 1200 mBq m −3 , comparable in magnitude to the KSG events, despite the nearest continental land fetch for Syowa being much more distant: 3800 km to Africa and 5000 km to South America. Tositti et al (2002) presented three summers of direct radon observations at Terra Nova Bay (74.69 • S, 164.12 • E: see Fig. 1).…”

“…Taguchi et al (2002) Indirect (by progeny) 1-2 hourly Dumont d 'Urville, 1967-1981. Tositti et al (2002 Direct (electrostatic deposition) Hourly Terra Nova Bay, Ferraz Station;3 summers, 19953 summers, -19983 summers, .…”