Influence of meteorological elements on chemical evolution of snow and ice of Urumqi Glacier No. 1, eastern Tianshan Mountains

For most mountain glaciers, chemical components in snowfall are subject to the elution process under the influences of meltwater before they are preserved in ice, creating difficulties for interpreting ice core records. To understand the formation process of ice core records and analyze the influences of meteorological factors on the ice core resolution, we measured ion concentrations of snowpacks from 2003 to 2006 in the PGPI (Program for Glacier Processes Investigation) site of Urumqi Glacier No. 1. The ion concentration variation in snowpack exhibits apparent seasonality. In summer, the higher snowmelt rates due to air temperature rise intensify dilution and lead to an exponential decrease in ion concentrations as the accumulated positive temperature increases. In winter, the snow ion concentrations are stable and low as a result of reduced temperature and rare precipitation. Many ions from summer precipitation are leached out by meltwater, and only the precipitation that occurs at the end of the wet season can be preserved. Through tracking the evolution of magnesium ion peaks in the snowpack, it is concluded that the ice core resolution is one year on Urumqi Glacier No. 1, albeit 70% of the concentration information is lost.