Geochemistry of Ice and Ground Penetrating Radar Profiles in Mexican Glaciers

During the last 15 to 20 years the glaciated Mexican high mountains have lost some 30% or more of their glacier ice. Geologically these glaciers are important because they are the only mountain glaciers between Ecuador and Canada, and the only worldwide at 19° north latitude. We have drilled three shallow ice cores in the glaciers for chemical and isotopes analyze (two at Pico de Orizaba and one at Iztaccihuatl). A Ground Penetrating Radar (GPR) profile was archived using a 900 MHz antenna in order to asses the ice internal structure and thickness at the border of Jamapa Glacier at Pico de Orizaba. We used a GPR system Zond 12 C (by Radar Systems Inc). The GPR profile was oriented S20W and had a total length of 175 m. It was composed by 7 sections of 25 m length. According to the slope of the recorded diffraction hyperbolas the estimated velocity of propagation of electromagnetic waves was about 10.6 cm /ns (corresponding to a dielectric constant of 8). A coherent reflector was recorded approximately at 2.5 m depth that could be related to the frozen water depth. Moreover irregularities in the ground, cavities related to blocks and other slope deposits were also recorded for the first 2 m of depth. Such as those recorded between 5 to 10 m from the start of the GPR profile. Ice chemistry indicates some concentrations of Cl, NO3, SO4, Fe, Ni Cu, Zn, Pb and As, very likely from aerosols and atmospheric dust. We present correlations between this compounds and elements in the Iztaccihualt ice (relatively close to Mexico City atmospheric influence) and Pico de Orizaba ice (relatively far from any big city).