Carbon stable isotopic fractionation associated with biosynthesis of fatty acids by marine microalgae under the stress of oil spills

In order to realize the effects of oil spill on marine microalgae growth, we studied the carbon stable isotope composition (13C) of Chaetoceros gracilis under the stress of different content of water accommodated fraction (WAF) of No.180 fuel oil. The result shows that the rate of fatty acid synthesis are affected by different degree of the stress of WAF in the process of microalgae growth, especially there are approximately linear relationships between the 13C values of unsaturated fatty acids (16:1 and 18:4) and WAF, which may result from the kinetic stable isotope fractionation effect. Therefore parts of unsaturated fatty acids such as 16:1 may be used as an alternative biomarker for estimating the pollution degree of oil spills.