Total beta activity, 137Cs and 90Sr in surface air in northern Finland in 1963

Abstract

Abstract Air filter samples collected at Sodankylä (67º22´ N, 26º39´ E) were analyzed to determine concentrations of 137Cs and 90Sr in surface air in northern Finland in 1963. Previously, activity concentrations of Pu isotopes have been determined from the same filters. Activity concentrations of 137Cs and 90Sr in surface air were <50 μBq/m3–13800 ± 2700 μBq/m3 and <10 μBq/m3–5340 ± 290 μBq/m3, respectively. Air concentrations of 137Cs and 90Sr varied seasonally with a maximum in spring due to the springtime enhanced transportation of air masses with radioactive aerosols from the stratosphere to the troposphere. Activity ratios 90Sr/239+240Pu and 90Sr/137Cs were 6.9 ± 0.8–75 ± 5 and 0.08 ± 0.03–1.46 ± 0.51, respectively. The median value for the 90Sr/137Cs ratio (0.508) indicates contamination from global nuclear test fallout. An air mass back trajectory analysis suggests that no direct transport of radioactivity from the Novaya Zemlya test site to northern Finland occurred in 1963.