The article synthesizes available information on isotopic composition of precipitation in Slovakia (the Western Carpathians). Monthly δ 18 O data from eleven stations and period 1988-1997 were used to investigate correlations among the stations, altitude, air temperature and precipitation amount effects. The mean annual altitude and air temperature gradients of δ 18 O in precipitation were 0.21‰/100 m and 0.36‰/1°C, respectively. Maps of spatial distribution of mean annual δ 18 O in precipitation based on both gradients were constructed. The two maps do not significantly differ for the majority of Slovakia. δ 2 H data were available for only three stations. Local meteoric water line derived for the station with the longest data series (δ 2 H = = 7.86δ18 O + 6.99) was close to the Global Meteoric Water line. Its parameters in periods 1991-1993 and 1991-2008 did not change. The study indicates that a more detailed monitoring of isotopic composition of precipitation in mountains should be carried out in the future. The highest station exhibited very small seasonal variability of δ 18 O in precipitation compared to other Slovak stations. The second highest mountain station had significantly higher deuterium excess than the neighboring stations located in the valley. In some analyses the data from the nearest stations situated abroad (Vienna, Krakow) were used.

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Izvleček UDK 556.3(437.6) Peter Malík & Juraj Michalko: Izotopi kisika v različnih podrežimih recesije kraških izvirov v Brezovskih Karpatih (Slovaška) Za povezovanje maj�ni� podatkovni� skupin vzorcev z različnimi �idrološkimi razmerami je bila razvita metoda separacije �idrograma kraški� izvirov, ki temelji na �itrem iterativnem reševanju več enostavni� eksponentni� in linearni� enačb. Metoda temelji na predpostavki, da je pretok izvira odvisen od stopnje zasičenosti vodonosnika s podzemno vodo, in da je enak pretok posledica enake zasičenost vodonosnika s podzemno vodo (piezometrični nivo). Vsak izvir la�ko opišemo z edinstvenim nizom konstantni� začetni� pretokov, vrednosti Q 0 , koeficientov recesije α (komponente laminarnega toka v eksponentni� enačba�) in ß (komponente turbulentnega toka v linearni� enačba�). Vsak podrežim la�ko določimo z analizo krivulje recesije za celotne časovne serije pretokov izvirov. Pri tej separaciji �idrograma je vsaka merjena vrednost pretoka, Q t , določena z reprezentativnim časom, t; to je teoretično preteklim časom t od skupnega maksimalnega pretoka Q max. Namen procesa iteracije je dobiti ta reprezentativni čas t za vsak pretok. Posamezne komponente toka so izračunane z uporabo isti� vrednosti t. Te spremembe v pretoki� podrežima v določenem trenutku la�ko povežemo s komponentami, analiziranimi v istem trenutku, da bi dobili končne člene teoretične mešanice. Ta te�nika je bila razvita in uporabljena na časovni� serija� pretokov štiri� kraški� izvirov v Brezovski� Karpati� (Slovaška), ki ji� gradijo predvsem zakraseli srednje in zgornje triasni dolomiti in apnenci. Podzemna voda posamezni� izvirov je bila opredeljena z vrednostmi δ 18 O (SMOW) in temperature, izračunani pa so bili končni členi dve� laminarni� in enega turbulentnega podrežima. Rezultati temeljijo na redki� nizi� podatkov in ročno izmerjeni� pretoki�, a predstavljajo perspektivno metodo za nadaljnjo obdelavo in intepretacijo pri omejeni količini podatkov.

Ideally, groundwater vulnerability assessment should take into account potential contaminant breakthrough curve, characterized by transit time, relative change of contamination concentration (input/output) and duration of overstepped concentration. Still, a majority of groundwater vulnerability assessment methods that tend to be more physically based count only with the value of mean transit time (MTT), the elapsed time when groundwater can exit the aquifer after its recharge. In this paper, indicative values of MTT derived from single d 18 O sampling values were used to estimate intrinsic vulnerability of individual springs occurring on the Muránska planina Plateau (Slovakia). For 295 springs sampled within 10 days, d 18 O was found in the range between -10.90 and -7.32 %, without signs of altitudinal effect. According to International Atomic Energy Agency (IAEA) Global Network of Isotopes in Precipitation (GNIP) stations, significant contrast in precipitation d 18 O values was found several weeks before sampling. Indicative MTT value, e max MTT (estimated longest possible mean transit time), was calculated from sine wave course of monitored precipitation isotopic composition, d 18 O value in the spring groundwater sample and altitudes of sampled point and precipitation station. Estimated e max MTT values suggest that heavier oxygen isotopes in samples probably reflect quick circulation and a more vulnerable environment as influenced by enriched summer precipitation. Depleted d 18 O suggests lower vulnerability represented by higher e max MTT values.