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8738300 
Journal Article 
Using respiration rates and stable carbon isotopes to monitor the biodegradation of Orimulsion by marine benthic bacteria 
Lapham, L; Proctor, L; Chanton, J 
1999 
1 
Environmental Science & Technology
ISSN: 0013-936X
EISSN: 1520-5851 
33 
12 
2035-2039 
English 
Carbon dioxide evolution rates and the δ13C of produced CO2 were measured in slurry experiments to determine the potential for biodegradation of Orimulsion, a new fuel consisting of 70% Cerro Negro bitumen, 30% water, and 0.1% emulsifying surfactant. Control slurries contained marine sediment as a bacterial inoculum and carbon source, while experimental slurries contained sediment amended with either Orimulsion or bitumen alone, surfactant-free. The δ13C values of the substrates, marine organic matter and Orimulsion/bitumen were significantly different, -23‰ and -27‰. Respiration rates were 40-80% greater in hydrocarbon-amended slurries relative to controls. The δ13C of the respired CO2 in the Orimulsion- amended slurries was 2-3‰ depleted in 13C relative to CO2 produced in controls. Mass balance calculations showed that the δ13C values of respired CO2 due to marine organic matter utilization ranged from -20 to - 23‰, while the δ13C of excess CO2 produced due to hydrocarbon degradation was generally more 13C depleted (-21 to -27‰), evidence of bacterial degradation of Orimulsion and bitumen. Although Orimulsion biodegradation rates were considerably less than degradation rates of oil- based fuels, bioremediation could be enhanced and should be part of a coordinated effort for cleaning up Orimulsion. Carbon dioxide evolution rates and the δ13C of produced CO2 were measured in slurry experiments to determine the potential for biodegradation of Orimulsion, a new fuel consisting of 70% Cerro Negro bitumen, 30% water, and 0.1% emulsifying surfactant. Control slurries contained marine sediment as a bacterial inoculum and carbon source, while experimental slurries contained sediment amended with either Orimulsion or bitumen alone, surfactant-free. The δ13C values of the substrates, marine organic matter and Orimulsion/bitumen were significantly different, -23qq and -27qq. Respiration rates were 40-80% greater in hydrocarbon-amended slurries relative to controls. The δ13C of the respired CO2 in the Orimulsion-amended slurries was 2-3qq depleted in 13C relative to CO2 produced in controls. Mass balance calculations showed that the δ13C values of respired CO2 due to marine organic matter utilization ranged from -20 to -23qq, while the δ13C of excess CO2 produced due to hydrocarbon degradation was generally more 13C depleted (-21 to -27qq), evidence of bacterial degradation of Orimulsion and bitumen. Although Orimulsion biodegradation rates were considerably less than degradation rates of oil-based fuels, bioremediation could be enhanced and should be part of a coordinated effort for cleaning up Orimulsion.