Nitrate records of a shallow ice core from East Antarctica: Atmospheric processes, preservation and climatic implications

Abstract

High-resolution records of nitrate (NO sub(3) sup(-)), oxygen isotope (delta sup(18) O) and non-sea salt sulphate (nssSO sub(4) sup(2-)) were studied using an ice core collected from central Dronning Maud Land in East Antarctica to identify the influence of environmental variability on accumulation of NO sub(3) sup(-) over the past 450 years. The results confirmed that multiple processes were responsible for the production and preservation of NO sub(3) sup(-) in Antarctic ice. Correlation between NO sub(3) sup(-) and nssSO sub(4) sup(2-) peaks revealed that sulphate aerosols released during major volcanic eruptions might have activated the production of nitric acid, which was scavenged by ion-induced nucleation in polar ice sheets. The correlation between the nitrate and delta sup(18) O records further suggest that enhanced NO sub(3) sup(-) preservation in the ice occurred during periods of lower atmospheric temperature. Major shifts in the NO sub(3) sup(-) record of the ice core presently studied and its comparison with 10Be record from a core collected from South Pole suggest that a reduction in solar activity influenced the NO sub(3) sup(-) accumulation in Antarctica through enhanced production of odd nitrogen species