Substance flow analyses of metals and organic compounds in an urban environment – the Stockholm example

Sammanfattning: The intensified use of materials, products and goods in our time involves massive consumption of metals and organic compounds that can be released from society to the environment in the various stages of production, use and waste. Depending on the circumstances this may give rise to environmental risks, as metals in general and certain organic substances may be toxic in the short or long term. So where have those metals and organic substances been utilized? In which products or environments? Substance flow analysis (SFA) is a method to deal with these issues. The results from the analysis are quantifications of flows and stocks in a systematic way and within defined system boundaries.In this thesis four main research areas are identified, which need to be addressed. i) Application of SFA on substances that have not been studied in this respect before, which can give knowledge about flows and stocks related to consumption of goods.  ii) Development of SFA to meet the needs in studies of trends for the substance cycles and studies of quantification of potential changes. iii) Assessment of which different agents and actions that induce the changes, such as chemical regulations, environmental objectives and aims. To what extent can these changes be related to substance flows? iv) Finally to assess, how can SFA be useful in environmental decisions? The specified aims focus on the metals antimony (Sb), cadmium (Cd), lead (Pb) and mercury (Hg) and the group of organic compounds alkylphenol/alkylphenol ethoxylates (AP/APEO), in urban environments, exemplified with case studies of Stockholm, the capital of Sweden.This thesis is a result of five studies. Three were based mainly on the methodology of SFA (Paper I-III). It has also been important to develop the chemical analysis of metals in goods where there has been a lack of information (Paper IV). Furthermore, assessment of policy questions and chemical regulations involve qualitative approaches and discussions (Paper I and V).The results show urban flows and stocks of the metals Cd, Hg, Pb and Sb and the group of organic substances AP/APEO. The results confirm that goods are important for the release of the substances studied. For Sb, emissions from brake linings (96%) dominate, but there are small emissions from textiles, potential emissions from flame retarded goods and probably small point sources. For AP/APEO the textile emissions were previously underestimated and the SFA presented here included this and pose textiles and cleaning agents as major emission source to wastewater.To repeat studies and to compare results from different years was a development of the SFA-method, which showed that Cd and Hg are being phased out as the inflow and stocks show diminished amounts, whereas the emissions remain approximately constant when comparing 1995 with 2002/2003. For Pb it is possible to talk about a phase-out of some specific goods, but not in general for inflow and stock.The changes in urban metabolism could be related to environmental decisions, e.g. effects of local initiatives and in some cases voluntary initiatives, but also as result of prevailing chemicals regulation. The utility of SFAs for decision makers may be related to methodological issues, such as the accounting approach. However, the utility was also found to depend on the structure of the monitoring, that is screening in the environment and concentration in wastewaters and sewage sludge precede the source mapping conducted with SFA. Substance Flow Analysis will likely continue to serve as the broad information tool for one substance at a time, which will offer source characterization of diffuse emissions in urban environments.