Equilibrium partitioning sediment

US EPA (2003a). Procedures for deriving equilibrium partitioning sediment benchmarks (ESBs) for the protection of benthic organisms endrin. EPA-600-R-02-009. Office of Research and Development, Washington, DC 20460. 

Reference ANZECC/ARMCANZ (2000) CCME (1999a) Lepper (2005) and environmental quality standards (EQSs) Substance data sheets for the EU priority substances (available at http //forum.europa.eu.int/ Public/irc/env/wfd/library l= /framework directive/i-priority substances/supporting background/ substance sheets vm= detailed sb= Title) Procedures for the Derivation of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the Protection of Benthic Organisms. Consult http // www.epa.gov/nheerl/ publications/ for these procedures for PAH mixtures, dieldrin, endrin, and heavy metals. 

Development and Application of Equilibrium Partitioning Sediment Guidelines in the Assessment of Sediment PAH Contamination... 

United States Environmental Protection Agency. Methods for the derivation of site-specific equilibrium partitioning sediment guidelines (ESGs)for the protection of benthic organisms nonionic EPA 822-R-00-002 U.S. EPA Office of Water Washington, DC. 2000. 

Dewulf, J., van Langenhove, H., Grare, S. (1999) Sediment/water and octanol/water equilibrium partitioning of volatile organic compounds temperature dependence in the 2-25°C range. Water Res. 33, 2424—2436. 

De Seze, G., Valsaraj, K.T., Reible, D.D., Thibodeaux, L.J. (2000) Sediment-air equilibrium partitioning of semi-volatile hydrophobic organic compounds. Part 2. Saturated vapor pressures, and the effects of sediment moisture content and temperature on the partitioning of polyaromatic hydrocarbons. Sci. Total Environ. 253, 27-44. 

Pavlou, S.P (1987) The use of equilibrium partition approach in determining safe levels of contaminants in marine sediments, p. 388 -12. In Fate and Effects of Sediments-Bound Chemicals in Aquatic Systems. Dickson, K.L., Maki, A.W., Brungs, W.A., Editors. Proceedings of the Sixth Pellston Workshop, Florissant, Colorado, August 12-17,1984. SETAC Special Publ. Series, Ward, C.H., Walton, B.T., Eds., Pergamon Press, N.Y. 

Table 4 Observed sediment toxicity values for H. azteca and C. dilutus and pore water concentrations predicted by equilibrium partitioning [25]...

In summary, the bioavailability and observed toxicity of synthetic pyrethroids in sediment-water systems is influenced by a number of physicochemical factors, including the quantity and type of organic and inorganic matter in sediment and in water, as well as by temperature. The use of equilibrium partitioning calculations can be a useful tool for estimating the dissolved and potentially bioavailable fraction of pyrethroids. 

Di Toro DM, Zarba CS, Hansen DJ et al (1991) Technical basis for establishing sediment quality criteria for non-ionic organic chemicals using equilibrium partitioning. Environ Toxicol Chem 10 1541-1583... 

Now, because the water-borne radioactive element is predominantly associated with the colloids, we no longer have a need for the distribution coefficient. There will still be a partitioning because the major portion of the radioactive elements will still be adsorbed to the sediment. This is a separate equilibrium partitioning coefficient, requiring a new experiment on the clay sediments and the colloids present. The partitioning colloid-clay ratio would most likely be dependent on the surface areas of each present in the sediments. A separate size distribution analysis has resulted in a sediment-colloid surface area ratio of 99 1 for the sediment. This results in a colloid retardation coefficient oiRc = 100 rather than Ri = 4.2 x 10 or i 2 = 6 x 10. ... 

Dissolved fraction and equilibrium partition coefficient, at sediment-water interface ... 

Clarke, J. U., and V. A. McFarland, Uncertainty analysis for an equilibrium partitioning-based estimator of polynuclear aromatic hydrocarbon bioaccumulation potential in sediments , Environ. Tox. Chem., 19, 360-367 (2000). 

This last equation forms the basis for the EPA s sediment quality guidelines that are used to assess the potential toxicity of contaminated sediments. The idea is to simply measure Cs and foe, look up K0w in a table, compute the predicted Cw, and compare this result to established water quality criteria for the protection of aquatic life or human life (e.g., carcinogenicity risk factors). The use of this simple equilibrium partitioning expression for this purpose is currently the subject of much debate among scientists as well as policy makers. 

Ditoro, D.M., C.S. Zarba, D.J. Hansen, W.J. Berry, R.C. Swartz, C.E. Cowan, S.P. Pavlou, H.E. Allen, N.A. Thomas, and P.R. Paquin. 1991. Technical basis for establishing sediment quality criteria for nonionic organic chemicals using equilibrium partitioning. Environ. Toxicol. Chem. 10(12) 1541-1583. 

The models are used most frequently and assume that bioaccumulation is described adequately by equilibrium partitioning between the sediment, the pore-water (or interstitial water), and the organism (e.g. Shea, 1988 Gobas et al., 1989b Bierman, 1990, DiToro et al., 1990) namely ... 

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