DEVELOPMENTS IN ECOSYSTEMS 1
WETLANDS
ECOSYSTEMS IN ASIA:
FUNCTION AND MANAGEMENT
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DEVELOPMENTS IN ECOSYSTEMS 1
WETLANDS
ECOSYSTEMS IN ASIA:
FUNCTION AND MANAGEMENT
EDITED BY
M.H. WONG
CROUCHER INSTITUTE FOR ENVIRONMENTAL SCIENCES
HONG KONG BAPTIST UNIVERSITY
KOWLOON TONG,HONG KONG
2004
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Abridged Contents
Session I. Natural Wetland Systems and Their Functions
1. A Comparison of Issues and Management Approaches in
Moreton Bay, Australia and Chesapeake Bay, USA
W.C. Dennison, T.J.B. Carruthers, J.E. Thomas, P.M. Glibert 3
2. Wetland Utilization and Protection in China
Q.G. Zhao, J. Song 27
3. Ecological and Environmental Function of Wetland Landscape
in the Liaohe Delta
D.N. Xiao, X.Z. Li 35
4. The Dyke-Pond Systems in South China: Past, Present and Future
M.H. Wong, K.C. Cheung, A. Yediler, C.K.C. Wong 47
Session II. Wetland Biogeochemistry
5. Heavy Metal Mobility and Aquatic Biogeochemical Processes
at Mai Po Marshes Nature Reserve, Hong Kong
Y. Liang, M.H. Wong 69
6. Biogeochemistry of Metals in the Rhizosphere of Wetland
Plants — An Explanation for “Innate” Metal Tolerance?
M.L. Otte, D.J. Matthews, D.L. Jacob, B.M. Moran, A.J.M. Baker 87
7. Mycotrophy and Its Significance in Wetland Ecology and

Wetland Management
A.G. Khan 95
8. Assessment of Risks to the Mai Po/Inner Deep Bay
Ramsar Site due to Environmental Contaminants
P.K.S. Lam, M.H.W. Lam 115
9. Modelling Contamination in an Urban Canal Sediment:
Some Preliminary Results from a Phytoremediation Project
N.M. Dickinson, R. King, A. Royle, I.D. Pulford, W. Hartley,
J. Jones, E. Gray-Jones, P.D. Putwain 131
Session III. Wetland Management Strategies in Asia
10. Conflicts in the Management of a Wetland Nature
Reserve — Case Study of the Mai Po Nature Reserve, Hong Kong
L. Young 145
11. Conservation and Uses of Mangroves in Hong Kong and
Mainland China
N.F.Y. Tam 161
12. An Integrated Analysis of Sustainable Human–Water Interactions
in Wetland Ecosystems of Taihu Lake Basin, East China
D. Hu, J.S. Yan, T.X. Liu, G.W. Chen, S.J. Yuan, R.S. Wang 183
13. Ecological Benefits of Italian Poplar Afforestation in Wetland Areas
along the Yangtze River, Fanchang County of Anhui Province
Z.J. Xi, D. Hu, R.X. Wang 221
14. Wetland Conservation and Management in the Philippines:
Where Are We Now? The Case of Seagrass and Mangrove
M.D. Fortes 233
15. Economic Valuation of Mangroves for Improved Usage and
Management in Thailand
C. Tingsabadh, S. Pongkijvorasin 263
Session IV. Constructed Wetlands
16. Constructed Wetlands for Wastewater Treatment: Principles

and Practices
C. Polprasert 285
17. Planting, Selection and Plant Establishment in Constructed
Wetlands in a Tropical Environment
M. Beharrell 311
18. Nitrogen Removal Processes in Constructed Wetlands
C.C. Tanner 331
vi Abridged Contents
19. Operation and Maintenance for Constructed Wetlands
M. Beharrell 347
20. Urban and Highway Runoff Treatment by Constructed Wetlands
R.B.E. Shutes, J.B. Ellis, D.M. Revitt, M. Forshaw, B. Winter 361
21. Wetland Ecosystems for Treatment of Stormwater in an
Urban Environment
J. Gan 383
22. The Application of Constructed Wetlands for Water Quality
Improvement in the Deep Bay Catchment of Hong Kong
M.W. Cha 401
23. Use of a Wetland System for Treating Pb/Zn Mine Effluent:
A Case Study in Southern China from 1984 to 2002
Z.H. Ye, M.H. Wong, C.Y. Lan 413
24. Wetland Creation in Hong Kong
S.S.S. Lau 435
Abridged Contents vii
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Contents
Abridged Contents v
Preface xxiii
About the Editor xxv
Acknowledgements xxvii

Session I. Natural Wetland Systems and Their Functions
Chapter 1. A Comparison of Issues and Management Approaches in
Moreton Bay, Australia and Chesapeake Bay, USA
W.C. Dennison, T.J.B. Carruthers, J.E. Thomas, P.M. Glibert 3
1.1. Introduction 3
1.2. Comparison of Systems 4
1.3. Moreton Bay Overview 6
1.4. Moreton Bay Sediments and Seagrass Loss 9
1.5. Moreton Bay Sewage Plumes 10
1.6. Moreton Bay Harmful Algal Blooms 11
1.7. Chesapeake Bay Overview 13
1.8. Chesapeake Bay Nutrient Over-Enrichment 14
1.9. Chesapeake Bay Critical Habitat Loss 15
1.10. Chesapeake Bay Sedimentation 17
1.11. Chesapeake Bay Harmful Algal Blooms 18
1.12. Overcoming Challenges 19
1.13. Healthy Waterways Campaign Overcomes Population Growth 19
1.14. Chesapeake Bay Blues 20
1.15. Mersey Basin Campaign Overcomes Cost Considerations 21
1.16. Mekong River Commission Overcomes Jurisdictional Issues 21
1.17. Conclusions 22
Acknowledgements 22
References 23
Chapter 2. Wetland Utilization and Protection in China
Q.G. Zhao, J. Song 27
2.1. Brief Introduction to Wetland Resources in China 27
2.2. Problems Arising from Wetland Exploitation and Utilization 28
2.2.1. Over-Exploitation and Shrinking Wetlands 28
2.2.2. Wetlands’ Quality Deterioration 29
2.2.3. Ecological Degradation and Reduced Biodiversity 32

2.3. Measures for Protection of China’s Wetlands 32
2.4. Utilization and Protection of Coastal Wetland in Jiangsu Province 33
2.4.1. Problems Associated with Utilization of Mudflat 33
References 34
Chapter 3. Ecological and Environmental Function of Wetland Landscape
in the Liaohe Delta
D.N. Xiao, X.Z. Li 35
3.1. Introduction 35
3.2. Hydrological Adjustment of Wetland 36
3.2.1. Wetland Water Storage Capacity and Reed Field
Evapotranspiration 36
3.2.2. Water Replacement Rate 37
3.3. Biomass Production and Output 39
3.4. Purification in the Wetland 39
3.4.1. Waste Water Irrigation in the Reed Field 39
3.4.2. Purification of the Reed Field to Waste Water from
Paper Factory 41
3.5. Methane (CH
4
) Emission from the Natural Wetland 43
3.5.1. Seasonal Dynamics of CH
4
Emission 43
3.5.2. The Effect of Reed Plants on CH
4
Emission 44
3.6. Biodiversity Protection 45
3.7. Conclusion 46
Acknowledgements 46
References 46

Chapter 4. The Dyke-Pond Systems in South China: Past, Present and Future
M.H. Wong, K.C. Cheung, A. Yediler, C.K.C. Wong 47
4.1. Introduction 48
4.2. The Dyke-Pond System in South China 49
4.2.1. Integrated Agricultural and Aquacultural Systems 50
4.2.2. General Principles of Using Manure in Polyculture of Fish 51
4.2.3. Nutrient Dynamics of Fish Ponds Using Manure as the
Major Input 52
4.3. Recent Socio-Economic Changes and Their Effects on the
Aquacultural Industries 53
4.3.1. South China and Persistent Organic Pollutants (POPs) 53
x Contents
4.3.2. Environmental Impacts of Inland Aquaculture 55
4.4. Good Aquacultural Practices and Organic Fish Farming 59
4.5. Conclusion 61
Acknowledgements 62
References 62
Session II. Wetland Biogeochemistry
Chapter 5. Heavy Metal Mobility and Aquatic Biogeochemical Processes
at Mai Po Marshes Nature Reserve, Hong Kong
Y. Liang, M.H. Wong 69
5.1. Introduction 69
5.2. Materials and Methods 72
5.3. Results and Discussion 73
5.3.1. Comparisons of Physicochemical Properties of the Water
and Sediments Between the Landward and Seaward
Sides in Gei Wais at Mai Po Marshes 73
5.3.2. Comparisons of Aquatic Biological Processes Between
the Landward and Seaward Sides in Gei Wais at
Mai Po Marshes 73

5.3.3. Relationships Between Heavy Metal Concentrations
in the Sediments and Aquatic Physicochemical Properties
in Gei Wais at Mai Po Marshes 76
5.4. Conclusions 83
Acknowledgements 84
References 84
Chapter 6. Biogeochemistry of Metals in the Rhizosphere of Wetland
Plants — An Explanation for “Innate” Metal Tolerance?
M.L. Otte, D.J. Matthews, D.L. Jacob, B.M. Moran, A.J.M. Baker 87
6.1. General Biogeochemistry of Wetland Soils 87
6.2. The Rhizosphere of Wetland Plants 88
6.3. Metal Mobility in the Rhizosphere of Wetland Plants 88
6.4. An Explanation for the Development of Innate Metal
Tolerance in Wetland Plants? 89
References 93
Chapter 7. Mycotrophy and Its Significance in Wetland Ecology
and Wetland Management
A.G. Khan 95
7.1. Introduction 95
7.2. Early History of Glomales 96
7.3. Evolution of Roots 97
7.4. Roots of Aquatic Plants 97
Contents xi
7.5. Mycotrophy of Aquatic Plants 97
7.5.1. Mycorrhizal Status 98
7.5.2. Plant Life Forms and Mycorrhizae 100
7.5.3. Relationships to Redox Potential 101
7.5.4. Relationship to Root Hairs 104
7.5.5. Relationship to P-Status (Oligotrophic vs. Eutrophic Status) 104
7.6. Significance of Mycotrophy in Wetland Ecology and

Management 108
Acknowledgements 109
References 109
Chapter 8. Assessment of Risks to the Mai Po/Inner Deep Bay Ramsar Site
due to Environmental Contaminants
P.K.S. Lam, M.H.W. Lam 115
8.1. Background 115
8.2. The Mai Po and Inner Deep Bay Ramsar Site 116
8.3. Levels and Risks of Environmental Contaminants in Sediments 118
8.4. Levels and Risks of Environmental Contaminants in Biota 120
8.5. Recommendations 126
8.6. Overall Conclusion 127
Acknowledgements 128
References 128
Chapter 9. Modelling Contamination in an Urban Canal Sediment:
Some Preliminary Results from a Phytoremediation Project
N.M. Dickinson, R. King, A. Royle, I.D. Pulford, W. Hartley,
J. Jones, E. Gray-Jones, P.D. Putwain 131
9.1. Introduction 131
9.2. Methods 133
9.3. Results and Discussion 135
9.4. Conclusions 139
References 140
Session III. Wetland Management Strategies in Asia
Chapter 10. Conflicts in the Management of a Wetland Nature Reserve —
Case Study of the Mai Po Nature Reserve, Hong Kong
L. Young 145
10.1. Introduction 145
10.1.1. Geography 146
10.1.2. Ecological Importance 146

10.2. Management of the Inner Deep Bay Wetlands 147
10.2.1. Historical Management 147
xii Contents
10.2.2. Management Plan for the Mai Po Nature Reserve 148
10.2.3. Management Plan for the Ramsar Site 150
10.3. WWF Hong Kong Management of Mai Po 151
10.3.1. Vegetation Management 151
10.3.2. Gei wai Management 155
10.3.3. Freshwater Pond Management 157
10.3.4. Mangroves 158
10.3.5. Visitor Management 158
10.4. Summary 159
References 160
Chapter 11. Conservation and Uses of Mangroves in Hong Kong and
Mainland China
N.F.Y. Tam 161
11.1. Introduction 161
11.2. Mangrove Distribution and Characteristics in Hong Kong and
Mainland China 163
11.3. Uses and Functions of Mangroves 164
11.3.1. Uses of Mangroves in the World 164
11.3.2. Functions of Mangroves in China 167
11.4. Conservation of Mangroves 169
11.4.1. General Principles 169
11.4.2. Conservation of Mangroves in HKSAR 170
11.4.3. Conservation of Mangroves in Mainland China 171
11.4.4. Mangrove Planting and Restoration 172
11.5. Problems and Possible Solutions in Mangrove Conservation 177
11.5.1. Habitat Loss Due to Land-Use Change 177
11.5.2. Water Pollution and Human Disturbance 177

11.5.3. Lack of Ecological and Baseline Data 178
11.5.4. Insect Infestation and Exotic Species Invasion 178
11.5.5. Insufficient Resources and Lack of Integration Between
Various Departments 180
References 181
Chapter 12. An Integrated Analysis of Sustainable Human–Water
Interactions in Wetland Ecosystems of Taihu Lake Basin,
East China
D. Hu, J.S. Yan, T.X. Liu, G.W. Chen, S.J. Yuan, R.S. Wang 183
12.1. Some Background Details of the Taihu Lake Basin 183
12.2. Concepts and Methodology for this Research 185
12.2.1. Basic Concepts 185
12.2.2. The Methodology of Research 185
12.3. Hydrology, Water Resources and Water Disasters
in the Taihu Lake Basin 187
Contents xiii
12.3.1. Hydrology in the Taihu Lake Basin 187
12.3.2. Water Resources in Taihu Lake Basin 189
12.3.3. Water Disasters in the Taihu Lake Basin 195
12.4. Water Quality Changes in the Taihu Lake Basin 197
12.4.1. Pollution Sources from Urbanization and
Industrialization 197
12.4.2. Present State of Water Quality in the Taihu Lake Basin 199
12.5. Driving Forces for Changes in the Taihu Lake
Wetlands Ecosystems 202
12.5.1. Driving Forces for Water Resources Changes 202
12.5.2. Driving Forces for Water Security Changes 203
12.5.3. Driving Forces for Water Environmental and
Aquatic Ecosystem Changes 204
12.5.4. Driving Forces of Engineering for Wetland Ecosystem

Changes 206
12.5.5. Driving Forces of Management for Wetland
Ecosystems Changes 209
12.6. Integrated Human Responses to Building Sustainable Security
for Ecosystems of the Taihu Lake Basin 209
12.6.1. Human Responses I (Water Resources):
Sustainable Development and Uses of Water Resources 209
12.6.2. Human Responses II (Environment): Protection
of the Water Environment 211
12.6.3. Human Responses III (Wetland Ecosystems):
Improving Structure and Function of Wetland Ecosystems,
Rehabilitating Disturbed or Destroyed Ecosystems, and
Improving Their Ecological Capacity of Services 215
12.6.4. Human Responses IV (Wetland Ecosystems Engineering) 215
12.6.5. Human Responses V (Ecosystems Management):
Building a Modern Ecological Culture for Realizing the
Sustainable Management of Wetland Ecological Security 215
12.7. Conclusions 218
Acknowledgements 219
References 219
Chapter 13. Ecological Benefits of Italian Poplar Afforestation in
Wetland Areas along the Yangtze River, Fanchang County
of Anhui Province
Z.J. Xi, D. Hu, R.X. Wang 221
13.1. Introduction 221
13.2. The Wetlands along the Yangtze River, Fanchang County 222
13.2.1. General descriptions 222
13.3. Characteristics of Wetlands in the Floodplain Areas 224
xiv Contents
13.4. Ecological Benefits of Poplar Trees Afforestation 224

13.4.1. Turning Reed Wetland into Poplar Forests Reduces
the Density of Oncomelania hupensis in Floodplain
and the Incidence of Schistosomiasis in the Floodplain 224
13.4.2. The Ecological Roles of Italian Poplar
in Mitigating Flood 225
13.4.3. Protecting the Biodiversity in Wetland Ecosystems
along the River 227
13.5. Social and Economic Benefits 228
13.5.1. Intercropping to Enhance the Efficiency of
Agricultural Landuse 228
13.5.2. Providing Raw Materials for Industrial Production 229
13.6. Some Problems and Suggestions for Sustainable Afforestation 229
13.7. Conclusion 230
Acknowledgements 230
References 231
Chapter 14. Wetland Conservation and Management in the Philippines:
Where are We Now? The Case of Seagrass and Mangrove
M.D. Fortes 233
14.1. Introduction 233
14.2. Status of Philippine Seagrass and Mangrove Habitats 234
14.3. Seagrass and Mangrove Biodiversity 237
14.4. Threats to Seagrass and Mangrove 238
14.5. Worldwide Decline 240
14.6. Monetary Value of Seagrass and Mangrove 241
14.7. Impediments to Addressing the Issues 244
14.8. Conservation and Management Strategies 246
14.8.1. For the Management of Seagrass and Mangrove
Resources 246
14.8.2. For the Protection of the Larger Coastal and Marine
Environment 252

14.9. The Challenges 259
References 260
Chapter 15. Economic Valuation of Mangroves for Improved Usage and
Management in Thailand
C. Tingsabadh, S. Pongkijvorasin 263
15.1. Introduction 263
15.1.1. The Ecological Role of Mangroves in Coastal
Ecosystems 263
15.2. Problem Statement 265
15.3. Review of the Literature 265
15.3.1. On Bandon Bay, Suratthani 266
Contents xv
15.4. Scope of the Chapter 267
15.5. Definition of the Model 267
15.5.1. Carbon Stock Sector 267
15.5.2. Fish Biomass Sector 268
15.5.3. Fishery Sector 269
15.6. Simulation Results 271
15.6.1. Baseline Scenario 271
15.6.2. Mangrove Reforestation Scenario 271
15.6.3. Comparison Between Baseline and Reforestation
Scenario 273
15.7. Discussion 276
Appendix A 276
Appendix B 277
References 281
Session IV. Constructed Wetlands
Chapter 16. Constructed Wetlands for Wastewater Treatment:
Principles and Practices
C. Polprasert 285

16.1. Introduction 285
16.2. Types and Functions of Constructed Wetlands 286
16.2.1. Free Water Surface Systems 286
16.2.2. Subsurface Flow (SF) Systems 286
16.2.3. Advantages and Disadvantages 287
16.3. Types and Functions of Vegetation 287
16.4. Wastewater Treatment Mechanisms 288
16.4.1. BOD Removal 288
16.4.2. Suspended Solids Removal 289
16.4.3. Nitrogen Removal 290
16.4.4. Phosphorus Removal 290
16.4.5. Heavy Metals Removal 290
16.4.6. Trace Organics Removal 290
16.4.7. Pathogen Removal 291
16.5. Design Equations 291
16.5.1. FWS Wetlands 291
16.5.2. SF Wetlands 296
16.6. Other Considerations 299
16.6.1. Hydraulic Budget 299
16.6.2. Site Selection 299
16.6.3. Flow Patterns 300
16.6.4. Slope 300
16.6.5. Liners 300
xvi Contents
16.7. Operation and Maintenance 301
16.7.1. Mosquito Control 301
16.7.2. Plant Harvesting 301
16.7.3. System Perturbations and Operation Modifications 301
16.8. Case Studies 302
16.8.1. Case Study A: Emmitsburg, Maryland, USA,

SF Constructed Wetland 302
16.8.2. Case Study B: The Eastern Seaboard Industrial
Estate (ESIE), Rayong Provice, Eastern Thailand,
Vertical-Flow Constructed Wetlands 302
16.8.3. Case Study C: Vertical-Flow Constructed Wetlands
for Septage Dewatering and Stabilization, Asian
Institute of Technology (AIT), Bangkok, Thailand 307
Acknowledgements 309
References 309
Chapter 17. Planting, Selection and Plant Establishment in
Constructed Wetlands in a Tropical Environment
M. Beharrell 311
17.1. Introduction 311
17.1.1. What is a Constructed Wetland? 312
17.1.2. Roles of Water Plants in Constructed Wetlands 312
17.1.3. What is a Wetland Plant? 313
17.1.4. Plant Protection 313
17.2. Wetland Plant Selection 314
17.2.1. What are We Looking for in Wetland Plant? 314
17.2.2. Wetland Water Depths 316
17.2.3. Additional Species 317
17.2.4. Trees in and Around the Wetland 318
17.3. Sourcing Plant Material 318
17.3.1. Direct Seeding 318
17.3.2. Translocation 319
17.3.3. Transplanting 319
17.3.4. Nursery Propagation 320
17.3.5. Planting Design 321
17.3.6. Planting Density 321
17.3.7. Seed Collection 322

17.4. Planting 322
17.4.1. Planting Timeframes 322
17.4.2. Planting Substrate 323
17.4.3. Selection of Substrate 323
17.4.4. Preparation of Substrate 324
17.4.5. Planting Methods for Wetlands 324
Contents xvii
17.4.6. Supervision 325
17.4.7. Irrigation 325
17.4.8. Plant Handling 326
17.5. Plant Establishment 326
17.5.1. Managing Water Levels After Planting 326
17.5.2. Weed Invasion and Plant Health 326
17.5.3. Supplementary Planting 327
17.5.4. Records 327
17.6. Conclusion 327
References 328
Chapter 18. Nitrogen Removal Processes in Constructed Wetlands
C.C. Tanner 331
18.1. Introduction 331
18.2. Microbial Nitrogen Transformation Processes 333
18.3. N Removal Performance of Constructed Wetlands 336
18.4. Dominant Mechanisms of N Removal in Constructed
Wetlands 337
18.4.1. Role of plants 337
18.4.2. Gaseous Emission 338
18.5. Conclusions 343
References 344
Chapter 19. Operation and Maintenance for Constructed Wetlands
M. Beharrell 347

19.1. Introduction 347
19.2. The Phases of Wetland Operation and Maintenance 348
19.2.1. Planning and Construction 348
19.2.2. Commissioning 348
19.2.3. Operation 349
19.2.4. Decommissioning or Refitting 349
19.3. Operation and Maintenance Plans 349
19.3.1. General Considerations in an Operation and
Maintenance Plan 350
19.3.2. What Does an Operation and
Maintenance Plan Need to Contain? 351
19.3.3. Monitoring 352
19.3.4. Evaluation of Operation and Maintenance Plans 352
19.4. Operation of Wetlands 353
19.4.1. Water Level Control 353
19.4.2. Flow Rates 353
19.5. Management Issues 353
19.5.1. Management of Sediment 354
19.5.2. Litter Management 354
xviii Contents
19.5.3. Vegetation Management 355
19.5.4. Mosquito Management 356
19.5.5. Algal Growth 357
19.6. Conclusion 358
References 358
Chapter 20. Urban and Highway Runoff Treatment by Constructed
Wetlands
R.B.E. Shutes, J.B. Ellis, D.M. Revitt, M. Forshaw, B. Winter 361
20.1. Constructed Wetland Types and Flow Systems 361
20.1.1. Pollutant Removal Efficiency of Constructed

Wetland Systems 363
20.2. Experimental Constructed Wetland Studies 368
20.2.1. Highway Runoff Wetland Treatment Study 368
20.2.2. Small-Scale Experimental Hydrocarbon Treatment Study 371
20.3. Urban Wetland Design 373
20.3.1. Design Criteria 373
20.3.2. Wetland Sizing 374
20.3.3. Optimal Hydraulic Loading 376
20.3.4. Flow Velocity 377
20.3.5. Substrate Structure 378
20.3.6. Planting Considerations 378
20.3.7. Pre- and Post-treatment Structures 379
20.4. Conclusion 380
Acknowledgements 380
References 380
Chapter 21. Wetland Ecosystems for Treatment of Stormwater in
an Urban Environment
J. Gan 383
21.1. Introduction 383
21.2. Stormwater Pollution 384
21.3. Management Options 385
21.4. Selection of Management Options 386
21.5. Issues and Causes 387
21.6. Design Terminology 387
21.7. Pollutant Loading Rates 387
21.8. Wetland Ecosystems for Treatment of Stormwater 387
21.8.1. Buffer Strip 391
21.8.2. Grass Swale 391
21.8.3. Bio-retention/Infiltration System 392
21.8.4. Wetland 393

21.8.5. Universal Stormwater Treatment Train 393
Contents xix
21.9. Victoria Park Project in Sydney, Australia 394
21.9.1. Project Description 394
21.9.2. Purpose 395
21.9.3. Bio-retention/Infiltration System Details 396
21.9.4. Bio-retention/Infiltration Variations 397
21.10. Management 397
Acknowledgements 399
References 399
Chapter 22. The Application of Constructed Wetlands for Water Quality
Improvement in the Deep Bay Catchment of Hong Kong
M.W. Cha 401
22.1. Introduction 402
22.2. Deep Bay Catchment 402
22.3. Strategies on Water Pollution Control in Deep Bay 403
22.4. Application of Constructed Wetlands in the Deep
Bay Catchment 405
22.4.1. Constructed Wetlands for Stormwater Runoff 405
22.4.2. Construction Wetlands for Polishing Treatment Plant
Effluents and Stream Water 407
22.5. Conclusion 411
Acknowledgements 411
References 411
Chapter 23. Use of a Wetland System for Treating Pb/Zn Mine Effluent:
A Case Study in Southern China from 1984 to 2002
Z.H. Ye, M.H. Wong, C.Y. Lan 413
23.1. Introduction 413
23.2. Description of the Study Site 414
23.3. Efficiency of Metal Removal from the Effluent by

the Wetland System 416
23.4. Metal Accumulation in Different Ecological
Compartments 419
23.4.1. Accumulation in Sediment 419
23.4.2. Accumulation in Plants 422
23.4.3. Accumulation in Animals 423
23.5. Ecological Succession: Changes in Diversity and Abundance
of Plants and Animals with Time and Space 424
23.5.1. Protozoa 424
23.5.2. Algae 426
23.5.3. Higher Plants 428
23.5.4. Benthic Invertebrates 428
23.5.5. Vertebrates (Fishes, Terrestrial Animals and Birds) 428
xx Contents
23.6. Conclusions 431
Acknowledgements 433
References 433
Chapter 24. Wetland Creation in Hong Kong
S.S.S. Lau 435
24.1. The Need to Create/Restore Wetlands 435
24.2. Some of the Last Remaining Wetland Paradise in Hong Kong 436
24.3. Some Current Wetland Mitigation Projects in Hong Kong 436
24.4. Wetland Mitigation Approach 437
24.5. Suggested Mitigation Sequence 439
24.6. Wetland Replication 440
24.7. Challenges in Wetland Mitigation in Hong Kong 441
24.7.1. Lack of Relevant Policy 441
24.7.2. Lack of Clear Mitigation Goals and Objectives 441
24.7.3. Lack of Comprehensive Monitoring Methods and
Requirements 442

24.7.4. Lack of Reference Wetlands 442
24.7.5. Lack of Appropriate Success Criteria 442
24.7.6. Lack of Basic Ecological Knowledge Regarding
Natural Wetlands in Hong Kong 443
24.7.7. Lack of Local Qualified Expertise 443
24.7.8. Inappropriate Scale and Location 443
24.7.9. Lack of Long-Term Commitment for Created/Restored
Wetlands 444
24.7.10. Rigid Specification of Civil Engineering Projects 444
24.8. Conclusion 444
Acknowledgements 445
References 445
Glossary 446
Subject Index 447
Contents xxi
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Preface
Compared to other ecosystems, wetlands have received an exceptional amount of
attention. Wetlands are valuable as sources, sink and transformers of a multitude
of chemical, biological and genetic materials. They stabilize water supplies, clean
polluted waters, protect shorelines, and recharge groundwater aquifers. They have
increasingly become recognized for their unique ecological functions in the
environment and are the focus of increased research by scientists and study
programs by schools, communities, and nature centers. On the other hand, the idea
of using constructed wetlands for wastewater treatment has been encouraging
because of their environmental friendliness and enhancement on landscape
quality. Consequently, interest in wetlands extends from students in landscape
architecture and environmental engineering programs to the real world of public
officials, developers, and private citizens.
Wetland management requires an understanding of the scientific aspects of

wetland balanced with legal institutional and economic realities. This book
consists of comprehensive information of wetland’s importance, functions,
conservation and management strategies, which will be beneficial to environ-
mental professionals in different fields for formulating wetland conservation
policy and conducting environmental research. The latest and advanced
information and management techniques of using constructed wetland for
wastewater treatment are also included in this book.
This book is the product of the Croucher Advanced Study Institute on Wetland
Ecosystems in Asia: Function and Management held in March 2003 at Hong Kong
Baptist University, attended by a selected number of specialists and practitioners,
to review the major problems involved in wetland management, and how they can
be solved, against a background of situations in Asian countries. The Asian region
contains some of the world’s largest and diverse seagrass beds and about half of
the approximately 50 seagrass species known world-wide occur along Asian
coasts. These seagrass beds, mainly via the detritus food chain, support a very
productive community of fish and invertebrates, especially mollusks and
crustaceans, many of which are of commercial importance. The South-East
Asian peat swamp forests cover nearly 30 million hectares compared to only one
million hectares in Amazonia. Asia’s major rivers (a wetland habitat) are some of
the world’s largest and most of the rivers of Asia have extensive floodplain
wetlands. The region also contains the world’s largest contiguous area of
mangroves – the Sundarbans in Bangladesh, and the country with the world’s
largest expanse of mangroves – Indonesia. It is also global center for mangrove
diversity and evolution. In terms of freshwater ecosystems, the swamp forests of
South-East Asia are not only among the largest and the best developed in the
world, but are botanically among the most diverse, while exhibiting a high degree
of endemism.
Unfortunately, wetlands throughout Asia are under threat, destruction and
degradation continues unabated. Analysis showed that of nearly 1,000 wetlands
considered to be of international importance for socio-economic or biodiversity

values in Asia, as many as 56% were considered to be moderately or seriously
threatened, while only 15% were threatened. In addition, only about 10% of these
internationally important wetlands are currently totally protected, while a further
15% is partially protected.
To date, in South-East Asia, 5 countries have developed their own National
Wetland Policy or Wetland Action Plan or National Wetland Strategy. They are
Indonesia, Philippines, Vietnam, Thailand and Cambodia. This book discussing
different wetland management strategies in Asia will act as a reference book for
environmental professionals in other Asian countries to formulate conservation
policy for their own countries.
The book consists of 4 sessions: I. Natural Wetland Systems and Their
Functions; II. Wetland Biogeochemisty; III. Wetland Management Strategies in
Asia and IV. Constructed Wetlands. The basic information of natural wetland
systems is introduced in Session I. More scientific discussion about the
biogeochemistry of wetland can be found in Session II. In Session III, wetland
management strategies of different Asian countries, including Malaysia, the
Philippines, Vietnam, Thailand and Hong Kong are discussed. Although only
Asian experience has been shared, past experience shows that there is a body of
general rules applicable to different wetland systems of different countries. The
latest and advanced information and management techniques of constructed
wetlands can be found in Session IV which will be useful for environmental
managers and engineers working on constructed wetland projects.
We hope that this book will not only be beneficial to environmental
professionals for formulating wetland conservation policy and conducting
environmental research, but it will also serve as a reference book for students of
undergraduate and graduate courses on ecology and conservation.
xxiv Preface