PT10 Toxicity of Complex Mixtures
Exhibit Hall
8:00 AM - Tuesday, 11 November 2003
(PT175) Significance of oil droplets in chemically enhanced water-accommodated fraction.
Ramachandran, S1, Khan, C1, Hodson, P1, Lee, K2, 1 Queens University, Kingston, Ontario, Canada2 Queens University, Kingston, Ontario, Canada
ABSTRACT- Chemical dispersion is an oil spill contingency measure fraught with controversy due to reports of negative impacts on aquatic life from the dispersant as well as the dispersed oil. While breaking up the spill to reduce shoreline impacts, the dispersant drives the oil into the water column in the form of droplets, hence temporarily increasing the hydrocarbon concentrations. Exposure experiments with rainbow trout using water-accommodated fractions (WAF) showed accumulation of polycyclic aromatic hydrocarbons (PAHs) was 6 to 1100 fold higher in chemically (Corexit 9500) dispersed water-accommodated fractions (CEWAF) than WAF. Dispersing crude oils would thus sustain hydrocarbon concentrations in a larger volume of water than if it were not dispersed. The effect of dispersants was due primarily to an increase in the concentration of suspended oil droplets. To examine the role of these droplets in 1) increasing the partitioning of PAHs into solution or 2) by adhering to gill filaments thereby facilitating direct uptake, exposure experiments have been conducted using CEWAF from Mesa and Scotian Light Crude Oil with and without oil droplets. Examination of gills from exposed fish showed fluorescing oil droplets adhering to the filaments.
Key words: crude oil, oil droplets, corexit 9500, water-accommodated fractions