ENVIRONMENTAL GEOCHEMISTRY
Site Characterization, Data Analysis and Case Histories
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ENVIRONMENTAL GEOCHEMISTRY
Site Characterization, Data Analysis and Case Histories Edited by
BENEDETTO DE VIVO Universita` di Napoli Federico II Dipartimento di Scienze della Terra, Napoli, Italy
HARVEY E. BELKIN United States Geological Survey, Reston, USA
ANNAMARIA LIMA Universita` di Napoli Federico II Dipartimento di Scienze della Terra, Napoli, Italy
AMSTERDAM • BOSTON • HEIDELBERG • LONDON NEW YORK • OXFORD • PARIS • SAN DIEGO SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO
Elsevier Radarweg 29, PO Box 211, 1000 AE Amsterdam, The Netherlands Linacre House, Jordan Hill, Oxford OX2 8DP, UK First edition 2008 Copyright # 2008 Elsevier B.V. All rights reserved No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the Publisher Permissions may be sought directly from Elsevier’s Science & Technology Rights Department in Oxford, UK: phone (þ44) (0) 1865 843830; fax (þ44) (0) 1865 853333; email:
[email protected]. Alternatively you can submit your request online by visiting the Elsevier web site at http://elsevier.com/locate/permissions, and selecting Obtaining permission to use Elsevier material Notice No responsibility is assumed by the publisher for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN: 978-0-444-53159-9 For information on all Elsevier publications visit our website at books.elsevier.com
Printed and bound in Hungary 08 09 10 11 12 10 9 8 7 6 5 4 3 2 1
CONTENTS
Contributors Preface
1. Field Methods in Regional Geochemical Surveys
xi xv
1
Reijo Salminen 1. Introduction 2. Sampling Media 3. Sampling Density 4. Sampling Networks 5. Quality Assurance in Sampling 6. Sampling Procedures 7. Documentation of Field Data 8. Photography 9. Sample Archive References
2. Sampling Methods for Site Characterization
1 2 4 5 7 7 10 10 10 11
13
Christopher Swyngedouw and Jean Michel Cre´pin 1. Introduction 2. Site Characterization 3. Basic Sampling Types 4. Some Further Sampling Considerations 5. Summary References
3. Contaminated Groundwater Sampling and Quality Control of Water Analyses
14 15 17 21 26 26
29
Julian K. Trick, Marianne Stuart, and Shaun Reeder 1. 2. 3. 4. 5. 6.
Introduction Groundwater Sampling Objectives Choosing the Right Portable Sampling Devices Avoiding Cross-Contamination Water-Level Measurements Well Purging Techniques
31 31 32 37 37 38
v
vi
Contents
7. On-Site Water-Quality Measurements 8. Preservation and Handling of Samples 9. Quality Assurance and Quality-Control Procedures 10. Data Validation 11. Health and Safety in Fieldwork References
4. The Collection of Drainage Samples for Environmental Analyses from Active Stream Channels
42 45 50 52 55 55
59
Christopher C. Johnson, Deirdre M. A. Flight, Louise E. Ander, Robert T. Lister, Neil Breward, Fiona M. Fordyce, and Sarah E. Nice 1. Introduction 2. Drainage Basins 3. Drainage Sampling 4. Sampling Strategy 5. Procedures 6. Discussion 7. Conclusions Acknowledgments References
5. Data Conditioning of Environmental Geochemical Data: Quality Control Procedures Used in the British Geological Survey’s Regional Geochemical Mapping Project
60 61 64 66 69 84 90 90 90
93
Christopher C. Johnson, Louise E. Ander, Robert T. Lister, and Deirdre M. A. Flight 1. Introduction 2. Planning Quality Control—Quality Assurance 3. Raw Data Checking 4. Statistical Analyses and Plotting of Control Sample Data 5. Levelling Data 6. Discussion Acknowledgments References
94 95 101 104 108 114 117 117
6. Gas Chromatographic Methods of Chemical Analysis of Organics and Their Quality Control
119
Christopher Swyngedouw, David Hope, and Robert Lessard 1. 2. 3. 4.
Introduction Sample Preparation—Aqueous Samples Sample Preparation—Soil Samples Cleanup Techniques
120 121 122 124
Contents
5. Instrumental Analysis 6. Data Analysis 7. Quality Control 8. Internal QC 9. External Laboratory QC References
7. Evaluation of Geochemical Background at Regional and Local Scales by Fractal Filtering Technique: Case Studies in Selected Italian Areas
vii
126 127 129 130 132 132
135
Annamaria Lima 1. Introduction 2. Multifractal Interpolation and Fractal Concentration–Area (C–A) Method 3. Background/Baseline Geochemical Map Obtained by Fractal Filtering (S–A) Method 4. Pb and U Background Values for Campania Region Stream Sediments 5. Pb Background Values for the Volcanic Soils of the Metropolitan and Provincial Areas of Napoli 6. Conclusions Acknowledgments References
8. Urban Geochemical Mapping
136 137 138 140 144 150 151 151
153
Stefano Albanese, Domenico Cicchella, Annamaria Lima, and Benedetto De Vivo 1. Introduction 2. Definition of Geochemical Background and Baseline at an Urban Scale 3. Planning Urban Geochemical Mapping 4. Sampling Protocols and Field Activities 5. Sample Preparation and Analyses 6. Geochemical Data Presentation Acknowledgments References
9. Chemical Speciation to Assess Potentially Toxic Metals’ (PTMs’) Bioavailability and Geochemical Forms in Polluted Soils
154 155 155 157 158 160 171 171
175
Paola Adamo and Mariavittoria Zampella 1. 2. 3. 4. 5. 6.
Introduction PTMs’ Forms in Soil and Bioavailability The Need of Speciation and Speciation Methods Plant Bioavailability Human Bioavailability PTMS’ Partitioning Between Soil Geochemical Phases
176 176 179 180 188 191
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Contents
7. Applications of PTMS’ Speciation for Risk and Remediation Assessment 8. Concluding Remarks Acknowledgments References
10. Overview of Selected Soil Pore Water Extraction Methods for the Determination of Potentially Toxic Elements in Contaminated Soils: Operational and Technical Aspects
201 203 203 203
213
Marcello Di Bonito, Neil Breward, Neil Crout, Barry Smith, and Scott Young 1. Introduction 2. Methods for Sampling Soil Pore Water 3. Description and Discussion of Selected Methods 4. Conclusions and Recommendations References
11. Sewage Sludge in Europe and in the UK: Environmental Impact and Improved Standards for Recycling and Recovery to Land
214 217 222 241 243
251
Marcello Di Bonito 1. Wastewater and Sludge: Definitions and Treatment 2. Wastewater and Sludge Composition 3. The Legislative Debate and Regulative Tools in Europe and in the UK 4. Reuse and Disposal of Sewage Sludge in the UK 5. Encouraging the Recycling of Sludge Acknowledgments References
12. Lead Isotopes as Monitors of Anthropogenic and Natural Sources Affecting the Surficial Environment
252 255 260 275 281 283 284
287
Robert A. Ayuso, Nora K. Foley, and Gail Lipfert 1. Introduction 2. Geologic Setting 3. Results 4. Discussion 5. Conclusions Acknowledgments References
13. Environmental Impact of the Disposal of Solid By-Products from Municipal Solid Waste Incineration Processes
288 291 298 306 312 312 313
317
Francesco Pepe 1. Introduction 2. MSW Incineration
318 319
Contents
3. Treatment of Flue Gas from MSW Incineration 4. Solid By-Products from MSW Incineration 5. Plasma Pyrolysis for Waste Treatment 6. Conclusions Acknowledgments References
14. Innovative Responses to Challenges: Redevelopment of Cos Cob Brownfields Site, Connecticut, USA
ix
323 326 329 330 331 331
333
Cynde Sears 1. Introduction 2. Introduction to Brownfields 3. The Challenges of Brownfields 4. Tools to Respond to Brownfields Challenges 5. Introduction to Case Study: Cos Cob Power Plant, Connecticut 6. Conclusions Acknowledgments References
15. Characterization and Remediation of a Brownfield Site: The Bagnoli Case in Italy
334 334 335 337 341 351 352 352
355
Benedetto De Vivo and Annamaria Lima 1. Introduction 2. Environmental Remediation of the Brownfield Site 3. Geological Settings of the Bagnoli–Fuorigrotta Area and Stratigraphy of the Brownfield Site 4. Potential Sources of Anthropogenic Pollution 5. Hydrogeological Characteristics of the Bagnoli–Fuorigrotta Plain 6. Site Characterization 7. Natural and Anthropogenic Components for the Pollution 8. Chemical–Structural Characterization of Waste Material and Leachability Tests 9. Asbestos Characterization and Remediation 10. Preliminary Operative Remediation Plan 11. Securing the Site Acknowledgments References
16. Relationships Between Heavy Metal Distribution and Cancer Mortality Rates in the Campania Region, Italy
356 357 358 360 361 362 373 376 377 377 382 383 384
387
Stefano Albanese, Maria Luisa De Luca, Benedetto De Vivo, Annamaria Lima, and Giuseppe Grezzi 1. Introduction 2. Geology, Geochemical Data, and Cancer Mortality Data of Campania Region
387 388
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Contents
3. Methods 4. Discussion of Results 5. Conclusions Acknowledgments References
17. Chronic Arsenic Poisoning from Domestic Combustion of Coal in Rural China: A Case Study of the Relationship Between Earth Materials and Human Health
391 395 398 399 399
401
Harvey E. Belkin, Baoshan Zheng, Daixing Zhou, and Robert B. Finkelman 1. Introduction 2. Previous Studies 3. The Size of the Problem 4. Symptoms and Etiology of Arsenosis 5. Methods 6. Geological Setting 7. Geochemistry of the Coal 8. Mineralogy and Mode of Occurrence of Arsenic in Guizhou Coal 9. Chinese Sedimentary Rock-Hosted, Carlin-Type, Gold Deposits 10. Metamorphism of Coal and Trace-Element Enrichment 11. Mitigation of Chronic Arsenic Poisoning in Guizhou Province 12. Conclusions Acknowledgments References Index
402 402 404 406 408 409 411 411 415 416 416 417 417 417 421
CONTRIBUTORS
Paola Adamo Dipartimento di Scienze del Suolo, della Pianta, dell’Ambiente e delle Produzioni Animali, Universita` degli Studi di Napoli Federico II, Via Universita` 100, 80055 Portici, Italy. Stefano Albanese Dipartimento di Scienze della Terra, Univerita` degli Studi di Napoli ‘Federico II’, Via Mezzocannone 8, 80134 Napoli, Italy. Louise E. Ander British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. Robert A. Ayuso U.S. Geological Survey, MS 954 National Center, Reston, Virginia 20192, USA. Harvey E. Belkin 956 National Center, U.S. Geological Survey, Reston, Virginia 20192, USA. Neil Breward British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, NG12 5GG, UK. Domenico Cicchella Dipartimento di Studi Geologici e Ambientali, Universita` del Sannio, Via Port’Arsa 11, 82100 Benevento, Italy. Jean Michel Cre´pin Executive Consultant, Business Development, Bodycote Testing Group, Edmonton, Alberta, T6B 3J4, Canada. Neil Crout School of Biosciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. Maria Luisa De Luca Dipartimento di Scienze della Terra, Universita` di Napoli ‘‘Federico II’’, 80134 Napoli, Italy. Benedetto De Vivo Dipartimento di Scienze della Terra, Univerita` degli Studi di Napoli ‘Federico II’, Via Mezzocannone 8, 80134 Napoli, Italy. Marcello Di Bonito Environment Agency, Trentside Offices, West Bridgford, Nottingham, NG2 5FA, UK.
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Contributors
Robert B. Finkelman Department of Geosciences, University of Texas at Dallas, Richardson, Texas 75083, USA. Deirdre M. A. Flight British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. Nora K. Foley U.S. Geological Survey, MS 954 National Center, Reston, Virginia 20192, USA. Fiona M. Fordyce British Geological Survey, Murchison House, Edinburgh, EH9 3LA, UK. Giuseppe Grezzi Dipartimento di Scienze della Terra, Universita` di Napoli ‘‘Federico II’’, 80134 Napoli, Italy. David Hope CEO, Pacific Rim Laboratories, Surrey, Canada. Christopher C. Johnson British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. Robert Lessard QA Manager, Bodycote Testing Group, Edmonton, Canada. Annamaria Lima Dipartimento di Scienze della Terra, Universita` di Napoli ‘‘Federico II’’, Via Mezzocannone, 8, 80134 Napoli, Italy. Gail Lipfert Department of Earth Sciences, University of Maine, Orono, Maine 04469, USA. Robert T. Lister British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. Sarah E. Nice British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK. Francesco Pepe Dipartimento di Ingegneria, Universita` del Sannio, Piazza Roma 21, 82100 Benevento, Italy. Shaun Reeder British Geological Survey, Keyworth, Nottingham, UK. Reijo Salminen Geological Survey of Finland, 02151 Espoo, Finland. Cynde Sears Sears Consulting LLC, 13117 New Parkland Dr., Oak Hill, VA, 20171, USA.
Contributors
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Barry Smith British Geological Survey, Kingsley Dunham Centre, Keyworth, Nottingham, NG12 5GG, UK. Marianne Stuart British Geological Survey, Keyworth, Nottingham, UK. Christopher Swyngedouw Consulting Scientist, Bodycote Testing Group, #5, 2712–37th Avenue N.E., Calgary, Alberta, T1Y 5L3, Canada. Julian K. Trick British Geological Survey, Keyworth, Nottingham, UK. Scott Young School of Biosciences, University of Nottingham, University Park, Nottingham, NG7 2RD, UK. Mariavittoria Zampella Dipartimento di Scienze del Suolo, della Pianta, dell’Ambiente e delle Produzioni Animali, Universita` degli Studi di Napoli Federico II, Via Universita` 100, 80055 Portici, Italy. Baoshan Zheng State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, 550002 Guiyang, Guizhou, PR China. Daixing Zhou Sanitation and Anti-Epidemic Station of Qianxinan Autonomous Prefecture, 562400 Xingyi, Guizhou, PR China.
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PREFACE
The volume ‘‘Environmental Geochemistry: Site Characterization, Data Analysis, Case Histories’’ contains selected papers presented at the ‘‘Workshop: Environmental Geochemistry—Site Characterization, Waste Disposal, Data Analysis, Case Histories’’ held in Napoli (Italy) on May 4–5, 2006. Participants from private and public institutions of Canada, Finland, Greece, Italy, the UK, and USA, took part. The theme of the Workshop was multidisciplinary methods of characterizing contaminated sites using modern geochemistry with examples from different countries in Europe, North America, and Asia. Special themes included soil, surface, and ground waters contamination, environment pollution, and human health, and data interpretation and management. At the more local scale, site characterization and site remediation technologies in soil were considered, as well as, sewage sludge disposal. Case histories of brownfield sites in Italy, UK, and USA were also presented. It is especially appropriate that this volume be completed in 2007 as it is the hundredth anniversary of the birth of Rachel Carson. Rachel Carson published Silent Spring in 1962, which brought environmental concerns to an unprecedented portion of the American public and the world in general. Silent Spring spurred a dramatic reversal in USA national pesticide policy—leading to a nationwide ban on DDT and other pesticides—and the grassroots environmental movement it inspired led to the creation of the United States Environmental Protection Agency and other similar agencies. Now, we are beginning a transition among governments where the methods and techniques of remediation are developed with a greater understanding of the baselines and economics of the applied cleanup processes. Clean up of polluted sites must be accomplished within the budgets of the communities together with the rigor of the science. A selection of papers on the general theme on soil, surface, and groundwater contamination, environment pollution and human health, and data interpretation and management are published in a special issue of Geochemistry: Exploration, Environment, Analysis Special Issue ‘‘Environmental Geochemistry’’, edited by B. De Vivo, J. A. Plant, and A. Lima. A selection of papers more professionally and educationally oriented are included in this Elsevier volume. Fifteen papers arising from the conference are included in this special volume. Their content is briefly summarized below. Salminen R. summarizes experiences from a number of recently completed regional-scale geochemical surveys. It briefly shows the most essential issues to be taken into account in planning and carrying out geochemical surveys in the field. Swingedouw C. and Crepin J. M. provide an overview of sampling methods and tools suitable to address most site characterizations. The basic sampling types discussed are the systematic, random, and judgmental sampling approaches. In addition xv
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to sampling procedures, sampling bias and sampling errors are introduced, leading to some guidance on sample handling, shipping, and chain-of-custody procedures. The presentation focuses on sampling methods for soil only. Trick J. K., Stuart M., and Reeder S. describe the tools available to the field sampler for the collection of groundwater samples, methods of on-site water quality analysis, and the appropriate preservation and handling of samples. The authors discuss the merits of different purge methodologies and show how on-site measurements such as pH, specific electrical conductance (SEC), oxidation–reduction potential (ORP), dissolved oxygen (DO), temperature, and alkalinity can be used to provide a check on subsequent laboratory analyses. Techniques for the preservation and analysis of samples and quality assurance and quality control are also presented. Johnson C. C., Flight D. M. A., Ander E. L., Lister T. R., Breward N., Fordyce F. M., and Nice S. F. discuss the collection of drainage samples from active stream channels for geochemical mapping studies. The authors describe details on the sampling methods used by the British Geological Survey in order to establish a geochemical baseline for the land area of Great Britain, involving the collection of stream sediments, waters, and panned heavy mineral concentrates for inorganic chemical analysis. The authors give detailed sampling protocols and discuss sampling strategy, equipment, and quality control. Johnson C. C., Ander E. L., Lister T. R., and Flight D. M. A. discuss data conditioning procedures involving the verification, quality control, and datalevelling processes that are necessary to make data fit for the purpose for which it is to be used. The authors describe the methods currently used by the British Geological Survey’s regional geochemical mapping project that has been generating geochemical data for various sample media for nearly 40 years. Swingedouw C., Hope D., and Lessard R. describe analytical organic chemistry employing common gas chromatographic techniques which involve dissolving the analyte in organic solvent, removing the interfering co-extractives by solid-phase extraction and then injecting the purified extract into a gas chromatograph coupled to a detector. The paper provides procedures to extract, isolate, concentrate, separate, identify, and quantify organic compounds. It also includes some information on the collection, preparation, and storage of samples, as well as specific quality control and reporting criteria. Lima A. describes statistical methods to evaluate background values, namely, statistical frequency analysis and spatial analysis. The author illustrates the application of GeoDASTM software to perform multifractal inverse distance weighted (MIDW) interpolation and a fractal filtering technique, named spatial and spectral analysis (S–A) method, to evaluate geochemical background at regional and local scale. Albanese S., Cicchella D., Lima A., and De Vivo B. present a synthesis of the main considerations necessary to undertake urban mapping activities in terms of planning, sampling, chemical analyses, and data presentation. In this context, modern Geographical Information Systems (GIS) represent an indispensable tool for better understanding the distribution, dispersion, and interaction processes of some toxic and potentially toxic elements. Adamo P. and Zampella M. provide a review of the single and sequential chemical extraction procedures that have been more widely applied to determine
Preface
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the plant and the human bioavailability of potentially toxic metals (PTMs) from contaminated soil and their presumed geochemical forms. Examples of complementary use of chemical and instrumental techniques and applications of PTMs speciation for risk and remediation assessment are illustrated. Di Bonito M., Breward N., Smith B., Crout N., and Young S. describe some of the current methodologies used to extract soil pore water. In particular, four laboratory-based methods, (i) high-speed centrifugation–filtration, (ii) low- (negative-) pressure RhizonTM samplers, (iii) high-pressure soil squeezing, and (iv) equilibration of dilute soil suspensions, are described and discussed in detail. Some consideration is then taken to assess advantages and disadvantages of the methods, including costs and materials availability. Di Bonito M. reviews the improved standards achieved with sewage sludge, touching on, in particular, the British experience in the field of regulating the disposal and reuse of these materials. Ayuso R. A., Foley N. K., and Lipfert G. present part of an extensive study of the coastal environment in the State of Maine (USA) where the occurrence of elevated levels of arsenic in drinking water (>0.010 mg/L) has prompted multifaceted research to understand the cause of this situation. A detailed Pb isotopic study of pesticides is used to understand the source, distribution, and fate of As and Pb in pesticides, soil, bedrock, and waters. Pepe F. discusses incineration and the most relevant problems as a very efficient technique for municipal solid waste (MSW) management. The author also discusses the different approaches proposed to mitigate the impact of fly ash disposal. Sears C. examines the efforts of the town of Greenwich, Connecticut (USA), to clean up and redevelop a large, environmentally contaminated former coal-fired power plant. The author shows how the town made several decisions that ensured that the site would be turned into a community asset by considering multiple options for land use, taking advantage of newly available Federal and state funding for environmental assessment and cleanup, and adopting alternative environmental assessment and strategies. De Vivo B. and Lima A. document the case history of the Bagnoli brownfield site government remediation project, which is still in progress. The site was the second largest integrated steelworks in Italy and is located in the outskirts of Naples, in an area which is part of the quiescent Campi Flegrei volcanic caldera. Hundreds of surficial and deep boreholes have been drilled, with the collection of about 3000 samples of soils, scums, slags, and landfill materials, and water samples from underground waters. In general, heavy metal enrichments in the cores and water suggest mixing between natural (geogenic) and anthropogenic components. The actual pollution to be remediated is the occurrence of polycyclic aromatic hydrocarbons (PAH), distributed in different spots across the brownfield site. Albanese S., De Luca M. L., De Vivo B., Lima A., and Grezzi G. report geochemical and epidemiological data as maps that represent the detailed patterns of toxic metal concentrations and some, potentially, related pathologies in the Campania region of Italy. Belkin H. E., Zheng B., Zhou D., and Finkelman R. B. describe a unique case study of chronic arsenic poisoning caused by the domestic combustion of coal in
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rural southwestern Guizhou Province, P. R. China. The coal, used by several villages, is enriched in arsenic (>100 ppm) and when burnt in nonvented stoves is absorbed by vegetables hung above and then ingested. Characteristic symptoms of arsenosis, such as hyperpigmentation and keratosis, have been used to define affected populations. Effective collaboration between earth scientists and the local public heath community has mitigated the incidence of this endemic arsenic poisoning.
C H A P T E R
O N E
Field Methods in Regional Geochemical Surveys Reijo Salminen* Contents 1 2 4 5 7 7 8 8 9 9 10 10 10 11
1. 2. 3. 4. 5. 6.
Introduction Sampling Media Sampling Density Sampling Networks Quality Assurance in Sampling Sampling Procedures 6.1. General aspects of the fieldwork 6.2. Stream waters 6.3. Sediments 6.4. Soils 7. Documentation of Field Data 8. Photography 9. Sample Archive References
Abstract This chapter summarizes experiences from a number of recently completed regionalscale geochemical surveys. The aim is to briefly show the most essential issues to be taken into account in planning and carrying out geochemical surveys in the field. Whether the aim of a geochemical survey is prospecting, environmental assessment, or something else, the main principles in the fieldwork are always the same.
1. Introduction Geochemical studies vary enormously in an area. At one extreme, they cover continent-wide areas (Gustavsson et al., 2001; Salminen et al., 2005), based on information from not more than a thousand sites, while at the other, detailed maps, based on several thousands of samples, are produced from a small prospecting target (e.g., Kauranne, 1976; McClenaghan et al., 2001). * Geological Survey of Finland, 02151 Espoo, Finland Environmental Geochemistry DOI: 10.1016/B978-0-444-53159-9.00001-2
#
2008 Elsevier B.V. All rights reserved.
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Reijo Salminen
Studies at different scales differ considerably in the way they are carried out. Not only sampling density, but sampling material, sampling depth, analytical methods, and data processing also essentially depend on the aim of the study, the size of the area to be studied, the objects to be recognized, and the contrast between the anomaly and the surrounding area. The sources of the anomalies detected by different sampling densities are also totally different in nature.
2. Sampling Media Minerogenic stream sediments are the traditional medium in small-scale, regional geochemical mapping, particularly if the aim is ore prospecting. In areas of residual overburden, minerogenic stream sediments have proven to be very useful, providing data from a wide drainage area where the stream has been in contact with the bedrock (Hale and Plant, 1994). The most suitable conditions prevail in areas of temperate climate where the rivers are draining in situ weathered bedrock, and mountainous areas where the bedrock is widely exposed. In glaciated areas, the stream is usually disconnected from the bedrock by till and the stream sediments may thus only reflect the variation of element contents in till. The interpretation of results for prospecting purposes becomes complicated. However, in till-covered mountainous areas such as Scotland (Plant et al., 1984) and Norway (Wennervirta et al., 1971), useful results were obtained by stream sediment geochemistry. Till has conventionally been exploited as a sampling material only on local-scale prospecting studies. However, results from Scandinavia and adjacent areas (B lviken et al., 1986; Koljonen, 1992; Reimann et al., 1998; Salminen et al., 1995) have shown beyond doubt that highly informative and easily interpreted results can be obtained from till geochemistry practiced on a regional or reconnaissance scale. In the 1990s and earlier, environmental applications became important in geochemical mapping. New sampling media such as surface water and terrestrial mosses were tested and became more commonly used in geochemical surveys (Lahermo et al., 1990, 1996; Reimann et al., 1998; Ru¨hling 1994; Salminen et al., 2005; Salminen, 2004; Steinnes et al., 1992). This development also brought some new variation not only in the sample media but also in sampling, analysis, and data management methodologies. In principle, most geochemical mapping data can also be used in environmental geochemical studies. In exploration geochemistry, the concept of a geochemical background value is used to differentiate anomalies caused by mineralized occurrences from the geogenic anomalies caused by normal nonmineralized bedrock. In environmental geochemistry, a new concept of the geochemical baseline was needed to differentiate contamination derived from a point source from that derived from the general background, which includes both natural geogenic element concentration and diffuse anthropogenic pollution (Salminen and Gregorauskiene, 2000). Environmental geochemical studies have concentrated increasingly on defining baselines rather than on detecting high anomaly points; methods to separate local and regional components (anomaly and baseline) have been developed (e.g., De Vivo et al., 2006).
Field Methods in Regional Geochemical Surveys
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In an attempt to establish a global, common understanding of continuously varying methodologies in regional geochemical surveys, the sampling media were discussed very thoroughly in the 1980s and 1990s as part of the IGCP 259 (International Geoscience Programme) (International Geochemical Mapping) and IGCP 360 (Global Geochemical Baselines) projects. Furthermore, this discussion has continued in the framework of the IUGS/IAGC (International Union of Geological Sciences/International Association of Geochemistry) Working Group on Global Geochemical Baselines. Darnley et al. (1995) concluded the earlier discussions with recommendations that were globally accepted. These recommended media, described below, are considered to be the most representative of the Earth’s surface environment, and are the most commonly used in past and current environmental geochemical investigations.
Stream water (filtered and unfiltered) Stream sediment: mineral sediment (
