Snow chemistry of Agassiz Ice Cap, Ellesmere Island, Northwest Territories, Canada

AbstractPit-wall samples were collected from two sites about 2 km apart on Agassiz Ice Cap, Ellesmere Island, Northwest Territories, Canada, in 1992, 1993 and 1994, and from a site a further 1 km distant, in order to study spatial and seasonal variations in snow chemistry. Two of the pits were dug in wind-scoured zones and one in an unscoured zone. Although a large part of the winter snow is removed from the scoured zones (which do not show very negativeδ18O values) the winter/spring anion peaks are still evident; this may be due to the predominance of dry deposition in mid-winter. The Cl−and SO42–ions peak in late winter/early spring, while NO3−peaks both in late winter/early spring and in summer. Vertical concentration profiles of all anions did not significantly alter over a 2 year period, indicating that there are no serious post-depositional changes due to evaporation, snow melting or photochemical reactions. However, comparisons between stake/board snow-accumulation measurements and those derived from the least scoured pit indicate that a single pit will represent annual accumulation rates for a local area only

Destiny profile of a 413.5 m deep fresh core recovered at Mizuho Station, East Antarctica

Within a month after the core recovery, the density data were obtained from the dimensions and the weights of the core samples and by the hydrostatic method. The density data were corrected for the surface effect with considerations of the bubble concentration and the average bubble size. A method has been presented to estimate the in situ density value (without cracks) from the nominal density data with cracked samples based upon the data on total gas content. This method has been applied to the data of deep portion (below 135m depth), where the core was cracked considerably. A reasonable depth profile of in situ density was thus estimated, which indicated that the shrinkage of trapped air bubbles was the main densification process of ice after the bubble close-off

Structure of 413.5-m deep ice core obtained at Mizuho Station, Antarctica

Ice cores down to a depth of 413.5m were obtained at Mizuho Station (70°41.9\u27S, 44°19.9\u27E), East Antarctica, in April to July, 1983. Grain features (size, periphery length and shape factor) and air bubble morphology were examined from thin section photographs taken within a month after the recovery of the ice cores. The showed discernible differences from those of the similar examinations previously done of ice cores of the same place recovered in 1972. The differences are attributed to the fact that the latter examinations were based on the photographs taken much later after the recovery. Fabric patterns were also examined at selected depths also within one month after the recovery