LAND RESOURCES AND SOILS
Contamination of the agricultural products
Accumulation of radioactive nuclei in foodstuffs depends on many factors, some of the most important being the level of soil contamination, the type of soil and its radioecological features, and agrochemical and water physical characteristics. The effects of these factors on the intensity of radioactive nucleus migration from one product to another are quantitatively evaluated with the use of the proportionality coefficients of the accumulation of radioactive nuclei accumulation in the agricultural plants and crops from the soil (Bq/kg; kBq/m²).
Agricultural production is conducted in agricultural enterprises of all types of property on a wide range of soil types with radioactive contamination levels from 37 to 555 kBq/m². The Ukrainian Polissia is characterized mainly by turf-podzol soil (69%), swamps and peat-bogs (13%), turf-grassland (about 10%), turf-carbonated, saline soils and gray podzolated soils (7-8%). There are some sizable areas with soil featuring a low density of clay minerals (turf podzol low humus sands), which makes it unsuitable to fix (block) 137Cs.
The ability of the agricultural plants to accumulate the radioactive nuclei of various concentrations largely depends on their biological characteristics. Difference in accumulation of 137Cs in 21 different agricultural plants of the turf-podzol soil ranges from 10- to 20-fold, namely in various beans (1.5 to 3 times). The accumulation levels of 137Cs in the kernels and hay of various grain crops differ by 8 to 10 times. Below, agricultural grain crops are arranged in decreasing order by levels of concentration of radioactive 137Cs:
All the agricultural crops can be divided into three major groups in accordance with their ability to accumulate 137Cs: grain crops (barley, wheat and oats) with low ability to accumulate the radioactive cesium; cereal crops (millet, Turkestan millet and buckwheat) with medium levels of 137Cs accumulation; and leguminous plants (haricot, peas and beans) with a high level of accumulation of 137Cs. The 137Cs accumulation features of the potato places it in the slot just between peas and beans.
Contamination of crops by radioactive cesium is being reduced steadily. The 1998 data produced by radioecological monitoring prove that contamination of milk (sampled from the public sector of agriculture of five regions) with 137Cs in average exceeds the permissible level (100 Bq/l) only in 10% of the samples. The same data for meat show that it is contaminated above the permissible level (200 Bq/l) in about 20-30% of the samples (information relates to 1998).
Average contamination of agricultural crops by region (1998)
Most contaminated are Zhitomyrska and Rivnenska regions. Since 1996 the levels of contamination of the agricultural crops have been decreasing, though the decrease is not significant within 10-15% of the average total.
In order to improve the radioactive situation, and to reduce the level of contamination of the foodstuffs and thus the effects of radiation on the population, certain anti-radiation measures have been conducted in the agricultural regions:
Dynamics of counter-measures implemented on contaminated agricultural lands of Ukraine,
The major needs in terms of soil improvement chemicals and fertilizers are determined in accordance with the Recommendations on the agricultural activities under the radioactive contamination of the territory of Ukraine in consequence of the Chernobyl nuclear power plant accident (1998).