Annual measurements of atmospheric carbon monoxide concentrations and isotopic ratios from Arrival Heights, Ross Island since June 1991

Carbon monoxide (CO) is a trace gas in the atmosphere. Although it occurs naturally in the atmosphere at very low concentrations, it may contribute to the greenhouse effect and concentrations are increasing due to anthropogenic activity. The use of the radioactive isotope 14C in carbon monoxide is useful for determining the oxidative capacity of the atmosphere via oxidation by hydroxyl (OH). Large whole air samples (1000-1400L) are collected from a compressor system at Arrival Heights annually (since 1991) and samples are analysed for CO concentrations and isotopic ratios of 14C and 13C to assess the characteristics and fluxes of sources and sinks of CO. CO is extracted as CO2 by selective combustion techniques and the 13C/12C and 18O/16O isotopic ratios are determined. Sample collection is aimed at the clean sector of the sky from the West through North to East, throughout the year. Measurements of CO carbon isotopes and its concentration in the atmosphere in Antarctica will help to determine the geographic variation, transport and the type and distribution of the sources of CO from the northern hemisphere.