Radioactivity Exploration from the Arctic to the Antarctic. Part 2: Ymer-80 expedition [article]

Bertil R.R. Persson
2015 unpublished
Levels of natural radioactivity such as 222 Rn (radon) and its long-lived daughters 210 Pb and 210 Po were measured. The radon gas was trapped on cooled charcoal filters and the long-lived daughter products sampled on fibre filters on a daily basis. In addition, short-lived progenies were followed continuously on the filters in order to achieve a time resolution of about one hour. The average 222 Rn concentration in air measured during the Ymer-80 expedition in samples north of latitude 78.8
more » ... of latitude 78.8 °N, was 33 ± 4 (one standard error) mBq.m -3 during Leg 1 (July-Aug.) , and 105.3 ± 8.3 mBq.m -3 during leg 2 (Aug-Sept.). During a two-week period of persistent polar winds, the mean radon concentration decreased to 19± 5 mBq.m -3 . During July, August and September, the monthly average concentrations of 210 Pb in air at positions north of 75 °N latitude were 31  15, 89  61 and 105 57 µBq.m -3 respectively with a the grand average for all 3 months of 75  28 µBq.m -3 . An extensive radiochemistry program was also established to measure 134+137 Cs and the transuranium elements 238+239+240 Pu and 241 Am in water, sediment and biota. The concentration of 137 Cs in surface seawater along the Norwegian coast was quite constant about 1577 Bq.m -3 . At a latitude about 72 o N it stat do decrease exponentially at a rate of 0.43 deg. -1 to about 20  10 Bq.m -3 above 78 o N. The results of 137 Cs in sediments indicate that the total integrated area-content of 137 Cs in a 1000 m water-column and sediment is about 12 kBq.m -2 . In biota, the highest activity concentration of 137 Cs about 1000 Bq/kgdwt was found in lichens. The activity concentration of 137 Cs in polar bears was about 10 Bq/kgdwt, in seals about 1 Bq/kgdwt, and in birds about 1-7 Bq/kgdwt. The activity-concentration of 137 Cs in Fucus and Laminaria was about 1-2 Bq/kgdwt, and the algae/sea-water activity-concentration ratio was about 75. The distribution of the trans-uranium element 239+240 Pu in sea water decrease from 14 to 10 mBq.m -3 up to 73N but increase again to 17 mBq.m -3 at high latitudes while 137 Cs decrease. The average 241 Am/ 239+240 Pu activity ratio was found to be 0.13 ±0.04 (2 S.E), of 31 samples with the range 0.04 -0.32 in surface water, Deep-water samples have been sampled at latitudes around 80.4 ±1.4 N and along longitudes 2 W -45.5 E. The results of the salinity and activity concentration of 137 Cs and 239+240 Pu with depth of water are indicate an exponential decrease with depth of both 137 Cs and 239+240 Pu. In conclusion, about 25% of 137 Cs present in the Arctic water and sediments originates from fallout specific to the area. Another 25% originates from mixing with Atlantic-water from latitudes with higher fall-out. The remaining 50% might originate from European reprocessing facilities. The levels of 241 Am in the Svalbard area originate from in situ build-up due to the decay of 241 Pu. Acta Scientiarum Lundensia (ISSN 1651-5013 open access) Algal-Laminaria leaves (3) Seal (1) Bird-Rissa tridactyla (7) Bird-FuLmarius glacialis (6) Algal-Laminaria stems (3) Fucus (1) Bird-Somateria mollissima (7) Bird-Uria lomvia (4) Bird-Pagophilia eburnea (2)
doi:10.13140/rg.2.1.3542.2164 fatcat:w5m2d6ervjfwfb3tqzctqe7w64