Entwicklung und Anwendung eines Laserablations-ICP-MS-Verfahrens zur Multielementanalyse von atmosphärischen Einträgen in Eisbohrkernen

Abstract

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 450,000 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. In deep ice layers where annual layers have a thickness of only a few millimetres, it is very difficult to obtain data with high time resolution. The aim of this work reported here was to develop a new method for ice core analysis. The LA-ICP-MS system (Laserablation Inductively Coupled Plasma Mass Spectrometry) is the first one which makes the detection of elements at ultra trace level in a high spatial and thus high time resolution in such thin layers with low risk of contamination possible. 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 inductively coupled plasma mass spectrometer where ionisation with subsequent detection occurs. The great advantages of the new technique in comparison to solution analysis are the high spatial resolution of 4 mm that can be gained (independent of ice depth/dense), the fast analysis of total element content (soluble and insoluble components) of about 62 isotopes and a reduced risk of contamination. Ice core samples different ages from Greenland were analysed with the new technique. The results were compared with values from solution analysis as well as available published data. 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 good agreement for many determined elements.