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Coastal and Estuarine Risk Assessment - Chapter 7

Dietary Metals Exposure and Toxicity to Aquatic Organisms: Implications for Ecological Risk Assessment - Ảnh hưởng của ô nhiễm yếu tố dấu vết trên các hệ sinh thái ven biển và cửa sông nhận được sự chú ý đáng kể trong 50 đến 60 năm qua. 1 Đánh giá rủi ro khuôn khổ cung cấp một phương tiện để xác định số lượng những ảnh hưởng này, và phát triển các lựa chọn thay thế quản lý để đối phó với ô nhiễm yếu tố lịch sử và liên tục theo dõi. Định lượng nguy cơ của kim loại cho các hệ thống thủy sản bây giờ. | 7 Dietary Metals Exposure and Toxicity to Aquatic Organisms Implications for Ecological Risk Assessment Christian E. Schlekat Byeong-Gweon Lee and Samuel N. Luoma CONTENTS 7.1 Introduction 7.2 Current Status of Regulatory Approaches for Metals in Aquatic Systems 7.2.1 The Importance of Phase and Speciation in Metal Risk Assessment 7.2.2 Incorporation of Metal Speciation into Risk Assessment 7.2.3 The Biotic Ligand Model 7.2.3.1 Mechanisms of Metal Toxicity at the Gill 7.2.3.2 Model Assumptions and Components 7.2.4 Limitations of Current and Projected Risk Assessment Practices 7.3 Processes Affecting Dietary Metal Exposure 7.3.1 Metal Partitioning 7.3.2 Biological Mechanisms 7.3.2.1 Food Selection 7.3.2.2 Feeding Rates 7.3.2.3 Mechanisms of Dietary Metal Absorption 7.3.2.3.1 pH 7.3.2.3.2 Amino Acid-Rich Digestive Fluids 7.3.2.3.3 Surfactants 7.3.2.3.4 Intracellular Digestion 7.3.3 Experimental Designs for Laboratory Exposures via Diet 2002 CRC Press LLC 7.4 The Relative Importance of Dietary vs. Dissolved Metal Uptake for Bioaccumulation and Toxicity 7.4.1 Mass Balance Approach 7.4.1.1 Deposit and Suspension Feeders 7.4.1.2 Predators 7.4.2 The Use of Mathematical Models in Metals Risk Assessment 7.4.2.1 Background 7.4.2.2 Equilibrium Models 7.4.2.3 Dynamic Multipathway Bioaccumulation Model 7.4.2.3.1 DYMBAM Structure 7.4.2.4 Application of Models 7.4.2.4.1 DYMBAM Case Study Selenium in San Francisco Bay 7.4.3 Comparisons among Metals and Organisms 7.5 Toxicological Significance of Dietary Metals Exposure 7.5.1 Examples of Dietary Metals Toxicity 7.5.2 Why is Dietary Toxicity Difficult to Measure 7.5.3 How Are These Subtle Effects To Be Handled in a Risk Assessment Framework 7.6 Conclusions Recommendations References 7.1 INTRODUCTION Effects of trace element contamination on coastal and estuarine ecosystems have received considerable attention over the past 50 to 60 years.1 Risk assessment frameworks offer a means to quantify these effects and to develop management .