Since 1976 in the United States, Canada, and Japan, and later in other countries, the exhaust system of gasoline powered cars has been equipped with catalytic converters containing Pt and/or Pd and/or Rh. This has resulted in a very significant decrease in urban air pollution for various chemical species such as NOx, CO, and hydrocarbons. There has however been concern that their ever increasing use might lead to Platinum Group Metals (PGMs) becoming widely dispersed in the environment. From the analysis of Pt, Pd, and Rh in central Greenland recent snow and ancient ice using the ultrasensitive inductively coupled plasma sector field mass spectrometry technique, we show here that the concentrations of these metals in snow dated from the mid 1990s are indeed 40−120 times higher than in ice dated from 7000 years ago. The fact that such an increase is observed far away from populated areas at a high altitude location indicates there is now a large scale contamination of the troposphere of the Northern Hemisphere for PGMs. Pt/Rh mass ratio in the most recent snow samples is close to the same ratio documented for catalytic converter exhausts in a recent study, which suggests that a large fraction of the recent increase for Pt and Rh might originate from automobile catalytic converters

Eight PM10 aerosol samples were collected in the vicinity of the "Mario Zucchelli" Italian Antarctic Station (formerly Terra Nova Bay Station) during the 2000-2001 austral summer using a high-volume sampler and precleaned cellulose filters. The aerosol mass was determined by differential weighing of filters carried out in a clean chemistry laboratory under controlled temperature and humidity. A two-step sequential extraction procedure was used to separate the water-soluble and the insoluble (dilute-HCl-extractable) fractions. Cd, Pb and Cu were determined in the two fractions using an ultrasensitive square wave anodic stripping voltammetric (SWASV) procedure set up for and applied to aerosol samples for the first time. Total extractable metals showed maxima at midsummer for Cd and Pb and a less clear trend for Cu. In particular, particulate metal concentrations ranged as follows: Cd 0.84-9.2 microg g(-1) (average 4.7 microg g(-1)), Pb 13.2-81 microg g(-1) (average 33 microg g(-1)), Cu 126-628 microg g(-1) (average 378 microg g(-1)). In terms of atmospheric concentration, the values were: Cd 0.55-6.3 pg m(-3) (average 3.4 pg m(-3)), Pb 8.7-48 pg m(-3) (average 24 pg m(-3)), Cu 75-365 pg m(-3) (average 266 pg m(-3)). At the beginning of the season the three metals appear widely distributed in the insoluble (HCl-extractable) fraction (higher proportions for Cd and Pb, 90-100%, and lower for Cu, 70-90%) with maxima in the second half of December. The soluble fraction then increases, and at the end of the season Cd and Pb are approximately equidistributed between the two fractions, while for Cu the soluble fraction reaches its maximum level of 36%. Practically negligible contributions are estimated for crustal and sea-spray sources. Low but significant volcanic contributions are estimated for Cd and Pb (approximately 10% and approximately 5%, respectively), while there is an evident although not quantified marine biogenic source, at least for Cd. The estimated natural contributions (possibly including the marine biogenic source) cannot account for the high fractions of the metal contents, particularly for Pb and Cu, and this suggests that pollution from long-range transport is the dominant source.

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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