Artificial Radioactivity Reference Horizons in Greenland Firn

摘要

Total beta measurements have been made on melt water samples from a stratigraphically dated firn core profile from the inland Greenland ice sheet (77 deg 10 min N, 61 deg 08 min W). A marked increase in radioactivity is found in the 1953 firn layer which corresponds to the first important fallout from nuclear test bombs. The pre-1953 natural beta activity is 5 dpm/kg. The influx of artificial debris from the Ivy tests in 1953 is noted by a sharp rise in beta activity to 10 dpm/kg. Total 90Sr deposit to June 1964 is 9.3 plus or minus 1.5 millicuries/km2 (24 plus or minus 4 mC/mi2). Average 210Pb activity at time of deposit is 3.9 plus or minus 0.4 dpm/kg. (Author)