Assessment of airborne platinum contamination via ICP-mass spectrometric analysis of tree bark

Tree bark is used as a passive bio-monitor to assess the environmental impa ct by the use of automotive catalysts containing platinum-group elements. P t in bark samples collected front UK. Spain, Japan and USA was determined b y ICP-MS both conventionally after acid digestion and directly utilising la ser ablation. Ali ultrasonic nebuliser equipped with a membrane desolvator was employed for digest analysis. to improve the sensitivity (limit of dete ction, 0.8 ng l(-1)) and to eliminate the potential spectral interference C aused by hafnium oxide. Pt concentrations found in the remote sites were be low 9 ng g (1). Similar concentrations were obtained for Spanish/UK cities with occasionally slightly elevated values. In contrast, the concentrations for bark samples in major Japanese/US cities ranged up to 38 ng g (1). The data are consistent with the usage Of Pt-containing automotive catalysts i n the respective sites. Spatial micro-analytical data, acquired oil raw, ba rk materials, indicate that Pt occurred in a highly dispersed particulate f orm and was not readily transformed/ solubilised by actions of weathering. Association of Pt with Pd and/or Rh (no correlation with Pb was observed) s uggests that the particles detected originated from automotive catalysts.