Agricultural impact of Chernobyl: a warning

Is there Chornobyl nuclear accident signature in Scots pine radial growth and its climate sensitivity?

The extensive radioactive fallout resulting from the 1986 Chornobyl accident caused tree death near the nuclear power plant and perturbed trees communities throughout the whole Chornobyl exclusion zone. Thirty years into the post-accident period, the radiation continues to exert its fatal effects on the surviving trees. However, to what extent the continuous multi-decadal radiation exposure has affected the radial tree growth and its sensitivity to climate variation remains unascertained. In this comparative study, we measure the Scots pine radial growth and quantify its response to climate at two sites along the western track of the nuclear fallout that received significantly different doses of radiation in 1986. The common features of the two sites allow us to disentangle and intercompare the effects of sub-lethal and moderate radiation doses on the pine's growth and climatic sensitivity. We extend the response function analysis by making the first use of the Full-Duration at Half-Maximum FDHM method in dendrochronology and apply the double-moving window approach to detect the main patterns of the growth-to-climate relationships and their temporal evolution. The stand exposed to sub-lethal radiation shows a significant radial growth reduction in 1986 with a deflection period of one year. The stand exposed to moderate radiation, in contrast, demonstrates no significant decrease in growth either in 1986 or in the following years. Beyond the radiation effects, the moving response function and FDHM enabled us to detect several mutual patterns in the growth-to-climate relationships, which are seemingly unrelated to the nuclear accident. To advance our predictive understanding of the response of forest ecosystems to a massive radioactive contamination, future studies should include quantitative wood anatomy techniques.

Total body potassium measurement--the effect of fallout from Chernobyl

As a result of fallout from the nuclear accident at Chernobyl in April 1986, the caesium radioisotopes, 134Cs and 137Cs, have been detected in man. A minor consequence of this is that total body potassium (TBK) measurements obtained from the whole body activity of 40K, a naturally occurring radioisotope of potassium, can be overestimated because of gamma spectrum overlap between 134Cs and 40K. Whole-body activities for 134Cs and 40K were measured in 18 healthy adults (13 M, 5 F) in June/July, 1986, using a whole-body counter with NaI crystal scintillation detectors. Studies using anthropometric phantoms containing known activities of the two radionuclides, allowed the contribution of 134Cs to the '40K activity' in the human subjects to be assessed. The group mean 134Cs level was 172 Bq, resulting in an average overestimate in TBK of 2.8%. It is recommended that when TBK measurements are being undertaken and 134Cs contamination is suspected, then 134Cs levels should be measured and their effect corrected for.

Chernobyl nuclide record from a North Sea sediment trap

Nuclides liberated by explosion and subsequent fire at Chernobyl No. 4 reactor on 26 April 1986, travelled to Western Europe with lower tropospheric air masses. They reached the northern Alps and Paris on 30 April, southern Great Britain on 2 May, the southern North Sea on 3 May, and the northern North Sea on 3 May and again on 8 May. Levels of deposited activity varied by a factor of 30 or more over distances less than 100 km because of variability of rainfall. A sediment trap deployed 222-m-deep in the North Sea off Bergen recorded the onset and magnitude of the deposition of Chernobyl nuclides. The trap collected 13 samples between 24 April and 21 September 1986. The flux of nuclides adsorbed to particles sinking from surface waters to sediments started less than ten days after contaminated air reached the site. Maximum specific activity occurred on 16-27 May for 137Cs, 134Cs, 106Ru and 103Ru, and on 8-20 June for 144Ce, 95Nb and 95Zr. The highest activity was found for 103Ru. The highest total specific activity of these nuclides in depositing sediments reached 670,000 Bq kg-1, and the highest total activity flux for one day amounted to 50 Bq m-2.

Distribution of fission products in dust samples from the region of Thessaloniki, Greece, after the Chernobyl nuclear accident

The distribution of the fission products (95)Zr, (95)Nb, (103)Ru, (106)Ru (determined through (106)Rh), (125)Sb, (129m)Te, (134)Cs, (137)Cs, (140)Ba, (140)La, (141)Ce and (144)Ce has been determined in dust samples from the region of Thessaloniki, Greece, after the nuclear accident at Chernobyl. The samples studied also included (110m)Ag, not belonging to the products of (235)U fission. Samples showing higher concentrations of radionuclides also show a higher content in clay minerals, whereas samples having low concentrations of radionuclides usually contain large amounts of quartz and feldspars. Desorption and leaching experiments using solutions of chlorides of sodium, potassium, calcium and magnesium (0.5 N), as well as distilled and tap water, were also performed. Sodium and potassium chloride solutions were found to be efficient in desorbing and/or leaching of caesium and ruthenium isotopes to an extent of about 30%.