Bioavailability of organic contaminants in sediments.

• Main Author: Yates, Kyari
• Other Authors: Davies, Ian, Pollard, Pat, Webster, Linda, Moffat, Colin, Lawton, Linda A.
• Format: Thesis
• Language: unknown
• Published: 2008
• Subjects: Norway; Vefsn
• Online Access: http://hdl.handle.net/10059/588; https://rgu-repository.worktribe.com/file/248047/1/YATES%202008%20Bioavailability%20of%20organic%20contaminants

The bioavailability of polycyclic aromatic hydrocarbons (PAHs) and chlorobiphenyls (CBs) in sediments is largely dependent on the freely dissolved concentration of these pollutants. However, measuring these is challenging, due to the low concentrations of lipophilic contaminants in the environment and their strong affinity for particles and for traditional sampling (filtration and centrifugation) equipment. An equilibrium passive sampling device made of silicone rubber was developed in this research to measure the freely dissolved concentrations of lipophilic contaminants and other parameters (water extractable proportions and sediment-water partition coefficients) that describe the availability of these contaminants in the environment. Equilibration between sampler and sediment for PAHs and CBs was found to be adequately achieved after 20 days shaking of a silicone rubber sampler in sediment slurry on an orbital shaker at 200 rpm. The reproducibility of uptake was better than 5 %. Silicone rubber-water partition coefficients for 34 PAHs and 32 CBs were measured in the laboratory using a co-solvent method using methanol as co solvent. Strong linear correlations of log K(sr,w), with octanol-water partition coefficients (log K(ow)). (log K(sr,w) = 0.97; log K(ow) -0.01; r2 = 0.94) and (log K(sr,w) = 1.17; log K(ow) -1.82; r2 = 0.90) were found for PAHs and CBs, with a systematic difference in correlations observed for the different classes of compounds which was attributed to structural differences of the compounds. The silicone rubber samplers were then used to measure concentrations of PAHs in the pore water of sediments from the Fladen Ground of the North Sea, Loch Shell, Firth of Forth, Firth of Clyde, Loch Etive and Aberdeen Harbour in Scotland and the Vefsn fjord, Norway. A proportion of the PAHs were found to be unavailable for exchange into the aqueous phase, and this was reflected in the high log K(oc) measured in all the sediments studied. The sediment-water partition coefficients also correlated ...