Stable isotope composition of precipitation and temperature seasonal distribution from the South Carpathians: insights for climate variations in the interval 2012 to 2025

Isotope distribution in precipitation along with climate monitoring data such as amount of precipitation, temperature and relative humidity were collected from a region characterized by a high continentality index, region situated in the external sector of the Southern Carpathians. Stable isotope composition of hydrogen and oxygen in precipitation were collected monthly from 2012 to 2025, with climate monitoring measured automatically each 30 minutes. The isotope and temperature signals were split in two groups including October to April and May to September, variations over an interval of 14 years being statistical presented. For the intervals considered, the LMWL show the effect of secondary evaporation of falling raindrops with lower slope for the warm season. The data support significant relationships between d18O and d D values and average air temperatures with r2 = 0.7, n = 150. Deuterium excess values over the year are compatible with seasonal variations for the origin of moisture, with high values during wintertime, possible resulting from the input of seasonal related Mediterranean moisture during November to February. The strong seasonal distribution of precipitation amount combined with elevated temperature peaks during July have a strong impact on the clastic multi-layered aquifers situated in the Lower Quaternary deposits, driving during the last years to complete evaporation of the highest aquifer.