This award will allow the measurement of stable isotopes on the new deep ice core and surface snow collected at Summit, Greenland as part of the second Greenland Ice Sheet Project (GISP II). The investigation will measure and interpret stable hydrogen isotope ratios (del D values) and, in collaboration with Dr. Pieter Grootes, University of Washington, will measure and interpret deuterium excess values. Del D and del 18 O values in ice cores change in response to changes in paleotemperatures, the rate of snow accumulation, and the elevation of the ice sheet at the core site. Del D and del 18 values are also useful in counting annual snow layers during the Holocene, and are thus helpful in dating and in determining accumulation rates during this period. Deuterium excess values will also be used to reconstruct evaporation conditions over the ocean, information needed to interpret delta values as well as to infer shifts in the moisture source regions over the ocean during the past.
