Seasonal Variations in Hydrogen Peroxide in Polar Ice Cores

Abstract

Hydrogen peroxide is present in polar snow and ice in remarkably high concentrations. With values up to 300 ppb, H2O2 is one of the most concentrated impurities in polar ice. We present a continuous H2O2 firn record from Siple Station (Antarctica); it covers the last 83 years with a resolution of 10–20 samples per year. A very strong seasonality is present in this record. This seasonality is also observed in a Greenland ice core from Dye 3, where we have continuously measured the top 10 m with the same resolution. The maximum concentrations correspond to summer snow layers and can exceed winter snow concentrations by a factor of 10. This property makes H2O2 a useful tracer for dating suitable cores by counting annual layers. The different steps needed to relate the atmospheric to the ice–core H2O2 concentration are discussed. As with isotopic tracers, diffusion in the firn smooths the original H2O2 concentration profile.