Concentration and characteristics of uranium isotopes in water collected in central Italy and Balkan regions

Full text: Uranium is a naturally occurring, ubiquitous heavy metal found in the environment in various chemical forms in all soils, rocks, seas and oceans. It is also present in air, food and drinking water. Due to its widespread existence in nature, uranium isotopes (238U, 234U and 235U) have become one of the most important source of natural radioactivity and make a significant contribution to external and internal dose to population. Uranium isotopes enter the human body mainly through ingestion, and by inhalation to a considerably smaller degree. Hence the internal radiation exposure for members of the public can be evaluated through the intake of the radionuclides from both food and water. Pietrzak-Flis et al., have investigated the uranium intake fractions of the different pathways, and concluded that the uranium intake from water by man is the most important pathway which contributes the largest fraction (75.1%-76.9%) of uranium intake. For the purpose of estimating the radiological impact of uranium isotopes in water to the residents, some natural water samples were collected in central Italy and Balkan Regions and analysed in the laboratory of Italian Environmental Protection Agency and Technical Services (APAT). The activity concentrations of 238U, 234U and 235U were obtained. The radioanalytical procedure used for determination of uranium isotopes in water mainly includes steps of uranium pre-concentration, mineralization, separation by a Microthene- TOPO column, electrodeposition and measurement by alpha-spectrometry. Based on the obtained activity concentrations of uranium isotopes in drinking water, annual consumption rate of the water, and the dose conversion factor per unit intake given by the International Commission on Radiological Protection, the annual effective dose resulting from 1-year ingestion for the adult population was calculated. (author)