Mercury characterisation in urban particulate matter

A five-step sequential extraction procedure was proposed in order to assess the distribution of mercury (Hg) forms in urban particulate matter (PM): exchangeable, HCl-soluble, organic-bound, elemental and other slightly soluble Hg species, mercury(II) sulphide (HgS), and residual Hg. This process was applied to the analysis of urban dust samples collected at locations in Prague (Czech Republic) with high traffic density. In addition to sequential extractions, thermal desorption analysis was performed. The differences in Hg concentrations between untreated and thermally treated samples were indicated as the thermally releasable amount of Hg. For the study of PM-adsorbing capacity, Hg vapours were passed through the samples as long as the enrichment of materials was observed. The retained elemental Hg was readily released by thermal desorption. All Hg analyses were based on the highly sensitive pyrolysis technique of atomic absorption spectrometry using the mercury analyser AMA-254.