Chemical and biological profiles of sediments as indicators of sources of contamination in Hamilton Harbour. Part II: Bioassay-directed fractionationusing the Ames Salmonella/microsome assay

Bottom sediment and suspended sediment samples from Hamilton Harbour (weste rn Lake Ontario) and from a major tributary were profiled using a bioassay- directed fractionation approach. Sample extracts were fractionated using an alumina/Sephadex gel clean-up procedure to afford non-polar aromatic fract ions which were characterized using chemical analyses and the Ames/microsom e bacterial assay in Salmonella typhimurium strains YG1025 with the additio n of oxidative metabolism (S9), and YG1024 without S9. Non-polar aromatic f ractions of selected samples were separated by normal phase HPLC into I-min fractions which were subjected to bioassay analyses. The bioassays using s train YG1025+S9, a TA100-type strain, were performed to assess genotoxicity arising from the presence of polycyclic aromatic hydrocarbons (PAH). Fract ions which exhibited mutagenic activity contained PAH with molecular masses of 252, 276 and 278 amu; these fractions contained over 80% of the genotox icity attributable to PAH. Individual compounds identified using Gas Chroma tography-Mass Spectrometry analyses in these active fractions included benz o[a]pyrene, indeno[cd]pyrene and dibenz[a,h]anthracene. The YG1025+S9 mutag enic activity profiles were similar for all samples. Mutagenic activity pro files generated using strain YG1024-S9, a TA98-type strain sensitive to com pounds characteristic of mobile source emissions, were very different. The mutagenic activities in strain YG1024-S9 were greatest for harbour-suspende d sediment samples collected from sites impacted by a major tributary. Susp ended sediments collected near areas known to contain high levels of coal t ar-contamination in the bottom sediments contained higher levels of genotox ic PAH than suspended sediments collected from other areas of the harbour. (C) 2000 Elsevier Science Ltd. All rights reserved.