IMPROVEMENTS AND APPLICATION OF THE LASER TECHNIQUES LA-ICP-MS FOR HIGH RESOLUTION NON DESTRUCTIVE ELEMENTAL ANALYSES ON ICE CORES
Supervisors: P. Bohleber (Univ. of Venice, IT), R. Rhodes (UKRI-BAS, UK)
Academic secondments: UKRI-BAS, UK), Univ. of Bern (CH); Non-academic secondments: Teledyne CETAC Technologies (USA)
The Beyond EPICA Oldest Ice (BE-OI) project aims to retrieve valuable climate information from ice located near the base of the Antarctic ice sheet, which has inevitably been compressed and strongly thinned. Analysis and interpretation of geochemical signals within such basal ice requires a step-change in analytical capability. This PhD project will further develop laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS), which involves ablating a few µL of ice sample and analyzing trace element concentrations in a mass spectrometer. This offers micron-scale resolution trace element profiling, and thus is a unique tool for the detection of highly thinned layers in deep ice. Further added value of LA-ICP-MS data concerns paleoclimate information, for example, snow accumulation rate reconstruction through annual layer detection as well as ice physics investigations such as understanding impurity localization in ice cores. Due to the large amount of data points generated by LA-ICP-MS (e.g. 104 pts/cm), data reduction including calibration is of highest importance to all further data exploitation. However, this crucial step still awaits proper treatment for ice core data. This PhD project will exploit a novel, automated Cryocell-LA-ICP-MS setup and develop a semi-automated data reduction scheme for processing of LA-ICP-MS trace element profiles and images. This data reduction is dedicated to 1) detecting signals corresponding to the stratigraphic layer sequence, e.g. related to annual, decadal or centennial climate proxy variability 2) converting LA-ICP-MS intensities into concentrations based on a calibration against artificial ice standards. For shallow core sections, the student will conduct a comparison with other ice core datasets, in particular to verify LA-ICP-MS layer detection against annual layers in Continuous Flow Analysis (CFA) data. For the deeper ice, the detection of highly thinned layers will provide important constraints for age models.
Keywords: Laser ablation inductively-coupled plasma mass spectrometry, trace element glacio-chemistry, software development for semi-automated data reduction
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