Title：Nitrate Deposition and Preservation in the Snowpack Along a Traverse from Coast to the Ice Sheet Summit (Dome A) in East Antarctica
Journal/Publisher：The Cryosphere
Year：2018
Authors：Guitao Shi, Meredith G. Hastings, JinhaiYu, Tianming Ma, Zhengyi Hu, Chunlei An, Chuanjin Li, Hongmei Ma, Su Jiang, and Yuansheng Li
Abstract
Antarctic ice core nitrate (NO− 3 ) can provide a unique record of the atmospheric reactive nitrogen cycle. However, the factors influencing the deposition and preservation of NO− 3 at the ice sheet surface must first be understood. Therefore, an intensive program of snow and atmospheric sampling was made on a traverse from the coast to the ice sheet summit, Dome A, East Antarctica. Snow samples in this observation include 120 surface snow samples (top ∼3cm), 20 snow pits with depths of 150 to 300cm, and 6 crystal ice samples (the topmost needle-like layer on Dome A plateau). The main purpose of this investigation is to characterize the distribution pattern and preservation of NO− 3 concentrations in the snow in different environments. Results show that an increasing trend of NO− 3 concentrations with distance inland is present in surface snow, and NO− 3 is extremely enriched in the topmost crystal ice (with a maximum of 16.1µeqL−1). NO− 3 concentration profiles for snowpitsvarybetweencoastalandinlandsites.Onthecoast, the deposited NO− 3 was largely preserved, and the archived NO− 3 fluxes are dominated by snow accumulation. The relationship between the archived NO− 3 and snow accumulation rate can be depicted well by a linear model, suggesting a homogeneity of atmospheric NO− 3 levels. It is estimated that dry deposition contributes 27–44% of the archived NO− 3 fluxes, and the dry deposition velocity and scavenging ratio for NO− 3 were relatively constant near the coast. Compared to the coast, the inland snow shows a relatively weak correlation between archived NO− 3 and snow accumulation, and the archived NO− 3 fluxes were more dependent on concentration. The relationship between NO− 3 and coexisting ions (nssSO2− 4 , Na+ and Cl−) was also investigated, and the results show a correlation between nssSO2− 4 (fine aerosol particles) and NO− 3 in surface snow, while the correlation between NO− 3 and Na+ (mainly associated with coarse aerosol particles)isnotsignificant.Ininlandsnow,therewerenosignificantrelationshipsfoundbetweenNO− 3 andthecoexisting ions, suggesting a dominant role of NO− 3 recycling in determining the concentrations.
