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

摘要

Air filter samples collected at Sodankyl? (67°22'N, 26°39'E) were analyzed to determine concentrations of ~(137)Cs and ~(90)Sr in surface air in northern Finland in 1963. Previously, activity concentrations of Pu isotopes have been determined from the same filters. Activity concentrations of ~(137)Cs and ~(90)Sr in surface air were < 50 μBq/m ~3-13 800 ± 2700 μBq/m ~3 and < 10 μBq/m ~3-5340±290 μBq/m ~3, respectively. Air concentrations of ~(137)Cs and ~(90)Sr 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 ~(90)Sr/ ~(239+240)Pu and ~(90)Sr/ ~(137)Cs were 6.9 ±0.8-75 ±5 and 0.08±0.03-1. 46±0.51, respectively. The median value for the ~(90)Sr/ ~(137)Cs 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.