Radon monitoring on the territory of Northern Tajikistan

The article presents the results of radon monitoring on the territory of Northern Tajikistan. Analysis of the results of the monitoring shows that at present, relatively high values of radon concentration in the atmospheric air are found in the areas where uranium tailings are located, primarily in the city of Istiklol and the Dehmoy tailings dam. This is primarily due to the lack of protective coatings on the surface of the tail material, which turns this area, in fact, into radon-prone areas of technogenic origin. In different parts of the Dehmoy tailings dam, the radon concentration in the atmospheric air varies between 200 and 1000 Bq/m3, and the radon flux density from the surface reaches 65,000 mBq/(m2∙s). On the territory of tailings dam in the city of Istiklol, the value of radon concentration in the atmospheric air is in the range of 44–195 Bq/m3. At the same time, it was found that the radon potential of the tailings dams, where the surface has a protective coating, is much lower. For example, the radon flux density from the surface of the Gafurov tailings dam, where surface is covered with loess-like loams up to 2.5–3.0 m thick, does not exceed 100 mBq/(m2∙s), with average values of 40-60 mBq/(m2∙s); the radon concentration in the atmospheric air is about 55 Bq/m3. Despite the intense exhalation of radon from the surface of some tailings dams, their territory is not currently a residential zone and, accordingly, does not affect the radon situation in buildings located in the settlements nearby. In the cities of Khujand, Buston, Gafurov, Istiklol and the village of Adrasman, the average values of indoor radon concentration do not exceed maximum permissible levels. It is recommended to conduct a full rehabilitation of uranium legacy sites, primarily uranium tailings dams in the city of Istiklol and Dehmoy tailings dam, for the improvement of the radon situation in Northern Tajikistan with consideration for possible expansion of the settlements