A 100 year record of ion chemistry from Agassiz Ice Cap Northern Ellesmere Island NWT, Canada

Two ice cores from the top of Agassiz Ice Cap, one from a snow scoured and the other from an unscoured zone, cover 80 and 100 yr of snow deposition respectively. The time scale for the cores is based on seasonal ion signals, a known stratigraphic horizon (1962), and a marked volcanic signature of high SO2-4, representing Katmai (1912). A marked increase in the SO2-4 and NO-3 ion which began in the middle of the 19th century is compared with the earlier increase in Greenland and attributed to a different combination of aerosol sources. A case is made for dry deposition of ions in winter, based on the continued presence of winter ion peaks at a site that δ18O indicates has almost no winter snow accumulation. This case is supported by the snowfall record at a nearby Automatic Weather Station, which shows there is very little winter snowfall at these sites, and by the fact that different accumulation rates and ion concentrations at each site effect almost the same ion fluxes. There is no evidence in either of the cores for a change in the levels of pollutant NO-3 and SO2-4 ion concentrations, due to improvement in emission technologies in the western nations, over the last two decades. The lack of change may indicate that Russia is the dominant source for aerosols at this site.