DETERMINATION OF URANIUM IN DRINKING WATER OF THE THIRD BIGGEST TOWN OF GREECE (PATRAS, NW PELOPONNESE) AND IN THREE FAMOUS GREEK SPA WATERS

摘要

Uranium is a radioactive toxic metal. It is widespread in nature, occurring mainly in granites and various other mineral deposits. Natural processes and many anthropogenic activities have resulted in re-distribution of this element, which can cause contamination of hydrosphere with uranium. Moreover, ~(222)Rn, is generated from the decay chain of ~(238)U. In case of inhalation, it is a dangerous radioactive gas. Spa waters may contain uranium as well as other metal salts in high concentrations, because the water comes from deep inside the Earth's crust. The occurrence of uranium in spa waters implies the occurrence of ~(222)Rn, especially under poor aeration conditions. Consequently, it is of great importance to identify the human health risks, which are associated with occurrence of uranium either in drinking water samples or in spa waters.The aim of this work was to determine uranium content in:1) drinking water of Patras, which is the third biggest city of Greece, with a population of about 200 000 people2) three famous spa waters, namely natural thermal springs of Kaiafas, Edipsos and Kyllini spa, which are well known from ancient times.Twenty one samples of drinking water were collected from an equal number of water reservoirs that provide potable water all over the city of Patras. Additionally, eight samples from different brands of bottled water produced in Greece and one imported mineral water, were analyzed for comparison reasons. 1 L from each sample was spiked with known amount of ~(232)U, and the total content of uranium was isolated by using Chelex-100 resin at pH=4.5. Uranium content was eluted from the resin by 15 mL of 2 M HNO_3. The latter volume was then evaporated to dryness in a water bath. Thereafter, uranium was re-dissolved in a solution of ammonium sulphate. After electro-deposition of uranium on stainless steel discs, the latter was counted for 5 days. Uranium concentration in the drinking water of Patras was found to be tenths or even hundreds of times below WHO guideline and the maximum contaminant level (MCL) of EPA. Furthermore, an assessment was made of the annual uranium radiation exposure of population, which uses the studied waters for human consumption.Uranium concentration in the studied spa waters was found as low as in potable water.