engleski

Isotopic Altitude Effect of Precipitation in the Kvarner Bay and the Surrounding Area(Croatia)

The precipitation as input into the water system and its stable isotope composition has to be known for the proper use and management of water resources. The Kvarner bay is a particularly interesting example due to its climate and the geomorphology, featuring high mountains quite close to the Adriatic Sea. The influence of elevation on the isotopic composition has already been examined for Mountain Učka ; a mixing layer of the precipitating air mass on the very top has been found to cause a deviation from the approximately linear behaviour of the δ18O altitude effect. A further specific local condition in the area is the comparatively large amount of precipitation (up to about 1600 mm/year, usually concentrated in a few months during the colder season). This amount effect is known to have a significant influence on the isotope composition of the precipitation, too, in general causing a depletion of the heavier isotopes δ18O in the order of −0.1‰ /100mm. We have now established a rather large density of precipitation collection stations in this area to obtain a better insight into the expected and possibly strong δ18O variations within short spatial distances. Depending on the exact location, the mean δ18O values vary with altitude at a rate of approximately −0.2‰ /100m. Also δ2H and the deuterium excess d = δ2H − 8δ18O is found to depend on location and altitude.

altitude effect; stable isotopes; precipitation; Local Meteoric Water Line; Kvarner bay

nije evidentirano