Automobile catalytic converters are dispersing platinum-group elements (PGEs) Rh, Pt, and Pd into the environment (1-3). This paper represents the first detailed study to assess the PGE content of soils and grasses from U.S. roadsides. These soils were analyzed using cation exchange pretreatment and ultrasonic nebulizer-ICP-MS (4). Highway and several urban sites showed Pt abundances of 64-73 ng/g immediately adjacent to the roadside, with corresponding Pd and Rh abundances of 18-31 ng/g and 3-7 ng/g, respectively. All Pt and most Pd and Rh abundances are statistically above local background soil values. Platinum, Rd, and Rh show positive correlations with traffic-related elements (Ni, Cu, Zn, and Pb) but no correlations with nontraffic-related elements (Y, Ga). Iridium and Ru show no correlations with any of these trace elements. These PGE abundances are comparable to European studies (5-7) and are approaching concentrations that would be economically viable to recover. This study also demonstrates transport of Pt statistically above background more than 50 m from the roadside. Further study is necessary to see how mobile the PGEs are in roadside environments, but these initial data indicate only Pt is taken up by plants.

We have evaluated the highly siderophile element (HSE) signatures of the martian (SNC) meteorites using new and literature data. These Ir and Os concentrations correlate with the Mg# [molar Mg/(Mg + Fe)], Cr and Ni, suggesting that olivine or chromite acts as a host for compatible siderophiles. Our analysis agrees with others who have suggested that the martian mantle has chondritic relative abundances of siderophiles. We also agree that, unlike the Sr and Nd isotopic systems, there is no evidence from Os isotopes for crustal assimilation. Comparisons of the siderophile element ratios of ALH 84001 to younger SNCs give no indication of a change in the martian siderophile element pattern over time. D 2002 Published by Elsevier Science B.V.

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Inductively coupled plasma‐mass spectrometry is well suited for the precise, accurate and rapid determination of rare earth elements in most geological samples. However, determination of rare earth elements in certain mantle‐derived materials, without applying preconcentration techniques, remains problematical due to low natural concentrations (generally < 1 ng g−1). Consequently, USGS reference materials DTS‐1 (a dunite) and PCC‐1 (a partially serpentinized harzburgite) have only suggested rather than recommended values for the rare earth elements in reference material compilations. We compared results obtained using two ICP‐MS instruments: a U‐5000AT ultrasonic nebuliser coupled to a PQ2+ quadrupole ICP‐MS and an ELEMENT sector field ICP‐MS equipped with a MCN‐6000 microconcentric desolvating nebuliser, with the suggested literature values for these two reference materials. Precision and accuracy of analytical methods employed by both instruments were demonstrated by excellent relative standard deviations (< 2%) and inter‐laboratory agreement (< 5%) for numerous analyses of BHVO‐1 and BIR‐1, which are well established with rare earth elements contents at the μg g−1 level. Repeat analyses of DTS‐1 and PCC‐1 at each laboratory indicate that each method is generally precise to better than 5% at sub‐g g−1 levels. Furthermore, values from both instruments generally agree to within 10%. Our DTS‐1 and PCC‐1 values agree reasonably well with selected data reported in the literature (except for Ce and Sm in DTS‐1) but exhibit poorer agreement with reported compilation values. With the demonstrated level of precision and accuracy, we contend that these new values for DTS‐1 and PCC‐1, generated by two different instruments, are the best estimates of the true whole‐rock composition of these samples reported to date.