Overview of isotopic investigations of groundwaters in a fractured aquifer system near Rogaška Slatina, Slovenia

Abstract

The isotopic investigations of groundwaters stored in the Rogaška Slatina fractured aquifer system were performed in the periods 1978-1985 and 2007-2011 aiming at answering open questions on the groundwater recharge and dynamics, on connections between different types of aquifers and on solute transport. Environmental isotopes 2 H, 18 O, 3 H, 13 C of dissolved inorganic carbon and 14 C were analysed in mineral, thermo-mineral and spring waters. Results indicated the source and mechanism of groundwater recharge, its renewability, a transit time distribution, hydraulic interrelationships, the groundwater origin and its evolution due to effects of waterrock interaction. They proved the hypothesis that the Boča massif should be a catchment area of the Rogaška mineral waters. The estimates of the mean residence time of mineral waters in the aquifer system are between 7200 and 3400 years, depending on the location and depth. Thermo-mineral water is the oldest water in the study area with the mean residence time of 14000 years. V obdobjih 1978-1985 in 2007-2011 so bile izvedene izotopske raziskave podzemne vode, uskladiščene v razpoklinskem vodonosnem sistemu na območju Rogaške Slatine, z namenom, da se odgovori na odprta vprašanja o napajanju podzemne vode in njeni dinamiki, o povezavi različnih vrst vodonosnikov in o prenosu snovi. V mineralnih, termomineralnih in izvirskih vodah smo analizirali 2 H, 18 O, 3 H, 13 C v raztopljenem anorganskem ogljiku in 14 C. V rezultatih smo opisali vire in mehanizme napajanja podzemne vode, njeno obnovljivost, zadrževalni čas v vodonosniku, izvor in geokemijski razvoj zaradi reakcij s kamninami. Potrdili smo hipotezo, da je masiv Boč napajalno območje Rogaških mineralnih vod, ki se zadržujejo v vodonosniku s povprečnim zadrževalnim časom od 7200 do 3400 let. Le ta je odvisen od lokacije in globine. Termomineralna voda je starejša -njen povprečen zadrževalni čas je 14000 let. Izvleček

Chemical and isotopic composition of CO2-rich magnesium–sodium–bicarbonate–sulphate-type mineral waters from volcanoclastic aquifer in Rogaška Slatina, Slovenia

“…We agree with previous interpretations on local meteoric origin of waters (Pezdič, 1997;Trček & Leis, 2017) and identification of CO 2 degassing (Clark & Fritz, 1997) at two end-members (Brenčič & Vreča, 2014;Trček & Leis, 2017): mineral water from andesitic aquifer (V-3/6-70, RgS-2/88) and Kraljevi vrelec, where freshwater mixes with naturally outflowing mineral water. We supplement these data with additional sample K-2/75 which is positioned in between (Fig.…”

“…It is interesting that the other well with Fig. 6 Carbon isotopes in dissolved inorganic carbon (DIC) for sampled waters (d 13 C DIC ) where Rt-1/92 and grey circles denote previous information from Pezdič (1997) and Trček and Leis (2017). Four processes are marked (Kanduč et al, 2014) freshwater intrusions, K-2/75, has almost double the radiocarbon concentration even though it is much deeper.…”

“…Its maximum production rate is estimated to about 1.5 l/s per a well and the average production is only about 0.5 l/s. The water could be produced from five wells (Nosan, 1973(Nosan, , 1975Trček & Leis, 2017): V-3/66-70 (for depths of interpreted wells, see Table 1), V-6/67 (265 m), K-2/75, K-2a/86 (534 m deep) and RgS-2/ 88. The latter borehole was unsuccessful; therefore, it was deepened in 1990 when the mineral water was successfully captured.…”

“…Groundwater residence time calculation is a major challenge in reservoirs where deep degassing or water-rock-gas interactions occur along the flow paths. We evaluated the potential effects on the apparent age (t) calculations by several equations (as reported in Clark & Fritz, 1997;Friedlander et al, 1981;Ingerson & Pearson, 1964;Sz} ocs et al, 2013;Trček & Leis, 2017…”

The effect of geochemical processes on groundwater in the Velenje coal basin, Slovenia: insights from mineralogy, trace elements and isotopes signatures

“…Similar, δ 13 C CO2gas values occur in thermal and mineral springs in the fractured aquifer system near Rogaška Slatina (Slovenia) and bottled waters [69,70]. Other nearby thermal waters, e.g., Dobrna Topolščica, Hotavlje and Bled, have δ 13 C DIC values between − 7 and − 2‰, supporting the hypothesis that there is an input of deep, geogenically Previous studies show that δ 13 C CO2 and δ 13 C CH4 values in Pliocene coal beds were highly variable, i.e., − 9.7 to + 0.6‰ and − 70.5 to − 34.2‰, respectively [45].…”