Di- and triaromatic hydrocarbons in fish liver from the North Sea: Multivariate and statistical analysis

Multivariate classification and comparison using principal component analysis and cluster analysis together with statistical analysis using onefactor ANOVA has been made on the alkylhomologue distribution (AHD) of naphthalene, dibenzothiophene and phenanthrene/anthracene (NPD) patterns in 32 fish liver samples. Nineteen samples have been taken from fish caught close to three oil drilling platforms (< 250 m) and 13 from fish caught at reference stations (> 10 000 m). Principal Component Analysis (PCA) of the a priori defined types of samples and on subsets of the total dataset show that there is a systematic difference in the pattern of naphthalenes in fish liver samples caught close to oil platforms and those caught at reference stations. Statistical analysis using ANOVA on each individual variable supports the multivariate interpretation. It is not possible to distinguish between the sets of platform samples from the different surveys. This suggests that the pattern of NPDs in fish liver does not depend on what type of drillmud is discharged from the platform and that there are only small differences in the analytical procedures between surveys. The results show that the livers of migratory fish caught close to oil platforms contain increased amounts of naphthalenes whereas the three-ring aromatic and the sulphur aromatic compounds are not accumulated significantly in the liver.