Marthe-Lise Søvik Heavy Metals in Soil and Water Near Mercury
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Thesis for the Master’s degree in chemistry Marthe-Lise Søvik Heavy metals in soil and water near mercury hotspots in Guizhou, China 60 study points DEPARTMENT OF CHEMISTRY Faculty of mathematics and natural sciences UNIVERSITY OF OSLO 11/2008 Preface This master thesis has been carried out at the Department of Chemistry, University of Oslo. The research described is conducted in relation to the Sino-Norwegian Cooperation Project on Mercury Pollution (SINOMER) project. The target of the project is capacity building with the aim to reduce the mercury releases in the People’s Republic of China. This is done through a case study in Guizhou province, southwest China. The project involves many participating institutions in both China and Norway. First of all, I appreciate the assistance and advice I have received from my supervisors Thorjørn Larssen, Rolf Vogt and Grethe Wibetoe. Thorjørn: I am incredibly grateful for your help and never ending confidence in me during the past two years! Furthermore, I appreciate the opportunity I was given to attend the SINOMER field work in Guizhou in September 2007. I express my gratitude to Feng Xinbin, Shang Lihai and Zhang Hua for the practical arrangements during the field work in Guizhou, and also for supporting data and general knowledge on mercury in the province. I am thankful for enlightening discussions and several amusing dinners and road trips. Further I would like to thank Oddvar Røyset for his ICP MS expertise and for spending his precious time helping me run my samples. Marit Villø is also thanked for her guidance during my laboratory work at NIVA. I am thankful to Hege Lynne, Hanne Røberg-Larsen, Anne-Marie Skramstad and Inge Mikalsen for helping me with instrumental difficulties and for providing analytical advice. Last, but not least, I express my appreciation to all the members of the Environmental Chemistry group, in particular Kristine Solberg, Yan Lin and Ruikai Xie. This work is dedicated to my family. 2 Table of contents Preface ....................................................................................................................................... 2 Table of contents ...................................................................................................................... 3 List of figures ............................................................................................................................ 5 List of tables ............................................................................................................................ 10 Abbreviations and symbols .................................................................................................... 11 Abstract.................................................................................................................................... 13 1 Introduction .................................................................................................................... 15 1.1 Heavy metals ............................................................................................................. 15 1.2 Mercury – a pollutant of global concern .................................................................... 16 1.3 The SINOMER project............................................................................................. 20 1.4 The aim of this study................................................................................................. 21 2 Theoretical basis............................................................................................................. 23 2.1 Soil composition and properties ................................................................................ 23 2.2 Heavy metals in the environment .............................................................................. 27 2.3 Heavy metal classification.......................................................................................... 28 2.4 Mercury..................................................................................................................... 32 2.5 Mercury in the environment ...................................................................................... 34 3 Sampling areas, analytical procedures and data processing ....................................... 39 3.1 Sampling areas........................................................................................................... 39 3.2 Sampling procedures ................................................................................................. 50 3.3 Sample preparations .................................................................................................. 50 3.4 Instrumentation and procedures................................................................................ 52 3.5 Softwares for data processing .................................................................................... 57 3.6 Quality control .......................................................................................................... 58 3.7 Reagents, analytical instruments and other equipment ............................................... 61 4 Results and discussion ................................................................................................... 64 4.1 Major ions in the water samples................................................................................. 64 4.2 Metal concentrations ................................................................................................. 66 4.3 Statistical analyses.................................................................................................... 100 4.4 Assessment of uncertainties and validation of methods ........................................... 111 3 5 Conclusions................................................................................................................... 117 References ............................................................................................................................. 119 List of appendices................................................................................................................. 127 4 List of figures Figure 1: The global mercuriferous belts (magenta) and productive deposits areas (red). The location of Guizhou Province is marked with a black cross (Dutchak et al. 2003) [reprinted with permission]................................................................................................................................ 17 Figure 2: Hg mine tailing in Aozhai Valley, Wanshan, China. (Photo: M-L Søvik) ..................... 19 Figure 3: Mercury production from mining in China from 1995-2004 (in metric tons) (NRDC 2006). ........................................................................................................................................ 20 Figure 4: Red acrisol horizon (ISRIC 2006) ............................................................................... 26 Figure 5: Yellow acrisol horizon (ISRIC 2006)........................................................................... 26 Figure 6: Speciation of Hg (II) based on change in pH in an aquatic environment with typical chemical composition of Guizhou Province. The normal pH range in Wanshan is marked light blue. .......................................................................................................................................... 36 Figure 7: The total global emissions of different Hg species to the atmosphere in 1995 (%) (Pacyna and Pacyna 2002).......................................................................................................... 37 Figure 8: The Chinese emissions of different Hg species to the atmosphere in 1999 (%) (Streets et al. 2005)................................................................................................................................. 37 Figure 9: Map of China with Guizhou province emphasized (orientaltravel 2008) ..................... 39 Figure 10: A typical landscape in the Wanshan district. (Photo: M-L Søvik, 2007) ..................... 41 Figure 11: Artisanal Hg smelting in Wanshan. (Photo: R. Vogt, 2008) ....................................... 42 Figure 12: The sampling sites downward (eastwards) the Aozhai River in the Wanshan area. The triangles indicate Hg mine tailings.............................................................................................. 43 Figure 13: The coal fired power plant in Qingzhen. (Photo: M-L Søvik, 2007) .......................... 44 Figure 14: Wind roses from Guiyang city during spring, winter, summer and autumn (2000/2001), respectively (Feng et al. 2003b)............................................................................. 45 Figure 15: The karstic landscape around Qingzhen. (Photo: M-L Søvik, 2007) .......................... 46 Figure 16: The sampling sites in the Qingzhen area with the Qingzhen power plant and the Hongfeng Reservoir specified. (A few of the sampling sites (B4, B5 and B6 in the grey shaded area) appear to be located inside the Hongfeng Reservoir, but this is actually the ash slurry field shown in Figure 17 (red marking))............................................................................................. 47 Figure 17: Photo from the area around the Qingzhen power plant (red star) with the ash slurry field inside the red marking (Google Earth 2008). ..................................................................... 49 Figure 18: The outlet of ash slurry from the power plant (Photo: