Seasonal variations in airborne heavy metals in Vanderbijlpark, South Africa

In this study, monthly settleable dust samples were collected in four seasons using the modified crude single open bucket units at five sites within the Vanderbijlpark area. The samples were captured in distilled water medium, filtered, air-dried, weighed to determine mass concentrations, digested with aqua regia acid solution and analyzed for heavy metals by inductively coupled plasma (ICP) 6000 Thermo-Electron model technique. The average ranges of ten metals identified were: zinc (Zn,1.12 – 5.87 mg/L), iron (Fe, 2.25 – 8.94 mg/L), chromium (Cr, 0.87 – 3.99 mg/L), titanium (Ti, 0.58 – 3.1 mg/L), manganese (Mn, 2.31 – 9.01 mg/L), lead (Pb, 0.5 – 2.34 mg/L), vanadium (V, 0.94 – 4.18) mg/L), copper (Cu, 0.78 – 3.01 mg/L), nickel (Ni, 0.7 – 3.64 mg/L) and cadmium (Cd, 1.0 – 2.92 mg/L) respectively. Average daily mass concentrations obtained ranged from 2.42 – 1270 mg/m 2 /day in autumn, 520 – 1520 mg/m 2 /day in winter, 142 – 683 mg/m 2 /day in spring and 156 – 846 mg/m 2 /day in summer. Both the South African and the American industrial limits were exceeded in winter and autumn seasons at a farm site. A South African standard for residential limit, 600 mg/m 2 /day, was also exceeded at a school site during the same seasons.