mercury fate and transport in the global atmosphere

Mercury Fate and Transport in the Global Atmosphere:

Measurements, Models and Policy Implications

Robert MasonDepartment of Marine Sciences

University of ConnecticutHartford, USA

Nicola PirroneChair of the UNEP MFTP

CNR - Institute for Atmospheric Pollution Rende, Italy

Editors:

Interim Report of the

UNEP Global Mercury Partnership Mercury Air Transport and Fate Research partnership area

14 July 2008

http://www.cs.iia.cnr.it/UNEP-MFTP/index.htm

List of contributors Preface Nicola Pirrone Italy Foreword Terry Keating United States Andr Zuber European Community Acknowledgments Nicola Pirrone Italy Executive summary Nicola Pirrone Italy Robert Mason United States Chapter - 1: Global Mercury Emissions to the Atmosphere from Natural and

Anthropogenic Sources Coordinating lead author Nicola Pirrone Italy Contributing authors Sergio Cinnirella Italy Rob Mason United States Xinbin Feng China Arun B. Mukherjee Finland Robert B. Finkelman United States Glenn Stracher United States Hans. R. Friedli United States David G. Streets United States Joy Leaner South Africa Kevin Telmer Canada Chapter - 2: Mercury Emissions from Coal Combustion in China Coordinating lead author David G. Streets United States Contributing authors Jiming Hao China Ye Wu China Shuxiao Wang China Chapter - 3: Mercury Emissions from Industrial Sources in China Coordinating lead author Xinbin Feng China Contributing authors Jiming Hao China David G. Streets United States Guanghui Li China Ye Wu China Chapter - 4: Mercury Emissions from Industrial Sources in India and its Effects in the

Environment Coordinating lead author Arun B. Mukherjee Finland Contributing authors Prosun Bhattacharya Sweden Ron Zevenhoven Finland Atanu Sarkar India Chapter - 5: Mercury Emissions from Point Sources in South Africa Coordinating lead author Joy Leaner South Africa

i

Contributing authors James Dabrowski South Africa Robert Mason United States Rico Euripides South Africa Tabby Resane South Africa Martin Ginster South Africa Marguerite Richardson South Africa Elizabeth Masekoameng South Africa

Chapter - 6: World Emissions of Mercury from Artisanal and Small Scale Gold

Mining Coordinating lead author Kevin H. Telmer Canada Contributing author Marcello M. Veiga Canada

Chapter - 7: Mercury Emissions from Natural Processes and their Importance in the

Global Mercury Cycle Coordinating lead author Rob Mason United States

Chapter - 8: Mercury Emissions from Global Biomass Burning: Spatial and

Temporal Distribution Coordinating lead author Hans. R. Friedli United States Contributing authors Avelino F. Arellano United States Nicola Pirrone Italy Sergio Cinnirella Italy

Chapter - 9: Spatial Coverage and Temporal Trends of Land-Based Atmospheric

Mercury Measurements in the Northern and Southern Hemispheres Coordinating lead author Ralf Ebinghaus Germany Contributing authors Catharine Banic Canada Nicola Pirrone Italy Steve Beauchamp Canada Laurier Poissant Canada Dan Jaffe United States Francesca Sprovieri Italy Hans Herbert Kock Germany Peter S. Weiss-Penzias United States Chapter - 10: Spatial Coverage and Temporal Trends of Atmospheric Mercury

Measurements in Polar Regions Coordinating lead author Aurlien Dommergue FranceContributing authors Marc Amyot Canada Francesca Sprovieri Italy Steve Brooks United States Alexandra Steffen Canada Christophe P Ferrari France Chapter - 11: Spatial Coverage and Temporal Trends of Over-Water, Air-Surface

Exchange, Surface and Deep Sea Water Mercury Measurements Coordinating lead author Francesca Sprovieri ItalyContributing authors Maria Andersson Sweden Nicola Pirrone ItalyRobert Mason United States

ii

Chapter - 12: Monitoring and Modeling Projects for Fate of Mercury Species in Japan Coordinating lead author Noriyuki Suzuki Japan Contributing authors Koyo Ogasawara Japan Yasuyuki Shibata Japan

Chapter - 13: The Need for a Coordinated Global Mercury Monitoring Network for

Global and Regional Models Validation Coordinating lead author Gerald J. Keeler United StatesContributing authors Russel Bullock United States Sanford Sillman United States Nicola Pirrone Italy

Chapter - 14: Our Current Understanding of Major Chemical and Physical Processes

Affecting Mercury Dynamics in the Atmosphere and at the Air-Water/Terrestrial Interfaces

Coordinating lead author A.J. Hynes United StatesContributing authors D. L. Donohoue United States Ian M. Hedgecock Italy M. E. Goodsite Denmark Chapter - 15: Mercury Chemical Transformation in the Gas, Aqueous and

Heterogeneous Phases: State-of-the-Art Science and Uncertainties Coordinating lead author Parisa A. Ariya CanadaContributing authors Marc Amyot Canada Graydon Snider Canada Kirk Peterson United States

Chapter - 16: Importance of a Global Scale Approach to Using Regional Models in the

Assessment of Source-Receptor Relationships for Mercury Coordinating lead author O. Russell Bullock Jr. United States Contributing author Lyatt Jaegl United States

Chapter - 17: Global Mercury Modelling at Environment Canada Coordinating lead author Ashu P. Dastoor Canada Contributing author Didier Davignon Canada

Chapter - 18: The Geos-Chem Model Coordinating lead author Lyatt Jaegl United States Contributing authors Daniel J. Jacob United States Sarah A. Strode United States Noelle E. Selin United States

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Chapter - 19: The ECHMERIT Model Coordinating lead author Gerlinde Jung Italy Contributing authors Ian M. Hedgecock Italy Nicola Pirrone Italy Chapter - 20: The EMEP/MSC-E Mercury Modeling System Coordinating lead author Oleg travnikov Russia Contributing author Ilia ilyinG. Jung Russia Chapter - 21: The AER/EPRI Global Chemical Transport Model for Mercury (CTM-HG) Coordinating lead author Christian Seigneur United States Contributing authors Leonard Levin United States Kristen Lohman United States Krish Vijayaraghavan United States

External Reviewers Marianne Bailey Office of International Affairs, U.S.

Environmental Protection Agency USA

Robin Dennis U.S. Environmental Protection Agency, NERL

USA

Bob Dyer U.S. Environmental Protection Agency USA Arthur E. Dungan President, The Chlorine Institute, Inc. USA Stanley Durkee Office of Research and Development, U.S.


Marilyn Engle Office of International Affairs, U.S. Environmental Protection Agency

USA

Luis E. Fernandez Stanford University USA Mark Freeman U.S. Department of Energy, USA Charles French U.S. Environmental Protection Agency USA Wendy Graham U.S. Environmental Protection Agency USA Loren Habegger Argonne National Laboratory USA Allen Kolker US Geological Survey USA Karissa Kovner U.S. Environmental Protection Agency USA Bruce J. Lawrence Bethlehem Apparatus Co. Inc USA Steve Lindberg Environmental Sciences Division, Oak Ridge

National Laboratory USA

Bian Liu School of Public Health, Harvard University USA Carl Mazza U.S. Environmental Protection Agency Belgium Peter Maxson Concorde Cons. Belgium Elsie Sunderland Office of Research and Development, U.S.


Wong, M.H. Hong Kong Baptist University China

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Table of Contents

Page

List of tables xvi List of figures xxiii Preface xxxii Foreword xxxiii Acknowledgments xxxiv Executive Summary xxxv

1. Introduction 1.1 Major Conclusions and Recommendations

2. Mercury Inputs to the Global Atmosphere 3. Mercury Cycling within the Atmospheric Reservoir 4. Mercury Processes and Modelling Studies

PART-1: Sources of Mercury released to the Global Atmosphere

Chapter 1 Global Mercury Emissions to the Atmosphere from Natural and Anthropogenic Sources

Summary 1 1.1 Introduction 1 1.2

Mercury emissions from natural sources 2 1.2.1 Volcanoes and geothermal activities 3 1.2.2 Water surfaces 3 1.2.3 Rocks, soils and vegetation 4 1.2.4 Biomass burning 5

1.3 Mercury emissions from anthropogenic sources 6 1.3.1 Anthropogenic emissions by sources category 7 1.3.2 Anthropogenic mercury emissions by region 22 1.3.2.1 Europe 22 1.3.2.2 North and Central America 23 1.3.2.3 Russia 23 1.3.2.4 China 24 1.3.2.5 Australia 25 1.3.2.6 India 26 1.3.2.7 South Africa 26 1.3.2.8 South America 27

1.4 Global Assessment 27 1.5 Further Research 30 1.6 References 31

Chapter 2 Mercury Emissions from Coal Combustion in China Summary 37

2.1 Introduction 37 2.2 Results and Discussion 37

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2.2.1 Coal use trends, 1995-2005 37 2.2.2 Mercury in coal 39

2.3

Mercury released to the atmosphere 40 2.4 Mercury emission trends in China 41 2.5 Future mercury emissions from coal combustion 44 2.6 Future Research and Policy Implications 45 2.7 References 46

Chapter 3 Mercury Emissions from Industrial Sources in China

Summary 47 3.1

Introduction 47 3.2 Mercury emission factors from different industrial sources in China 48 3.3 Speciation of mercury compounds from different industrial sources in

China 50

3.4 Mercury emissions from different industrial sources in China in 1999 50 3.5 Mercury emission trends from 1995 to 2003 52 3.6 Uncertainties 53 3.7 Future Research and Policy Implications 54 3.8 References 54

Chapter 4 Mercury Emissions from Industrial Sources in India and its Effects in the Environment

Summary 57 4.1 Introduction 57 4.2 Results 61

4.2.1 Coal combustion 62 4.3 Iron and Steel Industry 64

4.3.1 Non-ferrous metallurgical industry in India 65

4.3.1.1 Production of metals by different processes and emissions of mercury

65

4.3.2 Chlor-alkali industry in India 66

4.3.2.1 Chlorine and caustic soda production 66 4.4 Cement Industry 68 4.5 Wastes 69

4.5.1 Municipal Solid Waste (MSW) 69 4.5.2 Medical wastes 71 4.5.3 Electronic waste (E-waste) 71

4.6 Biomass burning 72 4.7 Miscellaneous 73

4.7.1 Brick industry 73 4.7.2 Instruments, batteries and thermometers 73

4.8 Mercury in the Indian Environment and the cycling in the bio-geosphere 74 4.9 Discussion 75

4.10 Future directions 78

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4.11 References 79

Capter 5 Mercury Emissions from Point Sources in South Africa Summary 83

5.1 Introduction 83 5.2 Current understanding of mercury emissions and levels in South Africa 84

5.2.1 Priority areas identified for monitoring air pollution in South Africa

84

5.2.2 Mercury emissions inventory for South Africa 86 5.2.2.1 Coal Combustion: Power Plants 87 5.2.2.2 Coal Combustion: Coal Gasification Process 88 5.2.2.3 Crude Oil Refining and Minerals Processing 89 5.2.2.4 Cement production 89 5.2.2.5 Ferrous Metal Production - Iron and Steel 90 5.2.2.6 Coal Combustion: Residential Heating 90 5.2.2.7 Non-Ferrous Metal Production: Primary Metals 90 5.2.2.8 Consumer Products, Waste Deposition (landfills) and

Incineration 91

5.2.2.9 Artisanal and Small-Scale Gold Mining Activities 91 5.3 Monitoring Hg emissions in South Africa 92 5.4 Gaps in our current understanding 92 5.5 Research needs 93 5.6 References 93

Chapter 6 World Emissions of Mercury from Artisanal and Small Scale Gold Mining

Summary 96 6.1

Introduction 97 6.1.1 Why mercury is used 98 6.1.2 How mercury is released to the Environment 100 6.1.2.1 Whole ore amalgamation 100 6.1.2.2 Amalgamation of a concentrate 102

6.2

Where ASGM is Occurring 102 6.3

Amount of Mercury Used in ASGM 109 6.3.1 Indonesia 110 6.3.2 Brazil 111 6.3.3 Other Countries with Documented Estimates 111 6.3.4 Other Countries Direct Anecdoctal Information 111 6.3.5 Remaining Countries Indirect Anecdotal Information 112

6.4

Reported Trade in Mercury and Gold 112 6.4.1 Using gold production to estimate mercury consumption in

ASGM 118

6.5

Knowledge Gaps about Mercury in ASGM 118 6.5.1 River Siltation in ASGM 120

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6.6

Reducing Mercury Use in ASGM 121 6.6.1 Reducing Emissions 121

6.7

Conclusions 124 6.8

References 125

Chapter 7 Mercury Emissions from Natural Processes and their Importance in the Global Mercury Cycle

Summary 130 7.1

Introduction 130 7.2 Estimates of oceanic evasion 133 7.3 Estimates of net terrestrial evasion 135 7.4 References 141

Chapter 8 Mercury Emissions from Global Biomass Burning: Spatial and Temporal Distribution

Summary 145 8.1 Introduction 146

Global distribution of vegetation 146

8.1.2 Biogeochemistry of mercury in forests 147

8.1.3 Mercury distribution in vegetation and organic soil by region 147

8.1.4 Mercury release from burning biomass and organic soil in different landscapes

148

8.1.5 Estimation of mercury emissions from biomass burning 149

8.1.6 Carbon emission model 149

8.1.7 Mercury emission factors 152 8.2 Results and discussion 155

8.2.1 Global Distribution of Carbon Emissions 155 8.2.2 Global Distribution of Mercury Emissions 156 8.2.3 Regional Estimates of Carbon and Mercury Emissions 158 8.2.2 Inter-annual Variability of Mercury Emissions 159 8.2.3 Global Hg emissions using global CO emission estimates 160 8.2.4 Comparison with other regional emission estimates 161

8.3 Future work 163 8.4 Policy implications 164 8.5 Aknowledgments 164 8.6 References 164

PART-2: Spatial Coverage and Temporal Trends of Mercury Measurements

Chapter 9 Spatial Coverage and Temporal Trends of Land-Based Atmospheric Mercury Measurements in the Northern and Southern Hemispheres

Summary 168 9.1 Introduction 168

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9.1.1 Quality of Data / Field intercomparisons 169 9.2 Measurements of air concentrations in North America 170

9.2.1 Measurements of air concentrations in Canada 170

9.2.1.1 Remote locations 170

9.2.1.2 Urban locations (including mining areas) 170

9.2.1.3 Temporal Trends at single locations 171

9.2.1.4 Monitoring networks and trend 171

9.2.1.4.1 Trend analysis 174 9.2.1.4.2 Comparison between air data and wet

deposition of mercury in North America 175

9.2.1.5 Mercury speciation analysis 177 9.2.1.6 Mercury measurements (incl. air craft) related to

emissions, and source attribution 180

9.2.2 Measurements of air concentrations in United States 181 9.2.2.1 Remote locations 182 9.2.2.2 Urban locations (including mining areas) 184 9.2.2.3 Temporal Trends at single locations 185 9.2.2.4 Monitoring networks and trends 187 9.2.2.5 Mercury speciation analysis 190 9.2.2.6 Mercury measurements related to emissions, and source

attribution 193

9.2.3 Measurements of air concentrations in Mexico 195 9.2.3.1 Remote locations 196 9.2.3.2 Urban locations (including mining areas) 197

9.3 Measurements of air concentrations in South America 197 9.3.1 Urban locations (including mining areas) 197 9.3.2 Mercury measurements (incl. air craft) related to emissions, and

source attribution 198

9.4 Measurements of air concentrations in Europe 199 9.4.1 Remote locations 199 9.4.2 Urban locations (including mining areas) 199 9.4.3 Temporal Trends at single locations 200 9.4.4 Monitoring networks and trends 200 9.4.5 Mercury speciation analysis 202 9.4.6 Mercury measurements (incl. air craft) related to emissions, and


9.5 Measurements of air concentrations in Asia 209 9.5.1 Remote locations 209 9.5.2 Urban locations (including mining areas) 209 9.5.3 Temporal Trends at single locations 210 9.5.4 Mercury speciation analysis 210 9.5.5 Mercury measurements (incl. air craft) related to emissions, and


9.6 Measurements of air concentrations in Africa 211 9.6.1 Monitoring networks and trends 211

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9.6.2 Mercury measurements (incl. air craft) related to emissions, and source attribution

212

9.7 Summary and Conclusion 212 9.8 References 214

Chapter 10 Spatial Coverage and Temporal Trends of Atmospheric Mercury Measurements in Polar Regions

Summary 220 10.1 Introduction 220 10.2 Results and discussion 222

10.2.1 Methods 222 10.2.1.1 Definitions 222 10.2.1.2 Atmospheric measurements in cold regions 222 10.2.2 Atmospheric mercury in the Arctic 223 10.2.2.1 Introduction 223 10.2.2.2 Atmospheric Mercury Depletion Events in the Arctic 223 10.2.2.3 Temporal trends of atmospheric mercury and

comparisons between sites 226

10.2.3 Atmospheric Mercury in the Antarctic 227 10.2.3.1 Introduction 227 10.2.3.2 Atmospheric measurements on the Antarctic Region 228 10.2.3.3 Temporal trends of atmospheric mercury in Antarctica 229 10.2.3.3.1 Coastal sites 230 10.2.3.3.2 Sites on the Polar Plateau 232 10.2.3.4 Antarctica vs Arctic 233 10.2.4 The role of snow surfaces on atmospheric Hg trends 234 10.2.4.1 Role of snow in emission and deposition processes 234 10.2.4.1.1 Snowpacks as promoters of atmospheric

Hg deposition 234

10.2.4.1.2 Snowpacks as promoters of Hg evasion 235 10.2.4.2 Potential influence on local, regional and global

mercury levels. 236

10.2.4.2.1 Local scale 236 10.2.4.2.2 Regional and global scale 236

10.3

Gap of knowledge, future Research and Policy Implications 237 10.4 References 238

Chapter 11 Spatial Coverage and Temporal Trends of Over-Water, Air-Surface Exchange, Surface and Deep Sea Water Mercury Measurements

Summary 243 11.1 Introduction 243 11.2 Over-water Mercury Measurements 245

11.2.1 Atlantic Ocean 246

11.2.2 Pacific Ocean 252

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11.2.3 Mediterranean Sea 253 11.3 Air-Water Mercury Exchange 256

11.3.1 Atlantic Ocean 258

11.3.2 Pacific Ocean 259

11.3.3 Mediterranean Sea 261

11.3.4 Other Oceans 269

11.3.4.1 Arctic Ocean 269

11.3.4.2 North Sea 270

11.3.4.3 Baltic Sea 271 11.4

Surface and Deep Sea Water Mercury Measurements 271 11.4.1 Atlantic Ocean 272 11.4.2 Pacific Ocean 273 11.4.3 Mediterranean Sea 275

11.5 References 281

Chapter 12 Monitoring and Modeling Projects for Fate of Mercury Species in Japan

Summary 288 12.1

Introduction 288 12.2

Monitoring Project for ambient atmospheric mercury and other heavy metals in remote Background Area

289

12.2.1 Project site for the field measurement 289 12.2.2 Methods of sampling and analysis 290 12.2. 3 Measurement results 290

12.3

Fate analysis of mercury species for the monitoring data using multimedia environmental fate model

293

12.3.1 Outline of the model 294 12.3.2 Results and comparison to the monitoring outputs 295

12.4

Future direction 295 12.5

References 296

Chapter 13 The Need for a Coordinated Global Mercury Monitoring Network for Global and Regional Models Validation

Summary 297 13.1


Existing Global Monitoring Programs 299 13.2.1 Ambient measurements 299 13.2.2 Mercury Measurements at Altitude 299 13.2.3 Episode-based Measurement Intensives 300 13.2.4 Meteorological Measurements 300 13.2.5 Atmospheric Deposition 300

13.3

Measurements and Model Development 301 13.3.1 General evaluation of model transport and photochemistry 301

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13.3.2 Source-receptor relationships: Long-range transport versus local sources

302

13.3.3 Evaluation of photochemical processes 305 13.3.4 Evaluation of gas-particle partitioning 306 13.3.5 Evaluation of emission inventories 306 13.3.6 Evaluation of past/future changes and effectiveness of control

strategies 307

13.3.7 Proposed Measurements to Enhance Model Development 307 13.4

Establishment of the coordinated global mercury monitoring network (CGMMN)

308

13.4.1 Key Components of a Coordinated Long-Term Network 308 13.4.2 Mercury Measurement Methods 309

13.5

Coordinated monitoring and modeling 310 13.5.1 Importance of establishing boundary conditions 311 13.5.2 Identification of key measurements parameters and species 311 13.5.3 Four-D Data Assimilation 312 13.5.4 Observation-based Apportionment Methods for Emission

Inventory Reconciliation 313

13.5.5 Case Study of coordinated measurement/modeling in the Mediterranean

315

13.6

References 318

PART-3: Understanding Atmospheric Mercury on Hemispheric and Global Scales

Chapter 14 Or Current Understanding of Major Chemical and Physical Processes Affecting Mercury Dynamics in the Atmosphere and at the Air-Water/Terrestrial Interfaces

Summary 322 14.1


Homogeneous Gas phase Transformation 323 14.2.1 Field Observations 323 14.2.2 Kinetic of Homogeneous Gas Phase Reactions 324 14.2.2.1 Terminology 324 14.2.2.2 Thermodynamics 326 14.2.2.3 Experimental Approaches 326 14.2.2.4 Ab-Initio Thermochemistry 326

14.3

Specific Reaction Systems 327 14.3.1 Hg(0) - O3 327 14.3.2 Hg(0) + OH 329 14.3.3 Halogen Reactions 331 14.3.3.1 Hg(0) + Cl 331 14.3.3.2 Hg(0) + Br 333

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14.3.3.3 Hg + BrO 334 14.3.3.4 Hg(0) + NO3 335

14.4

Gas Phase Oxidation: Issues and Uncertainties 335 14.5

Mercury Chemistry in the Atmospheric Aqueous Phase 335 14.5.1 Redox reactions 336 14.5.2 Does reduction actually occur in the aqueous phase? 336 14.5.3 Speciation 337 14.5.4 Is aqueous phase chemistry important compared to gas phase

oxidation? 337

14.5.5 The Sea Salt Aerosol 338 14.6

The Uncertainty due to Hg Chemistry in Atmospheric Models 338 14.7

Deposition Processes 339 14.8

References 341

Capter 15 Mercury Chemical Transformation in the Gas, Aqueous and Heterogeneous Phases: State-of-the-Art Science and Uncertainties

Summary 345 15.1

Introduction 345 15.2 Atmospheric oxidation and reductions 347 15.3 Theoretical evaluation of kinetic data 360 15.4 Reactions at interfaces: Heterogeneous reactions 363

15.4.1 Lake surface 363 15.4.2 Surface of oceans 364 15.4.3 Snow surface 365 15.4.4 Soil surface 366 15.4.5 Vegetation surface 366 15.4.6 Carbon (fly ash, charcoal) 367

15.5 Open questions and future directions 368 15.6 Acknowledgements 369 15.7 References 369

Chapter 16 Importance of a Global Scale Approach to Using Regional Models in the Assessment of Source-Receptor Relationships for Mercury

Summary 377 16.1

Introduction 378 16.2 Previous Testing and Application 379

16.2.1 Introduction of Dynamic Global Modeling for Boundary Conditions

380

16.3 Testing Model Sensitivities to Intercontinental Transport 383 16.4 Future Research and Policy Implications 386 16.5 References 387

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Capter 17 Global Mercury Modelling at Environment Canada Summary 389

17.1 Introduction 389 17.2 Model Description 390 17.3 Results and Discussion 391 17.4 Uncertainties and Future Research 398 17.5 References 398

Capter 18 The GEOS-CHEM Model Summary 401

18.1 Introduction 401 18.2 Model Description 402 18.3 Results / Discussion 404

18.3.1 Reference Simulation 404 18.3.2 Response of deposition to anthropogenic emission reductions 405 18.3.3 Response of land and ocean emissions 408

18.4 Uncertainties in Model Results and Future Research 409 18.5 References 410

Capter 19 The ECHMERT Model Summary 411

19.1 Introduction 411 19.2 Model description 412 19.3 Results/Discussion 414

19.3.1 Sensitivity Analysis of the Chemical Mechanism 414 19.3.2 Model Evaluation 417 19.3.3 Tracer transport studies 419 19.3.4 Emission Reduction Experiment 425

19.4

Future Research and Policy Implications 426 19.5

References 427

Capter 20 The EMEP/MSC-E Mercury Modeling System Summary 428

20.1


Model Description 428 20.3

Results and Discussion 431 204

Uncertainty and Future Research 437 20.5

References 437

Capter 21 The AER/EPRI Global Chemical Transport Model for Mercury (CTM-HG)

Summary 440

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21.1 Description of the CTM-Hg 440 21.2 Emission Inventory 441 21.3 Atmospheric Chemistry of Mercury 442 21.4 Model Performance Evaluation 443 21.5 Source/Receptor Relationships 445 21.6 Conclusion 447 21.7 References 448

List of Tables

Page

Executive Summary

Table E.1 Total mercury emissions by source category. Taken from Chapter 1 and references therein.


Table 1.1 Summary of gaseous mercury fluxes for oceans and lakes. 4 Table 1.2 Summary of mercury fluxes from terrestrial regions. 5 Table 1.3 Mercury emissions from biomass burning estimated by Friedli et al.

(2008, this report) compared with that reported in literature. 6

Table 1.4 Main source categories of mercury released annually in the environment.

6

Table 1.5 Global atmospheric releases of mercury from stationary combustion of fossil fuels for the year 2000.

8

Table 1.6 Mercury concentration in crude oil and refined products of different geographic origin.

9

Table 1.7 Estimates of mercury emissions from ore processing worldwide. 11 Table 1.8 Number of chlor-alkali plants, total chlorine production and

percentage of Processes that use mercury cells in EU countries in 2005.

12

Table 1.9 Mercury content in coals from selected countries. 13 Table 1.10 Mercury in Fluorescent Lamps. 15 Table 1.11 Mercury in Button Cell Batteries. 16 Table 1.12 Mercury content in common household item. 16 Table 1.13 Estimated mercury content (Mg y1) in waste in 2000 in the EU

member countries. 18

Table 1.14 Global mercury demand in 2000, by sector and by region. 20 Table 1.15 World production of mined mercury (Mg) as reported by the USGS. 21 Table 1.16 Mercury consumption from artisanal small scale gold

mining by region. 21

Table 1.17 Anthropogenic emissions of mercury in Europe in 2000 (Mg y-1). 22 Table 1.18 Trends in anthropogenic emissions of mercury in Europe since

1980 (Mg y-1) 22

Table 1.19 Mercury emission in USA, Canada and Mexico for the year 1990 and in USA for 2002.

23

Table 1.20 Mercury emissions to air and water in Russia. 24 Table 1.21 Mercury emission from different source categories in China in 2003. 25 Table 1.22 Emissions of mercury to the atmosphere from point sources in

Australia (> 5kg y-1) as reported in the Australian National Pollutant Inventory.

25

Table 1.23 Mercury emission from different source categories in India (Mg y-1). 26 Table 1.24 Mercury emissions (Mg y-1) from major anthropogenic sources in

South Africa during 2004. 27

Table 1.25 Global emissions of total mercury from major anthropogenic sources in 1990 (Mg y-1).

28


28


28

Table 1.28 Total mercury emissions by source category. 29

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Table 1.29 Global emissions of total mercury from major anthropogenic sources in major emitting countries/regions (Mg y-1).

29

Chapter 2 Mercury Emissions from Coal Combustion in China

Table 2.1 Mercury emissions from coal combustion (Mg y1). 42


Table 3.1 Emission factors for total Hg from industrial sources in China. 49 Table 3.2 Mercury emission factors from zinc smelting using different

smelting processes in China. 50

Table 3.3 Speciation of total mercury for each major source type (as fraction of the total).

50

Table 3.4 Summary of Hg emission estimates (Mg) for industrial sources associated with fuel consumption and materials production and use in 1999.

51

Table 3.5 Summary of total mercury emission estimates (Mg) from industrial sources from 1995 to 2003.

52


Table 4.1 Production of metals, Coal, residue fuel oil, and cement in India, 2000-2004, in Tg.

60

Table 4.2 Leading mercury users in India (1998 2001). 61 Table 4.3 Mercury concentration in different rock samples (from different

sources). 61

Table 4.4 Emission factors of mercury from industrial sources used for India. 63 Table 4.5 Samples collected from eight coal based power plants in India. 64 Table 4.6 Atmospheric mercury emissions from industrial sources in India for

2000 and 2004, respectively. 64

Table 4.7 Estimation of the essential parts of MSW in India based on the study for Allahabad city.

70

Table 4.8 Estimated medical waste generation in selected Asian countries. 72 Table 4.9 Mercury in electronic wastes (Mt) in India. 72 Table 4.10 Total mercury consumption in instrument manufacturing industry. 74 Table 4.11 Mercury concentration in fish and other species. 75 Table 4.12 Mercury concentration (mg kg-1) of different samples of the Ganges

River collected at Varanasi, India. 75

Chapter 5 Mercury Emissions from Point Sources in South Africa

Table 5.1 Current air quality parameters monitored in the Vaal Air-shed Priority Area of South Africa.

85

Table 5.2 Total amount of coal consumed or commodity produced by major industries in South Africa during 2004.

86

Table 5.3 Emission control devices used at coal-fired power plants of South Africa.

88

Table 5.4 Emission reduction factors used for estimating atmospheric total Hg emissions in different source categories in South Africa.

89

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Table 6.1 Mercury consumption by country for 2008 in artisanal small scale gold mining (ASGM) estimated by the authors.

Table 6.2 Knowledge Gaps about mercury use in ASGM. 120


Table 7.1 Observed seawater Hg data (meanstdev) and estimated evasion fluxes as reported in the literature.

135

Table 7.2 Ranges (90% confidence intervals) in the estimated fluxes from the ocean to the atmosphere for the various ocean basins.

136

Table 7.3 Average fluxes, or in some cases the range of fluxes, for various ecosystems measured by a number of investigators.

137

Table 7.4 Estimates of the uptake of mercury by vegetation, primarily trees as estimated from the concentration of Hg in litterfall collected at the end of the growing season, or from measurements of leaf concentration over time.

138

Table 7.5 Estimates of net evasion of mercury from terrestrial ecosystems. 139 Table 7.6 Overall summary of fluxes by vegetation type and for aquatic

systems. 140


Table 8.1 Published molar enhancement ratios (ER) observed from fire plumes worldwide.

153

Table 8.2 Emission factors (EF in g/kg fuel) used in the emission calculations.

154

Table 8.3 Emission factors used in this report (in g Hg/kg fuel). 154 Table 8.4 Mean seasonality of global mercury and carbon emissions (1997-

2006). 158

Table 8.5 Regional emission estimates for mercury and carbon (1997-2006). 159 Table 8.6 Global Hg emissions based on global CO emission estimates. 161 Table 8.7 Comparison of estimates of carbon and mercury emissions with

literature. 162


Table 9.1 Characteristics of the sampling sites and time periods which were available from the NAtChem database

172

Table 9.2 Statistical summary of TGM measurements at CAMNet sites. 174 Table 9.3 Results from trend analysis after seasonal decomposition. 174 Table 9.4 Summary of the trend statistics of total mercury

concentrations in precipitation within the MDN network compared with the TGM changes within CAMNet .

176

Table 9.5 Half lives for decrease in Hg concentration and deposition in precipitation.

177

Table 9.6 Statistical summary of mercury speciation measurements from January 2006 to June 2007 in Halifax (Nova Scotia, Canada).

178

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Table 9.7 GEM for different altitude ranges over Canada. The mean is given in bold, the median in italics.

180

Table 9.8 Summary of Hg(0) , RGM, and Hgp measurements made at remote, rural, and urban locations in the United States.

181

Table 9.9 Site description and sampling dates for measurements of TGM in air in Mexico

196

Table 9.10 Location and sampling dates for Puerto Angel and Huejulta MDN sites in Mexico.

196

Table 9.11 Summary of TGM concentrations (ng m-3) measured at 4 locations in Mexico.

196

Table 9.12 Summary of annual mercury concentration in precipitation between Oct 2004 to Oct 2005 at 2 rural-remote locations in Mexico.

197

Table 9.13 Applied rnethods for sampling and analysis of atmospheric mercury species

204

Table 9.14 Average median and range of observed concentrations of TGM, TPM and in Tuscany, June. 1998.

204

Table 9.15 MAMCS MOE multi-sites measurement campaigns. 204 Table 9.16 TGM, RGM and TPM average values observed at the five sites in

the Mediterranean during the 4 sampling campaigns of the MAMCS project.

206

Table 9.17 Time-schedule of sampling campaigns in the framework of the MERCYMS Project.

207

Table 9.18 Sampling time schedule applied during MERCYMS campaigns. 207 Table 9.19 Site locations and mercury species and methods used during

MERCYMS project. 208

Table 9.20 Average TGM, RGM and TPM values from coastal stations during four seasons.

208


Table 10.1 Atmospheric mercury measurements conducted in arctic and sub-arctic sites.

224

Table 10.2 Summary of atmospheric mercury measurements performed at different Antarctic locations from 1985 to 2005.

228


Table 11.1 Summary of the measurments of Total Gaseous Mercury (g m-3) over the Atlantic Ocean.

248

Table 11.2 Concentrations of total gaseous mercury and reactive gaseous mercury for samples collected using the filter pack method.

251

Table 11.3 Mercury measurements programme carried out during the cruises campaigns in the Mediterranean sea region from the 2000 to 2007.

254

Table 11.4 Sampling/Analytical Methods used to assess atmospheric mercury species in the MBL of the Mediterranean Sea basin during the cruise campaigns (2000-2007).

254

Table 11.5 Main Statistical Parameters for atmospheric mercury species concentrations observed over the East sector of the Mediterranean Sea Basin during the MED-OCEANOR campaigns from 2000 to 2006.

255

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Table 11.6 Main Statistical Parameters for atmospheric mercury species concentrations observed over the West sector of the Mediterranean Sea Basin during the MED-OCEANOR campaigns from 2000 to 2007.

255

Table 11.7 Main Statistical Parameters for atmospheric mercury species concentrations observed over the Adriatic Sea during the MED-OCEANOR campaigns from 2004 to 2005.

256

Table 11.8 Main Statistical Parameters for atmospheric mercury species concentrations observed over the Mediterranean Sea Basin during the MED-OCEANOR campaigns from 2000 to 2007.

256

Table 11.9 Summary of the results from the Atlantic Ocean. 259 Table 11.10 Concentrations of elemental mercury measured in various ocean

regions and the associated estimated evasional flux to the atmosphere.

260

Table 11.11 Mean calculated reactive gaseous mercury (Hg(II) dry deposition, total mercury (Hg) in wet deposition and dissolved gaseous mercury (DGM) evasion fluxes.

260

Table 11.12 Concentration of dissolved mercury (D), mercury associated with particulate matter (P) and emission from the seawater surface of three selected sites during the summer season.

262

Table 11.13 Some physical parameters at the sampling sites with corresponding mercury evasion estimations performed by the gas exchange model.

264

Table 11.14 Mercury evasion from some aquatic environments reported in the literature including this study. For a more detailed description on averages and methods the reader is ferred to the original article.

265

Table 11.15 Results for DGM/saturation, TGM, wind speed and temperature from each section of the Mediterranean Sea.

267

Table 11.16 Average concentrations and saturation from the different parts of the Mediterranean Sea.

268

Table 11.17 Average wind speed and flux from the stations in the different parts of the Mediterranean Sea.

269

Table 11.18 Measurements conducted in the Baltic Sea. 271 Table 11.19 Concentrations of mercury (expressed in pM). 278 Table 11.20 Summary table for mercury analysis and speciation insurface water

samples during the Urania cruise (results are expressed in pM concentrations of Hg).

279

Table 11.21 Comparison of results for mercury speciation in surface ocean waters.

279


Table 12.1 Measurement Items, Sampling, and Analytical methods. 290 Table 12.2 Monthly statistics of gaseous elementary mercury at CHAAMS from

October 2007 to January 2008, compared with Jaffe et al. (2005). 290


Table 13.1 Mercury emissions inventory for Broward and Dade County, Florida USA.

315

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Chapter 14 Or Current Understanding of Major Chemical and Physical Processes Affecting Mercury Dynamics in the Atmosphere and at the Air-Water/Terrestrial Interfaces

Table 14.1 Aqueous phase reactions of Hg. 337

Chapter 15 Mercury Chemical Transformation in the Gas, Aqueous and Heterogeneous Phases: State-of-the-Art Science and Uncertainties

Table 15.1 Compilation of known gas-phase kinetics of mercury. 348 Table 15.2 Liquid (water)-phase kinetics of mercury. 350 Table 15.3 Inter-phase (heterogeneous/surface) kinetics and emission rates of

mercury. 355

Chapter 17 Global Mercury Modelling at Environment Canada

Table 17.1 Reduction in mercury deposition (Mg y-1) over four receptor regions and the Arctic due to 20% reduction in emissions from four source regions.

395

Chapter 18 The GEOS-CHEM Model

Table 18.1 Budget of mercury in the GEOS-Chem model for the globe and the four HTAP regions.

402

Table 18.2 Global annual change in sources and sinks for the four perturbation simulations

405

Table 18.3 Absolute change (Mg y-1) in deposition over land for each pair of source-receptor regions and for the globe.

405

Table 18.4 Mean relative change (%) in deposition over land for each pair of source-receptor regions and for the globe.

407

Table 18.5 Relative change in Hg0, and HgII+Hgp concentrations (%) for each pair of source-receptor region.

407

Chapter 19 The ECHMERT Model

Table 19.1 Monthly mean emission of CO for source regions in total and as percentage of the global value.

420

Table 19.2 Annual mean anthropogenic emissions of Hg0 for source regions in total and as percentage of the global value.

421

Table 19.3 Hg tracer experiment monthly percentages of tracer concentrations in the atmosphere above the receptor region deriving from a specific source region.

423

Table 19.4 Changes (control run minus reduction experiment) in wet and dry deposition [%] in the receptor regions for a 20% emission reduction in all source regions, Jan-Mar 2001.

426

Chapter 20 The EMEP/MSC-E Mercury Modeling System

Table 20.1 Summary of mercury transformations included into the model. 430

Chapter 21 The AER/EPRI Global Chemical Transport Model for Mercury (CTM-HG)

Table 21.1 Global Mercury Emissions (Mg y-1) for 2000. 441

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Table 21.2 Equilibria and reactions of atmospheric mercury. 443 Table 21.3 Comparison of measured and modeled concentrations of Hg(0) (ng

m-3). 445

Table 21.4 Relative contributions of anthropogenic source areas and natural emissions to atmospheric Hg deposition in the contiguous United States.

446

Table 21.5 Hg deposition fluxes from the base simulation and reductions in deposition due to 20% reductions in anthropogenic Hg emissions in the four UNEP regions.

447

xxii

List of Figures

Page


Figure 1.1 Modeled annual total deposition flux in g km-2 (equiv. to mg m-2) over the modeling domain.

4

Figure 1.2 Modeled monthly total emission and deposition fluxes to the Mediterranean Sea.

4

Figure 1.3 Global mercury emissions to the atmosphere by source category in 1995 and 2000.

7

Figure 1.4 Global mercury emissions to the atmosphere by petrol and diesel consumption in 2000.

10

Figure 1.5 Percentages of global mercury consumption for different sector in 2000 (a) and 2005 (b).

14

Figure 1.6 Mercury in solid waste from chlor-alkali plants in EU-15+Switzerland.

15

Figure 1.7 Trend of global anthropogenic emissions by region. 28

Chapter 2 Mercury Emissions from Coal Combustion in China

Figure 2.1 Trends in total raw coal consumption in China, 1995-2005; annual-average growth rates for the entire period are shown in the caption.

38

Figure 2.2 Trends in industrial raw coal consumption in China, 1995-2005; annual-average growth rates for the entire period are shown in the caption.

38

Figure 2.3 Mercury content of raw coal, as mined, (g Mg-1). 39 Figure 2.4 Time development of the penetration of PM control devices in China

in (a) the power sector (upper) and (b) the industrial sector (lower), 1995-2003.

40

Figure 2.5 Calculation procedure for mercury emissions; FREL = fraction released to the air during combustion; FRED = fraction reduced by emission control devices; FS = fraction emitted by species type.

41

Figure 2.6 Trends in mercury emissions in China, 1995-2005; annual-average growth rates for the entire period are shown in the caption.

42

Figure 2.7 Uncertainty in mercury emission estimates for coal combustion, as 95% confidence intervals.

42

Figure 2.8 Speciation of mercury emitted from coal combustion in 1999, by province.

43

Figure 2.9 Gridded mercury emissions from coal combustion for the year 1999 at 30 min 30 min spatial resolution (units are Mg yr-1 per grid cell).

43

Figure 2.10 Expected extent of FGD implementation on coal-fired power plants in China in 2010 and 2020, showing percentage implementation rates in each province.

44

Figure 2.11 (a) Anticipated growth in power generation and coal use in power plants out to 2020; and (b) the effect of FGD and other controls on future mercury emission levels (blue), showing avoided emissions through application of emission control technology (red).

45

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Figure 3.1 Uncertainty (%) in Hg emission estimates by sector (95% confidence intervals).

54


Figure 4.1 Chemistry of wet deposition of mercury. 60 Figure 4.2 Coal reserves in India, 2004. 63 Figure 4.3 The scenario of worlds chlorine plants and production capacity,

2006. 67

Figure 4.4 Mercury cell Chlor-alkali industry in India. Red circles indicate Hg-based thermometer industry.

67

Figure 4.5 Locations of Chlorine industries in India, 2008. 68 Figure 4.6 Solid waste generation in India. 70 Figure 4.7 Land requirement for disposal of municipal solid waste (km2). 71 Figure 4.8 Mercury pollution due to use of Mercury-Cell Chlor-alkali plants in

India in the 20th century. 77

Figure 4.9 Sources of mercury in India. 77

Capter 5 Mercury Emissions from Point Sources in South Africa

Figure 5.1 Location of the Vaal Air-shed Priority Area in South Africa. 84 Figure 5.2 The Highveld Priority Area in South Africa. 85 Figure 5.3 Average atmospheric Hg emissions estimated for different source

categories in South Africa during 2004. 87


Figure 6.1 Illustration of some of the many knowledge gaps remaining about mercury in ASGM.

101

Figure 6.2 Map of mercury consumption by artisanal small scale gold mining globally.

103

Figure 6.3 a,b - (a) [left] International exports and imports of mercury by country in Mg for the 5 year period 2002-2006.

113

Figure 6.4 Price of mercury over the last 108 years. 115 Figure 6.5 a, b - International exports and imports of mercury per annum sorted

by top exporters [5a left] and importers [5b right] for the 5 year period 2002-2006.

115


Figure 7.1 Schematic representation of the major processes involved in the exchange of mercury between the terrestrial environment and the atmosphere.

132


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Figure 8.1 Olson's major world ecosystem complexes ranked by carbon in live vegetation: An updated database using the GLC2000 land cover product (cdiac.ornl.gov).

147

Figure 8.2 Average monthly carbon emissions for the period 1997-2006. 156 Figure 8.3 Average monthly mercury emissions for the period 1997-2006. 157 Figure 8.4 Map of regions used in GFEDv2 (from van der Werf et al. 2006). 158 Figure 8.5 Average annual emissions of mercury and carbon (for 1997 -2006). 159 Figure 8.6 Annual mercury emissions for 1997-2006. 160


Figure 9.1 Sites in the Canadian Atmospheric Mercury Measurement Network (CAMNet).

172

Figure 9.2 Monthly Box-whisker plot trends of Gaseous Elemental Mercury from 2006 and 2007 at Halifax (Nova Scotia, Canada).

179

Figure 9.3 Monthly Box-whisker plot trends of Reactive Gaseous Mercury from 2006 and 2007 at Halifax (Nova Scotia, Canada).

179

Figure 9.4 Monthly Box-whisker plot trends of Particulate Mercury from 2006 and 2007 at Halifax (Nova Scotia, Canada).

180

Figure 9.5 Map of locations in the United States from which there are published measurements of gaseous and particle mercury species.

183

Figure 9.6 Time series plot of average daily concentrations of TGM measured at Desert Research Institute (Reno, Nevada) from 2002 to 2005.

186

Figure 9.7 Monthly Total Hg wet deposition at Underhill, VT. 187 Figure 9.8 Total mercury concentration from the Mercury Deposition Network

in 2006. 187

Figure 9.9 Sulfate concentration from the National Trends Network in 2006. 188 Figure 9.10 The relationship between the annual occurrence (sum) of high

mercury deposition weeks (>250 ng m-2) and the average annual deposition for those weeks for 13 MDN monitoring sites located in northeast North America.

189

Figure 9.11 Estimated over-water wet deposition flux (July 1, 1994-October 31, 1995).

190

Figure 9.12 Diurnal variation of Hg species (median concentrations) in Detroit (2003).

191

Figure 9.13 Scatter plot of total airborne mercury (TAM) vs. CO measured during 22 pollution events at Mt. Bachelor Observatory, Oregon during 2004-2005.

193

Figure 9.14 MOE measurement sites. (1) Neuglobsow, Germany; (2) Zingst, Germany; (3) Rrvik, Sweden; (4) Aspvreten, Sweden; and (5) Mace Head, Ireland.

201

Figure 9.15 Regional differences of TGM concentrations measured during the MOE project.

201

Figure 9.16 Regional differences of TPM concentrations measured during the MOE project.

203

Figure 9.17 Regional differences of RGM concentrations measured during the MOE project.

203

Figure 9.18 The measurement sites: 1. Mallorca (394030 N, 24136E); 2. Calabria (3925N, 1600E); 3. Sicily (3640N, 15l0E); 4. Turkey (362812N, 302024E); 5 Israel (3240N, 3456E); 6. Germany (530834N, 130200); 7. Germany (542614N, 124330E); 8. Sweden (572448N, ll5606E); 9 Sweden (584800, 172254E); 10. Ireland (5320N, 954W)

205

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Figure 9.19 Average TGM, TPM and RGM values obtained at campaign MOE 1 5 and MAMCS 1 4. The TGM value from the MAMCS campaign 4 should be regarded with some caution since it is based on measurements from two sites only.

205

Figure 9.20 Average TGM, TPM and RGM values obtained at campaign MOE 1 5 and MAMCS 1 4. The TGM value from the MAMCS campaign 4 should be regarded with some cautioun since it is based on measurements from two sites only.

206

Figure 9.21 Average TGM, IPM and RGM values obtained at campaign MOE 1 5 and MAMCS 1 4. The IGM value from the MAMCS campaign 4 should be regarded with some caution since it is based on measurements from two sites only.

207

Figure 9.22 MERCYMS coastal measurement sites. 207


Figure 10.1 Measurements site for Atmospheric mercury in the Arctic. 225 Figure 10.2 Temporal trends of GEM measurements conducted in the Arctic in

2002. 226

Figure 10.3 Measurement sites for atmospheric mercury in Antarctica. 229 Figure 10.4 Distribution of BrO around the Antarctic Continent. 230 Figure 10.5 Ozone and TGM concentrations during the AMDEs observed at

Neumayer, Antarctica from August to October 2000. 231

Figure 10.6 Two-hourly mean concentrations of GEM and RGM measured at Terra Nova Bay, Antarctica from November to December, 2000.

232

Figure 10.7 Weekly averages of total filterable mercury concentrations (the sum of RGM and PHg) collected as Hg on high volume filters, and the annual solar elevation angles at South Pole Station.

233


Figure 11.1 The 1996 South Atlantic cruise track from Montevideo to Barbados. 246 Figure 11.2 Tracks of the Polarstern cruises from Bremerhaven to Punta Quilla

(Argentina) in 1996, from Bremerhaven over Cape Town (South Africa) to Antarctica in 19992000, and from Antarctica to Punta Arenas (Chile) in 2001.

247

Figure 11.3 Total gaseous mercury concentrations over the ocean and other remote locations as reported by a) Slemr et al. (2003) and b) Laurier and Mason (2007).

249

Figure 11.4 Concentrations of reactive gaseous mercury (RGHg in figure), Hg0and ozone, as well at the UV radiation, measured during the cruise in the North atlantic in August 2003.

250

Figure 11.5 Relationship between the maximum measured daily reactive gaseous mercury concentration (2 hr average) and the midday ozone concentration from a number of different measurements over the ocean.

251

Figure 11.6 The cruise track for the 2002 North Pacific cruise from Japan to Hawaii. Note that the mercury data cover the period between May 14 and June 4, which includes sampling in a north-south transect and sampling in a west-east transect.

252

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Figure 11.7 Routes followed during the oceanographic campaigns in the

Mediterranean Sea Basin during different seasons and covering two sectors of the Mediterranean (Eastern and Western) from 2000 to 2007.

253

Figure 11.8 Concentrations of total mercury and dissolved gaseous mercury for surface samples collected using the fish sampler during the may/June 2002 cruise.

261

Figure 11.9 (A) Floating flux chamber. 1) Teflon tube for external air sampling; 2) inlet port; 3 )and 4), outlet ports; 5) floating PVC foam bar the second floating bar is not shown in the figure.; AAS, atomic absorption spectrometer; SD, sampling device; (B) Semi-automatic air sampling device for measurements of mercury degassing rate.

262

Figure 11.10 Hg measurements performed at near shore sites during 2000 MEDOCEANOR cruise over the western sector of the Mediterranean sea basin.

263

Figure 11.11 Cruise 1, summer 2003. 265 Figure 11.12 Cruise 2, Spring 2004. 266 Figure 11.13 Cruise 3, Fall 2004. 266 Figure 11.14 Concentrations of total mercury (reactive mercury for the earlier

studies) measured on the three cruises discussed in the text: the 1980 North Pacific cruise, the VERTEX cruise data and the 2002 IOC cruise.

274

Figure 11.15 Concentrations of reactive mercury measured at the VERTEX site over a season in 1986/87 showing the changes in the concentrations in the upper waters over time.

275


Figure 12.1 Project site: Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS) in Okinawa.

289

Figure 12.2 Observation of gaseous elemental Hg(0) at CHAAMS from October 2007 to January 2008

291

Figure 12.3 NOAA HYSPLIT backward trajectory for Episode #2 Japanese Standard Time (JST) = Coordinate Universal Time (UTC) + 9 hours.

291

Figure 12.4 NOAA HYSPLIT backward trajectory for Episode #3 Japanese Standard Time (JST) = Coordinate Universal Time (UTC) + 9 hours.

292

Figure 12.5 Monthly mercury wet deposition flux, concentration and precipitation observed at CHAAMS in 2007.

293

Figure 12.6 Transformation scheme of mercury species in the modeling study. 294 Figure 12.7 Preliminary results of atmospheric concentration and comparison to

the simulated air concentration at the Cape Hedo location. 295


Figure 13.1 Annual mercury wet deposition fluxes over the United States for 2003 2004.

302

Figure 13.2 Simulated annual surface-level Hg0 (nanograms per cubic meter of standard air) from three regional-scale models (CMAQ, REMSAD, TEAM) for North America using results from three different global models (CTM, GEOS-CHEM and GRAHM) as boundary conditions.

303

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Figure 13.3 Volume-weighted mean concentrations of V, Ni, Pb, and Sb (g L-1) and Hg (ng L-1) in precipitation arriving from the east at SoFAMMS urban (BCN, BCS, FLG, IND, MNS, NVR, PTI, SBI, and SOT) and coastal (ADK, CGT, and JHL) sites.

304

Figure 13.4 Measured O3, CO, particulate scattering (sp) and total gaseous mercury (TGM) during a pollution transport event at Mt. Bachelor, Oregon. Simultaneous elevated concentrations is interpreted as evidence of transport, most likely from Asia.

305

Figure 13.5 Model correlation between Hg0 and RGM in pg m-3 for Florida (green circles), the northeast corridor(Xs) and Great Lakes (pink squares).

305

Figure 13.6 Spring mean mixing ratio 1 standard deviation for background O3 at 5 sites sites representing the marine boundary layer along the U.S. Pacific coast, with linear regression lines.

308

Figure 13.7 Annual Average Western Boundary Values for the three mercury species determined by the three Global Mercury Models for the NAMMIS.

312

Figure 13.8 Measured RGM (pg m3) versus altitude (km) from aircraft measurements over the Atlantic Ocean off the coast of south Florida during June 2000 (points).

313

Figure 13.9 Calculated monthly dry and wet deposition to the surface of the Mediterranean Sea during the MAMCS campaign.

315

Figure 13.10 Calculated monthly total deposition and evasion of mercury to and from the surface of the Mediterranean Sea during the MAMCS campaign.

316

Figure 13.11 The measured and calculated Hg0(g) concentration during the Med-Oceanor 2004 oceanographic campaign.

316

Figure 13.12 Comparison of monthly average Hg concentration in rain for the EMEP site at Rorvik during 2000.

317

Chapter 15 Mercury Chemical Transformation in the Gas, Aqueous and Heterogeneous Phases: State-of-the-Art Science and Uncertainties

Figure 15.1 A simplified schematic of mercury transformation in the Earths environment.

346

Figure 15.2 Energy dispersive spectroscopy (EDS) image of HgO b)

Comparative HRTEM image of HgO deposit at RH = 0% and 50%, and c) CI of HgO product at RH = 0% and 50%.

354

Chapter 16 Importance of a Global Scale Approach to Using Regional Models in the Assessment of Source-Receptor Relationships for Mercury

Figure 16.1 Total Hg deposition to the UK, Italy and Poland: (a) in February 1999; (b) in August 1999; and (c) in the whole year 1999.

379

Figure 16.2 Contribution of national anthropogenic (NAS), European anthropogenic (EAS), and global, natural and re-emission sources (GNR) to Hg deposition over Poland: (a) in February 1999; (b) in August 1999; and (c) in the whole year 1999.

380

Figure 16.3 Comparison of simulated annual-average gas-phase mercury concentrations (ng m-3) with measured data for 1998.

381

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Figure 16.4 Comparison of simulated and measured 1998 wet deposition fluxes (g m-2) of total mercury over the United States (CA, California; FL, Florida; GA, Georgia; ME, Maine; MN, Minnesota; NC, North Carolina; NM, New Mexico; PA, Pennsylvania; SC, South Carolina; TX, Texas; WA, Washington; WI, Wisconsin).

382

Figure 16.5 Comparison of CMAQ-simulated total Hg wet deposition for 2001 to observations from the Mercury Deposition Network (MDN).

382

Figure 16.6 CMAQ-simulated results for the percent reduction in mercury deposition by 2020 when proposed regulations are fully implemented.

383

Figure 16.7 Annual average air concentrations of Hg0, RGM and particulate Hg (PHg) across the western boundary of the NAMMIS regional domain as determined from the CTM, GEOS-Chem and GRAHM global simulations.

384

Figure 16.8 R2 correlation statistics for simulated annual Hg wet deposition compared to observed values for each of the regional model simulations conducted in the North American Mercury Model Intercomparison Study.

384

Figure 16.9 Mean fractional bias (percent) for simulated annual Hg wet deposition compared to observed values for each of the regional model simulations conducted in the North American Mercury Model Intercomparison Study.

385

Figure 16.10 Mean fractional error (percent) for simulated annual Hg wet deposition compared to observed values for each of the regional model simulations conducted in the North American Mercury Model Intercomparison Study.

385

Chapter 17 Global Mercury Modelling at Environment Canada Figure 17.1 Inter-hemispheric gradient of TGM from observations (top:Lamborg et

al. (2002)) and GRAHM model simulation (bottom). 392

Figure 17.2 GRAHM simulated average surface air Hg(0) concentrations (ng standard m-3) for (a) winter, (b) spring, (c) summer and (d) fall and observed and model simulated time series of surface air Hg(0) concentrations at Alert, Canada for 2002.

393

Figure 17.3 Total mercury deposition for year 2001 from reference simulation (top) and reduction in deposition due to 20% reduction in anthropogenic emissions (scaled to 100% in the figure) from North America (middle left), Europe and North Africa (middle right), South Asia (bottom left) and East Asia (bottom right).

394

Figure 17.4 The surface air GEM concentration (top) and column GEM burden (bottom) sensitivities at receptor regions (x axis) and the Arctic to unit emission reductions from the source regions defined as South Asia (SA), East Asia (EA), Europe and North Africa (EU) and North America (NA).

396

Figure 17.5 Mercury deposition sensitivities at receptor regions and the Arctic to unit emission reductions from the source regions defined as South Asia (SA), East Asia (EA), Europe and North Africa (EU) and North America (NA) (top).

397

Figure 17.6 GRAHM air concentrations of mercury (ng/standard m3) on 18Z April 25, 2004 at 500mb showing episode of Asian outflow of mercury reaching N. America which was observed at Mt. Bachelor in central Oregon.

398

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Chapter 18 The GEOS-CHEM Model

Figure 18.1 Global distribution of annual emissions (g m-2 yr-1) in the GEOS-Chem model: a) Anthropogenic, b) biomass burning, c) land, and d) ocean emissions.

403

Figure 18.2 Annual mean distribution of surface concentrations of a) Hg0(ng m-3) and b) HgII+HgP (pg m-3).

404

Figure 18.3 Percentage change in annual surface concentrations of Hg0 and Hg(II)+Hgp (top 2 rows) and in deposition (bottom row) for each perturbation simulation.

406

Figure 18.4 Same as Figure 18.3, but focusing on the source regions where anthropogenic emissions are reduced by 20%.

406

Figure 18.5 Change in annual deposition. Same as bottom panel in Figure 18.3, but scaled to a 100 Mg/year anthropogenic emission decrease for each region.

407

Figure 18.6 Distribution of absolute change (g m-2 yr-1) in annual mean ocean (top), and land (bottom) emissions for each perturbation simulation.

409

Chapter 19 The ECHMERT Model

Figure 19.1 Difference [ppq] in Hg0 concentrations between a run excluding and one including the reaction of OH with Hg0, both using the Hg+O3 reaction rate constant of Hall (1995).

416

Figure 19.2 Difference [ppq] in Hg0 concentrations between a run including the Hg+O3 reaction rate constant of Hall (1995) and excluding the OH reaction and one run including OH reaction and using the Hg+O3 reaction rate constant of Pal and Ariya (2004)

416

Figure 19.3 Monthly mean ozone concentration [ppb], January 2001. 416 Figure 19.4 Hg0 concentration [ppq] using the Hg0+O3 reaction rate of Pal and

Ariya (2004) and including the Hg0+OH reaction. 417

Figure 19.5 Simulated O3 concentrations [ppb] versus observations, February 2001.

418

Figure 19.6 Simulated O3 concentrations [ppb] versus observations, June 2001. 419 Figure 19.7 Simulated TGM concentrations [ng/m] versus observations,

February 2001. 419

Figure 19.8 Source and receptor regions for HTAP experiments. 420 Figure 19.9 Hg-like tracers with different lifetimes [days], concentration [ppq] in

500 hPa. 421

Figure 19.10 Hg-like tracer (lifetime 360 days) for 4 different source regions, concentration [ppq] in 500 hPa, July 2001.

421

Figure 19.11 Hg-like tracer (lifetime 360 days) for 4 different source regions, concentration [ppq] in surface layer, July 2001.

422

Figure 19.12 CO-like tracer: contribution of source regions to receptor regions, January 2001.

424

Figure 19.13 CO-like tracer: contribution of source regions to receptor regions, July 2001.

424

Figure 19.14 Hg-like tracer: contribution of source regions to receptor regions, January 2001.

424

Figure 19.15 Changes (control run minus reduction experiment) in Hg0 concentration [ppq] with a reduction of 20% in all 4 source regions, Jan-Mar 2001.

425

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Figure 19.16 Changes (control run minus reduction experiment) in wet (below) and dry (up) deposition due to a 20% emission reduction in all 4 source regions, Jan-Mar 2001.

426

Chapter 20 The EMEP/MSC-E Mercury Modeling System

Figure 20.1 Hemispheric (a) and the EMEP regional (b) grids of the MSCE-HM-Hem and MSCE-HM models.

429

Figure 20.2 Long-term changes of mercury anthropogenic emissions in the Northern Hemisphere (a) and spatial distribution of Hg anthropogenic emissions in 2000 (b). Solid lines depict source regions selected for the analysis.

431

Figure 20.3 Spatial distribution of total mercury deposition in the Northern Hemisphere and in Europe in 2001.

432

Figure 20.4 Long-term changes of mercury deposition flux in Europe (a), North America (b), Eastern and Southeastern Asia (c), and in the Arctic (d). Solid line presents average flux over the region; shaded area shows 90%-confidence interval of the flux variation over the region.

433

Figure 20.5 Long-term changes of mercury deposition flux to different landuse categories in Europe (a) and comparison of calculated mercury deposition to forests with throughfall measurements at forest sites in Europe (b).

434

Figure 20.6 Location of monitoring sites used in the model evaluation (a), calculated vs. measured values of mean annual concentration of total gaseous mercury (a) and mercury concentration in precipitation (b). Dashed lines depict two-fold difference interval.

434

Figure 20.7 Modelled vs. measured long-term variation of monthly mean total gaseous mercury concentration in air (a, b) and total mercury concentration in precipitation (c, d) at some monitoring sites in Europe (Aas and Breivik, 2006) and North America (http://nadp.sws.uiuc.edu/mdn/).

435

Figure 20.8 Spatial distribution of relative decrease of mercury deposition due to 20% emission reduction in East Asia (a), Europe (b), North America (c), and South Asia (d).

436

Figure 20.9 Probability distribution of mercury deposition decrease over the Northern Hemisphere due to 20% emission reduction in the selected source regions (a) and contribution of the source regions to the deposition decrease in different receptor regions (b).

437

Chapter 21 The AER/EPRI Global Chemical Transport Model for Mercury (CTM-HG)

Figure 21.1 Modeled global Hg(0) concentrations (ng/m3).

444

Figure 21.2 Atmospheric deposition of mercury (g/m2-y) in the base simulation: Top: Hg(0) dry deposition; middle: Hg(II) dry deposition; bottom: Hg(II) wet deposition.

445

Figure 21.3 UNEP source areas used in the global emission scenarios. 447 Figure 21.4 Contribution of 20% of anthropogenic emissions from a region to

total atmospheric mercury deposition (g m-2 y-1): (a) South Asia, (b) East Asia, (c) Europe and North Africa, (d) North America, (e) all four regions.

448

xxxi

Mercury Fate and Transport in the Global Atmosphere: Measurements, models and policy implications

xxxii

Preface During the last decade the importance of environmental issues related to mercury released to

the atmosphere by major anthropogenic sources, which include, but are not limited to, power plants for energy production and a variety of industrial plants, has gained growing attention for their effects on human health and ecosystems. In this framework the UNEP Mercury Programme has started, since 2002, a process for assessing to what extent contamination by mercury released from anthropogenic and natural sources may affect human health and ecosystems. A number of concerted initiatives have been undertaken at global scale to assess the current state of our knowledge on atmospheric mercury emissions, transport and deposition to and evasion from terrestrial and aquatic ecosystems and to evaluate the relative contributions of natural and anthropogenic sources to the global atmospheric mercury budget. At the beginning of 2005 the Governing Council of the United Nations Environment Programme (UNEP-GC) urged (Decision 23/9 IV), governments, inter-governmental and non-governmental organizations and the private sector to develop and implement partnerships as one approach to reducing the risks to human health and the environment from the release of mercury and its compounds improving global understanding of international mercury emission sources, fate and transport. In this framework, the UNEP Global Partnership for Mercury Air Transport and Fate Research (UNEP-MFTP) was started in 2005 aiming to encourage collaborative research activities on different aspects of atmospheric mercury cycling on local to hemispheric and global scales.

Members of the UNEP-MFTP are Italy (lead), Canada, Japan, South Africa, United States,

Electric Power Research Institute (EPRI), Natural Resources Defence Council (NRDC) and UNEP. Since 2005, the UNEP-MFTP has met four times. The 1st meeting was held in Madison, Wisconsin in conjunction with the 8th International Conference of Mercury as a Global Pollutant, followed by the meeting in Gatineau, Quebec, Canada (9-10 January 2007) aimed to discuss and define the elements included in Decision 23/9 IV. A 3rd meeting was held in Washington, D.C. on 10-11 October 2007 aimed to review the Business Plan of the UNEP-MFTP, submitted later (February 2008) to UNEP Chemicals, whereas the 4th meeting of the partnership was held in Rome (7-11 April 2008) in conjunction with the international workshop jointly organised by the UNEP MFTP and the Task Force on Hemispheric Transport of Air Pollution (TF HTAP) of the UNECE Convention on Long-Range Transboundary Air Pollution in which leading scientists from all over the world presented their contribution to the UNEP-MFTP Technical Report.

This technical report aims to provide UNEP Chemicals, governments, inter-governmental and non-governmental organisations as well as the private sector, a state-of-the-art assessment of the cycling of mercury in the atmosphere. It covers the interactions of mercury with terrestrial and aquatic ecosystems, and evaluates the relative contribution of anthropogenic and natural sources to the global atmospheric mercury budget. The preparation of this report has been made possible thanks to the contributions of all members of the UNEP-MFTP and of over 70 scientists from leading universities and research institutions recognised as worldwide experts on different aspects related to emissions, monitoring and modelling mercury in the atmosphere and other environmental compartments. The draft of this report was delivered to UNEP Chemicals in February 2008 as contribution to the preparation of the overall emission report prepared jointly by UNEP Chemicals and AMAP. Being sure to share the views of all contributing authors of the UNEP-MFTP report, we hope that the content of this report will help nations and the next UNEP Governing Council in shaping the most efficient and economic concerted actions to reduce the impact of mercury contamination on human health and the environment.

Dr. Nicola Pirrone Chair of the UNEP-MFTP

CNR-Institute for Atmospheric Pollution Italy


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Foreword Mercury pollution is a long-standing and serious environmental problem. Negative impacts

were detected first close to industrial sites, but soon were found far from the emissions sources. Even in very remote and pristine areas, we can detect elevated levels of mercury pollution in the atmosphere, in other environmental media, and in biota such as in fish, birds, mammals and humans. These elevated levels of mercury are driven, in large part, by the long range transport of mercury in the atmosphere and may have significant adverse effects on humans and the ecosystems. Our understanding of the transport and fate of mercury in the atmosphere plays a crucial role in assessing present and future risks for humans and ecosystems and the effectiveness of policy options at the local, regional and global scales.

In February 2005, the UNEP Governing Council urged governmental and non-governmental

organizations to work together through public-private partnerships to reduce the risks of mercury pollution. In response to this decision, the cooperative Global Partnership for Mercury Air Transport and Fate Research (UNEP-MFTP) was formed. In June 2005 as the concept for the UNEP-MFTP was beginning to take shape, a Task Force on Hemispheric Transport of Air Pollution (TF HTAP) was convened under the UNECE Convention on Long-range Transboundary Air Pollution to improve the understanding of the intercontinental transport of air pollutants, including mercury, in the Northern Hemisphere. From the outset, the common objectives of the UNEP-MFTP and the TF HTAP in improving our understanding of the atmospheric transport of mercury on global to intercontinental scales have led the two efforts to work cooperatively, seeking to capture both efficiencies and synergies through coordination. This report represents the first product of the UNEP-MFTP and its cooperative relationship with the TF HTAP.

This report brings together new analyses and syntheses by many of the leading mercury

experts in the world. Updating the information presented in the UNEP Mercury Programmes 2002 Global Mercury Assessment, the report presents significant new information about the sources, cycling, fate, and transport of mercury in the atmosphere. The report provides new estimates of sources and sinks of atmospheric mercury, including estimates for some previously unquantified sources. The report assesses the current state of mercury observations and our understanding of the atmospheric chemistry of mercury. The report compares the results of a number of state-of-the-art regional and global atmospheric mercury models.

The report provides crucial scientific evidence for consideration by the UNEP Mercury

Programme as they prepare their own assessment for UNEP Governing Councils meeting in February 2009. In addition to contributing to the UNEP Mercury Programmes summary assessment, this extensive report provides a rich technical supplement that will serve as a resource for scientists and government representatives. The report will also inform scientific and policy discussions under the UNECE Convention on Long-range Transboundary Air Pollution and will serve as the foundation for further analysis to be presented in the TF HTAPs 2010 assessment report.

While there is a clear need to take action to decrease the anthropogenic sources of mercury in the atmosphere, the report also makes clear that there are important gaps in our understanding of the sources, fate, and transport of mercury in the atmosphere. Continued international cooperative efforts, such as the UNEP-MFTP and TF HTAP, are needed to address these gaps and improve the common scientific foundation upon which international policies can be constructed. As Co-Chairs of the TF HTAP, we would like to thank Nicola Pirrone, Rob Mason and all of the contributors to the UNEP-MFTP and to this report for helping to improve that foundation. Andr Zuber, Ph.D. Terry Keating, Ph.D. Co-Chair TF HTAP Co-Chair TF HTAP European Commission-DG Environment U.S. Environmental Protection Agency


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Acknowledgments

As Chair of the UNEP-MFTP I would like to express my gratitude to the members of the partnership for their continued support to the activity of the partnership during the last three years.

I would like to acknowledge the support received from the Italian Ministry for the

Environment Land and Sea, and in particular Dr. Corrado Clini, Director General of the Department for Environmental Research and Development.

The preparation of this technical report would have not been possible without the great

contribution of all colleagues that have led the preparation of the chapters and to all co-authors that have provided valuable contributions. The contribution of the external reviewers is greatly acknowledged. Special thanks to the co-Editor, Dr. Robert Mason who has provided continued and full support during these months.

I would like to acknowledge the great contribution from both co-chairs of the TF HTAP, Dr.

Andre Zuber and Dr. Terry Keating who have provided timely input to the activity of the UNEP-MFTP and to the preparation of this technical report.

I would like to express special thanks to my staff, Dr. Sergio Cinnirella, Dr. Ian M.

Hedgecock, Dr Gerlinde Jung and Dr. Francesca Sprovieri for their hard work and time dedicated to the preparation of this report, and to my secretary, Mrs Maria Orrico, for her hard work in formatting and preparing the final edited version of the report.

Dr. Nicola Pirrone Chair of the UNEP-MFTP

CNR-Institute for Atmospheric Pollution Italy


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Executive Summary

1. Introduction

Mercury, primarily because of its existence and bioaccumulation as methylmercury in aquatic organisms, is a concern for the health of higher trophic level organisms, or to their consumers. This is the major factor driving current research in mercury globally and in environmental regulation, and is the driver for the current UNEP Global Partnership for Mercury Transport and Fate Research (UNEP-MFTP) initiative. The overall focus of the UNEP MFTP report is to assess the relative importance of different processes/mechanisms affecting the transfer of mercury (Hg) from emission sources to aquatic and terrestrial receptors and provide possible source-receptor relationships. This transfer occur through atmospheric transport, chemical transformations and subsequent deposition, and involves the intermittent recycling between reservoirs that occurs prior to ultimate removal of Hg from the atmosphere. Understanding the sources, the global Hg transport and fate, and the impact of human activity on the biosphere, requires improved knowledge of Hg movement and transformation in the atmosphere. An improved understanding of Hg emission sources, fate and transport is important if there is to be a focused and concerted effort to set priorities and goals for Hg emission management and reduction at the national, regional and global levels; and to develop and implement such policies and strategies. To achieve this, a series of coordinated scientific endeavors focused on the estimation of sources, measurement and validation of concentrations and processes, and modeling, coupled with interpretation of the results within a policy framework, is likely to be required. Details of what has been achieved to date are laid out in the UNEP-MFTP Report in three sections. The details concerning our understanding of emissions and inputs of Hg from human activity and via natural processes is dealt with in Section I of the report. Section II details the measurements that have been made and compiles the available information. Current modeling efforts and the understanding of atmospheric processes at regional and global scales are detailed in Section III.

Mercury is ubiquitous in the atmosphere and the ground level background concentrations

appears to be relatively constant over hemispheric scales, varying by less than a factor of two for remote locations (Chapter 9). This is expected for a trace gas that has a relatively long residence time in the atmosphere. The southern hemisphere has a lower concentration than the northern hemisphere and this primarily reflects the current and historic concentration of anthropogenic emissions in the northern hemisphere. Recent measurements of free tropospheric air, either at high altitude sites or from measurements made on board aircraft, indicate that the concentration changes are usually but not always also relatively small vertically up to the tropopause, although there are differences apparent between measurement campaigns. In the stratosphere, Hg has been found associated with the stratospheric aerosol. Mercury fate and transport in the boundary layer is complex, and its concentration is modified by inputs and removal to the terrestrial/ocean surface (Chapter 15). In addition, rapid global transport of Hg can occur in the free troposphere. The fate of Hg is therefore determined by the different chemical environments that these regions of the atmosphere represent, the different physical and meteorological processes which occur in them, the differences in chemical reactivity, and also by exchange that occurs between reservoirs (Pirrone et al. 2005; Hedgecock et al. 2006; Lindberg et al. 2007).

Anthropogenic inputs of Hg have greatly exacerbated the global Hg cycle (Chapter 1). Much

of this impact is related to energy resources exploitation, especially fossil fuel consumption. The impact of these enhanced emissions is such that atmospheric concentrations have increased by a factor of three on average since pre-industrial times. Globally, fossil fuel power plants are the single most important anthropogenic emission source of Hg to the atmosphere, and these emissions, in combination with the emissions of other co-emitted pollutants, have an impact on the atmospheric chemistry of Hg and influence its resultant deposition patterns. Such synergistic impacts are also apparent for other industrial sources that release Hg to the atmosphere. While the primary impacts are observable in the short term, the medium to long term impact that exploitation of fossil fuels and other anthropogenic activities have on atmospheric Hg cycling is through their impact and influence by global climate change (Hedgecock and Pirrone, 2004; Eisenreich et al. 2005).


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For the thorough understanding of the atmospheric fate and transport of Hg it is necessary to document and comprehend the distribution and extent of emissions from point sources and from more diffuse sources, whether these are of anthropogenic origin or due to natural sources and processes. This report provides an evaluation and summation of the current state of the science and of the extent of current efforts to document and understand the degree to which concentrations in the atmosphere are changing, and whether this is entirely due to changes in inputs of Hg into the biosphere, or due to changes in other pollutants or chemicals, or global climate. Both direct and indirect impacts of Hg fate and transport through the atmosphere need to be considered.

1.1 Major Conclusions and Recommendations

1. About a third of the Hg currently emitted to the atmosphere is derived from point and other identifiable anthropogenic sources (2503Mg y-1). Coal combustion is the largest anthropogenic source globally.

2. The remainder of the emissions are associated with natural processes 5207 Mg y-1 but many of these processes have been exacerbated by human activity (e.g. biomass burning) and much of the Hg emitted from these sources had an original anthropogenic source. Current estimates suggest that about a third of the current total Hg emissions to the atmosphere from natural processes are due to the pre-industrial (natural) emission component and the remainder is recycled (previously deposited) Hg.

3. Changes in atmospheric Hg concentration over time have been detected in some locations but at the global scale it has been difficult to demonstrate a measurable change for the remote atmosphere over the last 20 years because of the lack of detailed and coordinated measurements.

4. There is the need to coordinate activities at the global level to ensure that future research provides the maximum benefits in terms of assessing global and regional trends in Hg concentration. It is recommended that a global monitoring network be established as soon as possible to ensure that the relevant information is obtained, and to provide the information necessary for model testing and evaluation.

5. Model development and focused process studies must continue and be expanded and enhanced to ensure that the models are correctly parameterized and that there is agreement between individual models and between model output and experimental data. 6. Without accredited models, it is difficult to make the pertinent forecasts and scenario predictions that are crucial to the development of sound management strategies for the control and mitigation of the current global Hg problem.

2. Mercury Inputs to the Global Atmosphere This section briefly outlines the conclusions and recommendations, and the details of the

chapters in Section I of the report. There are 8 chapters in total for this section. Chapter 1 is an overall summary chapter, while the other chapters deal with emission estimates for countries where emissions exhibit an upward trend and represent a substantial contribution for the global atmospheric mercury budget, these include China (Chapters 2 & 3), India (Chapter 4) and South Africa (Chapter 5). Another important worldwide anthropogenic source, not accounted for in previous assessments the artisanal gold mining sector in which Hg amalgamation is used as basic component of the extraction process (Chapter 6). The remaining two chapters cover sources that are important but relatively more areal, and less well-characterized, and include Hg emissions from natural processes. It must be kept in mind that Hg released from natural processes may have an anthropogenic origin. Thus, the distinction should be made between Hg that is emitted from primary natural sources and that which is recycled (re-emitted) Hg from prior atmospheric deposition. Howeve

mercury fate and transport in the global atmosphere

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