A major glacial-interglacial change in aeolian dust composition inferred from Rare Earth Elements in Antarctic ice

We present the first Rare Earth Elements (REE) concentration record determined in 294 sections of an Antarctic ice core (EPICA Dome C), covering a period from 2.9 to 33.7 kyr BP. REE allow a detailed quantitative evaluation of aeolian dust composition because of the large number of variables (i.e. 14 elements). REE concentrations match the particulate dust concentration profile over this period and show a homogeneous crustal-like composition during the last glacial stage (LGS), with only a slight enrichment in medium REE. This signature is consistent with the persistent fallout of a mixture of dust from heterogeneous sources located in different areas or within the same region (e.g. South America). Starting at ∼15 kyr BP, there was a major change in dust composition, the variable character of which persisted throughout the Holocene. This varying signature may highlight the alternation of single dust contributions from different sources during the Holocene. We observe that the frequent changes in REE composition at the onset of the Holocene (10-13.5 kyr BP) are linked to dust size and in turn to wind strength and/or the path of the atmospheric trajectory. This may indicate that atmospheric circulation dictated the composition of the dust fallout to East Antarctica at that time. Although the dust concentrations remained fairly low, a notable return towards more glacial dust characteristics is recorded between 7.5 and 8.3 kyr BP. This happened concomitantly with a widespread cold event around 8 kyr BP that was 400-600 years long and suggests a moderate reactivation of the dust emission from the same potential source areas of the LGS

Trace metal analysis in arctic aerosols by an inductively coupled plasma-time of flight-mass spectrometer combined with an inductively heated vaporizer

Two newly developed instruments were combined to analyze the trace metal content in size separated arctic aerosols during the measurement campaign ASTAR 2004 (Arctic Study of Tropospheric Aerosols, Clouds and Radiation 2004) at Spitsbergen in MayJune 2004. The aim of this extensive aerosol measurement campaign was to obtain a database for model-calculations of arctic aerosol, which play an important role in the global climate change. The ASTAR project was centered on two aircraft measurement campaigns, scheduled from 2004 to 2005, addressing both aerosol and cloud measurements, combined with ground-based and satellite observations. In the present paper one example for the analysis of ground-based aerosol particles is described. The sampling of aerosol particles was performed in a well-known manner by impaction of the particles on cleaned graphite targets. By means of a cascade impactor eight size classes between 0.35 and 16.6 μm aerodynamic diameters were separated. To analyze the metal content in the aerosol particles the targets were rapidly heated up to 2700 °C in an inductively heated vaporizer system (IHVS). An argon flow transports the vaporized sample material into the inductively coupled plasma (ICP) used as ionization source for the time of flight-mass spectrometer (TOF-MS). The simultaneous extraction of the ions from the plasma, as realized in the TOF instrument, allows to obtain the full mass spectrum of the sample during the vaporization pulse without any limitation in the number of elements detected. With optimized experimental parameters the element content in arctic aerosol particles was determined in a mass range between 7Li and 209Bi. Comparing the size distribution of the elemental content of the aerosol particles, two different meteorological situations were verified. For calibration acidified reference solutions were placed on the cleaned target inside the IHVS. The limits of detection (LOD) for the element mass on the target range between 2 and 200 pg for the elements studied, except Na, Mg, and Cr, which are influenced by high background