Hypoxia in the Northern Gulf of Mexico / Edition 1

Hypoxia in the Northern Gulf of Mexico / Edition 1

by Virginia H. Dale
     
 

ISBN-10: 0387896856

ISBN-13: 9780387896854

Pub. Date: 03/19/2010

Publisher: Springer New York

Since 1985, scientists have been documenting a hypoxic zone in the Gulf of Mexico each year. The hypoxic zone, an area of low dissolved oxygen that cannot s- port marine life, generally manifests itself in the spring. Since marine species either die or ee the hypoxic zone, the spread of hypoxia reduces the available habitat for marine species, which are important for…  See more details below

Overview

Since 1985, scientists have been documenting a hypoxic zone in the Gulf of Mexico each year. The hypoxic zone, an area of low dissolved oxygen that cannot s- port marine life, generally manifests itself in the spring. Since marine species either die or ee the hypoxic zone, the spread of hypoxia reduces the available habitat for marine species, which are important for the ecosystem as well as commercial and recreational shing in the Gulf. Since 2001, the hypoxic zone has averaged 2 1 16,500 km during its peak summer months , an area slightly larger than the state 2 2 of Connecticut, and ranged from a low of 8,500 km to a high of 22,000 km . To address the hypoxia problem, the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force (or Task Force) was formed to bring together represen- tives from federal agencies, states, and tribes to consider options for responding to hypoxia. The Task Force asked the White House Of ce of Science and Technology Policy to conduct a scienti c assessment of the causes and consequences of Gulf hypoxia through its Committee on Environment and Natural Resources (CENR).

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Product Details

ISBN-13:
9780387896854
Publisher:
Springer New York
Publication date:
03/19/2010
Series:
Springer Series on Environmental Management
Edition description:
2010
Pages:
284
Product dimensions:
6.20(w) x 9.20(h) x 0.90(d)

Table of Contents

1 Introduction 1

1.1 Hypoxia and the Northern Gulf of Mexico - A Brief Overview 1

1.2 Science and Management Goals for Reducing Hypoxia 3

1.3 Hypoxia Study Group 4

1.4 The Study Group's Approach 7

2 Characterization of Hypoxia 9

2.1 Historical Patterns and Evidence for Hypoxia on the Shelf 9

2.2 The Physical Context 12

2.2.1 Oxygen Budget: General Considerations 12

2.2.2 Vertical Mixing as a Function of Stratification and Vertical Shear 13

2.2.3 Changes in Mississippi River Hydrology and Their Effects on Vertical Mixing 15

2.2.4 Zones of Hypoxia Controls 18

2.2.5 Shelf Circulation: Local Versus Regional 20

2.3 Role of N and P in Controlling Primary Production 23

2.3.1 Nitrogen and Phosphorus Fluxes to the NGOM Background 23

2.3.2 N and P Limitation in Different Shelf Zones and Linkages Between High Primary Production Inshore and the Hypoxic Regions Farther Offshore 24

2.4 Other Limiting Factors and the Role of Si 29

2.5 Sources of Organic Matter to the Hypoxic Zone 31

2.5.1 Sources of Organic Matter to NGOM: Post 2000 Integrated Assessment 33

2.5.2 Advances in Organic Matter Understanding: Characterization and Processes 34

2.5.3 Synthesis Efforts Regarding Organic Matter Sources 37

2.6 Denitrification, P Burial, and Nutrient Recycling 38

2.7 Possible Regime Shift in the Gulf of Mexico 41

2.8 Single Versus Dual Nutrient Removal Strategies 44

2.9 Current State of Forecasting 46

3 Nutrient Fate, Transport, and Sources 51

3.1 Temporal Characteristics of Streamflow and Nutrient Flux 51

3.1.1 MARB Annual and Seasonal Fluxes 56

3.1.2 Subbasin Annual and Seasonal Flux 65

3.2 Mass Balance of Nutrients 76

3.2.1 Cropping Patterns 76

3.2.2 Nonpoint Sources 77

3.2.3 Point Sources 84

3.3 Nutrient Transport Processes 87

3.3.1 Aquatic Processes 87

3.3.2 Freshwater Wetlands 93

3.3.3 Nutrient Sources and Sinks in Coastal Wetlands 94

3.4 Ability to Route and Predict Nutrient Delivery to the Gulf 96

3.4.1 SPARROW Model 97

3.4.2 SWAT Model 103

3.4.3 IBIS/THMB Model 104

3.4.4 Discussion and Comparison of Models 106

3.4.5 Targeting 106

3.4.6 Model Uncertainly 107

4 Scientific Basis for Goals and Management Options 111

4.1 Adaptive Management 111

4.2 Setting Targets for Nitrogen and Phosphorus Reduction 115

4.3 Protecting Water Quality and Social Welfare in the Basin 120

4.3.1 Assessment and Review of the Cost Estimates from the CENR Integrated Assessment 121

4.3.2 Other Large-Scale Integrated Economic and Biophysical Models for Agricultural Nonpoint Sources 125

4.3.3 Research Assessing the Basin-Wide Co-benefits 128

4.3.4 Principles of Landscape Design 129

4.4 Cast-Effective Approaches for Nonpoint Source Control 133

4.4.1 Voluntary Programs - Without Economic Incentives 134

4.4.2 Existing Agricultural Conservation Programs 135

4.4.3 Emissions and Water Quality Trading Programs 137

4.4.4 Agricultural Subsidies and Conservation Compliance Provisions 138

4.4.5 Taxes 140

4.4.6 Eco-labeling and Consumer Driven Demand 141

4.5 Options for Managing Nutrients, Co-benefits, and Consequences 143

4.5.1 Agricultural Drainage 143

4.5.2 Freshwater Wetlands 146

4.5.3 Conservation Buffers 151

4.5.4 Cropping Systems 155

4.5.5 Animal Production Systems 158

4.5.6 In-Field Nutrient Management 164

4.5.7 Effective Actions for Other Nonpoint Sources 183

4.5.8 Most Effective Actions for Industrial and Municipal Sources 186

4.5.9 Ethanol and Water Quality in the MARB 190

4.5.10 Integrating Conservation Options 195

5 Summary of Findings and Recommendations 205

5.1 Characterization of Hypoxia 205

5.2 Nutrient Fate, Transport, and Sources 207

5.3 Goals and Management Options 209

5.4 Conclusion 211

Appendices 215

References 239

Subject Index 277

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