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Oil pollution in the North Sea—a microbiological point of view

Minas, W. and Gunkel, W. (1995) Oil pollution in the North Sea—a microbiological point of view. Helgoländer Meeresuntersuchungen, 49 (1-4). pp. 143-158. ISSN 0174-3597. doi:10.1007/BF02368345.

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In this study we determined oil degradation rates in the North Sea under most natural conditions. We used the heavy fuel oil, Bunker C, the major oil pollutant of the North Sea, as the model oil. Experiments were conducted in closed systems with water sampled during winter and repeated under identical conditions with water collected during summer. No nitrogen or phosphorous was added and conditions were chosen such that neither oxygen nor nutrients, present in the water, would become limiting during the experiments. We detected a fourfold increased degradation rate for water samples taken in summer (18°C water temperature) as compared to water sampled in winter (4°C water temperature). Under the assumption that biodegradation of oil can be regarded as a Michaelis-Menten type kinetic reaction, the kinectic constants Vmax and KM were determined for oil biodegradation at 4°C and 18°C. At both temperatures KM was about 40 ppm, whereas Vmax was 3–4 times higher at 18°C. From both Vmax and the results of fermentation studies, we determined the maximum rates of Bunker C oil degradation in the North Sea as ∼20 g m−3a−1 at 4°C in winter and 60–80 g m−3a−1 at 18°C in summer. Furthermore, while over 25% of the oil was degraded within 6 weeks in summer, only 6.6% of the oil was degraded in winter. A higher incubation temperature in winter (18°C) increased both the rate and the percentage of oil degraded, but degradation did not reach the level obtained during the summer. While these data reflect the oxidation only of the hydrocarbons, we conducted experiments directly in the open sea to determine the contribution of abiotic factors to oil removal. Approximately 42% of the oil was lost within 6 weeks under these conditions in summer and 65% in winter. However, GC-MS analysis of the recovered oil showed no significant change in the alkane pattern that would indicate enhanced degradation. Thus, mainly abiotic factors such as erosion and dispersion rather than degradation were responsible for enhanced oil removal. Especially the high loss during winter can be attributed to frequent storms resulting in greater dispersion. In conclusion, the higher oil degrading potential of the microbial population in the North Sea was represented by a four times faster oil degradation during the summer. In-situ experiments showed that abiotic factors can have an equal (summer) or even higher (winter) impact on oil removal.

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Additional Information:© 1995 Biologische Anstalt Helgoland, Hamburg. We thank Professor Dr. H. Kaltwasser and the late Professor Dr. R. Schweisfurth for helpful discussions, also the crew of the MB Aade and the BAH underwater diving team for their help during sampling. This study (Project No. 335-01) was funded by the German Society for Petroleum Science and Coal Chemistry.
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German Society for Petroleum Science and Coal Chemistry335-01
Issue or Number:1-4
Record Number:CaltechAUTHORS:20160421-121716980
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66365
Deposited By: George Porter
Deposited On:21 Apr 2016 19:27
Last Modified:10 Nov 2021 23:57

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