ALBERT

Description: Abstract: The direct determination of element signatures in polar ice core samples from Greenland by laser ablation with subsequent inductively coupled plasma mass spectrometry analysis has been investigated. A cryogenic sample chamber enables the element determination in ice directly from the solid (frozen) state. A procedure was developed to analyse up to 38 elements (traces: Mg, Al, Fe, Zn, Cd, Pb and rare earth elements; minor constituents: Na) in ice samples from Greenland with a previously not achieved spatial resolution of 4 mm along the core axis. This resolution is helpful to detect seasonal variations of element concentration in thin annual layers of deep-ice. We report operating conditions and analytical performance of the experimental set up, the improvement of signal stability by 17OH internal standardisation and applying of a desolvation unit. Calibration of the system was performed with frozen multielement standard solutions along a special preparation procedure. Detection limits for the tracers Na, Mg (sea salt), Al (mineral dust) and Zn (anthropogenic source) are between 0.1-1 µgkg-1. Best detection limits in the range of 0.001-0.01 µgkg-1 were reached for Co, Pb and all rare earth elements. To validate the method, frozen standard reference materials were measured. The recovery is about ± 10 %. Greenland ice core samples from different ages were analysed with the new technique. The results obtained by laser ablation were compared with values from solution analysis, available published data and the particle content. Most elements have shown good correlation with the particle content in the Greenland samples, however, differences could be seen between the values obtained by laser ablation and solution bulk analysis after a tri-acid digestion. The influence of particles is discussed. The high spatial resolved 2d-mapping of element concentrations show strong inhomogeneities along the core axis most probably due to seasonal variations of element deposition.Key words: LA-ICP-MS ice core 2d-mapping cryogenic chamber element- signatures Greenland polar research

Description: Application of LA-ICP-MS in polar ice core studiesReinhardt, H., Kriews, M., Miller, H., AWI Bremerhaven/DLüdke C., Hoffmann E., Skole J., ISAS Berlin/DDr. Heiko Reinhardt, Alfred-Wegener-Institute for Polar and Marine Research,Am Handelshafen 12, 27570 BremerhavenEmail: hreinhardt@awi-bremerhaven.deThe direct determination of element signatures in polar ice core samples from Greenland by laser ablation with subsequent inductively coupled plasma mass spectrometry analysis has been investigated. The ice shields of the polar regions are important climate archives and they provide useful insight to the history of the Earth climate back to about 500,000 years. The analysis of element signatures in ice cores yields information about the strength of sources and transport mechanisms for aerosols in the paleoatmosphere as well as about the paleovolcanism. By means of a laserbeam at a wavelength of 1064 nm material from the ice surface is ablated. The ablated sample aerosol is introduced to an ICP-MS (ELAN 6000). The great advantages of the new technique in comparison to solution analysis are the high spatial resolution, the fast analysis of total element content (soluble and insoluble components) and a reduced risk of contamination. A cryogenic sample chamber (CRYOLACTM) enables the element determination in ice directly from the solid (frozen) state. A procedure was developed to analyse up to 39 elements (traces: Mg, Al, Fe, Zn, Cd, Pb and some rare earth elements; minor constituents: Ca and Na) in ice samples from Greenland with a previously not achieved spatial resolution of 4 mm along the core axis. This resolution is helpful to detect seasonal variations of element concentration in thin annual layers of deep-ice. We report operating conditions and analytical performance of the experimental set up, the improvement of signal stability by 17OH internal standardisation and applying of a desolvation unit. Calibration of the system was performed with frozen multielement standard solutions along a special preparation procedure. Detection limits for the tracers Na, Mg (sea salt), Al (mineral dust) and Zn (anthropogenic source) are between 0.1-1 µgkg-1. Best detection limits in the range of 0.001-0.01 µgkg-1 were reached for Co, Pb and all rare earth elements. Due to interferences, the element Ca could not be analysed at trace levels. To validate the method, frozen standard reference materials were measured. The recovery is about ± 10 %. Greenland ice core samples from different ages were analysed with the new technique. The results were compared with values from solution analysis, available published data and the particle content. The high spatial resolved analysis show strong inhomogeneous element concentrations along the core axis due to seasonal variations of element deposition. The data from solution analysis (solution ICP-MS and ion chromatography) are in a good agreement for many determined elements.Literature:[1] Reinhardt, H., Kriews, M., Miller, H., Schrems, O., Lüdke, C., Hoffmann, E., Skole, E., Fres. J. Anal. Chem. 2001, 370, 629.

Description: 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.

Description: The snow and iceshields of the polar regions serve as a climate archiveand deliver a useful insight back to about 250.000 years of earth climatehistory1,2. The aim of our investigation reported here was to establisha new method for the determination of trace elements in ice cores frompolar regions with Laserablation Inductively Coupled Plasma MassSpectrometry (LA-ICP-MS)3. Primarily, the construction of a cryogeniclaserablation chamber and the optimization of the analysis system forthe sample matrix were the main goals. This paper reports preliminaryresults from measurements of frozen ice samples, the achievable signalintensities, standard deviations and calibration graphs as well as the firstsignal progression of 208Pb in an 8000 years old ice core sample fromGreenland.