Possible Chemical Transformations in Snow and Ice Induced by Solar (UV PHOTONS) and Cosmic Irradiation (MUONS)

Abstract

Over the last decade there has been a growing interest in the chemical composition of the snow packs in the polar regions (Bales and Wolff, 1995). Delmas (Delmas, 1992; Delmas, 1994) has noted that “information recorded in polar ice cores over the last several hundred millennia is invaluable to studies aimed at understanding the pre-industrial environmental system and anticipating the future evolution of the climate and the atmosphere.” For example, the isotopic composition of the ice (H_2O) matrix is a reliable paleothermometer. From the analysis of deep Antarctic and Greenland ice cores the ice age environmental conditions appeared to correspond to about 6 °C cooler temperatures and atmospheric CO_2 and CH_4 levels lower by factors of nearly 2 and 4, respectively. The biogeochemical cycles of S and N also appear to be affected by climatic changes that result in modifications in the source intensity and the transport of gaseous precursors. Even though atmospheric sulfate is derived principally from marine biogenic sources (i.e., dimethyl sulfide emission), cataclysmic volcanic eruptions can contribute sporadically to the atmospheric sulfur budget through large point source emissions of SO_2. These events are ultimately detected in polar ice as H_2SO_4 spikes. Nitrate, which is the next most abundant anion found in polar snowfall, exhibits concentration changes that are poorly understood, but which could be linked with the polar ozone hole formation. In addition to ions derived primarily from gas-to-particle conversions, continental dust and sea-spray aerosol components are also present in the ice at much higher concentrations during ice ages than during interglacial periods due to an intensification of their production and long range transport under glacial climatic conditions.