The Camborne Mining District in 1904 a View Taken from the Engine
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The Camborne Mining District in 1904 A view taken from the Engine House of Dolcoath Mine, looking eastwards along the strike of the lodes. Mines in the picture include South Crofty, East Pool and Agar, Cooks Kitchen, Carn Brea and Tincroft (Geological Survey Photograph No. A.37). DISTRIBUTION, DISPERSION AND AGRICULTURAL SIGNIFICANCE OF METALS IN SOILS OF THE MINING REGIONS OF SOUTH WEST ENGLAND by Peter W. Abrahams July, 1983 A thesis submitted for the degree of Doctor *of Philosophy of the University of London and for the Diploma of Membership of the Imperial College. Applied Geochemistry Research Group Imperial College, London, SW7. I This thesis is dedicated to Mum, Dad and the many friends I have met over the last few years; without them, all this would not be worthwhile. "you may say I 'm a dreamer but I'm not the only one i hope someday you'll join us and the world will be as one." John Lennon (1940-1980) (i) ABSTRACT Previous stream sediment sampling within the Hayle/Camborne- Redruth area of South-west England revealed extensive trace-element contamination which was related to areas of mineralisation and historic metalliferous mining activity. A soil reconnaissance survey confirmed these initial observations, and indicated the order of soil trace- element contamination as Sn> As> Cu> Zn> Pb. Whilst the highest trace- element concentrations occur generally within the topsoils (0-15cm), elevated concentrations are also found within the subsoils (30-45cm). The topsoil As, Cu, Pb and Zn concentrations are significantly correlated with the distribution of these trace-elements in the stream sediments. On the basis of these statistical correlations, the stream sediment data comprising the Wolfson Geochemical Atlas of England and Wales was used to delineate the areas of soil contamination throughout 2 South-west England. In all, a total of ip92km of land, equivalent to 11.9% of the total area studied, is believed to be highly or moderately contaminated by one or more of the elements As, Cu, Pb and Zn. Elevated concentrations of several trace-elements occur in the slate, granite and greenstone parent materials of the Hayle/Camborne- Redruth study area. Any natural soil enrichment is largely masked by trace-element contamination derived from sources associated with the mining industry : the contamination from mine spoil, a former tin smelter and a former arsenic calcining works is described. The uptake and translocation of As, Cu, Fe, Mn and Zn in pasture herbage varies according to the trace-element concerned. The factors (ii) influencing the trace-element content of herbage has been studied by ridge regression analysis. In addition, the relative accumulation of As, Cu, Fe, Mn and Zn by herbage suggests that the pasture species also control the rate of trace-element uptake and translocation within the plant. The involuntary ingestion of soil by cattle is seasonal and may account for up to 18% of the ruminant dry matter intake. Pasture herbage is particularly susceptible to As and Fe soil contamination. Thus soil is a major source of both elements to cattle, accounting for up to 97% and 95% of the As and Fe intake respectively. It is proposed in this study that cattle may ingest up to 31 times the amount of As compared to areas of normal soil As content. (iii) ACKNOWLEDGEMENTS This thesis, funded by the Natural Environmental Research Council and supervised by Dr. Iain Thornton, would not have been possible without the help of numerous people who have been interested in my work. Within the Applied Geochemistry Research Group, I would particularly like to thank Mr. M. Ramsey for analytical advice, Dr. R. Howarth and Miss A. Leech for their computational/statistical skills and Mr. A. Doyle for his time and patience in the laboratory. A number of people with specialist knowledge of South-west England have also contributed to this work; in this context, my grateful thanks go to Dr. D. Hughes and Mr. R. Thomas, both formerly of ADAS at Starcross, Mr. S. Staines of the Soil Survey for his expert knowledge relating to the soils of the province, Professor K. Hosking for his help, advice and anecdotes relating to the geochemistry and mining history of South-west England, and to Dr. R. Taylor of the I.G.S. at Exeter. In addition, this research would not have been possible without the help of the farmers in South-west England, and without Mr. and Mrs. R. Frost who provided bed, breakfast and evening meals at such reasonable cost, and who tolerated both myself and my muddy boots for the whole of three years. Finally, I would like to thank Jacqui and Jill for their time and patience in typing this manuscript : any misEakes are either mine or the typewriters or the typewriters. (iv) TABLE OF CONTENTS Page Abstract . (i) Acknowledgements . (iii) Table of Contents . (iv) List of Figures . (ix) List of Tables . (xiii) List of Plates . (xvii) CHAPTER 1 Geochemistry and the environment (I) Introduction and outline of thesis (II) The pathways of trace-elements in rock-soil-herbage- animal-human systems and their environmental significance 7 (a) Trace-elements in rocks 7 (b) Trace-elements in soils : their concentration, distribution and fractionation with soils and their profiles 12 (c) The availability of trace-elements and their uptake by plants 22 (d) Trace-elements in animals and man 28 CHAPTER 2 Mineralisation and mining consequences to the soil- plant-animal system (I) Introduction.. 31 (II) Sources of metals in mineralised and mined areas 34 (III) Mining contamination and its implications to the soil-plant-animal system.. 39 (IV) The environmental impact of mining on man .. 42 CHAPTER 3 South-west England (I) Introduction.. 45 (II) Previous environmental geochemical research in South-west England.. 50 (III) Geochemistry and human disease in South-west England 61 (IV) The Hayle/Camborne-Redruth district .. .. .. 62 (a) Geology and geomorphology.. .. .. .. 64 Page (b) Soils and land use 73 (c) Results of the geochemical stream sediment follow-up survey.. 79 (d) Conclusions of the stream sediment follow-up survey 92 CHAPTER 4 The distribution of metal contaminants in the soils of South-west England (I) Introduction 94 (II) The trace-element content of soils in the Hayle/ Camborne-Redruth area 94 (a) Details of the soil traverses 94 (b) The trace-element content of soils on the traverses 97 (c) Discussion.. 143 (III) The distribution of trace-elements in soil profiles of the study area 155 (a) Soils of the slate lowland 156 (i) soils developed over mineralised slates 156 (ii) soils developed over non-mineralised slates 158 (iii) man-made (plaggen) soils developed on the slates .. .. .. .. .. .. 161 (b) Soils of the granite hills .. .. .. .. 162 (i) soils developed over mineralised granites 162 (ii) soils developed over unmineralised granites 165 (c) Discussion 166 (IV) The contamination of soils throughout the South- western peninsula 171 (a) Statistical correlations between the trace- element concentrations of the soils and stream sediments within the Hayle/Camborne-Redruth study area 171 (b) The extent of trace-element contamination throughout South-west England 182 (c) Discussion and conclusions 192 CHAPTER 5 The sources of anomalous trace-element concentrations in the Hayle/Camborne-Redruth district (I) Introduction .. .. .. .. .. .. .. 196 (II) Geochemistry of the major geological formations .. 196 (a) Analytical results obtained from the rock samples 196 (b) Discussion.. .. .. .. .. .. .. 200 (Vi) Page (III) The dispersion of contaminants from mine spoil and smelting sources within the Hayle/Camborne-Redruth district .. .. .. .. .. .• • - 203 (a) Introduction .. .. .. .. .• •. 203 (b) The contamination of agricultural land from spoil heaps .. .. .. .. .. .. 203 (i) Wheal Tremayne .. .. .. .. 204 (ii) Wheal Sisters.. .. .. .. .. 217 (c) Contamination due to smelting operations in the province .. .. .. .. .. .. 228 (d) Contamination due to the calcination of arsenic ores .. .. .. .. .. .. .. 236 (IV) Summary on the sources of trace-elements to the soils of South-west England .. .. .. .. .. 241 CHAPTER 6 Trace-element uptake by pasture herbage on the contaminated soils of South-west England (I) Introduction.. .. .. .. .. .. .. 246 (II) Trace-element uptake by pasture herbage .. .. 248 (III) Seasonal variations in the arsenic and metal content of the pasture herbage .. .. .. .. .. 249 (a) The contamination of pasture herbage by soil 249 (b) The concentrations of trace-elements in the pasture herbage of South-west England.. .. 252 (IV) Factors influencing the trace-element content of pasture herbage .. .. .. .. .. .. 255 (a) The relationship between the trace-element content of the pasture herbage and the 'total' soil trace-element concentrations .. .. 255 (b) The use of multiple regression techniques in investigating the uptake of trace-elements by pasture herbage .. .. .. .. 258 (c) The relative accumulation of As, Cu, Fe, Mn and Zn by pasture herbage.. .. .. .. 279 (V) Discussions and conclusions relating to the trace- element uptake of As, Cu, Fe, Mn and Zn by pasture herbage .. .. .. .. .. .. .. 282 CHAPTER 7 Trace-element intake by cattle in South-west England (I) Introduction.. .. .. .. .. .. .. 289 (II) The total daily intake of trace-elements by cattle grazing within the Hayle/Camborne-Redruth study area 303 (Vii) Page (III) Comparison of the faecal trace-element concentrations with the daily intake of As, Cu, Fe, Mn and Zn .. 307 (IV) The theoretical intake of trace-elements by cattle grazing uncontaminated soils outside the