Plutonium and americium inventories in atmospheric fallout and sediment cores from Blelham Tarn, Cumbria (UK)

Anthropogenic radionuclide emissions into the environment

“…This isotope was mainly released into the atmosphere by ignition and disintegration of the satellite SNAP-9A in 1964 (6.3 x 1014 Bq) and to a minor extent from nuclear tests (3.3 x 1014 Bq; UNSCEAR 1982). Although the contribution of 238pu on total Pu is insignificant in the soil samples presented in Figure 1, a good correlation between the isotopes of Pu is indicated and the 238pu/239+24~ ratio of 0.03 __+ 0.01 calculated via regression analysis (Eikenberg et al 2002(Eikenberg et al , 2003 agrees well with that obtained from other sites in the northern hemisphere (Hoelgye & Filgas, 1995;Hodge et al 1996;Michel et al 2002). Figure 1 also displays the 241Am vs. 239+24~ data of the same samples, which also strongly correlate, and the regression line through the data yields a result for 241Am/239+Z4~ of 0.38 q-0.04 (reference date: Pu/ Am progenitor/progeny relationship assuming (i) meaningless initial :41Am after the atomic weapon tests (Fig.…”

“…Figure 3 and Table 3 indicate that reactor components (such as Chernobyl reactor fuel material) are characterized by 238 higher levels of Pu and 241Am compared to 239+24~ because of the longer neutron-flux exposure time of fuel material in a reactor in comparison to nuclear bomb explosions. The measured 238pu/Z39+240pu and 241Am/239+Z4~ isotope ratios in western Europe (Hoelgye & Filgas 1995;Bunzl et al 1995;Hodge et al 1996;Geering et al 2000;Michel et al 2002;Eikenberg et al 2003) are within uncertainty identical to the average actinide isotope ratios resulting from the surface atomic bomb tests. Table 3 lists also the 241pu//239+24~ ratios of 1.8 measured in central Europe (Eikenberg et al 2002(Eikenberg et al , 2003 and these values additionally agree with the data from UNSCEAR (2000) for global bomb fallout (241pu/239+24~ = 1.9, decay corrected at reference date 1 January 2003).…”

“…Apart from locally contaminated sites, typical present-day environmental levels of 239+24~ in topsoil layers of the northern hemisphere vary between 0.1 and a few Bq/kg depending on the soil type, vegetation, and altitude (Hardy et al 1973;Hardy 1974;Hoelgye & Filgas 1995;Hodge et al 1996;Eisenbud & Gesell 1997;Michel et al 2002). For instance, Pu isotope measurements performed by Geering et al (2000) in Switzerland yielded significantly higher contributions of atmospheric fallout Pu in the Alps while the northern lower altitudes were less affected.…”

“…Disregarding the significant contribution of actinides from the Chernobyl accident to the inventory of Pu in western Europe, and inserting the average 239+240pu/137Cs ratio of 0.03 reported for North American soils (Hodge et al 1996; i.e., pure atomic bomb component) as the initial pre-Chernobyl Pu/Cs ratio, then the frac- (2002,2003), counting uncertainties 2o"; tCalculated with the initial 241pu/239+240pU ratio of 13 (UNSCEAR 2000) at reference date, 1 January 2003; *Literature data for regions that were not contaminated by Chemobyl hot particles (i.e., actinide fallout) (Hoelgye et al 1995;Hodge et al 1996;Geering et al 2000;Michel et al 2002); w for Chernobyl from Buzulukov & Dobrynin (1993); Decay corrected at reference date. tions of ~37Cs from both events can be roughly estimated using the following relationships:…”

Input contribution and vertical migration of plutonium, americium and cesium in lake sediments (Belham Tarn, Cumbria, UK)

“…A comparison of the fallout and the sediment inventory [2] allows the activity estimation of these different contributions.…”