C.H. Marvin

Preliminary comparisons between mutagenicity and magnetic susceptibility of respirable airborne particulate

The magnetic susceptibility of respirable urban airborne particulate and the mutagenic potency and organic content of extracts prepared from these particles are both related to mobile and stationary combustion processes. Analyses of the organic extracts prepared from these particulate samples showed the presence of certain polycyclic aromatic hydrocarbons (PAH), certain keto-PAH and thia-PAH. The enhanced magnetic signatures of air particulate material collected in an urban environment are directly related to the presence of magnetite-rich spherules which are likely to have been produced by the oxidation of pyrite to magnetite during the combustion process. A total of 62 filters collected between May 1990 and June 1991 at an air quality monitoring station in Hamilton, Ontario were examined. A plot of magnetic susceptibility of these filters and the mutagenic potencies of the organic extracts prepared from these filters in the Salmonella/microsome assay show a significant correlation. Neither magnetic susceptibility nor mutagenicity show a similar simple direct relationship to particulate loading. Plots of wind direction vs wind speed indicate that the highest mutagenicity and susceptibility levels are predominantly associated with (a) easterly derived winds, (b) low to moderate wind velocities, and (c) enhanced levels of SO2 and NO2. In contrast, low mutagenicity and susceptibility levels are intimately associated with (a) southwesterly derived winds, (b) moderate to high wind velocities, and (c) the presence of high ozone levels which accompany higher summer temperatures. These observations suggest that rapid magnetic susceptibility measurements could be used to pre-select filters for more extensive evaluations such as organic compound analyses or biological assays.

Analysis of high-molecular-mass polycyclic aromatic hydrocarbons in environmental samples using liquid chromatography-atmospheric pressure chemical ionization mass spectrometry.

Polycyclic aromatic hydrocarbons (PAHs) with molecular masses higher than 300 u were analysed using LC-atmospheric pressure chemical ionization (APCI) MS in extracts of environmental samples from Hamilton, Canada including zebra mussels from Hamilton Harbour, air particulate and coal tar. The LC-APCI-MS profiles of three molecular mass classes of PAHs (326 u, 350 u and 374 u) were compared to identify potential sources of PAH contamination in Hamilton Harbour. The Hamilton air particulate profile was also compared with an urban air reference standard (NIST SRM 1649) from Washington, DC, USA. Profiles of all extracts were similar and suggested an environmental predominance of PAHs within the three isomeric molecular mass classes studied. However, PAHs of molecular mass 326 u and 350 u were detected in extracts of coal tar and zebra mussels from Hamilton Harbour but were not detected in Hamilton air. These results indicated that some high-molecular-mass PAHs may be characteristic of contamination by coal tar.

A Comparison of Ultrasonic Extraction and Soxhlet Extraction of Polycyclic Aromatic Hydrocarbons from Sediments and Air Particulate Material

Abstract The extraction of polycyclic aromatic hydrocarbons (PAH) from sediments and from an urban dust standard reference material (SRM 1649) was compared using two methods; ultrasonication and Soxhlet extraction. Sample weights ranging from 0.5 g to 5 g were extracted using ultrasonication. The yield of organic material from sediment samples using ultrasonication with two solvents was 2.53 ± 0.10% while the Soxhlet method yielded 2.41 ± 0.14% of the initial sample weight. Sequential ultrasonic extraction with two solvents was much more rapid (45 minutes) than Soxhlet extraction (two days) and resulted in equal extraction efficiency. The levels of PAH extracted by ultrasonication from the urban dust standard reference material varied by no more than 15% from the certified values.

Chemical and biological profiles of sediments as indicators of sources of genotoxic contamination in Hamilton Harbour. Part I : Analysis of polycyclic aromatic hydrocarbons and thia-arene compounds

Bottom sediment and suspended sediment samples from Hamilton Harbour (western Lake Ontario) and from a major tributary were profiled using polycyclic aromatic hydrocarbons (PAH) and thia-arenes as source apportionment tracers. Ratios of selected PAH and ratios of monomethyl and dimethyl/ethyl dibenzothiophenes to the parent dibenzothiophenes were calculated. Thia-arene and PAH profiles of Standard Reference Material SRM 1649 (urban dust/organics), SRM 1650 (diesel), SRM 1597 (coal tar), Hamilton coal tar and a composite Hamilton air particulate sample provided source sample data. The gas chromatography-mass spectrometry (GC-MS) chromatograms of all sample extracts were dominated by homocyclic PAH but interpretation of PAH profiles with respect to source was difficult. In contrast, thia-arene analyses revealed more distinct differences in profiles of samples collected in different areas of the harbour, including the tributary. These results indicated that areas of coal tar-contaminated sediment are potential contributors to the overall contaminant burden of sediments and suspended sediments in Hamilton Harbour. These data also indicated that contaminants related to mobile combustion sources were entering the harbour via a major tributary.

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

Bottom sediment and suspended sediment samples from Hamilton Harbour (western 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 fractions which were characterized using chemical analyses and the Ames/microsome bacterial assay in Salmonella typhimurium strains YG1025 with the addition of oxidative metabolism (S9), and YG1024 without S9. Non-polar aromatic fractions of selected samples were separated by normal phase HPLC into 1-min fractions which were subjected to bioassay analyses. The bioassays using strain YG1025+S9, a TA100-type strain, were performed to assess genotoxicity arising from the presence of polycyclic aromatic hydrocarbons (PAH). Fractions which exhibited mutagenic activity contained PAH with molecular masses of 252, 276 and 278 amu; these fractions contained over 80% of the genotoxicity attributable to PAH. Individual compounds identified using Gas Chromatography-Mass Spectrometry analyses in these active fractions included benzo[a]pyrene, indeno[cd]pyrene and dibenz[a,h]anthracene. The YG1025+S9 mutagenic activity profiles were similar for all samples. Mutagenic activity profiles generated using strain YG1024-S9, a TA98-type strain sensitive to compounds characteristic of mobile source emissions, were very different. The mutagenic activities in strain YG1024-S9 were greatest for harbour-suspended sediment samples collected from sites impacted by a major tributary. Suspended sediments collected near areas known to contain high levels of coal tar-contamination in the bottom sediments contained higher levels of genotoxic PAH than suspended sediments collected from other areas of the harbour.

Bioassay-directed fractionation of PAH of molecular mass 302 in coal tar-contaminated sediment

Bioassay-directed fractionation was used to characterise genotoxic polycyclic aromatic hydrocarbons (PAH) of molecular mass 302 amu in organic solvent extracts of coal tar-contaminated sediment from Sydney Harbour, Nova Scotia. A normal phase HPLC technique was employed to separate PAH-rich solvent extracts into fractions containing PAH of single molecular mass classes. The 302 amu molecular mass fraction was isolated and further separated using reversed phase HPLC; subfractions were collected every 30 s and subjected to bioassay analyses with Salmonella typhimurium strain YG1025 with the addition of oxidative metabolism (4% S9). Compounds eluting in the most active subfractions included naphtho[2,1-alpha]pyrene and naphtho[2,3-alpha]pyrene. The results of this study underscore the significant contribution that molecular mass 302 PAH make to the biological activity of complex environmental mixtures.

Preliminary comparisons between magnetic susceptibility and polycyclic aromatic hydrocarbon content in sediments from Hamilton Harbour, western Lake Ontario

Abstract Sediments in Hamilton Harbour, a small body of water located at the western end of Lake Ontario, are known to contain high levels of contaminants including heavy metals, PCBs and PAH. In developing a ‘clean-up’ strategy for contaminated sediment, it is necessary to determine what is meant by polluted sediment and then to establish the volume and distribution of the pollutants in the sediment. PAH have been described as priority pollutants, hence they could be used as a discriminant of the depth extent of polluted sediment. To map the spatial extent of polluted sediment using chemical analyses for PAH would be impractical in terms of time and cost. Analyses of samples from a core from the central basin of Hamilton Harbour indicate there is a close correlation between magnetic susceptibility and PAH content. Like previous studies of lake sediments and peat profiles, this correlation suggests that measuring magnetic susceptibility may be useful in providing a rapid and cheap proxy for mapping the distribution of contaminated sediment.

Methodology for bioassay-directed fractionation studies of air particulate material and other complex environmental matrices

A normal phase HPLC methodology using a semi-preparative polyaminocyano column in conjunction with a selection of short-term genotoxicity assays has been developed for bioassay-directed fractionation studies of complex environmental mixtures. To illustrate the effectiveness of this methodology, an organic extract prepared from respirable air particulate samples collected in Hamilton, Canada was separated into a non-polar aromatic fraction and a polar aromatic fraction using a combination of alumina and Sephadex LH20 chromatography. These fractions were evaluated for their genotoxic potential using the Salmonella/microsome (Ames) assay with six different strains of Salmonella. The non-polar aromatic fraction was analyzed by normal phase HPLC and the eluent was collected in one-minute subfractions ; these subfractions were bioassayed in three different Salmonella strains (YG1021 -S9. YG1024 -S9 and YG1029 +S9) to afford three different mutation profiles of this sample. Some subfractions which exhibited high mutagenic responses were subjected to further chemical analyses using GC/MS in order to identify those compounds responsible for the genotoxic responses. The nitroarene compounds 2-nitrofluoranthene, 1-nitropyrene and 2-nitropyrene and higher molecular weight polycyclic aromatic hydrocarbons such as benzo[a]pyrene and indeno[1,2,3-cd]pyrene were identified and quantified in some of the biologically active subfractions. The normal phase gradient conditions afforded very reproducible retention times for a series of polycyclic aromatic standards with a broad range of compound polarities. In addition, polycyclic aromatic hydrocarbons (PAH) were observed to elute from the normal phase HPLC column in a series of peaks ; successive peaks contained PAH of increasing molecular weight while any individual peak was shown to contain PAH of the same molecular weight.

A bioassay-directed investigation of Sydney Harbour sediment

Abstract A coal tar-contaminated sediment sample from Sydney Harbour, Nova Scotia, Canada was examined for genotoxicity using a bioassay-directed fractionation approach. An organic solvent soluble fraction, prepared from the marine sediment by ultrasonic extraction, was fractionated into compound classes using a sequential alumina and Sephadex LH20 clean-up procedure followed by high performance chromatographic techniques. The PAH-containing fractions were analyzed using gas chromatography-mass spectrometry (GC-MS) and reversed phase-high performance liquid chromatography (RP-HPLC). The composition of the fractionated material was also characterized using Salmonella typhimurium microbiological assays to identify fractions with mutagenic potency. The fraction containing the PAH was the major source of mutagenicity requiring microsomal activation. Compounds responsible for some of the mutagenic activity in the PAH-containing fraction, including benzo[a]pyrene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene, were identified through a combination of RP-HPLC followed by GC-MS of individual subfractions.

Thia-Arenes as Pollution Source Tracers in Urban Air Particulate

Abstract Respirable air particulate samples have been analyzed using gas chromatography/mass spectrometry (GC/MS) to determine the ratios of the amounts of monomethyl and dimethyl thia-arenes to the amounts of the parent thia-arenes. Standard Reference Materials 1649, 1650 and 1597 as well as local coal tar and coke oven emissions were also examined as source samples. These thia-arene profiles were used to distinguish diesel exhaust emissions from coke oven emissions in respirable air particulate collected in Hamilton, Ontario.