Regional atmospheric Cr(VI) pollution from the Bushveld Complex, South Africa

Özet

Hexavalent chromium, Cr(VI), is a proven human carcinogen. Of interest in this paper was the regionalatmospheric pollution of Cr(VI) from the ferrochromium and related industries located in the westernBushveld Complex (wBC) of South Africa. A significant fraction of the world's ferrochromium and platinumgroup metals is produced in this region. Particulate matter (PM), in two size fractions, i.e. PM2.5(2.5 mm) and PM2.510 (2.5e10 mm), was sampled for a full calendar year at a regional background site,which is situated downwind of the wBC on the dominant anti-cyclonic recirculation route of air massover the South African interior. Results indicated that Cr(VI) concentrations in air masses that had passedover the regional background were below the detection limit of the analytical technique applied, but thatCr(VI) in air masses that had passed over the wBC were elevated and had a median concentration of4.6 ng/m3. The majority of Cr(VI) was found to be in the finer size fraction (PM2.5), which could beexplained by the nature of Cr(VI)-containing PM being emitted by the sources in the wBC and the atmosphericlifetimes of different PM size fractions. The results further indicated that it is possible that notonly pyrometallurgical sources in the wBC, but also other combustion sources outside the wBCcontributed to the observed atmospheric Cr(VI) concentrations.