Characteristics of Vertical Distributions of Fatty Acids in Surface Sediments of the Yellow Sea and East China Sea

Fatty acids (FAs) in sediment collected from three different stations in the Yellow Sea and the East China Sea were analyzed for their distributions and to determine evidence of harmful algal blooms in the sediment core. Less diverse FAs were found in the Yellow Sea (YS) station, whereas in the two stations of the East China Sea (ECS) the FAs were more diverse. Concentrations of some FA species in the two ECS stations displayed an occasional surge in their vertical profile. The highest concentration of FAs was found in the surface layer of station QT3 (43.28 mu g g(-1)). Monounsaturated FAs were more susceptible to degradation compared to their saturated counterparts, and changes of 16:0, 18:2 and 20:5 accounted for the most variability in total concentrations of FAs as those species made up most of the quantified FAs. The origins of the major fraction of FAs were attributed to autotrophic sources, and bacterial FAs accounted for only a small fraction of the total FAs in the region. Nutrient availability was a possible regulating factor controlling bacteria abundances in marine sediments in the ECS and the YS. A principal component analysis (PCA) was applied to analyze the FA dataset and to reveal the principal environmental factors that control the composition of FAs in the sediments. PC2, which explains 15% of the variance, was estimated to reflect the diagenetic effects on the FA compositional changes in sediments influenced by bacterial degradation.