STABLE ISOTOPES OF OXYGEN AND HYDROGEN IN THE TRUCKEE RIVER PYRAMID LAKE SURFACE-WATER SYSTEM .3. SOURCE OF WATER-VAPOR OVERLYING PYRAMID LAKE

During 1988 and 1989, a series of water-vapor extractions were conduct ed in the Pyramid Lake basin to determine the source of moisture that overlies the lake. Calculations of the isotopic and water-vapor balanc es were made from isotopic and meteorological data from the Pyramid La ke and Reno, Nevada, areas. The results indicate that in the warm seas on, most of the moisture that overlies the lake is derived from evapor ation as opposed to advected moisture. Isotopic fluxes at the lake sur face can be approximated by climatic data from the lake site, which si mplifies the calculation of this input in numerical simulations of the isotopic evolution of the lake.