The transfer of 137Cs and 90Sr to dairy cattle fed fresh herbage collected 3.5 km from the Chernobyl nuclear power plant
Introduction
A number of studies following the Chernobyl accident have demonstrated the importance of the form in which radiocaesium is ingested by grazing animals in determining absorption across the gut and the subsequent activity concentrations in milk and meat (Beresford et al., 1992; Cooke et al., 1996; Mayes, Beresford, Howard, Vandecasteele & Stakelum, 1996). These studies have been concerned with artificially contaminated or environmentally contaminated sources from western Europe. Radiocaesium deposited in western Europe from the Chernobyl accident was predominantly in the form of aerosols. Closer to the Chernobyl nuclear power plant (NPP) large areas were contaminated with particulate material (hot particles) ejected into the atmosphere as the result of the explosion. Animals grazing in such areas may ingest radioactivity associated with these particles if they are resuspended onto vegetation surfaces; the availability for transfer to meat and milk of radionuclides associated with such ingested particles is unknown. We describe a study to measure the transfer of 137Cs and 90Sr to dairy cattle conducted within the Ukrainian Chernobyl exclusion zone at a site contaminated by particulate fallout.
Section snippets
Experimental animals and study site
The six experimental cows were of a local dairy breed with a mean (±SE) live-weight of 410±15 kg. The animals were in their second to fourth month of lactation and had a mean milk yield of 9.1±0.84 kg d−1; individual yields ranged from 7.2 to 11.9 kg d−1.
The cattle were moved to experimental housing 20 d prior to the start of the experiment. The housing consisted of open-sided stalls with concrete flooring at the edge of ca. 0.15 km2 pasture (standing biomass approximately 900 kg dry matter (DM) ha−1
Results
The activity concentrations of 137Cs and 90Sr in the daily cuts of herbage fed over the final week of the study are shown in Fig. 1. Daily variation in the activity concentration of herbage was low for both radionuclides with the exception of results for 137Cs in samples collected on 27/7/93. Mean activity concentrations (±SE; n=21) over the week were 41.9±1.44 kBq kg−1 DM for 90Sr and 28.4±1.55 kBq kg−1 for 137Cs. The ratio of 134Cs : 137Cs in herbage was 0.048±0.0005 . The 134Cs and
Animal performance
The dry matter intakes of the cattle met the requirements advised by the National Research Council (NRC) (1989) for cows with such a live-weight and milk yield. However, the dry matter digestibility of the complete diet was low (51%) and is likely to have limited dry matter intake and hence possibly milk production rate (NRC, 1989). The milk yields of the animals were low considering that they were in early lactation when production should have been close to maximum. If we assume that the dry
Conclusion
These results suggest that the radiocaesium present in vegetation close to the Chernobyl NPP was poorly absorbed by lactating cattle. The transfer of both radiocaesium and radiostrontium to milk was probably influenced by the poor quality of the diet, increasing plasma-to-milk transfer of radiocaesium and reducing the transfer of radiostrontium to milk. Derived parameters for the transfer of 90Sr to milk are likely to have been influenced by the animals’ calcium intake prior to the study.
Acknowledgements
The authors would like to thank those members of staff of the Department of Radiology and Land Reclaiming (RIA Pripyat) who took part in this study, and also Cath Barnett (ITE), Dave Benham (ITE), Beverley Dodd (ITE), Stuart Lamb (MLURI), Arthur Sanchez (ITE), the staff of the Chernobyl Central Laboratory, and members of the Analytical Chemistry Section at ITE Merlewood for their assistance during experimental planning and sample analyses. We also acknowledge the support of Michael Sedov
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2017, Journal of Environmental RadioactivityThirty years after the Chernobyl accident: What lessons have we learnt?
2016, Journal of Environmental RadioactivityCitation Excerpt :An understanding of the metabolism in farm animals can better inform on the practicality and implementation of remedial measures (e.g. Åhman, 1999; Voigt and Kiefer, 2007; Howard et al., 1987). Key advances made in animal radioecology included the use of faecal marker approaches to estimate herbage (and hence radionuclide) intake in grazing animals (Mayes et al., 1994; Beresford et al., 1989) and the application of dual isotope techniques to determine absorption of radionuclides from the diet (Mayes et al., 1996; Cooke et al., 1996), including under field conditions in the Chernobyl exclusion zone (Beresford et al., 2000). Deposition of radionuclides from the Chernobyl led to the long-term implementation of remedial measures in the fSU and other European countries.
Studies on soil to grass transfer factor (F<inf>v</inf>) and grass to milk transfer coefficient (F<inf>m</inf>) for cesium in Kaiga region
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2010, Journal of Environmental RadioactivityCitation Excerpt :In the nuclear context, contamination arises from the dispersion of radionuclides in the environment, and these subsequently transfer from water, soil and air into food products. To evaluate radionuclide contamination of agriculture, extensive research has been done to measure substrate-to-food transfer factors (Beresford et al., 2000, 2006a,b, 2008; Fesenko et al., 2007a,b, 2009a,b; Howard et al., 2007a,b, 2009a,b,c; Vandecasteele et al., 2000; and citations therein). However, almost all of this work was done one radionuclide at a time and often in artificial experimental settings.
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2009, Journal of Environmental RadioactivityCitation Excerpt :After the Chernobyl accident, transfer coefficients (radionuclide activity concentration in animal product relative to the daily radionuclide intake) for recently deposited radiocaesium were reported to be lower than for plant-incorporated radiocaesium (Ward and Johnson, 1989; Hansen and Hove, 1991; Howard et al., 1989; Selnæs and Strand, 1992); the At of radiocaesium cut three days after deposition from the Chernobyl accident was lower than that of Cs incorporated into vegetation by root uptake (Fig. 1). A low value of 0.23 determined for cattle grazing within the 30 km Chernobyl zone (Beresford et al., 2000b) was also excluded; the lower availability of Cs in this study was thought to be a consequence of a low dietary dry matter digestibility and the potential presence of Cs associated with adherent soil-associated fuel particles. We are not aware of evidence in domestic ruminants that the absorption of caesium is affected by the normal intake range of its analogue, K.
The transfer of <sup>239/240</sup>Pu to cow milk
2007, Journal of Environmental RadioactivityCitation Excerpt :Animals grazing in such areas may ingest radioactivity associated with uranium oxide particles if they are resuspended onto vegetation surfaces or if soil is directly ingested. In a study conducted during the summer of 1993, Beresford et al. (2000a) measured the gastrointestinal absorption of 137Cs and 90Sr by dairy cattle fed freshly cut herbage collected 5 km from the Chernobyl NPP; transfer parameters to milk were also determined. Particulate fallout was known to comprise a significant amount of the total deposition to the site (Askbrant et al., 1996).