Tracing Copper from society to the aquatic environment Model development and case studies in Stockholm Qing Cui Licentiate thesis in Industrial Ecology School of Industrial Engineering and Management Royal Institute of Technology Stockholm, Sweden 2009 Title: Tracing Copper from the society to the aquatic environment: Model development and case studies in Stockholm Author: Qing Cui Registration: ISSN 1402-7615 TRITA-IM 2009: 29 Published by: Royal Institute of Technology School of Industrial Engineering and Management Department of Industrial Ecology SE-100 44 Stockholm, Sweden Phone: (+46) 8 790 87 93 (distribution) (+46) 8 790 61 98 (Author) Fax: (+46) 8 790 50 34 E-mail: [email protected] Print by: E-print, Stockholm, Sweden, 2009 Summary Copper remains at elevated levels in the aquatic environment of Stockholm due to diffuse urban sources. Management of these diffuse sources requires their quantification but they cannot be measured directly by field observations. The working hypothesis of this thesis was that Copper levels in the sediments of urban lakes would reflect diffuse emissions within their catchment areas. In order to test this hypothesis, a source – transport – storage conceptual model was developed for tracing the urban diffuse sources of Copper to the sediment in the urbanised catchment. A substance flow analysis (SFA) approach was taken in the source module and a fate, mass-balance model was applied in the lake module. Five separate urban lakes (Judarn, Laduviken, Långsjön, Råcksta Träsk and Trekanten) within the Stockholm area and a main water flow pathway from Lake Mälaren to the inner archipelago of the Baltic Sea, through Stockholm, were selected as case studies. In comparison to actual source strength data in the literature for the five case study lakes, the SFA approach gave similar results to previous models, but with reduced uncertainty. The SFA approach was also able to indicate the actual sources of urban copper, which was not accomplished by the other approaches and which is a great advantage in managing the sources. For the five lakes in Stockholm, traffic and copper roofs were found to be major contributors of Copper. For the three more polluted lakes, good agreement was obtained between simulated sediment copper contents and independent field observations, thereby supporting the applicability of the model in such cases. Furthermore, simulation results showed sediment copper content to be linearly dependent on the urban load. While this suggests that the urban copper sediment level reflects the urban load, considerable integration of this load over time (decade(s)) was suggested by the simulation results, so time must be allowed in order to detect a change in the urban load by field monitoring of the sediments. Published data on the main water flow pathway from Lake Mälaren to the archipelago showed a peak in sediment copper content close to the city centre, confirming a considerable urban influence. An approach to quantitatively follow Cu from its urban source through such a complex, aquatic system was developed and applied to Stockholm. The compliance of future quantitative model results with monitoring data may help test the choices made in this conceptual model and the applicability of the model. Data availability proved to be a major obstacle to achieving a quantitative model, particularly as several municipalities with different levels of data availability surround the main water flow pathway studied. Finally, the applicability of the quantitative, coupled source – transport – storage was demonstrated in a simplified scenario analysis. The ability of the model to estimate the copper load to air and soil and to the urban aquatic environment was also demonstrated. i Keywords: Diffuse source, source analysis, sediment pollution levels, urban lake, Copper, Stockholm archipelago, SFA ii Acknowledgements I am blessed with the opportunity to carry out my studies at the Department of Industrial Ecology, Royal Institute of Technology. Thank you to Prof. Ronald Wennersten for inviting me here and China Scholarship Council for sponsoring my studies in Sweden. A great deal of gratitude is expressed to my supervisors, associate professor, Maria Malmström and Nils Brandt for their painstaking attention, inspired guidance in these three years. I have learnt a lot from them, such as how to work with this research, the serious attitude for researching. Without their critical eyes, my work would never have reached completion. Although only my name is signed on the cover of this thesis as the author, the research aggregated many people‟s contributions. First, I am indebted to Drs. Arne Jamtrot, Anja Arnerdal and Stina Thörnelöf from the Environmental and Health Administration, Stockholm, Sweden, Christer Lännergren from Stockholm Vatten and Prof. Lars Håkanson, Department of Earth Science, Uppsala University, for providing data and valuable discussions, and to Richard Ekström from Roslagståg AB for supporting information and providing opinions on my study. I gained many benefits from communications with them, although some of us still haven‟t met each other. Second, my thanks go to Valentina Rolli, Rajib Sinha, and Daniel Cursino da Cruz. They accomplished their Master‟s thesis in the relevant studies, which were very inspiring and helpful to me. I am grateful to my colleagues at the Department of Industrial Ecology. The interesting and pleasant communication with them made my life in Sweden a wonderful experience. I am also very thankful to Yingfang He, International Office, KTH. Her warm help made my life in Stockholm much more convenient. Last, but not least, thanks to my parents and friends for their thoughtful support behind me, no matter where they are. Stockholm, Dec 2009 Qing Cui iii List of Appended Papers This thesis is based on the following papers, which are referred to in the text by their Roman numerals: I. Cui, Q., Brandt, N. and Malmström, M. E. (2009) Sediment metal contents as indicators of urban metal flows in Stockholm. In the proceedings of the international conference ConAccount 2008 „Urban Metabolism: Measuring the Ecological City‟ Havránek, M. (Eds) Prague, Czech, Charles University Environment Center. p255-282. The contribution of the author was the work on formulating the conceptual model, establishing the numerical model, data collecting, model simulation and analysis of the simulation results. The author was responsible for carrying out the research and writing the paper. The author also made an oral presentation of the paper at the conference. II. Cui, Q., Brandt, N., Sinha, R. and Malmström, M.E. Copper content in lake sediment as tracer of urban emissions: evaluation through a source – transport – storage model. Submitted. The contribution of the author was the work on modifying the numerical model, data collecting, model simulation, and the sensitivity and uncertainty analyses. The author was responsible for carrying out the research work and writing the paper. III. Malmström, M. E., Rolli, V., Cui, Q. and Brandt, N. (2009) Sources and fates of heavy metals in complex, urban aquatic systems: Modelling study based on Stockholm, Sweden. In the proceedings of the international conference: Ecosystems and Sustainable Development VII. Brebbia, C. A. & Tiezzi, E. (Eds.) Southampton, UK, WIT Press. p153-161. The author was part of the research group, took part in discussions on this work and contributed to the literature search and data collection. iv Contents Summary ........................................................................................................................................................ i Acknowledgements ....................................................................................................................................... iii List of Appended Papers ................................................................................................................................ iv Contents ......................................................................................................................................................... v 1. Introduction .............................................................................................................................................. 1 1.1 Background and study motivation ...................................................................................................... 1 1.2 Aims and objectives ............................................................................................................................. 2 2. Background information from previous studies ....................................................................................... 5 2.1 Copper ................................................................................................................................................. 5 2.1.1 The life cycle of Copper ................................................................................................................ 6 2.1.2 The toxicity and environmental effects of Copper ....................................................................... 6 2.2 The urban water system in Stockholm, Sweden ................................................................................. 6 2.3 Copper sources, fate and environmental levels in Stockholm ............................................................ 8 2.3.1 Anthropogenic sources of Copper in Stockholm .......................................................................... 9 2.3.2 The