Spatial distribution of equivalent gamma dose rate in the vicinity of mine water sedimentation ponds in Upper Silesian Coal Basin

In the Upper Silesian Coal Basin highly mineralized mine waters are pumped into numerous sedimentary ponds before discharge to the Vistula river. They contain elevated concentrations of natural radionuclides (mainly radium). In ponds, some fraction of radionuclides is removed from the water column by adsorption on settling particles, precipitation or co-precipitation, thus increasing radioactivity levels in the deposits. Due to fluctuations of water level and wind action, fine fraction of the deposited material can be distributed in the vicinity of ponds. Three ponds have been selected for survey of the gamma equivalent dose: Brzeszcze, Kaniów, and Rontok Duży. The lowest dose rates, below 0.33 miSv/h, were detected in the area of the Brzeszcze pond. The highest values were measured over the sediments of the Kaniow pond (8.37 miSv/h), being 30 times higher than the dose rate received by population in Poland from natural sources.