[Accumulation of 90Sr in field crops in conditions of radioactive pollution of agricultural lands]. / Nakoplenie 90Sr polevymi kul'turami v usloviiakh radioaktivnogo zagriazneniia sel'skokhoziaistvennykh ugodii.

In the field experiment the influence of manure, peat, lake silt and their combinations on the uptake of 90Sr by barley, corn and potatoes was studied. Saturation of soil with organic substance, the decrease in soil acidity resulted in the lower accumulation of 90Sr by plants. In the beginning of the experiment, the specific activity of barley grain was from 75 to 132 Bq/kg. After three years of application of fertilizers the content of 90Sr in the barley grain decreased to 39 Bq/kg. There were no increase in 90Sr accumulation by the basic field crops with time.

Modeling radionuclide effluxes from agricultural and natural ecosystems in Belarus.

A mathematical model is described which is appropriately constructed to calculate effluxes of radionuclides from agricultural and natural ecosystems. The application of this model is demonstrated by estimating effluxes in the Bragin region and in the Narovlya region in the Republic of Belarus both highly affected by the Chernobyl accident fallout. Depending on the nature of the area and the deposition, the total efflux and the exported radioactivity are calculated. It is shown that the exported radioactivity for natural foodstuffs represents more than 64% (Bragin region) and 86% (Narovlya region) of the total 137Cs efflux, and for agricultural products 2.7% and 2.3%, respectively. The contribution of the different foodstuffs deriving from natural and agricultural used land to the individual and collective dose for 137Cs and 90Sr are estimated and presented. In the Bragin region for the collective annual dose the highest contribution is due to milk and meat consumption (137Cs) and flour and milk (90Sr), for individual annual dose milk and mushrooms (137Cs), and milk and flour (90Sr) contribute most. In the Narovlya region this contribution for the collective and individual annual dose is due to milk and mushroom consumption (137Cs) and flour and milk (90Sr).

[Evaluation of the effectiveness of protective measures for reduction of the rural population exposure related to contamination of forest ecosystems]. / Otsenka éffektivnosti zashchitnykh meropriiatii po snizheniiu dozovykh nagruzok na sel'skoe naselenie, obuslovlennykh produktsiei lesnykh ékosistem.

The contribution of different forest pathways to the irradiation of inhabitants of the forest settlements after the ChNPP accident is estimated. It has been shown that the long-term negative impact of forest ecosystems contaminated to the rural population requires application of special protective measures for a long time after the ChNPP accident.

Remediation strategies for rural territories contaminated by the Chernobyl accident.

The objective of the present paper is to derive remediation strategies for rural settlements contaminated by the Chernobyl accident in which annual doses to a critical group still exceed 1 mSv. Extensive radioecological data have been collected for 70 contaminated settlements. A dose model based on these data resulted in estimates that are on average close to and a bit less than the official dose estimates ('catalogue doses') published by the responsible Ministries of Belarus, Russia and Ukraine. For eight remedial actions that can be applied on a large scale, effectiveness and costs have been assessed in light of their dependence on soil type, contamination level and on the degree of previous application of remedial actions. Remediation strategies were derived for each of the 70 settlements by choosing remedial actions with lowest costs per averted dose and with highest degree of acceptability among the farmers and local authorities until annual doses are assessed to fall below 1 mSv. The results were generalised to 11 contamination/internal-dose categories. The total numbers of rural inhabitants and privately owned cows in the three countries distributed over the categories were determined and predicted until the year 2015. Based on these data, costs and averted doses were derived for the whole affected population. The main results are (i) about 2000 Sv can be averted at relatively low costs, (ii) the emphasis on reducing external exposures should be increased, (iii) radical improvement of hay-land and meadows and application of Prussian blue to cows should be performed on a large scale if annual doses of 1 mSv are an aim to be achieved, (iv) additional remedial actions of importance are fertilising of potato fields, distribution of food monitors and restriction of mushroom consumption, and (v) for inhabitants of some settlements (in total about 8600) annual doses cannot be reduced below 1 mSv by the remedial actions considered.

The mobility of 137Cs and 90Sr in agricultural soils in the Ukraine, Belarus, and Russia, 1991.

Results are presented from studies concerning the behavior of the Chernobyl-derived radionuclides 137Cs and 90Sr in soil-plant agricultural systems in the Ukraine, Belarus, and Russia during 1991. The sites, representing ploughed and natural pastures, were located at varying distances between 50 and 650 km and varying directions from the Chernobyl reactor site. The 137Cs activity concentrations in the upper 0-5 cm soil layer ranged from 25-1,000 kBq m-2 and were higher in natural pastures as compared to ploughed pastures. For 90Sr, activity levels ranged from 1.4-40 kBq m-2, and the highest 90Sr deposition was observed in the Gomel Region, Belarus. The highest 90Sr: 137Cs ratio was also observed in the Gomel soils, i.e., 15% as compared to between 0.72 and 7.4% in the other soils. The mobility of radionuclides was studied by means of sequential extraction. For all soils, between 60 and 95% of the 137Cs was found to be strongly bound to soil components. In the Russian and Ukrainian soils, between 40 and 98% of the 90Sr was found in the easily extractable fractions, and the distribution of 137Cs and 90Sr followed that of the naturally occurring stable isotopes of cesium and strontium. However, in the Gomel soils, between 20 and 50% of the 90Sr was easily extractable and the distribution of 90Sr within the extraction fractions did not follow that observed for stable strontium. These results are thought to reflect the association of 90Sr with fuel particles deposited in the Gomel Region. The mobility of 90Sr is expected to increase with time (as the particles weather) in these soils.

Effectiveness of countermeasures applied in Belarus to produce milk and meat with acceptable levels of radiocaesium after the Chernobyl accident.

Countermeasures taken in Belarus to reduce transfer of radiocaesium from feeds to animals have combined live monitoring and monitoring of radiocaesium (137Cs and 134Cs) in bulk milk on dairy farms with the setting of upper limits for radionuclide contents for animal feeds. Only uncontaminated feeds have been used in the final fattening of animals before slaughter. Combined with widespread soil management programmes these measures have allowed the continued use of the majority of contaminated agricultural lands without substantial changes in farming practices.