Multiparametric approach for chemical dating of snow layers from Antarctica

A dating method for successive snow layers is proposed which is based on a combination of concentration profiles of three chemical parameters measured for each sample: H2O2, MSA, and nssSO(4)(2-). In the studied area (Northern Victoria Land, Antarctica), these substances demonstrate a clear seasonal character with summer maxima and winter minima which together can constitute an univocal annual indicator. The proposed method involves searching for maximum values and normalizing the concentration/depth profile of each substance; a smoothed sum of the contribution for each component, for each depth value, gives a resulting profile which is better adapted to objective interpretation of the seasonal trends. This method is applied to the dating of snow and firn samples coming from two snowpits and one shallow firn core at three different stations, which are found at different altitudes and distances from the sea, within approximately 200 Km from the Italian base at Terra Nova Bay. The variations in concentration of the three substances with depth were examined and the relative trends were evaluated as a function of the geographic position of the sampling stations.