EFFECT OF HYPORHEIC FLOW ON THE FATE AND BEHAVIOUR OF SPILLED OIL IN RIVERS
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The growing global need for oil and oil products results in an increasing reliance on land-based transportation near sensitive freshwater systems. Of particular concern in Canada is the transport of diluted bitumen (dilbit), a mixture typically of 30% diluent and 70% bitumen. The varying proportions of hydrocarbons in dilbit cause challenges with determining how it will behave in freshwater environments. The hyporheic zone is the portion of sediments surrounding the river that is permeated with river water, and water flow through that zone may transport contaminants from trapped oil into the river. There are several influencing factors related to hyporheic flow, two of which are path length and flow rate. The goal of this project was to assess the extent to which polycyclic aromatic compounds (PAC) partition from trapped oil to interstitial waters under varying flow rates and path lengths. To test path length columns were cut to lengths of 15, 30, and 60 cm and were filled with gravel and loaded with a fixed amount of oil. The water flow rate through the columns was set to 20 mL/min and 40 mL/min. Water effluent samples were taken daily and the amount of PAC in the water was analyzed using fluorescence spectroscopy. The main findings of the experiment were that desorption columns were effective at trapping oil, the longer path length (60 cm) had lower total oil concentrations in the effluent, and the impact of flow rate had varying results on droplet compared to dissolved oil concentrations. These findings provide valuable information on the effect of a hyporheic flows path length and flow rate on spilled oil. This increased understanding can then be extended into real world scenarios and help improve risk assessments and spill clean-up strategies.