The Peroxide Record from the DSS Ice Core, Law Dome, Antarctica: Preliminary Results

Abstract

Hydrogen peroxide is a major trace constituent of polar ice cores, and is the only archived species so far detected that reflects atmospheric oxidation capacity (Neftel & Führer 1993). As has been noted by Neftel (this volume) and Bales & Choi (this volume) our ability to interpret this archived record is limited by our lack of understanding of the atmosphere to snow transfer function. The Law Dome site, and in particular the Dome Summit South (DSS) ice core, offers distinct features which may well shed light on the difficult issue of the atmosphere/ice relationship. Firstly, the high accumulation rate (0.7 m/yr ice equivalent) leads to well preserved seasonal cycles which, in conjunction with atmospheric measurements or models, should provide useful constraints on exchange processes. Secondly, the climatology of the site (mean temperature −20.8°C) leads to a near total absence of summer melt, which is known to interfere with both measured peroxide levels and diffusion processes in the firn. Thirdly, and related to the first point, there is a significant gradient in accumulation across Law Dome. This means that the timescale of firnification differs significantly between the DSS core and other sites which sample the same air mass (e.g. DE08, 16 km from DSS, with approximately twice the accumulation rate). Consequently if post-industrial changes in H₂O₂ levels are detected (Sigg & Neftel 1991), these can be distinguished from firnification effects.