PLATINUM IN ROAD DUSTS AND URBAN RIVER SEDIMENTS

Platinum concentrations in road dusts and urban river sediments were a nalysed by dry-ash digestion followed by adsorptive stripping voltamme try. The analysis gave a detection limit of 0.5 ng/g, with up to 85% r ecovery of added platinum and a standard deviation of +/- 2.2%. A comp arison of platinum concentrations in size-fractionated road dusts coll ected in 1984 and 1991 showed average increases in all fractions: <63 mum, 3.0-8.9 ng/g; 63-125 mum, 1.5-3.6 ng/g; and 125-1000 mum, <0.5-2. 8 ng/g. Present-day surface loadings of platinum were calculated for a car park (26 ng/m2) and a kerbside (1.28 mug/m2), and mean event plat inum concentrations in highway run-off were calculated to be 0.1-0.7 n g/l. Concentrations of platinum in urban river sediments varied from < 0.5 to 2.2 ng/g.