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Light-absorbing impurities (LAI) have the potential to substantially affect snow albedo, with subsequent changes on snow melt and impact on climate. To more accurately quantify the snow albedo, the contribution from different LAI needs to be assessed. Here we estimate the main LAI components, elemental carbon (EC) (as a proxy for black carbon) and mineral dust in snow from Indian Himalaya and compared it to snow samples from Arctic Finland. The impurities are collected onto quartz filters and are analyzed thermal-optically for EC, as well as with an additional optical measurement to estimate the light-absorption of dust separately on the filters. Laboratory tests were conducted using substrates containing soot and mineral particles specially prepared to test the experimental setup. Analyzed ambient snow samples show EC concentrations that are in the same range as presented by previous research, for each respective region. In terms of the mass absorption cross section (MAC) our ambient EC had surprisingly about half of the MAC value compared to our laboratory standard EC (chimney soot), suggesting a less light absorptive EC in the snow, which has consequences for the snow albedo reduction caused by EC. In the Himalayan samples, larger contributions by dust (in the range of 50% or greater for the light absorption caused by the LAI) highlighted the importance of dust acting as a light absorber in the snow. Moreover, EC concentrations in the Indian samples, acquired from a 120 cm deep snow pit (covering possibly the last five years of snow fall), suggest an increase in both EC and dust, while at the same time there is a tendency for a reduction in the MAC value with snow depth. This work emphasizes the complexity in determining the snow albedo, showing that LAI concentrations alone might not be sufficient, but additional transient effects on the light-absorbing properties of the EC need to be considered and studied in the snow. Equally imperative is to confirm the spatial and temporal representativeness of these data by comparing data from several and longer pits explored at the same time. [ABSTRACT FROM AUTHOR]

Arctic regions are generally nutrient limited, receiving an extensive part of their bio-available nitrogen from the deposition of atmospheric reactive nitrogen. Reactive nitrogen oxides, as nitric acid (HNO3) and nitrate aerosols (p-NO3), can either be washed out from the atmosphere by precipitation or dry deposited, dissolving to nitrate (NO3-). During winter NO3-, is accumulated in the snowpack and released as a pulse during spring melt. Quantification of NO3- deposition is essential to assess impacts on Arctic terrestrial ecology and for ice core interpretations. However, the individual importance of wet and dry deposition is poorly quantified in the high Arctic regions where in-situ measurements are demanding. In this study, three different methods are employed to quantify dry deposition around the atmospheric and ecosystem monitoring site, Ny-Ålesund, Svalbard, for the winter season (September 2009 to May 2010): (1) A snow tray sampling approach indicates a dry deposition of -10.27±3.84 mg m-2 (± S.E.); (2) A glacial sampling approach yielded somewhat higher values -30.68±12.00 mg m-2; and (3) Dry deposition was also modelled for HNO3 and p-NO3 using atmospheric concentrations and stability observations, resulting in a total combined nitrate dry deposition of -10.76±1.26 mg m-2. The model indicates that deposition primarily occurs via HNO3 with only a minor contribution by p-NO3. Modelled median deposition velocities largely explain this difference: 0.63 cm s-1 for HNO3 while p-NO3 was 0.0025 and 0.16 cm s-1 for particle sizes 0.7 and 7 µm, respectively. Overall, the three methods are within two standard errors agreement, attributing an average 14% (total range of 2-44%) of the total nitrate deposition to dry deposition. Dry deposition events were identified in association with elevated atmospheric concentrations, corroborating recent studies that identified episodes of rapid pollution transport and deposition to the Arctic. [ABSTRACT FROM AUTHOR]

ABSTRACT Simultaneous measurements of aerosol black carbon (BC) in both fresh snow and in air on Svalbard are presented. From these, washout ratios for BC are calculated and compared to sparse previous measurements of this metric in the arctic. The current ratios are significantly higher than previously found measured values. We argue that the degree of snow riming within the accretion zone can explain most of this difference. Using an analytical model of the scavenging process, BC scavenging efficiencies are estimated to lie in the range 0.25-0.5, comparable to measured values. [ABSTRACT FROM AUTHOR]

The article focuses on a study which examined the chemistry of mercury (Hg) in the atmosphere and the formation of oxidized species, as well as the fate of mercury inside a sunlight-irradiated snow pack. Ny-Âlesund, Svalbard, Norway was the site chosen for this study. A Tekran 2537A analyzer was used to measure Gaseous Elemental Mercury (GEM) concentrations, while the chamber technique was used to measure Hg emission fluxes from the snow pack to the atmosphere. Results of the study showed that there were low Particulate Mercury (PM) and Reactive Gaseous Mercury (RGM) during the first Atmospheric Mercury Depletition Events (AMDEs). According to the study, apparent destruction rates can be attributed to advection of air masses already depleted in ozone.