It is generally observed that precipitation is gradually depleted in ¹⁸O and ²H isotopes as elevation increases (‘altitude’ effect) or when moving inland from seacoasts (‘continental’ effect); the regionally accurate estimation of these large-scale effects is important in isotope hydrological or paleoclimatological applications. Nevertheless, seasonal and spatial differences should be considered. Stable isotope composition of monthly precipitation fallen between January 2016 and December 2018 was studied for selected stations situated along an elevation transect and a continental transect in order to assess the isotopic ‘altitude’ and ‘continental’ effects in modern precipitation across the Adriatic–Pannonian region. Isotopic characteristics argue that the main driver of the apparent vertical depletion of precipitation in heavy stable isotopes is different in summer (raindrop evaporation) and winter (condensation), although, there is no significant difference in the resulting ‘altitude’ effect. Specifically, an ‘altitude’ effect of −1.2‰/km for δ¹⁸O and −7.9‰/km for δ²H can be used in modern precipitation across the Adriatic–Pannonian region. Isotopic characteristics of monthly precipitation showed seasonally different patterns and suggest different isotope hydrometeorological regimes along the continental transect. While no significant decrease was found in δ¹⁸O data moving inland from the Adriatic from May to August of the year, a clear decreasing trend was found in precipitation fallen during the colder season of the year (October to March) up to a break at ~400 km inland from the Adriatic coast. The estimated mean isotopic ‘continental’ effect for the colder season precipitation is −2.4‰/100 km in δ¹⁸O and −20‰/100 km in δ²H. A prevailing influence of the Mediterranean moisture in the colder season is detected up to this breakpoint, while the break in the δ¹⁸O data probably reflects the mixture of moisture sources with different isotopic characteristics. A sharp drop in the d-excess (>3‰) at the break in precipitation δ¹⁸O trend likely indicates a sudden switch from the Mediterranean moisture domain to additional (mainly Atlantic) influence, while a gradual change in the d-excess values might suggest a gradual increase of the non-Mediterranean moisture contribution along the transect.

Multi-elemental (Ca, Mg, Na, K, Al, As, Ba, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Tl, V, and Zn) and stable isotope (i.e., δ²H, δ¹⁸O, and δ¹³C_DIC) analyses were performed on 13 (8 Slovenian and 5 imported) bottled mineral and spring waters from the Slovenian market. In addition, ⁸⁷Sr/⁸⁶Sr isotope ratios were determined for the first time. In all analyzed bottled waters, the majority of elements were present although in low concentrations, and according to EU legislation, all were suitable for human consumption. Also, concentrations of major elements (Ca, Mg, Na, and K) were in general agreement with the values reported on the bottle labels, and any differences were the consequence of the natural variability of the water source used for bottling. The exception was one spring water, for which the source location changed, which was confirmed by the δ²H, δ¹⁸O, and δ¹³C_DIC data. Two mineral waters had distinctive elemental compositions due to the particular geology of their recharge areas. The δ¹³C_DIC was also investigated to decipher the carbonate contribution in the bottled waters. The results suggest that dissolution of carbonates and non-equilibrium carbonate dissolution by carbonic acid produced from soil zone CO₂ are the predominant geochemical processes influencing the δ¹³C_DIC values of bottled water.