Stable water isotope data (δ18O and δ2H) of monthly precipitation from 2021 to 2023 (NW Croatia)

The stable water isotopic composition (δ18O and δ2H) of monthly precipitation from three locations in north-western Croatia is presented. Rain sampler RS1B, manufactured by Palmex, was used to collect cumulative monthly precipitation samples on three locations: Petrov vrh peak near Daruvar town (45.58817°N, 17.31188°E, 550 masl ); Lobor water pumping station (46.17441°N, 16.05755°E, 325 masl); Hrvatsko Žarište village, near the town of Vojnić (45.31958°N, 15.63002°E, 175 masl). The dataset consists total of 72 precipitation samples collected during the period from March 2021 to March 2023. Stable hydrogen and oxygen isotope analyzes of the samples were carried out using a Picarro L2130-i Isotope analyzer, with a precision of 1‰ for δ2H and 0.2‰ for δ18O. Results are presented in δ-notation (‰) normalized to the international standard VSMOW (Vienna Standard Mean Ocean Water). Additionally, the d-excess values for each sample and the Local meteoric water lines (LMWL) for each location were calculated, considering precipitation amounts. The objective of acquiring the presented data in the scope of the project was the comparison of naturally emerging thermal water at the springs in Croatia with modern precipitation.