Origin of atmospheric lead in Johannesburg, South Africa

The origin of lead in the atmosphere of Johannesburg, South Africa was investigated on the basis of elemental and lead isotopic analyses of coals, mine dumps, gasoline, and about 30 epiphytic lichen samples. Lead predominantly comes from automotive exhausts in urban and suburban areas, as leaded antiknock additives were still in use in South Africa at the time of the study. Although dust emissions from the numerous mine-tailing dumps were expected to contribute significantly to the heavy metal budget, the southern townships that are surrounded by the dumps (such as Soweto and other historically Black residential areas) do not appear to be more than partially influenced by them, and this influence seems to be geographically limited. Domestic coal burning, suspected to account for the total lead content in the air, is also recognised, but only acts as a minor source of lead, even in townships.