A mélyben lévő zavartalan vízbázisok minden ország megbecsült természeti kincsei. A hévizek és ásványvizek vizek több nagyságrendnyi tartományban változó radioaktivitása döntően a geológiai környezetben felvett radontól és rádiumtól ered. Ezen alfa-radioaktivitást hordozó elemek egyrészt nyomjelzői a mélységi vizek transzportfolyamatainak, másrészt a lakossági sugárterhelés egyik fontos összetevőjét képezik a kiemelkedő aktivitású vizek felhasználóinak körében. Dolgozatomban, a MTA Atommagkutató Intézetének Radon Csoportjában, vízminták 222Rn- és 226Ra-tartalmának meghatározására szolgáló maratottnyom-detektoros módszer meghatározó hozzájárulásommal végzett fejlesztésének eredményeiről számoltam be, valamint bemutattam a módszer alkalmazása során kapott hazai és külföldi felszínalatti vízminták radon- és rádiumtartalom meghatározásának és a fogyasztásuk által okozott járulékos sugárterhelés becslésének eredményeit.

Radioactivity of thermal and mineral waters, which may vary over several orders of magnitude, is mainly due to the radon and radium originating from the geological environment. Radon and radium content of waters may be interesting from different points of view. Firstly, waters with high activity may contribute significantly to the public radiation exposures. Secondly, radon and radium can be useful in tracing underground water transport. From the public health point of view, the investigation of the radon and radium content of drinking and mineral waters and the estimation of their contribution to the radiation exposure are our current tasks nowadays. People have had an increasing interest in the comsumption of bottled mineral waters due to the wordwilde decrease of good quality drinking waters. The consumption of mineral waters is significantly increasing from year to year in Europe and in Hungary, as well. Both drinking and natural mineral waters originate from different aquifers, situated at different depths below the surface. Thus, they represent a wide variety of mineral and radionuclide content, and sometimes extremely high values can also be observed. The daily consumption of mineral waters with high 226Ra content and of waters with high 222Rn content may have a significant contribution to the internal natural radiation exposure of the population. For this reason, the permissible activity concentration of radium and radon in drinking waters is limited in numerous countries. However, in Hungary there are no limitations, and even relating measurements of radioactivity of mineral waters were very occasional, and many of them took place only in the last years. 222Rn and 226Ra isotopes can be found in the environment in trace amounts, but due to their radioactivity they are easily measurable. Consequently, they are favourable natural tracers of near-surface and underground water transports. The 226Ra content of natural waters can give information related to their origin, mixing and underground path. Moreover, the 226Ra content of waters flowing from recultivated uranium vaste dumps and troughs can indicate directly the state of the covering layer. It is obvious that a simple, low-cost and reliable radium measuring method in permitting a large number of measurements is of great value, because an increasing interest in radioactivity determinations of natural waters can be expected in the very near future.