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Potential Effects of Contaminants on Fraser River Sockeye Salmon

Potential Effects of Contaminants on Fraser River Sockeye Salmon

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sockeye salm<strong>on</strong> or another salm<strong>on</strong>id species that extended formore than 96 hours. The lowest EC 25 was then multiplied by asafety factor <str<strong>on</strong>g>of</str<strong>on</strong>g> 0.5;3. For hardness-dependent water quality guidelines, substitute theintercept value for sockeye salm<strong>on</strong> or the most sensitive salm<strong>on</strong>idspecies for the intercept value for the n<strong>on</strong>-salm<strong>on</strong>id species used toderive the toxicity screening value (the slope was not adjusted,however);4. Calculate the ratio <str<strong>on</strong>g>of</str<strong>on</strong>g> the final acute value for sockeye salm<strong>on</strong> or themost sensitive salm<strong>on</strong>id species to the final acute value for thespecies that was used to derive the water quality guideline.Multiply the toxicity screening value by the ratio <str<strong>on</strong>g>of</str<strong>on</strong>g> final acute valuesderived in this manner to estimate the toxicity threshold for sockeyesalm<strong>on</strong>; or,5. Identify the toxicity threshold directly from the maximum acceptabletoxicant c<strong>on</strong>centrati<strong>on</strong> reported for a sub-lethal endpoint obtainedbased <strong>on</strong> the results <str<strong>on</strong>g>of</str<strong>on</strong>g> an acceptable l<strong>on</strong>g-term study <strong>on</strong> sockeyesalm<strong>on</strong> or another salm<strong>on</strong>id species.• For substances for which the selected toxicity screening value wasbased <strong>on</strong> toxicity data for salm<strong>on</strong>id species, toxicity thresholds forsockeye salm<strong>on</strong> were established using the following procedures:1. Calculate the ratio <str<strong>on</strong>g>of</str<strong>on</strong>g> the final acute value for sockeye salm<strong>on</strong> to thefinal acute value for the salm<strong>on</strong>id species that was used to derivethe water quality guideline. Multiply the toxicity screening value bythe ratio <str<strong>on</strong>g>of</str<strong>on</strong>g> final acute values derived in this manner to estimate thetoxicity threshold for sockeye salm<strong>on</strong>.In some cases, the toxicity screening values used in the preliminary evaluati<strong>on</strong> wereadopted directly as the toxicity thresholds for sockeye salm<strong>on</strong>. In these cases, thetoxicity screening value was already based <strong>on</strong> salm<strong>on</strong>id toxicity data and/or nosockeye-salm<strong>on</strong> specific toxicity data were available.Toxicity Thresholds for Sediment - A total <str<strong>on</strong>g>of</str<strong>on</strong>g> five substances were identified asc<strong>on</strong>taminants <str<strong>on</strong>g>of</str<strong>on</strong>g> c<strong>on</strong>cern in sediment, based <strong>on</strong> the results <str<strong>on</strong>g>of</str<strong>on</strong>g> the preliminaryevaluati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> c<strong>on</strong>taminants <str<strong>on</strong>g>of</str<strong>on</strong>g> potential c<strong>on</strong>cern and subsequent refinement <str<strong>on</strong>g>of</str<strong>on</strong>g> thec<strong>on</strong>taminants <str<strong>on</strong>g>of</str<strong>on</strong>g> c<strong>on</strong>cern list. <strong>Sockeye</strong> salm<strong>on</strong>-specific, salm<strong>on</strong>id-specific, orfish-specific sediment quality guidelines were not located in the literature to support thedetailed evaluati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> sediment chemistry data for the <strong>Fraser</strong> <strong>River</strong> Basin. For thisreas<strong>on</strong>, effects-based sediment quality guidelines for the protecti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> benthicinvertebrates were obtained from multiple jurisdicti<strong>on</strong>s and reviewed to identify toxicitythresholds that could be used to assess sediment quality c<strong>on</strong>diti<strong>on</strong>s in the study area.A tiered-approach was used to select toxicity thresholds for use in the evaluati<strong>on</strong> whichinvolved:A-39

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