C13A-0425:
Snow Impurities on Central Asian Glaciers: Mineral Dust, Organic & Elemental Carbon

Monday, 15 December 2014
Julia Schmale1, Shichang Kang2, Richard Peltier3, Michael Sprenger4, Junming Guo2,5, Yang Li2,5 and Qianggong Zhang2,5, (1)Institute for Advanced Sustainability Studies, Potsdam, Germany, (2)State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute (CAREERI), Chinese Academy of Sciences (CAS), Lanzhou, China, (3)University of Massachusetts, Environmental Health Sciences, Amherst, United States, (4)Swiss Federal Institute of Technology Zurich, IAC, Zurich, Switzerland, (5)Key Laboratory of Tibetan Environment Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences (CAS), Lanzhou, China
Abstract:
In Central Asia, 90 % of the population depend on water stored in glaciers and mountain snow cover. Accelerated melting can be induced by the deposition of e.g., mineral dust and black carbon that reduce the surface albedo. Data on source regions and chemical characteristics of snow impurities are however scarce in Central Asia.

We studied aerosol deposited between summers of 2012 and 2013on three different glaciers in the Kyrgyz Republic. Samples were taken from two snow pits on the glacier Abramov in the northern Pamir and from one snow pit on Ak-Shiirak and Suek in the central Tien Shan. The snow was analyzed for elemental and total organic carbon, major ions and mineral dust. In addition, dissolved organic carbon was speciated by using the Aerodyne high-resolution time-of-flight aerosol spectrometer.

Elevated mineral dust concentrations were found on all glaciers during summer and winter with lower annual average concentrations (20 mg l-1)in the northern Pamir (factor 5 to 6). Correlations between dust tracers varied, indicating different source regions. Average EC concentrations showed seasonal variation in the northern Pamir (> 100 µg l-1 in summer, < 30 µg l-1 in winter) while there was little variation throughout the year in the central Tien Shan (~ 200 µg l-1). Similarly, OC:EC ratios showed no seasonal cycle in that region averaging around 3. On Abramov, the ratio was significantly higher in winter (> 12) than in summer (< 4). The average O:C ratios across all glaciers ranged between 0.65 and 1.09, indicating a high degree of oxygenation which suggests long-range transport of the organic snow impurities. Marker substances such as potassium and mercury and their correlations suggest contribution from biomass burning emissions.

Atmospheric measurements in August 2013 were conducted to obtain information on background aerosol characteristics in the remote high mountain areas. The average black carbon concentration was 0.26 µg/m³ (± 0.24 µg/m³).

Back to: Dust, Black Carbon, and Other Aerosols in the Cryosphere I Posters
<< Previous Abstract | Next Abstract >>