Sediment sorption coefficient measurements for four phthalate esters: Experimental results and model theory
- ABC Laboratories, Columbia, MO (United States)
- Exxon Biomedical Sciences, East Millstone, NJ (United States)
- Eastman Kodak Co., Rochester, NY (United States)
Sediment partition coefficients were measured for four commercial phthalate esters: dihexyl phthalate (DHP), di(2-ethylhexyl) phthalate (DEHP), diisodecyl phthalate (DIDP), and ditridecyl phthalate (DTDP). The experimental procedure was based on the US Environmental Protection Agency (EPA) test Guideline 796.2750, ``Sediment and Soil Adsorption Isotherm.`` Three sediments were used: EPA 8 (0.15% organic carbon), EPA 18 (0.66% organic carbon), and EPA 21 (1.88% organic carbon). The Freundlich equation was used to calculate organic carbon-normalized sediment/water partition coefficients (K{sub oc}), which averaged 5.26 {times} 10{sup 4} {+-} 4.54 {degree} 10{sup 3}; 4.82 {times} 10{sup 5} {+-} 3.52 {times} 10{sup 5}; 2.86 {times} 10{sup 5} {+-} 2.74 {times} 10{sup 5}; and 1.82 {times} 10{sup 6} {+-} 1.05 {times} 10{sup 6} for DHP, DEHP, DIDP, and DTDP, respectively. In general, these K{sub oc} values did not correlate well to either sediment or chemical properties. This lack of correlation suggested that the measured K{sub oc} values are suppressed, potentially as a function of experimental conditions. On the basis of these data, it was decided to investigate the dependence of K{sub oc} on sediment solids concentration and dissolved organic carbon. Analysis of these and earlier reported partition coefficient data indicated that measured K{sub oc} values for phthalate esters obtained in shake-flask experiments exhibited an inverse dependence on solids concentration. These results were consistent with partitioning models that are discussed. Depending on compound hydrophobicity, the particle-corrected K{sub oc} values were from one to three orders of magnitude higher than the measured K{sub oc} values. Therefore, if partition coefficient values obtained by using Test Guideline 796.2750 or similar shake-flask procedures are not corrected for solids effect, the estimates of the sediment pore-water concentration of the chemical is likely to be overestimated.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 118678
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 14, Issue 9; Other Information: PBD: Sep 1995
- Country of Publication:
- United States
- Language:
- English
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