engleski

Isotopic characteristics of precipitation in Slovenia and Croatia: Comparison of continental and maritime stations

Stable isotopic composition of hydrogen and oxygen (d2H and d18O) and tritium activity (3H) were monitored in monthly precipitation at two continental stations (Ljubljana, Zagreb) and six stations along the eastern Adriatic coasts of Slovenia and Croatia in the period 2001 &#8211; 2003. Mean air temperatures and amount of precipitation were also recorded. Distinct differences in both meteorological and isotopic data between the continental and maritime stations were observed. Seasonal variations in &#948; 18O are smaller at the maritime stations than at the continental ones due to smaller seasonal temperature variations. Good correlation between the &#948; 18O and &#948; 2H was obtained for each station, and the Local Meteoric Water Lines are close to the Global Meteoric Water Line with the decreasing trend of slope for the south-Adriatic stations (<7). Good correlations between the &#948; 18O in monthly precipitation and mean monthly air temperature were observed at all stations. The slope of &#948; 18O vs. T varied between 0.37&#8240; /°C and 0.15&#8240; /°C. Mean 3H activity and seasonal variation of 3H activity are smaller at maritime stations than at the continental ones. Additionally, 3H activity decreases in the NW-SE direction of the Adriatic coast. The study of spatial variations over this relatively small area rich in geographical and climatic diversities showed the complexity of the isotopic composition of precipitation and the need for better knowledge and/or monitoring. However, the isotopic data obtained for monthly precipitation over the 3-years period at 8 stations, most of them in the karstic area along the Adriatic coast, represent a necessary input data in regional hydrological investigations and will also enable better modelling of isotope variability over the Mediterranean basin.

tritium; stable isotopes; 2H; 18O; precipitation; atmosphere; hydrology; meteorology

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