Distinguishing Between Natural and Anthropogenic Sources of Arsenic in Soils from the Giant Mine

242 Pages·2014·9.12 MB·English

TABLED DOCUMENT 121-17(5)
TABLED ON OCTOBER 16, 2014
DISTINGUISHING BETWEEN NATURAL AND
ANTHROPOGENIC SOURCES OF ARSENIC IN SOILS FROM
THE GIANT MINE, NORTHWEST TERRITORIES AND THE
NORTH BROOKIFIELD MINE, NOVA SCOTIA
By
Lori Ann Wrye
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A thesis submitted to the Department of Geological Sciences artd Geological Engineering
In conformity with the requirements for
the degree of Master of Science
Queen's University
Kingston, Ontario, Canada
September, 2008
Copyright ©Lori Ann Wrye, 2008
CJ
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Abstract
Anthropogenic and geogenic sources of arsenic (As) have been identified in mining
impacted soils from the Giant mine (1948-1999), NT and the North Brookfield mine (1886-
1906), NS. Both used roasting to extract gold from the arsenopyrite ore, decomposing it to
As-bearing iron oxides (roaster oxides or RO) containing As, and releasing As3+ -bearing
arsenic trioxide (AszOs). Arsenic trioxide is considered highly soluble with the dissolved
As3+ species being more mobile and toxic than other oxidation states.
Soil profiles from the Giant mine show elevated As and antimony (Sb) at the surface
(As=140-3300ppm) and decreasing concentrations with depth (As=22-600ppm). Surface soils
contain anthropogenically-derived AszOs identified using synchrotron methods (J.LXRD,
J.LXANES) and environmental SEM. The persistence of AszOs is attributed to Sb in AszOs
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grains, dry climate and high organics in the soils. Anthropogenically-derived RO of
maghemite (containing both As3+ and AsS+) and natural arsenopyrite were observed.
Sequential selective extractions (SSE) from surface soils show between 20% and 75% of As
extracted in the crystalline iron-oxide phase is attributed to AszOs and RO, while at depth As
is bound by organics in the weaker leaches.
North Brookfield mine soils show lower total As (2ppm to 45ppm) except near the
roaster (4300ppm). No AszOs was identified, probably due to the smaller scale and age of
the mine, lower organic content and the lack of Sb. As-bearing phases include RO of
hematite (AsS+), As-rich rims on titanium-oxides, and As associated with clays and goethite.
Adjacent to the roaster, SSE show As was also in the amorphous iron-oxide phase, also
shown by As in arsenopyrite weathering rims.
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There are many differences between the North Brookfield and Giant mine soils
including roasting techniques which produced different RO mineralogy, the scale of mining,
climate, soil type, and the presence of As203. Currently, the Giant property is not publically
accessible but may become so in the future while the North Brookfield property is accessible.
Understanding the form and distribution of As phases is critical because of the potential risk
to human and ecosystem health associated with ingestion of soil particles and their control
on the total dissolved As in surface and groundwater.
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Co-Authorship
Chapters 4 and 5 of this thesis were prepared as separate manuscripts for journal
publication as co-authored papers. Both chapters are co-authored with Dr. H.E. Jamieson
who conceived the project, contributed to interpretations of the geochemistry and acted in a
supervisory and review capacity throughout the entire project. Dr. Jamieson was also
involved with field work and synchrotron data collection.
Chapter 4 is prepared to be submitted to Environmental Science and TechnoloiJ!j, and
Chapter 5 is to be submitted to Applied Geochemistn;.
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Acknowledgements
I would first like to thank my supervisor Dr. Heather Jamieson, her guidance was
exceptional and her enthusiasm unfaltering throughout the entire thesis. Her curiosity and
passion for the environment makes her an inspiration to all.
Everyone in Dr. Jamieson's research group and other students within the department
(you know who you are) have been an invaluable resource for me, whether it was through
field work, late nights followed by early mornings at the synchrotron, or just by giving me
support for the particular task at hand. Thank you-Steve, Steph, Mallory, Karina, Paul and
Skya.
Steve Walker and Stephanie DeSisto deserve additional special mention for their
indescribable help. Steve, your insightful talks and sharing of ideas on arsenic at the Giant
and North Brookfield mines as well as your overall helpfulness for all things synchrotron,
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helped me more than you know. Steph, all those long days in the office, and sharing of ideas
helped to keep me focused for the last year of this thesis, thank you.
I would also like to thank AI Grant, Dave Kempson and Roger Innes from the
Department of Geological Sciences for their technical assistance. Dr. Tony Lanzirotti at
NSLS, Patricia Hunt and Gwendy Hall from the Geological Survey of Canada-Ottawa,
Brenda Coglin from ALS Chemex, Allison Rutter from ASU and Linda Campbell from Dr.
Grogan's Lab also deserve a sincere thank you for everything that you have done to help
with sample preparation and analysis. Many thanks to Paul Smith and Terry Goodwin from
Nova Scotia Department of Natural Resources and Dr. Michael Parsons from the Geological
Survey of Canada- Atlantic for their help with sample collection and historical information
on the North Brookfield mine. A sincere thank you to Bill Mitchel and the Giant Mine
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Remediation Team from Indian and Northern Affairs in Yellowknife for their generous
support, without which this project would not have been possible.
Thank you to Kathryn Kitney and Steve Garvin for your hospitality, being amazing
friends, great company and awesome chefs! To my parents Janet and Robert Wrye I would
like to say thank you for your love and unwavering support, you were always there when I
needed you. To my sister Kathy and her husband, thank you for giving me the chance to
escape from my work and relax, your horne was always inviting. Finally, to my fiance
Adam Best, I dedicate this thesis to you. I cannot begin to describe the sacrifices you have
made and patience you have shown me over the past two years, thank you so much.
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Table of Contents
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Abstract •........................................................................................................................................ i
Co-Authorship ............................................................................................................................ iii
Acknowledgements ................................................................................................................... iv
List of Figures ............................................................................................................................... x
List of Tables. ............................................................................................................................. xii
List of Equations ...................................................................................................................... xiii
List of Abbreviations ............................................................................................................... xiv
Chapter 1 : Introduction .............................................................................................................. l
1.1 Arsenic in the Environment-The Problem. ..................................................................... l
1.2 Site Descriptions .................................................................................................................. 7
1.2.1 Giant mine, Northwest Territories ............................................................................ 7
1.2.1.1 Regional Geology and Mineralization ..................................................................... 7
1.2.1.2 Mining and Ore Processing History ..................................................................... 11
1.2.1.3 Generation and Emission of Arsenic Trioxide from Roasting ............................... 15
0 1.2.2 North Brookfield mine, Nova Scotia ....................................................................... 17
1.2.2.1 Regional Geology and Gold Mineralization .......................................................... 19
1.2.2.2 Mining and Ore Processing History ..................................................................... 21
1.2.2.3 Generation and Emission of Arsenic Trioxide from Roasting ............................... 25
1.3 Research Goals and Thesis Organization ...................................................................... 26
Chapter 2 : Literature Review .................................................................................................. 29
2.1 Arsenic Solid Phases ......................................................................................................... 29
2.1.1 Arsenic in Soils ........................................................................................................... 29
2.1.2 Stability of Arsenic Trioxide ..................................................................................... 34
2.1.3 Studies of Soils Impacted by Arsenic Trioxide ...................................................... 38
2.2 Arsenic Toxicity and Bioavailability in Soils ................................................................ .40
2.3 Background Information .................................................................................................. 43
2.3.1 Previous Work at the Giant mine, Northwest Territories .................................... 43
2.3.2 Previous Work at the North Brookfield mine, Nova Scotia ................................. 51
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Chapter 3 : Field and Analytical Methods ............................................................................. 52
3.1 Sampling Design ............................................................................................................... 52
3.1.1 Sample Locations ....................................................................................................... 52
3.1.2 Sample Collection ...................................................................................................... 57
3.2 Analytical Methods ........................................................................................................... 59
3.2.1 Elemental and Organic Carbon (OC) Analysis ...................................................... 59
3.2.2 Thin Section Preparation and Petrography ............................................................ 63
3.2.3 Synchrotron-based Analyses .................................................................................... 64
3.2.3.1 X-Ray Adsorption Near Edge Structure (XANES) Spectra and Analyses .......... 66
3.2.3.2 Micro-X-Ray Diffraction (pXRD) Analyses ......................................................... 69
3.2.4 Conventional X-Ray Diffraction (XRD) .................................................................. 69
3.2.5 Sequential Selective Extraction (SSE) Analyses ..................................................... 70
3.2.6 Environmental Scanning Electron Microscopy (ESEM) ....................................... 72
Chapter 4 : The Presence and Persistence of As203 in Soils from the Giant mine,
Northwest Territories .......................................................................................... 74
4.1 Introduction ....................................................................................................................... 74
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4.2 Methods .............................................................................................................................. 76
4.2.1 Sample Collection ...................................................................................................... 76
4.2.2 Elemental and Organic Carbon (OC) Analysis ...................................................... 78
4.2.3 Petrography and Synchrotron Analyses ................................................................. 79
4.2.4 Environmental Scanning Electron Microscopy (ESEM) ....................................... 82
4.3 Results ................................................................................................................................. 82
4.3.1 Soil Profiles ................................................................................................................. 83
4.3.1.1 The Townsite- Sites 19, 13 and 14 ......................................................................... 83
4.3.1.2 The Fault- Site 28 and 29 ...................................................................................... 87
4.3.1.3 The Roaster- Site 31 ............................................................................................... 90
4.3.2 Characterization of As-oxides .................................................................................. 92
4.3.2.1 pXRD and pXANES Analyses ............................................................................. 92
4.3.2.2 Relationship between Organic Carbon (OC) and As,03 ....................................... 94
4.3.2.3 Calculation of As,O, in Soils ................................................................................. 95
4.4 Discussion .......................................................................................................................... 97
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4.4.1 Predictions of Asz03 Based on As, Sb, and OC at Giant ....................................... 97
4.4.2 The Wash Down Effect .............................................................................................. 98
4.4.3 Long-term Stability and Persistence of Asz03 ........................................................ 98
Chapter 5 : Characterizing the Source of Arsenic in Soils from the Giant Mine,
Northwest Territories and the North Brookfield Mine, Nova Scotia ...... 102
5.1 Introduction ..................................................................................................................... 102
5.2 Site Descriptions .............................................................................................................. 104
5.2.1 Giant Mine, Northwest Territories ........................................................................ 104
5.2.2 North Brookfield Mine, Nova Scotia ..................................................................... 106
5.3 Methods ............................................................................................................................ 109
5.3.1 Sample Collection and Preparation ....................................................................... 109
5.3.2 pXANES, pXRD and Bulk XRD Analysis ............................................................. 110
5.3.3 Environmental Scanning Electron Microscopy (ESEM) ..................................... 112
5.3.4 Sequential Selective Extraction (SSE) Analysis .................................................... 113
5.4 Results and Discussion. .................................................................................................. 115
0 5.4.1 Soil Descriptions and Selected Bulk XRD ............................................................. 115
5.4.2 pXANES, pXRD and ESEM Analyses of As-rich particles ................................. 116
5.4.2.1 Giant Mine ........................................................................................................... 116
5.4.2.2 North Brookfield Mine ......................................................................................... 119
5.4.3 Mineralogical Interpretation of Sequential Selective Extractions ..................... 123
5.4.3.1 Giant Mine ........................................................................................................... 123
5.4.3.2 North Brookfield Mine ......................................................................................... 128
5.4.4 Differences in Mineralogy and SSE Between Giant and North
Brookfield Mines ....................................................................................................... 132
5.4.5 Differentiating the Sources of Arsenic in Soils .................................................... 134
5.5 Conclusions ...................................................................................................................... 136
Chapter 6: Conclusions and Future Work ......................................................................... 138
6.1 Conclusions ...................................................................................................................... 138
6.2 Future Work. .................................................................................................................... 143
References .............................................................................................................................. 146
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Appendix A: Sample Location Photographs ........................................................................ 162
Appendix B: Soil Descriptions ................................................................................................ 165
Appendix C: List of Examined Sub-Samples and Analyses Performed ........................... 168
Appendix D: Giant Mine-Soil Chemistry on Unsieved Samples ...................................... 171
Appendix E: North Brookfield Mine-Soil Chemistry on Unsieved Samples .................. 186
Appendix F: Organic Carbon Results .................................................................................... 194
Appendix G: Selected Sequential Selective Extraction (SSE) Results ............................... 197
Appendix H: Sequential Selective Extraction Plots for Manganese and Titanium at
Giant and North Brookfield Mines ................................................................... 207
Appendix 1: Conventional X-Ray Diffraction Results ......................................................... 210
Appendix J: Petrography, Synchrotron Analyses, and ESEM Photomicrographs by
Sample Location .................................................................................................. 214
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