Abstract
The study of atmospheric aerosols through polar ice cores is one of the most common and robust tools for the investigation of past changes in the circulation and chemistry of the atmosphere. Only a few subannual resolution records are available for the development of paleochemical and environmental interpretations. Here, we report the ionic content record for the period of 1882–2008 A.D. in an ice core recovered at the ice divide of the West Antarctic Ice Sheet. The ion concentrations found in the core were determined by ion chromatography on more than 2,000 samples and the basic statistics were calculated for major inorganic and organic ions. The dating of the core layers was based on the seasonality of SO 4 2‑ , NO 3 - , and Na + , checked by the identification of the Krakatau (1883), Agung (1963) and Pinatubo/Hudson (1991) volcanic eruption signals. Significant aerosol input events were identified and grouped considering the ions present, their provenance and the season. The ionic balance, together with the decomposition of some origin indicators, showed that 36% of the ionic charge is derived from sea salt aerosols, 13% from mineral dust, and 17% from biogenic marine activity, while 34% are mainly products of chemical reactivity in the atmosphere.
Highlights
The chemical investigation of polar ice cores is an excellent tool in paleoclimatology, especially due to its wide environmental representation when compared to other existing paleoclimatic techniques
The carboxylic groups HCOO, H3CCOO- and C2O42- represent less than 5% of the total anionic content estimated, while the major anions compose more than 92%, including Cl- (38%), NO3- (33%) and SO42- (22%)
The results indicate that approximately 51% of Mg2+ content, 27% of Ca2+, 47% of K+, 86% of Cl- and 15% of SO42- measured are from sea salt aerosols, which represents approximately 36% of the total ionic load present during the 1882–2008 A.D. period
Summary
The chemical investigation of polar ice cores is an excellent tool in paleoclimatology, especially due to its wide environmental representation when compared to other existing paleoclimatic techniques. An ice core is a reliable local record of past atmospheric conditions that may be representative for a region. It can be especially useful for regions with limited instrumental records. There is a lack of long-term records useful for improvement of climate models and for assessment within, at least, the time scale of the last two centuries. The ionic content in snow is widely used to study atmospheric aerosols. The characterization of most ionic variability profiles obtained provides the first understanding to investigate and assess atmospheric aerosols, which in turn are proxies linked with long transport pathways, environmental conditions of source regions, and chemical kinetics in the past atmosphere. With other trace chemical species, the contents of the main ions found in ice cores are used to provide co-registered paleochemical records
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