Study on radon concentrations in Antarctica's instrumentation and analysis

Continuos measurements of the natural radioactive gas sup(222)Rn are made at the Brazilian Antarctic station Comandante Ferraz (62 sup(0)S, 58 sup(0)W) to study the continental influence of air masses over the Antarctic peninsula. The technique employed in the measurements is base on the process of electrostatic collection of the ionized Polonium isotopes (the Radon decay products). The efficiency of collection is of the order of 50% to 57% for an applied electric potential of 17 kV. The collection chamber has a hemispheric shape in order to optimize the collection yield. The observed radioactivity at the Ferraz station for the period March to November 1986 and 1987 exhibited different behaviors. The year 1986 showed an average radioactivity of (2.6 ± 1.8) x 10 sup(-2) Bq.m sup(-3), while in 1987 a 50% decrease in the concentration was observed with a value of (1.44 ± 0.8) x 10 sup(-2) Bq.m sup(-3). Associated variations of wind velocity and continental aerosol loads were also observed. Periodicities in the radon time series displayed more intense peaks at 25 to 30 day periods. No seasonal trend was observed. Transient increases of radon correlated with short deicing periods. The average flux of Rn were calculated from a sampling network consisting of 20 points spread over the exposed regoliths and outcrops of the King George island, with values of 250 atoms m sup(-2) s sup(-1) for the sup(220)Rn and 7500 atoms m sup(-2) s sup(-1) for the sup(222)Rn isotope. (author)