Abstract:
HCL-extractable zinc, lead, cadmium and copper in soils as well as concentrations of these elements in bracken (Pteridium esculentum) were found to decrease along four leeward traverses at right angles to the Hume Highway near Marulan. Similar results were obtained for the above-ground portions of rye corn (Secale cereale) grown in a glasshouse on soils collected along one of these traverses. Zinc accession is similar to, but cadmium and lead accessions are considerably lower than, those observed by other workers in the United States probably owing in the case of cadmium to the use of purer zinc oxide in Australian tyre manufacture and in the case of lead to smaller cars and a smaller proportion of vehicles operating on leaded fuel. Zinc and cadmium analyses of Australian and foreign tyres confirmed the relative purity of the zinc oxide used in the manufacture of tyres in Australia. No serious health hazard appears to arise from heavy metal contamination of roadside soils and vegetation by vehicular traffic on the Hume Highway.