PARENT SESSION
SA6 - Sorption of Hydrophobic Pollutants
Chair: Koelmans, Albert Bart1, 1 P.O. Box 8080, Wageningen, Wageningen, The Netherlands
8:00 AM to 12:00 PM - Sunday, 17 November 2002
Room Ballroom B
(055) Influence of desorption and contact time on sediment-water distribution of spiked PCBs and PAHs, relation with in-situ distribution.
ten Hulscher, Theodora*,1, Vrind, Bea1, van den Heuvel, Henny1, van Noort, Paul1, Govers, Harrie2, 1 Institute for Inland Water Management and Waste Water Treatment (RIZA), Lelystad, the Netherlands2 Department of Environmental and Toxicological Chemistry, Institute for Biodiversity and Ecosystems Dynamics, Amsterdam, the Netherlands
ABSTRACT- The long-term sediment-water distribution of PCBs and PAHs, spiked to lake Ketelmeer sediment, was studied using a gas-purge technique. Contact time varied from 2 d to 1461 d for the PCBs, and from 5 d to 100 d for the PAHs. Purge induced desorption experiments lasted 300 to > 4000 h. The initial distribution coefficients that were observed during the first part of the experiment were close to literature values for distribution after short contact times. The distribution coefficients increased during the purge-induced desorption experiments and reached a platteau value. The observed final distribution coefficients were 1-2 orders of magnitude higher than the initial values. These values were close to distribution coefficients reported earlier for in situ PCBs and PAHs present in a field contaminated sediment for years to decades. The change in distribution coefficients during a gas-purge experiment may resemble the long term change in a field sediment. Final distribution coefficients seem to be a more relevant measure for the distribution coefficients of hydrophobic organic chemicals in aged field sediments than values obtained after short contact times.
Key words: sequestration, sediment-water distribution, contact time, pcbs and pahs