| Used crankcase oil is a very dangerous pollutant because it contains an amount of polycyclic aromatic hydrocarbons (PAHs) as well as heavy metals and additives. PAHs, especially those with four or more rings, are generally recognised as strong mutagens and/or carcinogens. Used crankcase oil pollution is a world-wide problem because the major sources are automobile and industrial activities.; Many studies were conducted to determine the levels of PAHs in environmental samples such as air, soil, water and sediment. As a major pollution source, used crankcase oil was relatively seldom studied mainly due to its complex matrix. In the present study, supercritical fluid extraction (SFE) combined with silica gel chromatography was used to extract and clean up PAHs from new and used crankcase oils before chemical analysis. Compared with conventional liquid-liquid extraction, SFE provided higher reproducibility and recovery to 16 certified PAHs. Levels of PAHs in new crankcase oil and used crankcase oil collected from petrol-engine-driven vehicles at various driven distances (from 500 to 7,500 km) were analysed by gas chromatography-mass spectrometry (GC-MS). The level of PAHs in crankcase oils was initially very low and increases with vehicle driven distance. More than 180 compounds in used crankcase oil were separated by GC. Among them, 99 compounds were identified by MS and by comparing their GC retention indices with those reported previously and 16 certified PAHs were quantified accurately.; PAHs pose a potential hazard not only to human but also to other living organisms. PAHs can enter aquatic environments through various ways because sediments in aquatic systems usually serve as reservoirs for PAHs. Local marine species may be exposed to high level of PAHs which mainly result from illegal disposal of used crankcase oils in Hong Kong. Therefore, three local marine species, Chlorella pyrenoidosa CU-2, Elasmopus rapax and postlarvae of Metapenaeus ensis were used to evaluate the growth inhibition and survival effects of PAHs. In addition, Microtox{dollar}spcircler{dollar} test for acute toxicities of PAHs and Mutatox{dollar}spcircler{dollar} test for genotoxicities of PAHs were also conducted in the present study in order to determine the correlationship between the bioassays by local marine species and the commercial available standard toxicity test. Eleven major certified PAHs present in used crankcase oils and the PAH fractions of used crankcase oils to these organisms showed acute toxicities and genotoxicities to different extent. Especially, fluorene and phenanthrene were strongly direct-acting mutagens and benzo(a)anthracene, benzo(a)pyrene and pyrene were strong promutagens. Meanwhile, there were no toxic effects for the PAH fractions of new crankcase oils in all toxicity and genotoxicity tests.; Statistical analyses showed that total PAH contents in new and used crankcase oils and their toxicities in various acute toxicity tests had significantly linear or Spearman's rank-order correlations except Microtox{dollar}spcircler{dollar} test. Among three local marine species bioassays, there were statistically significant linear or Spearman's rank-order correlations. However, there were no linear or Spearman's rank-order correlations between Microtox{dollar}spcircler{dollar} test and the bioassays by three local marine species. |
