Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1169417 | Analytica Chimica Acta | 2009 | 9 Pages |
Abstract
Measurements of Pb isotope ratios in ice containing sub-pg gâ1 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 gâ1 and fg gâ1 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 from abrasion 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 â¼5%, â¼14% and â¼0.8% to monthly resolved samples with respective Pb, Ba and In concentrations of 0.12 pg gâ1, 0.3 pg gâ1 and 2.3 fg gâ1. Uncertainties in the Pb isotopic ratio measurements were degraded by only â¼0.2%.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Laurie J. Burn, Kevin J.R. Rosman, Jean-Pierre Candelone, Paul Vallelonga, Graeme R. Burton, Andrew M. Smith, Vin I. Morgan, Carlo Barbante, Sungmin Hong, Claude F. Boutron,