The potential of a double focusing ICP-MS instrument in of sample contamination during collection, storage, treatment terms of high sensitivity, sample throughput and low volume of and analysis. As an example, the very few reliable data sets sample consumed was investigated for the direct, simultaneous available for Cd, Pb, Zn and Cu show that their concentrations determination of Co, Cu, Zn, Mo, Pd, Ag, Cd, Sb, Pt, Pb, Bi range from tenths of pg g−1 (10−12 g g−1) in Antarctic and U at the low and sub-pg g−1 level in polar snow. The Holocene ice4,5 up to tens-hundreds of pg g−1 for presententire analytical procedure, including cleaning of material, day Greenland surface snow.6 field sampling, sample handling, determination of the blanksThe ideal analytical technique to be used in the challenging and instrumental analysis, is described. The mean task of heavy metal determination in polar snow should present concentrations detected in snow samples collected in Central extremely low detection limits, multi-element capability and Greenland (2.7 m deep pit) are (in pg g−1): Co 5.8, Cu 4.6, low sample consumption and should avoid, as far as possible, Zn 47, Mo 1.6, Pd 1.1, Ag 0.60, Sb 0.86, Pt 0.61, Bi 2.5 and any preconcentration step which is time consuming and could U 1.8. The Cd, Pb and U concentrations in a snow core be the source of contamination. section collected in East Antarctica are: Cd 0.39, Pb 5.0, Various instrumental methods have been used in the U 0.04 pg g−1. Repeatability of measurements ranges between past, i.e., laser excited atomic fluorescence spectrometry 8 and 25% depending on the element considered. For some of (LEAFS),7-11 thermal ionisation mass spectrometry the elements investigated these results constitute the first (TIMS),5,12-15 instrumental neutron activation analysis available for polar snow. The results of direct analysis by (INAA),16,17 graphite furnace atomic absorption spectrometry double focusing ICP-MS on Cd and Pb in the Antarctic snow (GFAAS),4,18-20 diÂerential pulse anodic stripping voltamsamples and on Zn and Cu in Greenland samples are metry (DPASV),21-25 atomic fluorescence spectrometry consistent with those obtained by diÂerential pulse anodic (AFS)26,27 and inductively coupled plasma mass spectrometry stripping voltammetry (DPASV ) and graphite furnace atomic (ICP-MS).28-30 Of these only LEAFS and DPASV have demabsorption spectrometry (GFAAS ), respectively.onstrated enough sensitivity for a direct determination at the required levels.7-11,21-25 However, skilful operators and time Keywords: Double focusing inductively coupled plasma mass consuming procedures are required in both cases and DPASV spectrometry; trace elements; snow; Greenland; Antarctica requires a large amount of sample, which is not always available. The other techniques are less sensitive and require The Greenland and Antarctic snow and ice caps are among diÂerent preconcentration or extraction methods,5,31,32 which the best preserved and most detailed archives for the reconin addition to slowness, requir...

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High altitude cold snow and ice cores from midlatitude mountain ranges have been used very little to obtain historical records of environmental contamination by heavy metals. Co, Cr, Mo, and Sb have been measured by DF-ICP-MS-MCN (double focusing inductively coupled plasma mass spectrometry with microconcentric nebulizer) in various sections of a 140 m snow/ice core drilled at a high altitude location near the summit of Mont Blanc in the French−Italian Alps. The bottom of the core is older than 200 years. It gives the first snow and ice time series for these metals of high environmental interest for the post Industrial Revolution period. Measured concentrations range from 26 to 433 pg/g for Co, from 8 to 469 pg/g for Cr, from 0.2 to 50 pg/g for Mo, and from 0.2 to 109 pg/g for Sb. For all four metals, concentrations in recent snow are found to be, on the average, significantly higher than concentrations in ice dated from before the middle of the 19th century. There are however differences in the timing and the amplitude of the observed increases from one metal to another. Mo shows the greatest increase (×16), followed by Sb (×5), and Co and Cr (×2−3). Contribution from natural sources is, on the average, limited except for Mo in ice dated from before the middle of the 19th century. For recent snow, contribution from oil and coal combustion is the dominating source for Co, Mo, and Sb. For Cr, on the other hand, the most important contribution is from iron, steel, and ferro-alloy industries.