Assessment of soil degradation in areas of nuclear explosions at the Semipalatinsk nuclear test site

The degree of the soil cover degradation at the Balapan and Experimental Field test sites was assessed on the basis of the Allium-test of soil toxicity and international guidelines on the radioactive restriction of solid materials (IAEA, 2004) and the environment (Smith, 2005). Large scale soil-cover degradation maps (1: 25000) were made. The main part of the mapped area contains highly contaminated toxic degraded soil. It was found that the relationship between soil toxicity and total radionuclide activity concentration is described by power functions. When the calculated value (413-415 Bq/kg of air-dried soil) increases, the soil becomes toxic to plants. This value is 7. 8 times higher than the maximum value for background territories (53 Bq/kg) surrounding the SNTS. The Russian sanitary and hygienic guidelines (Radiation safety standards, 2009; Sanitary regulations of radioactive waste management, 2003) underestimate the degree of soil radioactive contamination for plants. © 2011 Pleiades Publishing, Ltd.