Chemicals in the Aquatic Environment

Hazard assessment of a compound (xenobiotic) discharged to the aquatic environment requires data on both exposure and effects to various components of the ecosystem. The multitude of ecological gradients in the Baltic Sea is used as a background example for discussing the complexity of the issue and the need for new approaches. Therefore, this book attempts to go beyond the simplistic, standardized short-term laboratory tests traditionally used as a basis for hazard assessment of chemicals, and gives strong emphasis to the interpretation of ecotoxicological data in their real, ecological context, pointing out the need to consider the natural mortality distribution of the population under study, the role of keystone species and of species with broad ecological niches versus those with narrow, specialized niches.

Contenu

I Background.- 1. Introduction.- 1.1 Background.- 1.2 Objectives.- 1.3 Working Program.- 1.4 Contents of the Book.- References.- 2. Ecosystem Variability and Gradients. Examples from the Baltic Sea as a Background for Hazard Assessment.- 2.1 Introduction.- 2.2 The Baltic Sea - a Sea of Gradients.- 2.2.1 Background.- 2.2.2 Physical and Chemical Gradients.- 2.2.3 Biological Gradients.- 2.2.4 Forces Counteracting the General Patterns of Gradients.- 2.2.4.1 Seasonal Variations.- 2.2.4.2 Water Exchange and Circulation.- 2.2.4.3 Migrations.- 2.3 Acute, Chronic and Intermittent Exposure.- 2.4 Test Organisms and Test Strategies.- 2.5 Extrapolations.- 2.6 Field Validation.- 2.6.1 General Considerations.- 2.6.2 Eco-epidemiology.- 2.6.3 Behavioral Aspects of Field Validation.- 2.6.4 Recovery Studies as a Tool in Field Validation.- 2.7 Environmental Gradients, Toxic Chemicals and Stress.- References.- 3 The ESTHER Approach to Environmental Hazard Assessment of Chemicals.- 3.1 Testing and Hazard Assessment: One Phase in the Decision Making on Chemicals.- 3.2 Initial Hazard Assessment of Chemicals - the ESTHER Manual.- 3.2.1 Background.- 3.2.2 Design of the ESTHER Manual for Initial Hazard Assessment of Chemicals.- 3.3 Defining Targets of Exposure.- 3.3.1 General Aspects.- 3.3.2 Rationale for Selecting Targets of Exposure.- 3.3.3 Possible Methodologies to Define Targets of Exposure.- 3.4 Objectives of an Advanced Hazard Assessment.- 3.5 Major Differences Between Initial and Advanced Hazard Assessment.- 3.6 "The ESTHER Approach".- References.- II Special Topics.- 4 Factors Determining the Fate of Organic Chemicals in the Environment: the Role of Bacterial Transformations and Binding to Sediments.- 4.1 Introduction.- 4.2 Experimental Procedures.- 4.2.1 Chemical Considerations.- 4.2.1.1 Quantification and Identification of Substrates and Metabolites.- 4.2.1.2 Binding of Substrates and Metabolites: Extraction Procedures.- 4.2.2 Microbiological Considerations.- 4.2.2.1 General Aspects.- 4.2.2.2 Experimental Aspects.- 4.3 Aerobic Reactions.- 4.3.1 Significant Areas.- 4.3.1.1 The Effect of Co-substrates: Concurrent Metabolism.- 4.3.1.2 The Effect of Substrate Concentration and Cell Density.- 4.3.1.3 Rates of Transformation.- 4.3.2 Problem Areas and Unresolved Issues.- 4.3.2.1 The Problem of Translating Laboratory Data to Field Situations.- 4.3.2.2 Aspects of Metabolism and Regulation.- 4.4 Anaerobic Reactions.- 4.4.1 Significant Areas.- 4.4.1.1 Metabolic Reactions.- 4.4.1.2 The Role and Significance of Syntrophy.- 4.4.2 Problem Areas and Unresolved Issues.- 4.4.2.1 The Stability of Consortia and Their Metabolic Dependence.- 4.4.2.2 The "Natural" Substrates for Growth.- 4.5 The Role of Sediments in Determining Environmental Fate.- 4.5.1 Background.- 4.5.2 Sorption and Binding: the Degree of Reversibility.- 4.5.3 Some Important Unresolved Issues.- 4.6 A Personal Summing-up.- References.- 5 Bioavailability and Uptake of Xenobiotics in Fish.- 5.1 Introduction.- 5.2 Background.- 5.3 Physiological Factors Affecting the Uptake Rate.- 5.4 Pow Value Versus Rate of Uptake.- 5.5 Importance of pH.- 5.6 General Discussion and Conclusions.- References.- 6 Bioaccumulation and Biomagnification of Hydrophobic Persistent Compounds as Exemplified by Hexachlorobenzene.- 6.1 Uptake and Elimination Via the Water.- 6.2 Abiotic Environmental Factors Affecting Bioavailability.- 6.3 Uptake and Passive Elimination Via the Food.- 6.4 Active Excretion.- 6.5 Net Bioaccumulation and the Occurrence of Biomagnification.- 6.6 Conclusions.- References.- 7. Fish Bile Analysis for Monitoring of Low Concentrations of Polar Xenobiotics in Water.- 7.1 Introduction.- 7.2 Design of the Study.- 7.3 Chemical Synthesis and Analysis.- 7.3.1 Isotope-labeled 4,5,6-Trichloroguaiacol.- 7.3.2 Chemical Analysis by Radiometric Techniques.- 7.3.2.1 Content of 4,5,6-TCG in Water.- 7.3.2.2 Content of Metabolites in Bile.- 7.4 Factors Affecting Regulation of Foreign Compounds in FishBile.- 7.4.1 Biotransformation.- 7.4.1.1 In Vitro and in Vivo Metabolism of 4,5,6-TCG.- 7.4.1.2 Enzyme Induction and Seasonal Variations.- 7.4.2 Fish Species.- 7.4.3 Fish Size.- 7.4.4 Nutrition.- 7.5 Exposure of Fish to 4,5,6-TCG.- 7.5.1 Short-term Exposure.- 7.5.2 Long-term Exposure.- 7.6 Field Application.- 7.7 Conclusions.- References.- 8 Ecological Concepts Important for the Interpretation of Effects of Chemicals on Aquatic Systems.- 8.1 Introduction.- 8.2 Assessment of Toxic Effects at the Population Level.- 8.2.1 Mortality Distribution in Aquatic Populations.- 8.2.2 Compensatory Mortality in the Interpretation of Effects.- 8.2.3 The Survivor Effect at the Population Level.- 8.3 Assessment of Toxic Effects at the Community Level.- 8.3.1 Community Analysis.- 8.3.2 The Guild: A Community Tool for Complex Ecological Interactions.- 8.3.3 The Specialist-Generalist Concept Applied to Hazard Assessment.- 8.3.4 Role of Keystone Species in Effect Assessment.- 8.3.5 The Survivor Effect at the Community Level.- 8.4 Assessment of Effects at the Ecosystem Level.- 8.4.1 Stress and Ecosystems.- 8.4.2 Cumulative Environmental Effects.- 8.5 Decision Rules for Interpreting the Effects of Chemicals.- References.- 9 Selected Assays for Health Status in Natural Fish Populations.- 9.1 Concepts in Health Monitoring.- 9.1.1 Effects Expressed at Different Biological Levels.- 9.1.2 Criteria for Health Assays in Fish.- 9.2 Development of Health Assays.- 9.2.1 Level of Organization.- 9.2.2 Physiological Methods in Fish Health Assessment.- 9.2.3 Laboratory Studies.- 9.2.4 Use of Physiological Methods in Field Studies.- 9.3 Assays for Health Status in Natural Fish Populations.- 9.3.1 ?-Aminolevulinic Acid Dehydratase.- 9.3.2 Mixed Function Oxidase.- 9.3.3 Metallothionein.- 9.3.4 Smoltification in Salmonids.- 9.4 Future Development: Remarks and Recommendations.- References.- 10 Community Testing, Microcosm and Mesocosm Experiments: Ecotoxicological Tools with High Ecological Realism.- 10.1 Introduction.- 10.2 Strategies Used in Designing Multi-species Test Systems.- 10.3 Shortcomings of Some Early Model Ecosystem Designs.- 10.4 Community Testing with Natural Associations of Periphyton and Phytoplankton.- 10.4.1 Introduction.- 10.4.2 Rationale.- 10.4.3 Design and Procedures.- 10.4.4 Advantages and Disadvantages.- 10.4.5 Validation.- 10.4.6 Applications.- 10.5 Pollution-Induced Community Tolerance (PICT).- 10.5.1 Rationale.- 10.5.2 Evidence.- 10.5.3 Applications.- 10.6 Enclosure of Marine Profundal-zone Benthic Communities.- 10.6.1 System to be Studied.- 10.6.2 Trophic Structure and Feeding Strategies.- 10.6.3 Rationale of Microcosm Enclosures.- 10.6.4 Design and Procedures.- 10.6.5 Similarity with Mother System.- 10.6.6 Applications.- 10.7 Land-based, Marine Littoral-zone Enclosures.- 10.7.1 Problem of Setting up Land-based Aquatic Mesocosms.- 10.7.2 Rationale.- 10.7.3 Design and Procedures.- 10.7.4 Stability, Reproducibility and Similarity with Mother System.- 10.7.5 Application and Field Validation.- 10.8 Limnic in Situ Enclosures - Limnocorrals.- 10.8.1 Rationale.- 10.8.2 Choice of Mother System and Design of Limnocorrals.- 10.8.3 Similarity…