| Autor: |
Stoyanovich SS, Saunders LJ, Yang Z; Emergencies Science and Technology Section, Environment and Climate Change Canada, Ottawa, Ontario K1V 1C7, Canada., Hanson ML; Department of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada., Hollebone BP; Emergencies Science and Technology Section, Environment and Climate Change Canada, Ottawa, Ontario K1V 1C7, Canada., Orihel DM; Department of Biology and School of Environmental Studies, Queen's University, Kingston, ON K7L 3N6, Canada., Palace V; International Institute for Sustainable Development, Experimental Lakes Area, 111 Lombard Avenue, Suite 325, Winnipeg, Manitoba R3N 0T4, Canada., Rodriguez-Gil JL; Department of Environment and Geography, University of Manitoba, Winnipeg, MB R3T 2N2, Canada.; International Institute for Sustainable Development, Experimental Lakes Area, 111 Lombard Avenue, Suite 325, Winnipeg, Manitoba R3N 0T4, Canada., Mirnaghi FS; Emergencies Science and Technology Section, Environment and Climate Change Canada, Ottawa, Ontario K1V 1C7, Canada., Shah K; Emergencies Science and Technology Section, Environment and Climate Change Canada, Ottawa, Ontario K1V 1C7, Canada., Blais JM |
| Abstrakt: |
Due to the sudden nature of oil spills, few controlled studies have documented how oil weathers immediately following accidental release into a natural lake environment. Here, we evaluated the weathering patterns of Cold Lake Winter Blend, a diluted bitumen (dilbit) product, by performing a series of controlled spills into limnocorrals installed in a freshwater lake in Northern Ontario, Canada. Using a regression-based design, we added seven different dilbit volumes, ranging from 1.5 to 180 L, resulting in oil-to-water ratios between 1:71,000 (v/v) and 1:500 (v/v). We monitored changes in the composition of various petroleum hydrocarbons (PHCs), including n -alkanes, polycyclic aromatic hydrocarbons (PAHs), and oil biomarkers in dilbit over time, as it naturally weathered for 70 days. Depletion rate constants ( k D ) of n -alkanes and PAHs ranged from 0.0009 to 0.41 d -1 and 0.0008 to 0.38 d -1 , respectively. There was no significant relationship between k D and spill volume, suggesting that spill size did not influence the depletion of petroleum hydrocarbons from the slick. Diagnostic ratios calculated from concentrations of n -alkanes, isoprenoids, and PAHs indicated that evaporation and photooxidation were major processes contributing to dilbit weathering, whereas dissolution and biodegradation were less important. These results demonstrate the usefulness of large scale field studies carried out under realistic environmental conditions to elucidate the role of different weathering processes following a dilbit spill. |
