Description: South East Asia is one of the fastest developing regions on Earth and has experienced a recent large increase in atmospheric pollution. Glaciers of the nearby Himalayan mountains represent a unique archive that provides the potential to be used to determine the strength and timing of the onset of anthropogenic atmospheric pollution in the region. Within the Third Pole Project several ice cores from the Tibetan Plateau and the Himalaya are analyzed for their trace element concentrations. Here we present results of a new trace element record from the Dasuopu ice core spanning 1790 - 1993 AD. The Dasuopu ice core was drilled in 1997 at 7200 m altitude in the Himalaya and provides the highest elevation ice core record ever obtained. Due to the high altitude this site has the potential to archive not only contamination records of regional significance, but possibly also long distant pollution from, for example, Europe and climatic signals influenced by the North Atlantic. This area is heavily influenced by the monsoon regime providing seasonally and highly variable snow accumulation rates. The upper 50 m of the core covering the time interval from 1950 to 1997 consist of Firn and is sampled non-continuously in a resolution of approximately one sample/year. The time interval between 1790 and 1950 is presented by a continuous record in subannual resolution. Crustal enrichment factors are used to discriminate between the terrigenous and the anthropogenic contributions. In this study we focus two research topics: (1) determine the onset of the earliest anthropogenic contamination from trace elements at this elevation (7200 m) Himalayan site and (2) determine intra-annual variations of atmospheric trace elements, with a focus on discriminating between pre-monsoon season (when the aerosol input is governed by the high dust input in spring) and the monsoon and dry season. We find trace element concentrations to be very low and very variable throughout the year with concentration changes of up to 2-3 orders of magnitude (e.g. Pb concentrations range from 0.1 ppt to 1000 ppt). Average concentration levels are comparable to those recorded at some polar sites. We find an increase in elements of crustal origin in the second half of the 20th century.

Description: We analyse ice cores from Vestfonna ice cap (Nordaustlandet, Svalbard). Oxygen isotopic measurements were made on three firn cores (6.0, 11.0 and 15.5 m deep) from the two highest summits of the glacier located on the SW-NE and NW-SE central ridges. Sub-annual d18O cycles were preserved and could be counted visually in the uppermost parts of the cores, but deeper layers were affected by post-depositional smoothing. A pronounced d18O minimum was found near the bottom of the three cores. We consider candidates for this d18O signal to be a valuable reference horizon since it is also seen elsewhere in Nordaustlandet. We attribute it to isotopically depleted snow precipitation, which NCEP/NCAR reanalysis shows was unusual for Vestfonna, and came from northerly air during the cold winter of 1994/95. Finding the 1994/95 time marker allows establishment of a precise depth/age scale for the three cores. The derived annual accumulation rates indirectly fill a geographical gap in mass balance measurements and thus provide information on spatial and temporal variability of precipitation over the glacier for the period spanned by the cores (1992-2009). Comparing records at the two locations also reveals that the snow net accumulation at the easternmost part of Vestfonna was only half of that in the western part over the last 17 years.

Description: The chemistry of snow and ice cores from Svalbard is influenced by variations in local sea ice margin and distance to open water. Snow pits sampled at two summits of Vestfonna ice cap (Nordaustlandet, Svalbard), exhibit spatially heterogeneous soluble ions concentrations despite similar accumulation rates, reflecting the importance of small-scale weather patterns on this island ice cap. The snow pack on the western summit shows higher average values of marine ions and a winter snow layer that is relatively depleted in sulphate. One part of the winter snow pack exhibits a [SO4-/Na+] ratio reduced by two thirds compared with its ratio in sea water. This low sulphate content in winter snow is interpreted as the signature of frost flowers, which are formed on young sea ice when offshore winds predominate. Frost flowers have been described as the dominant source of sea salt to aerosol and precipitation in ice cores in coastal Antarctica but this is the first time their chemical signal has been described in the Arctic. The eastern summit does not show any frost flower signature and we interpret the unusually dynamic ice transport and rapid formation of thin ice on the Hinlopen Strait as the source of the frost flowers.