Estimation of hydrocarbon biodegradation rates in marine environments: A critical review of the Q10 approach

• The Q10 approach for estimating biodegradation rates is discussed.
• High variation in Q10 values is attributed to indirect effects of temperature.
• Bioavailability and bacteria number influences Q10 in temperature controlled tests.
• Choosing one universal Q10 is neither feasible nor anticipated.
• Temperature compensation based biodegradation rate predictions are questionable.

Offshore oil & gas industry is moving exploration and production activities into Arctic and deep water regions. Governmental regulations require environmental impact assessments before operations to evaluate the possible effects of accidental oil releases. These are often performed by numerical fate models, like the Oil Spill Contingency and Response (OSCAR) model, which has become an industry standard in Norway. In this model, biodegradation rates are adjusted to local conditions by temperature compensation according to a Q10 approach. Q10 is the multiplier by which rates of enzymatic reactions increase at a 10 °C temperature rise. Herein, this Q10 approach implemented in the OSCAR model is investigated based on published data and novel obtained results. Overall, biodegradation rate predictions calculated by temperature compensation are found to be questionable, and choosing one universal Q10 value is considered not feasible. The high variation in Q10 values is herein attributed to indirect effects of temperature.