Contaminated Marine Sediments Assessment and Remediation (1989) / Chapter Skim
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Use of Apparent Effects Threshold Approach (AET) in Classifying Contaminated Sediments
Use of Apparent Effects Threshold Approach (AET) in Classifying Contaminated Sediments
Pages 64-77
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From page 64... ...
approach is a tool for deriving sediment quality values for a range of biological indicators used to assess contaminated sediments. The AET is the contaminant concentration in sediment above which adverse effects are always expected for a particular biological indicator.
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From page 65... ...
None of the available approaches is fully capable of addressing all concerns over interactive effects among chemicals; hence, field verification using diverse environmental samples is important to the evaluation of each approach. The following presentation summarizes the concept of the AET approach and its application and verification in multiple areas of Puget Sound, Washington.
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From page 66... ...
A single biological test or single concentration for a chemical may not always define "acceptable contamination." Hence, a range of sediment quality values such as provided by the AET approach may be necessary to serve the needs of different programs. DESCRIPTION OF AET APPROACH The focus of the AET approach is to identify concentrations of contaminants that are associated exclusively with sediments exhibiting statistically significant biological effects relative to reference sediments.
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From page 67... ...
. Because the potential effect threshold for a chemical cannot be related in a meaningful way to the observed biological effects, it is not used to set sediment quality values.
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From page 68... ...
GENERATION OF PUGET SOUND AET -AET were originally generated for a combined measure of sediment toxicity (i.e., either amphipod mortality [Swartz et al., 1985]
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From page 69... ...
As the result of additional refinement studies sponsored by the Environmental Protection Agency's (EPA) Region 10, the AET data base has recently been expanded to include additional data on sediment chemistry, benthic infaunal abundance, and amphipod mortality for over 100 sediment samples collected in two additional embayments of Puget Sound, Elliott Bay and Everett Harbor.
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From page 70... ...
. `~e - Phlox FIGURE 3 Location of sampling sites for AET data sets.
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From page 71... ...
and results from the addition of Eagle Harbor Preliminary investigation data (Barrick et al., 1986~. The value shown exceeds AET established from Commencement Bay Remedial Investigation data (Barrick et al., 1985)
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From page 72... ...
Sediment quality values that are highly efficient may be cost-effective and defensible in pursuing high priority remedial action but are not necessarily protective. The concepts of sensitivity and efficiency will be used in this paper as an evaluation tool for assessing the reliability of AET.
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From page 73... ...
AET were developed for each chemical of concern for multiple biological indicators because different kinds of biological indicators respond in different ways to the same chemical exposure. For example, an assessment of acute lethal toxicity to contaminated sediments is expected to result in different sediment quality values than an assessment of acute or chronic sublethal toxicity to the same sediments.
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From page 74... ...
In the Commencement Bay Feasibility Study, sediment quality values based on the lowest AET for a range of biological indicators were developed as potential target cleanup goals (not considering cost or technical feasibility)
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From page 75... ...
Id> Chemistry Predictions r Tier 3 :> Biological Confirmation —A> DISPOSAL ~ DECISION FIGURE 5 Use of sediment quality values based on AET in Puget Sound remedial action programs. those sediment contaminant concentrations that are not predicted to result in adverse effects according to the biological effects indicators used to generate AET.
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From page 76... ...
It is recognized that site-specific factors could anomalously influence predictions of biological effects based on sediment quality values. Therefore, in evaluating final requirements for sediment remedial action, selected verification of predicted effects is recommended (extensive biological testing of each sample may not be feasible)
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From page 77... ...
1988. Sediment quality values refinement: 1988 Update and evaluation of Puget Sound AET.
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