LEAD AND ZINC FLOWS FROM TECHNOSPHERE TO BIOSPHERE IN A CITY REGION

By identifying the main product categories and quantifying the pools o f metals; the amounts, flows and uses of lead and zinc in the city of Stockholm have been studied. The emissions of metals into different en vironmental media are estimated. The pools and flows in the biosphere are introduced, and compared with the anthropogenic pools and emission s. Finally, the product emissions are compared with the measured dissi pative use, based on the metal concentrations in the sludge at the mai n waste water treatment plant and in storm water. The amount of lead t hat is recorded in the waste water treatment plants can mainly be expl ained by deposition. However, emissions from many of the product categ ories quantified for lead in Stockholm are not likely to collect at se wage treatment plants. Instead, the emissions are more likely to be no ticed in the storm water, the soil and the sediments around the city. In total, about 45 000 tonnes of lead and about 6000 tomes of metallic zinc are quantified in the study. The product emissions were roughly estimated to be 30 tonnes of lead each year. There are however, large uncertainties in the emission factors. The city can definitely be rega rded as a source of zinc pollution. This can be seen in the flows that are registered in the waste water treatment plants, and the estimated storm water flows. From these estimates, the city appears to contribu te about 30 tonnes of metallic and biogenic zinc each year to surround ing waters and to sludge. For the product groups and the emission fact ors used in this study, a zinc emission of about 17 tonnes per year wa s estimated, with the main contributions coming from street furniture, tyres and buildings.