Variations of δ18O in Rivers of Crimea in Winter

The results of studies of variations of delta O-18 values in river water in Crimea Peninsula in January-February 2015-2017 are given. The variation range of delta O-18 in river water over the three years of studies never exceeded 3 parts per thousand. A tendency toward an increase in delta O-18 in the water of the Salgir, Kacha, Al'ma, Bel'bek, Biyuk-Karasu from their sources to mouths was identified and explained by a decrease in evaporation in the mouth areas of the rivers relative to their sources and upper reaches, and the inflow of isotopically light precipitation (rain and snow) into the rivers in their upper reaches. The values of delta O-18 in waters of the rivers with regulated stream were found to increase under the effect of the Simferopol Reservoir on the Salgir River and the Izobil'nenskoe Reservoir on the Ulu-Zen' River. The values of delta O-18 in the upper reaches of the large rivers of Kacha and Bel'bek (the northwestern slope of the Crimean Mountains) vary from -8.7 to -9.7 parts per thousand, except for the rivers of Al'ma (-7.7 parts per thousand) and Kokozka (-10.2 parts per thousand) because of the different shares of groundwater in the recharge of these rivers.