SITE INFORMATION AND CORRESPONDENCE

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Sediment Quality Guidelines DRAFT Derived Through Equilibrium Partitioning Principles: 1. Concentrations of pollutants in sediment interstitial (pore)water have been shown empirically to be predictive of biological effects. 2. Water column criteria, such as the USEPA National Ambient Water Quality Criteria, may be used to determine the degree of biological effects from pollutants in water. 3. The equilibrium between pollutants in pore water and in sediment can be used to derive sediment quality guidelines (SQGs). 4. For non-ionic organic pollutants, partitioning between pore water and sediment is influenced largely by the association between the pollutant and organic carbon in the sediment. Therefore, the degree of association between a non-ionic organic pollutant and sediment is dependent on the fraction of organic carbon in bulk sediment (fo,). 5. The octanol-water partition coefficient (Kaw) for a pollutant can be used to estimate organic carbon-water partition coefficient (K,) for the pollutant using the following relationship: KOC = 0.983(K,,,)+ 0.00028 6. Equilibrium partitioning may be applied to mixtures of toxic pollutants in sediment. 7. The toxicity of some metallic pollutants in sediment is largely dependent on their association with dissociable sulfides in the sediment. Unassociated metallic pollutants in pore water are available to cause biological effects. Sulfide bound metallic pollutants are not available to cause biological effects. 8. Dissociable sulfides are produced by bacterial breakdown of organic matter in sediment. Sulfide levels in sediment are lower in winter and early spring and increase with depth in the sediment. Sampling of the top 2.0 cm is recommended for"in-place" sediments. 9. Dissociable sulfides in sediment may be measured as acid volatile sulfide (AVS). Sediments are extracted with cold 1N HCl, producing H,S. 10. Metals extracted during the AVS procedure include Cadmium, Copper, Lead, Nickel, and Zinc, collectively called simultaneously extracted metal(SEM). Silver may also be included in SEM.