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, H 2 O 2 is one of the most concentrated impurities in polar ice. We present a continuous H 2 O 2 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 H 2 O 2 a useful tracer for dating suitable cores by counting annual layers. The different steps needed to relate the atmospheric to the ice–core H 2 O 2 concentration are discussed. As with isotopic tracers, diffusion in the firn smooths the original H 2 O 2 concentration profile.