An ultra-clean technique for accurately analysing Pb isotopes and heavy metals at high spatial resolution in ice cores with sub-pg g−1 Pb concentrations

• Published in: Analytica Chimica Acta
• Main Authors: J. Burn, Laurie, J.R. Rosman, Kevin, Candelone, Jean-Pierre, Vallelonga, Paul, R. Burton, Graeme, M. Smith, Andrew, Morgan, Vin I., Barbante, Carlo, Hong, Sungmin, F. Boutron, Claude
• Other Authors: Department of Imaging and Applied Physics, Curtin University, Environmental Sciences Department, University of Ca’ Foscari Venice, Italy, Australian Nuclear Science and Technology Organisation (ANSTO), Australian Nuclear Science and Technology Organisation, Antarctic Climate and Ecosystems Cooperative Research Centre (ACE-CRC), Korea Polar Research Institute (KOPRI), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Australian Research Council grant DP0345625 and Antarctic Science Advisory Council grant #2786.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: Mass spectrometry; Lead isotopes; Barium; Indium; Ice cores; Antarctica; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Antarctic; Antarc*; ice core
• Online Access: https://insu.hal.science/insu-00420615; https://doi.org/10.1016/j.aca.2008.11.067

International audience Measurements of Pb isotope ratios in ice containing sub-pg g−1 concentrations are easily compromised by contamination, particularly where limited sample is available. Improved techniques are essential if Antarctic ice cores are to be analysed with sufficient spatial resolution to reveal seasonal variations due to climate. This was achieved here by using stainless steel chisels and saws and strict protocols in an ultra-clean cold room to decontaminate and section ice cores. Artificial ice cores, prepared from high purity water were used to develop and refine the procedures and quantify blanks. Ba and In, two other important elements present at pg g−1 and fg g−1 concentrations in Polar ice,were also measured. The final blank amounted to 0.2±0.2 pg of Pb with 206Pb/207Pb and 208Pb/207Pb ratios of 1.16±0.12 and 2.35±0.16, respectively, 1.5±0.4 pg of Ba and 0.6±2.0 fg of In, most of which probably originates fromabrasion of the steel saws by the ice. The procedure was demonstrated on a Holocene Antarctic ice core section and was shown to contribute blanks of only ∼5%, ∼14% and ∼0.8% to monthly resolved samples with respective Pb, Ba and In concentrations of 0.12 pg g−1, 0.3 pg g−1 and 2.3 fg g−1. Uncertainties in the Pb isotopic ratio measurements were degraded by only ∼0.2%.