The Magnitude and Spatial Distribution of In-Use Zinc Stocks in Cape Town, South Africa
Cape Town is a major urban area that possesses large reservoirs of in-use zinc. These reservoirs will gradually become available for re-use as the zinc-containing products become obsolete, should re-use prove technologically and economically feasible. Hence, we have identified and quantified the principal zinc uses in Cape Town and estimated their lifetime, using a model incorporating Geographic Information System (GIS) software. We estimated the in-use stock at approximately 57 Gg and predicted end-of-life flows for several decades into the future. By 2030, we anticipate an in-use zinc stock more than twice as high as currently present. Our GIS analysis demonstrated that although the per capita stock of in-use zinc is lowest for poor community areas, these areas have higher spatial densities of zinc than wealthy areas because of the very high housing and population densities. If all end-of-life zinc is reprocessed, rather than discarded as waste or transferred outside the region, it could supply up to 50% of Cape Town's zinc demand over the next three decades.