Polycyclic Aromatic Hydrocarbons in Biota from the Brisbane River Estuary, Australia

Six species of aquatic organisms from the Brisbane River estuarine system were sampled and their tissues analysed for polycyclic aromatic hydrocarbons (PAHs). These were the sea mullet,Mugil cephalus, bony bream,Nematolosa come, blue catfish,Arius graffei, mud crab,Scylla serrata, pelican,Pelecanus conspicillatus, and silver gull,Larus novaehollandiae. PAHs in the muscle (fish and birds) and soft (crab) tissue samples were isolated by first hydrolysing these samples and then solvent extraction followed by column chromatography. The compounds were then identified and quantified by gas chromatography and gas chromatography coupled with mass spectrometry. The samples contained low levels of PAHs that ranged in molecular weight from 128 (naphthalene) to 252 (benzo[k]fluoranthene). The highest total PAH level of 195 ng g−1, wet weight, was recorded in mullet samples whereas the blue catfish samples yielded the lowest level of 43 ng g−1. Relative ratios of low molecular weight (≤3-rings) compounds to those with high molecular weights (≤4-rings) suggested a petroleum related origin for the PAHs detected in the organisms. Results indicated that significant biomagnification of PAHs in the estuarine ecosystem sampled is highly unlikely. Characteristics such as the trophic level and size/age were not significant factors in determining the corresponding tissue PAH levels in the fish and crab species. Tissue lipid content, however, was found to be a primary factor in determining the PAH concentrations in fish species. PAH levels recorded in the samples are comparable to those levels reported from similarly urbanized areas in other geographical locations.