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Publications (12)101.19 Total impact

  • Y K Chau, P. T. S. Wong, G A Bengert, J L Dunn
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    ABSTRACT: A tissue solubilizer is used to dissolve biological samples without altering the chemical forms of the alkyllead species. The various alkyllead species and lead(II) are isolated quantitatively by chelation extraction with sodium diethyldithlocarbamate, followed by n-butylation to their corresponding tetraalkyl forms, R/sub n/PbBu/sub (4-n)/, and BuâPb, respectively (R = Me, Et), all of which can be determined by a GC/AAS (gas chromatography/atomic absorption spectrometry) method. The method determines simultaneously the following species in one sample: tetraalkyllead (MeâPb, MeâEtPb, MeâEtâPb, MeEtâPb, EtâPb); ionic alkyllead (MeâPb/sup 2 +/, EtâPb/sup 2 +/, MeâPb/sup +/, EtâPb/sup +/); Pb/sup 2 +/. Analyses of sediment, fish, and aquatic weeds are given. Detection limits expressed for Pb are 7.5 ng/g and 15 ng/g, respectively, for biological and sediment samples.
    Analytical Chemistry 03/1984; 56(2):271-4. · 5.83 Impact Factor
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    ABSTRACT: Fish, marine vegetation, bottom sediment, and water samples taken from various lakes and rivers in Ontario, Canada, were analyzed for the presence of tetraalkyllead compounds. Experimental materials and methods are described. Of all 107 fish samples analyzed, 17 samples contained tetraalkyllead compounds. There were no detectable amounts of tetraalkyllead in water, vegetation, or sediment, although in some cases hexane extractable lead was present. Results indicate that: there is no relationship between species and size of fish and tetraalkyllead concentration; tetraalkyllead is found in fish from various lakes and rivers in Ontario; the type of tetraalkyllead varied in different locations; and the concentration of tetraalkyllead is generally low, representing less than 10% of the total lead. (10 references, 1 table)
    Bulletin of Environmental Contamination and Toxicology 03/1980; 24(2):265-9. · 1.22 Impact Factor
  • Analytical Chemistry 03/1979; 51(2):186-8. · 5.83 Impact Factor
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    ABSTRACT: Crystals (30--100 micrometer) of selected naturally occurring apatite (Ca10 (PO4)6(OH, F)2) samples were added to P-free (less than 0.001 microgram/ml total P) Bristol's medium (1-1000 microgram/ml of apatite) as the sole source of ortho-PO43-. The media were inoculated with washed, non-axenic cells of three chlorophycean algal species cultivated under PO43--deficient conditions. Phase-contrast and scanning electron microscopy revealed that at low slurry densities (1-10 microgram/ml of apatite), Ankistrodesmus braunii (ATCC 2744) cells were morphologically distorted. At concentrations of 100 and 1000 microgram/ml of apatite, more than 85% of the cells had undergone autospore formation within 7--10 days of incubation at 20 degrees C. Most autospores formed failed to germinate under high nutrient conditions. Scenedesmus longus (No. 1236) formed colonies when cultivated in Bristol's medium but daughter cells displayed a Chodatella-like unicellular morphology when grown in apatite media. Test algal species (Chlamydomonas dysosmos, S. longus, A. braunii) showed a marked preference for growth on apatite crystals over non-nutritive surfaces. Unialgal and mixed-algal cultures produced an extensive matrix of extracellular fibrous material in response to growth on crystals at concentrations greater than 10 microgram/ml of apatite.
    Canadian Journal of Microbiology 10/1977; 23(9):1188-96. · 1.18 Impact Factor
  • B A Silverberg, P. T. S. Wong, Y K Chau
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    ABSTRACT: The toxicity of tetramethyl lead (Me4Pb) towards freshwater algae was studied by bubbling biologically generated Me4Pb from one flask containing 5 mg of Pb 1-1 as Me3PbOAc into the culture medium in another flask where a test alga Scenedesmus quadricauda was grown. As Me4Pb is not soluble in water and is volatile, the exposure of an alga to this lead compound was only momentary. It was estimated that less than 0.5 mg of Pb(Me4Pb) had passed through the culture medium. The primary productivity and cell growth (determined by dry weight), however, decreased by 85% and 32% respectively, as compared with the controls without exposure to Me4Pb. Furthermore, cells exposed to Me4Pb tended to clump together and striking alterations in cell fine-structure were observed. An electron microscopic analysis by an energy dispersive spectrometer revealed that Pb ions had penetrated the cell and were deposited within concretion bodies. Similar results were obtained with the green algae Ankistrodesmus falcatus and Chlorella pyrenoidosa.
    Archives of Environmental Contamination and Toxicology 02/1977; 5(3):305-13. · 1.96 Impact Factor
  • Source
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    ABSTRACT: Aeromonas sp. will methylate trimethyl lead acetate (Me3PbOAc) to volatile tetramethyl lead (Me4Pb). Examination of cultures grown in the presence of Me3PbOAc revealed no major irregularities between cells of the treated and untreated cultures. Some cells, however, showed evidence that intracytoplasmic materials had been leached from the cells. The lead-treated cells were interpreted to contain lead ions on the basis of energy-dispersive X-ray analysis.
    Applied and Environmental Microbiology 12/1976; 32(5):723-5. · 3.95 Impact Factor
  • Y K Chau, P.T.S. Wong, P D Goulden
    Analytica Chimica Acta 10/1976; 85(2):421-4. · 4.52 Impact Factor
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    ABSTRACT: Conversion of inorganic and organic selenium compounds to volatile selenium compounds (dimethyl selenide, dimethyl disetenide, and an unknown compound) by microorganisms in lake sediment has been observed. This conversion could also be effected by pure cultures of bacteria and fungi. Such transformations are significant in the transportation and cycling of elements in the environment.
    Science 07/1976; 192(4244):1130-1. · 31.48 Impact Factor
  • Y K Chau, P T Wong, H Saitoh
    Journal of chromatographic science 04/1976; 14(3):162-4. · 1.03 Impact Factor
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    ABSTRACT: Bacteria isolated from lake sediment samples reduced sodium selenite to elemental selenium. Finestructural observations were made on a number of different bacterial species cultured in the presence of sodium selenite. Examination of Escherichia coli and a Pseudomonas species revealed electron-dense deposits of irregular shape, composed of smaller units, within the cytoplasm but not on the cell wall and cell membrane. Cells of Aeromonas and Flavobacterium species exhibited conspicuous intranuclear fibrillary aggregates and different electron-dense inclusions. It appeared that the membrane structures were somewhat more easily stained in some bacterial cells after growth on agar plates containing sodium selenite. The deposits and fibrillary accumulations were interpreted to contain selenium on the basis of energy dispersive X-ray analysis. Control preparations and cells grown in the presence of sodium selenate were void of any fine-structural abnormalities. Alterations in fine structure are discussed in relation to the metabolism of selenium by bacterial cells and possible sites of inhibition.
    Archives of Microbiology 03/1976; 107(1):1-6. · 1.86 Impact Factor
    Abstract) Proc. 19th. Ann. Meet. Can. Fed. Biol. Soc., 19_. 01/1976; 87.
  • P. T. S. Wong, Y K Chau, P L Luxon
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    ABSTRACT: LEAD is one of the most toxic metals found in the environment and is of great concern because of its widespread occurrence in nature, but its fate is largely unknown1. Much of the lead dispersed by man is eventually washed into natural waters and is presumably precipitated into the sediments2. The methylation of mercury and arsenic by microorganisms in the environment has been documented and well summarised3. Nothing, however, has been known about the existence of organic forms of lead in the environment as a result of biotransformation4.
    Nature 02/1975; 253(5489):263-4. · 42.35 Impact Factor