Renata Kierepko

Plutonium isotopes in the atmosphere of Central Europe: Isotopic composition and time evolution vs. circulation factors

This paper reports evidence of Pu isotopes in the lower part of the troposphere of Central Europe. The data were obtained based on atmospheric aerosol fraction samples collected from four places in three countries (participating in the informal European network known as the Ring of Five (Ro5)) forming a cell with a surface area of about 200,000km(2). We compared our original data sets from Krakow (Poland, 1990-2007) and Bialystok (Poland, 1991-2007) with the results from two other locations, Prague (Czech Republic; 1997-2004) and Braunschweig (Germany; 1990-2003) to find time evolution of the Pu isotopes. The levels of the activity concentration for (238)Pu and for ((239+240))Pu were estimated to be a few and some tens of nBqm(-3), respectively. However, we also noted some results were much higher (even about 70 times higher) than the average concentration of (238)Pu in the atmosphere. The achieved complex data sets were used to test a new approach to the problem of solving mixing isotopic traces from various sources (here up to three) in one sample. Results of our model, supported by mesoscale atmospheric circulation parameters, suggest that Pu from nuclear weapon accidents or tests and nuclear burnt-up fuel are present in the air.

Plutonium traces in atmospheric precipitation and in aerosols from Krakow and Bialystok

Abstract The appearance of plutonium isotopes in the environment was connected with the human activity, mainly: nuclear weapon tests (global fallout), nuclear accident in Chernobyl (1986), disintegration of satellite SNAP 9 (1963) and releases from nuclear reprocessing factories. At present, the concentration of plutonium in the atmosphere is very small but still observable. The aim of the study is to report and to discuss the results of plutonium alpha-emitters determination from sampling aerosols in air (Krakow 1990–1998, 2001–2002 and Bialystok 1996–1998, 2001) and in precipitation (Krakow 2005–2006). Plutonium activity concentration in air samples (in Krakow and Bialystok) varied in range: 0.22±0.04 nBq/m3 to 17.1±1.3 nBq/m3 for 239+240Pu and 0.033±0.018 nBq/m3 to 2.54±0.22 nBq/m3 for 238Pu and deposition of atmospheric precipitation (Krakow): from 0.041±0.011 mBq/m2 to 2.81±0.24 mBq/m2 for 239+240Pu and for 238Pu below 1.29±0.45 mBq/m2. One of the mechanisms responsible for the airborne plutonium is resuspension but on the other hand the main source of plutonium in the air seems to be marines aerosols from North See. This new hypothesis will be checked during the future research. The most interesting finding is the seasonal variation of plutonium air concentration. The conclusion from calculated ratio of plutonium isotopes (238Pu/239+240Pu) is that they are usually not typical for the global fallout.