Urban heavy metals : Stocks and flows
Sammanfattning: Levels of heavy metals in different media are high today, both in Stockholm and other urban areas. Where do the metals come from? Production emissions and point sources are not the answer, since earlier research has shown that production emissions are lower than emission from goods during use (the diffuse emission). Hence, in order to understand the flow of different metals to different recipients it is necessary to understand the use of heavy metals in goods. This thesis quantifies the use of heavy metals (Cd, Cr, Cu, Hg, Ni, Pb, Zn) in goods in Stockholm, Sweden. It also quantifies the diffuse emission from the goods.The results of this thesis show that the stock of heavy metals in goods in Stockholm is large. Per capita, it has been estimated to about:170 kg Cu, 70 kg Pb, 40 kg Zn, 8 kg Cr, 4 kg Ni, 0.2 kg Cd and finally 0.01 kg Hg. Accumulation probably still continues, with the exception of Hg and possibly Cd. The accumulation rates have not been calculated due to lack of reliable recycling data.The waste flow is large, hundreds of tons for Cu, Zn and Pb, for example. The majority of the goods are used in protected environments, hence the diffuse emission is negligible. Other goods are used in exposed environments and the diffuse emission is rather large.It is also shown that diffuse emission from goods is the main source of heavy metals to the wastewater treatment plant Henriksdal in Stockholm. The diffuse sources are not efficiently regulated in the Environmental Code in Sweden, which makes it difficult for the water company (and others) to decrease diffuse emissions.
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