Initial study for biological recultivation of areas technologically polluted by uranium industry

The exploitation of the Eleshnitsa (BG) uranium mine has led to a serious change in ecological status which necessitates a specified approach in restoration of environment and soil fertility. The investigations reported in the paper comprise the creation of a radiometric map of the region, measurement of the integral gamma-background, the potential alpha energy and volume activity of radon daughters, determination of uranium, thorium and their daughters in soil, plant and water samples, and assessment of the soil fertility and heavy metal contents. The conclusions based on the results obtained show the following disturbances in the ecological status: 1. significantly increased gamma-background; 2. proven radiological risk for the population due to the inhalation of radon daughters; 3. increased uranium and radium content; 4. aggravated fertility and chemical characteristics of the substrates. Based on these conclusions, seven versions for biological recultivation of different terrains, a schedule for its conducting, radiation control, monitoring programme and evaluation of the measures have been suggested. (author)