Seasonal and Spatial Variability of Microparticles in Snowpits on the Tibetan Plateau, China

The work presents microparticle concentrations in snowpits from the East Rongbuk Glacier on Mt. Qomolangma (Everest) (ER) (28.02°N, 86.96°E, 6536 m a.s.l.), the Zhadang Glacier on Mt. Nyainqentanglha (NQ) (30.47°N, 90.65°E, 5800m a.s.l.), and the Guoqu Glacier on Mt. Geladaindong (GL) (33.95°N, 91.28°E, 5823m a.s.l.) over the Tibetan Plateau (TP). Variations of microparticle and major ions (e.g. Mg2+, Ca2+) concentrations in snowpits show that the values of the microparticles and ions in the non-monsoon seasons are much higher than those in the monsoon seasons. Annual flux of microparticle deposition at ER is lower than those at NQ and GL, which could be attributed to the long distance away from the possible dust source regions as well as the elevation for ER higher than the others. Compared with other remote areas, microparticle concentrations in the southern TP are much lower than those in the northern TP, but still much higher than those in Greenland and Antarctica. The seasonal and spatial microparticle variations are clearly related to the variations of atmospheric circulation according to the air mass 5-day backward trajectory analyses of HYSPLIT Model. Resultingly, the high microparticle values in snow are mainly attributed to the westerlies and the strong dust storm outbreaks on the TP, while the monsoon circulation brings great amount of precipitation from the Indian Ocean, thus reducing in the aerosol concentrations.

Characteristics of ion concentrations in snowpits in Longyearbyen,Svalbard,Arctic

Snowpits samples were collected from three glaciers in the Longyearbyen region, Svalbard during March to May, 1996. Among major chemical species (Na +, K +, Ca 2+ , Mg 2+ , Cl -, NO - 3 and SO 2- 4), Cl - and Na +, which come mainly from sea salt aerosol, are the dominant soluble impurities in snowpits. In dirty layers of snowpits (representing autumn), the crustal cation Ca 2+ has the highest concentration among all species. Thus, snowpits have been dated by high values of Ca 2+ concentrations and less negative δ 18 O, which represent autumn and summer layers respectively. Seasonal variations in concentrations of sea salt ions ( Na +, Mg 2+ and Cl -), SO 2- 4 and NO - 3 have been identified. Results indicate that concentrations of these ions show high value in spring and summer. The spring maximum value likely results from long range transport of marine aerosol from north Atlantic storms( Na +, Mg 2+ and Cl -) and mid latitude anthropogenic pollution (SO 2- 4 and NO - 3 ). In summer, high concentrations of the sea salt species are attributed to local marine aerosol. The summer SO 2- 4 maximum likely reflects a combination of local marine aerosol, high scavenging ratios, and oxidation of marine biogenic emissions. In comparison, NO - 3 maximum may reflect lightening in the atmosphere and high scavenging ratios. In general, the major ion concentrations in snowpits in Svalbard is high in comparison with those found in snowpits from other remote regions, such as Greenland, Antarctic and Qinghai Tibetan Plateau, especially for sea salt species.