A method for the analysis of butyltin chlorides in air by gas chromatography with atomic emission detection.

An initial screening test compared the use of tropolone (2-hydroxy-2,4-6-cycloheptatrienone) in acetic acid with sodium diethyldithiocarbamate (NaDDC) as chelating agents for the extraction of butyltin chlorides from glass fiber filters and XAD-2 resin tube. NaDDC was chosen for subsequent analyses. Mono-, di-, and tributyltin chloride were spiked onto glass fiber filters and XAD-2 resin, extracted in toluene with NaDDC and derivatized with pentylmagnesium bromide. Derivatized butyltin species were determined by gas chromatography with plasma atomic emission detection. Glass fiber filters and XAD-2 resin were found to provide high retention of butyltin compounds during sampling and efficient recovery of butyltin compounds by extraction with NaDDC.

Toxicity of organomercury compounds: bioassay results as a basis for risk assessment.

A former mercury plant, where mercury salts and organomercurials for pesticide use were produced, caused soil contamination in high concentrations. Typical organomercurial products included ethylmercury, phenylmercury, methoxyethylmercury and ethoxyethylmercury compounds. Risk assessment of these sites must be carried out before any major clean-up processes can be planned. A sensitive speciation technique for the various organomercury species in environmental matrices is a prerequisite for toxicity investigations. In this connection, a high-performance liquid chromatography-atomic fluorescence spectrometry (HPLC-AFS) technique has been developed to differentiate between and determine the presence of eight organomercury compounds in environmental samples. Using this technique, methylmercury, ethylmercury and phenylmercury and some unknown organomercury species were found in soil samples collected from the sites of an old mercury products producing plant. With regard to risk assessment, it is necessary to assess the toxicity of the organomercurials. As different microbial metabolic pathways react differently to mercury and its compounds, batteries of bioassays are, therefore, useful to evaluate the toxicity of pollutants. To describe the toxicity and genotoxicity of MeHg+, MeOEtHg+, EtHg+, EtOEtHg+ and PhHg+, p-tolymercury chloride, nitromersol and Hg2+ six bioassays were used: resazurin reduction method, Spirillum volutans test, nematode toxicity assay Panagrellus redivivus, Toxi-Chromotest and SOS-Chromotest. A ranking of the toxicity of the organomercurial is shown. The SOS-Chromotest indicated genotoxicity for 5-7 organomercurials.

Determination of butyltin species in sewage and sludge by gas chromatography-atomic absorption spectrometry.

A method for the extraction and determination of butyltin compounds in sewage and sludge is reported. Sewage and sludge samples are acidified and shaken for 2 h. The various butyltin species are extracted quantitatively by tropolone (cycloheptatrienone) in toluene, followed by ethylation to their tetraalkyl-substituted forms, BuSnEt3, Bu2SnEt2, Bu3SnEt and Et4Sn, all of which can be separated and determined by a gas chromatographic-atomic absorption spectrometric technique. The non-pesticidal octyltin species and acid-leachable SnIV species can also be determined by this method. Detection limits expressed as Sn are 40 ng dm-3 and 2 ng g-1 dry mass for sewage and sludge, respectively. Analyses of some samples from Canadian treatment plants are given.

Occurrence of butyltin species in sewage and sludge in Canada.

Samples of sewage treatment influent, effluent and sludges collected monthly from five Canadian cities over the period from July 1990 to January 1991 were analysed for butyltin and octyltin species. Monobutyltin was found in all influent samples, but dibutyltin and tributyltin were found only infrequently, and octyltin species were not found at all. In the case of monobutyltin, there was significant reduction in its concentration by degradation and adsorption to sludge during passage through the sewage treatment plant. The average reduction was 40%. The monobutyltin found in the effluent likely came from its use as a poly (vinyl chloride) stabilizer, and from the degradation of tributyltin, which is used as a slimicide. No butyltin or octyltin species was found in five landfill leachate samples in southern Ontario during the same period.

Chemical alkylation of lead (II) salts to tetraalkyllead (IV) in aqueous solution.

Methylation of lead in the environment would have serious consequences for water quality and for the well being of aquatic biota. As there is strong evidence that tetraalkylleads, the end products of lead alkylation, are considerably more toxic than lead (II) compounds, the elevated levels of inorganic lead now present in inland waterways and sediments as a result of industrial and motor vehicle emissions will pose a serious environmental hazard if mechanisms exist for the conversion to alkyllead (IV) species in aquatic systems. In the belief that the key to biological Pb(II) methylation lies in methyl transfer to Pb(II) from a carbonium ion donor (for example, S-adenosylmethionine), we recently initiated chemical and biological studies on the reactions of CH3+ donors with neutral and anionic Pb(II) compounds. We describe here the unequivocal synthesis of volatile tetramethyllead and other tetraalkylleads from Pb(II) salts and simple chemical reagents in aqueous solution. The known occurrence of methyl iodide in natural waters and our demonstration that Me4Pb is readily synthesized from this reagent and Pb(II) salts in aqueous solution could have far reaching significance not only for the chemical synthesis of toxic organoleads but also for possible mechanisms of microbiological methylation.

Effect of tetramethyl lead on freshwater green algae.

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.

Ultrastructural examination of Aeromonas cultured in the presence of organic lead.

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.

Methylation of selenium in the aquatic environment.

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.

Localization of selenium in bacterial cells using TEM and energy dispersive X-Ray analysis.

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.

Determination of scandium in sea-water by atomic-absorption spectroscopy.

A method for the determination of scandium in sea-water at the sub-microgram level has been developed. Scandium is coprecipitated with iron(III) hydroxide at pH 8-9, and then separated from the iron by ion-exchange. The final concentration is achieved by extracting the scandium into a solution of oxine in butanol. A nitrous oxide-acetylene flame is used for the determination by atomic-absorption spectroscopy. Recoveries of 99-100% are obtained. The storage of the solutions before analysis has been investigated by radiometric techniques with (46)Sc. The scandium concentration in surface waters of the South China Sea was found to be 0.01 +/- 0.005 microg/l .