Airborne radioactivity in Antarctica

Abstract

The radioactive aerosol content of the surface air in Antarctica has been measured continuously since 1956, first at Little America station and later at the South Pole station. On‐site measurements were made daily of the radioactivity due to bomb‐produced fission products and to naturally occurring radionuclides of the radon and thoron series. Later, composite samples covering 3‐month periods were subjected to radiochemical analysis for such long‐lived radionuclides as Sr90, Cs137, Ce144, Pm147, and Pb210. The natural radioactivity was lower in Antarctica than has been observed at any other geographical location, as might be expected from, the small area of exposed land surface in the vicinity. Fission‐product concentrations, however, often exceeded those found in the southernmost part of South America and exhibited more well‐defined seasonal variations, with maximums in the antarctic summer.

Radionuclides in the south pole atmosphere

“…This also indicates that the collection efficiency of the Whatman 541 filter material for the long-lived radionuclides must be similar to that of the Microsorban polystyrene filter used in the HASL program, which is close to 100%[Lockhart et al, 1964]. From several investigations[Lockhart, 1960;Lockhart et al, 1966;Aldaz, 1967;Feely et al, 1977] it is well established that fission product concentrations in ground level air at the south pole show a yearly oscillation and exhibit maxima in the austral summer, when greatest downward mixing of stratospheric air occurs. For the ?Be surface air concentration a oscillation similar to that for the fission products appears to exist[Feely et al, 1977].…”

“…The •'•øPb HASL data for the south pole and for Puma Arenas (53ø08'S, 60ø36'W) were compared. in the case of a tropospheric path the surface air concentration of •'•øPb at Punta Arenas should exceed that at the south pole, whereas the opposite should hold for a stratospheric pathway [Lockhart et al, 1966]. From the HASL data it appears that the •'•øPb levels at the south pole were higher than at Punta Arenas during the austral summer but were lower during the austra!…”

“…This was done by taking radon filter samples outside the chemistry building and counting the short-lived radon daughters with both the plastic scintillators and with a calibrated Ge ( [1974] also calculated the transit time from the •Rn/•øPb ratio, but this approach can hardly be used for south pole data because of an important stratospheric contribution for •xøpb as discussed below. It is interesting to note that the ratio of the radon concentration observed in ground level air over South America [Lockhart et al, 1966] The data in Figure 1 show that on some days very high radon levels were observed. These high radon levels were real, as was confirmed by following the decay of the beta particle count rate.…”

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

“…At some sites, however, shallow, stable boundary layers (or proximity to terrestrial sources, as is the case for KSG), can lead to winter mean radon concentrations higher than typical baseline values. Local radon sources at the permanently frozen South Pole station are virtually zero (Lockhart et al, 1966). The amplitude of the seasonal radon cycle at this site (10-30 mBq m −3 ; Fig.…”

“…Lockhart, 1960;Lockhart et al, 1966;Lambert et al, 1970;Maenhaut et al, 1979;Polian et al, 1986;Heimann et al, 1990;Wyputta, 1997). Seasonal radon cycles have been reported for numerous sites (Fig.…”