Comparison of two ice-core chemical records recovered from the Qomolangma (Mount Everest) region, Himalaya

A 40.9 m ice core was recovered from Far East Rongbuk Glacier (FER), Qomolangma (Mount Everest), Himalaya, and an 80.4 m core from neighboring East Rongbuk Glacier (ER). Both are dated by seasonal variations of delta(18)O and major-ionic profiles, together with references of beta-activity peaks. In this paper we compare the chemical records of these two cores to show post-depositional modification processes. The smoothed delta(18)O profiles of the two cores show a similar trend. However, the mean delta(18)O value of the FER core for the period 1954-96 is 3.12parts per thousand less than that of the corresponding part of the ER core, and the major-ionic profiles of the two cores differ considerably. We suggest that melting-away of the snow layer deposited during the pre-monsoon season may account for lower delta(18)O values of the FER than of the ER core, and higher terrestrial ion concentrations in the FER core for the period 1957-63 may contribute to changes by chemical reactions in the presence of snowmelting. The significantly decreased NH4+ and, to a lesser degree, SO42- concentrations in the FER core could be caused by the ion elution process that moved most chemicals away with runoff.