Calibrating the uptake kinetics of semipermeable membrane devices using exposure standards
- Netherlands Inst. for Sea Research, Den Burg (Netherlands)
- Ministry of Transport, Public Works and Water Management, Haren (Netherlands). National Inst. for Coastal and Marine Management
The water phase is an important compartment in the modeling of the fate of organic contaminants in the aquatic environment. Organic contaminant exchange kinetics between semipermeable membrane devices (SPMDs) and water were studied in two suspensions of estuarine and marine sediments under conditions of high and low turbulence over a period of 56 d. Prior to exposure, the SPMDs were spiked with a number of exposure standards not occurring in the environment. The release rate of these compounds was used as an independent measure of the exchange kinetics between the SPMD and water. The uptake rates of chlorobenzenes, polychlorinated biphenyls, (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were lower by a factor of three under conditions of low turbulence. For compounds with a log octanol-water partition coefficient (K{sub ow}) > 5.5 the uptake rate was constant during the entire period. Within each compound class, uptake rate constants correlated well with log K{sub ow}. The uptake rate constants of PAHs were lower than those of PCBs and chlorobenzenes by a factor of 10, but these estimates probably are artificially low due to an overestimation of the aqueous PAH concentrations. Release rate constants of the exposure standards fell within the range of the uptake rate constants of chlorobenzenes and PCBs, although with poor precision. Suggestions for improving the measurement of exchange rate constants of exposure standards are presented. The role of triolein in the exchange kinetics is shown to be minor.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 675428
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 17, Issue 7; Other Information: PBD: Jul 1998
- Country of Publication:
- United States
- Language:
- English
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