Radium and radon in natural underground water supply in the region of Lódź, Poland

The region of Lódź, located in the central part of Poland, is very specific with respect to water supply coverage. In this densly populated and extensively industrialised region there is a lack of natural reservoirs of surface water in the nearest vicinity of Lódź. Therefore, over 50% of water for public and domestic use is provided from underground water intakes. It is well known from the literature that in underground water may occur radionuclides in the uranium and thorium decay series. Underground water intakes in Lódź used for public water supplies have been surveyed for the presence of radium-226 and radon-222 since the earlier studies of quality standards of the gross alpha and gross beta activity pointed to their possible excessive values. The surveillance was based on the guidelines set by the World Health Organisation (WHO). The measurements of radium-226 activity showed its different concentrations depending on the age of the water-bearing level. These concentrations fell within the range of < 10 divided by 50 Bqm-3. Measurements of radon yielded similar results and its highest concentrations were found in the Lower cretaceous and Jurassic formations. Radon concentrations ranged from 200 to 11,400 Bqm-3. A maximum annual dose taken into the body in the population drinking this water may account for 0.85 microSv which is lower than the limit recommended by WHO.