Comparison of the 14C Activity of Groundwater and Recent Tufa from Karst Areas in Yugoslavia and Czechoslovakia

Abstract

14C activity of dissolved inorganic carbon (DIC) in water and in recent tufa samples in several karst areas of Yugoslavia and Czechoslovakia was measured. Groundwater from 11 karst springs were measured for their isotopic content (14C, 3H, 13C), chemical composition (HCO3-, Cat2+, Mgt2+) and physico-chemical properties (temperature, pH). Seasonal variations of the 14C activity of DIC in two karst springs in Plitvice Lakes area, Yugoslavia, were measured systematically from 1979 -1987.14C activity of recent tufa samples from several locations downstream were also measured. The activity of DIC in karst spring water in both countries ranged from 63-87 pMC, which is attributed to differences in geologic structure of the recharge area, topsoil thickness and composition. Grouping of 1 C activities of DIC ca (82 +/- 4)% is evident. Tritium activity at all the springs indicated short mean residence time (1-10 yr). Concentration of HCO3-, Ca2+ and Mg2+ in spring water varied with geomorphology. 14C activity of streamwater and recent tufa increased downstream from karst springs due to the exchange between atmospheric CO2 and DIC.