Sediment quality guidelines for the Regional Discharges Project / [R.B. Williamson, G.N. Mills].

Prepared for Auckland Regional Council By Diffuse Sources Ltd, PO Box 13002, Hillcrest, Hamilton NEW ZEALAND.

Reviewed by: Megan Stewart, Project Leader Marine, ARC. Approved for ARC Publication by: Grant Barnes, Group Manager Monitoring & Research, ARC. Date: 01/09/09

Includes bibliographical references (p. 48-51).

1 Executive Summary -- 1.1 ARC Requirements -- 1.2 Recommended Targets -- 1.3 Present Situation in Auckland Estuaries -- 1.4 Future Levels in Auckland Estuaries -- 1.5 Bioavailability Procedures -- 1.6 Monitoring -- 1.7 Recommended decision process -- 1.7.1 Settling Zone -- 1.7.2 Outer Zone -- 2 Brief -- 2.1 Glossary -- 2.2 The ARC’s requirements -- 2.3 What are the options? -- 2.3.1 Will the Guidelines generate false positives? (target value exceeded but not toxic) -- 2.3.2 Will the Guidelines generate false negatives? (target not exceeded but toxic) -- 2.4 Possible Target Values -- 3 Application of targets to Auckland estuaries -- 3.1 Comparison of target values with the current levels of contaminants in Auckland Estuaries -- 3.1.1 Contaminant database for Auckland estuaries -- 3.1.2 Comparison of metals data -- 3.1.3 Comparison with organic contaminants levels -- 3.1.4 Implications for the Environmental Targets programme -- 3.2 Future Levels in Auckland Estuaries -- 3.2.1 Why do we need to consider future levels? -- 3.2.2 Implications for monitoring and management -- 3.3 Where will targets be exceeded at present and in the future? -- 4 What happens when SQG triggers are exceeded? -- 4.1 Acid Soluble Metals 274.2 The AVS model -- 4.2.1 What are the AVS Concentrations in Auckland Sediments? -- 4.2.2 Implications of AVS model for Auckland -- 4.3 Pore water metal concentrations -- 4.4 Comparison with Equilibrium Partitioning (Eq P) guidelines -- 4.5 Pore water organic concentrations -- 4.6 Toxicity testing -- 4.7 Conclusions on Bioavailability Procedures -- 4.7.1 Acid soluble -- 4.7.2 AVS -- 4.7.3 Pore water -- 4.7.4 Equilibrium Partitioning -- 4.7.5 Recommendations -- 5 Incorporating monitoring and future predictions into the Environmental Targets Programme -- 5.1 Monitoring -- 5.2 Monitoring methods -- 5.3 Is a simple version of the USC Model useful? -- 5.4 Recommended decision process -- 5.4.1 Settling Zone -- 5.4.2 Outer Zone -- 6 Summary: Environmental Targets and the Settling and Outer Zone Concept -- 6.1 ARC Requirements -- 6.2 Recommended Targets -- 6.3 Suggested changes to ISQG-Low -- 6.4 Suggested changes to ANZECC Decision Tree -- 6.5 Present Situation in Auckland Estuaries -- 6.6 Monitoring -- 6.7 Recommended decision process -- 6.7.1 Settling Zone -- 6.7.2 Outer Zone -- 7 References -- Appendix 1: Co-occurrence Based Sediment Quality Guidelines -- Appendix 2: Dataset of contaminants in estuarine sediments from around the Auckland region -- Metals Data (Total metals, mg/kg dry weight) -- Organic contaminant data -- Appendix 3: Pore water metals data (μg/L, ppb)

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