Acta Facultatis Ecologiae - Technická univerzita vo Zvolene

136AA ( 222 Rn) [kBq/m 3 ]precipitation [mm]snow cover [x10 -2 m]120100806040200V-1 (10m) 20070Rnrain1snow water23456789100 30 60 90 120 150 180 210daywater level [m]B V-1 (10m) 2007 CV-1 (10m) 20078080R 2 = 0.44R60= 0.76604040202000642w ater level [m]10 8 6w ater level [m]A ( 222 Rn)kBq/m 3 ]A ( 222 Rn)[kBq/m 3 ]4Fig. 3 The courses of the 222 Rn activity concentration in water, precipitation amount, the state of the waterlevel and snow cover in V-1 since January to July 2007 (A). The negative correlation between 222 Rnactivity concentration in water and the state of water level in borehole was observed (B). If the waterlevel in borehole was less than 6 m, the positive correlation between those variables appeared (C).V–2 BOREHOLEThe V-2 borehole is the deepest one and it containedwater during the whole studied period duringboth years of our research. The radon concentrationin borehole water reached the highest valuesamong all investigated samples.No perceptible influence of precipitation tothe state of water level or to the changes of radonconcentration in water was recognized in this borehole.From January to July 2006 one conspicuousmaximum of 222 Rn activity concentration was noticed.It was observed in March, at the beginningof the snow cover melting. Radon concentration inborehole water attained more than 150 kBq/m 3 .A rapid snow melting, lasting approximatelyten days in March 2006, created a large amount ofwater that increased the water level in this boreholeabout 5 m. Simultaneously, the radon concentrationin water decreased. Since April the water levelin borehole stayed at the level about 2 m lower incomparison to previous state before snow melting.During the studied period in 2007 a very expressivemaximum of 222 Rn activity concentrationappeared. The values of radon concentration reachedup to 240 kBq/m 3 . It was not connected withsnow melting or precipitation. Those high valueslasted during whole April, since then the radonconcentration started to fall. The previous statewas reached approximately after three months. Thedecrease of radon concentration was much smallerin comparison to the radon decay.In 2007 no significant rise of water causedby snow melting was observed, due to the lack ofsnow. Similarly, the characteristics of the V-2 boreholewere not affected by precipitation likewisethan in the previous year, only with one exception.A strong precipitation with 40 mm amount of waterper day increased the water level about 1 m for oneday in June. Equally the radon concentration in boreholewater increased after this rainfall. After thatboth the values of 222 Rn activity concentration andthe height of water level returned to the previousstate quickly.