Effect of the input pathway on the distribution of 1,2,3,4,7-pentachlorodibenzo-p-dioxin in an aquatic mesocosm
- Univ. of Winnipeg, Manitoba (Canada). Dept. of Chemistry
- Univ. of Manitoba, Winnipeg, Manitoba (Canada). Dept. of Soil Science
- Freshwater Inst., Winnipeg, Manitoba (Canada). Dept. of Fisheries and Oceans
The effect of the input pathway on the distribution of 1,2,3,4,7-pentachlorodibenzo-p-dioxin (P{sub 5}CDD) in small-pond mesocosms was determined by introducing {sup 14}C-labeled dioxin (468 {micro}g) into the water sorbed to sediment particles and by a surface sprayover in a water-miscible organic solvent. Rates of clearance from the water column were rapid and unrelated to the input method in either case, with pseudo-first-order half-lives (t{sub 1/2}) of 0.38 {+-} 0.19 d (r{sup 2} = 0.81) and 0.57 {+-} 0.08 d (r{sup 2} = 0.98) for the particle-sorbed and sprayover applications, respectively, over the first 24 h after input. However, redistribution pathways were strongly influenced by the route of entry of P{sub 5}CDD into the ecosystem. Ponds receiving a sprayover of P{sub 5}CDD showed higher concentrations of the dioxin in surface microlayers with larger amounts also collected in air above these ponds. Concentrations of P{sub 5}CDD in the bottom sediments of these ponds were significantly lower (0.6 ng/g dry weight) compared to concentrations in sediments of ponds receiving a sediment slurry input (1.2 ng/g dry weight). Evaluation of the results using several fugacity-based aquatic-fate models indicated that when P{sub 5}CDD entered the aquatic ecosystem in the sorbed state, sedimentation dominated its redistribution. However, with a sprayover input, film-to-water transfer, partitioning and deposition to bottom sediment, volatilization, and photolytic degradation in surface microlayers were important processes affecting the fate of P{sub 5}CDD in the mesocosm.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 136750
- Journal Information:
- Environmental Toxicology and Chemistry, Vol. 14, Issue 11; Other Information: PBD: Nov 1995
- Country of Publication:
- United States
- Language:
- English
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