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  • methylation  (2)
  • Industrial Chemistry and Chemical Engineering  (1)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 6 (1992), S. 587-595 
    ISSN: 0268-2605
    Keywords: methylmercury ; methyltin ; kinetics ; abiotic ; methylation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The usual presence of mercury(II) with monodi-, and tri-methyltin in water, sediments, and plants in estuarine environments suggests possible abiotic formation of methylmercury via methyl transfer from methyltin compounds. Kinetics studies of reactions between mercury(II) and methyltin compounds under pseudo-first-order conditions in seawater show that relative rate of methylmercury formation under the same conditions are: monomethyltin 〈trimethyltin〉 dimethyltin. This order is explainable mainly by the speciation and charge of methyltin compounds in seawater and by the existence of mercury(II) as a tetrachloro anion. A factorial experiment with the variables pH and salinity (seawater diluted with deionized water) showed that pH, but not salinity, is significant at the 95% confidence level; and that reaction rates increase as pH increases. These results suggest the possibility of abiotic methylation of mercury(II) in seawater. Additional experiments in seawater demonstrated an absence of methylation of mercury(II) (14 days) and mercury(0) (35 days) by methyl iodide.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 8 (1994), S. 351-359 
    ISSN: 0268-2605
    Keywords: Tin ; methylation ; Spartina alterniflora ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyltin compounds (MeSn) which do not originate from man-made pollution are common in estuaries and particularly in salt marshes containing the marsh grass Spartina alterniflora. This study reports the results of experiments in which estuarine water containing S. alterniflora leaves is spiked with inorganic tin, and estuarine water alone is spiked with inorganic tin and MeSn. When decaying leaves are present, inorganic tin concentrations in the water decrease and there is a 10-fold increase in inorganic tin concentration in the leaves. This biosorption follows pseudo-first-order kinetics. MeSn3+ and Me2Sn2+ occur occasionally in the water. The Me2Sn2+ concentration decreases with time and the Me3Sn2+ concentration increases with time in S. alterniflora leaves. The results of estuarine water amended with inorganic tin and MeSn in the absence of leaves are quite different. The overall inorganic tin concentration decreases significantly during the experiment, the MeSn3+ concentration is approximately constant, and concentrations of Me2Sn2+ and Me3Sn+ increase. This means that net methylation of inorganic tin has occurred. We conclude that decaying S. alterniflora is likely to be important in the cycling of tin in salt marshes.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 761-769 
    ISSN: 0268-2605
    Keywords: methylmercury ; dimethylmercury ; mercury speciation ; estuarine sediment ; sodium borohydride derivatization ; atomic fluorescence spectrometry ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper presents a method capable of quantitatively separating sub-nanogram amounts of monomethylmercury cation (MeHg+) and dimethylmercury from sediments by vacuum distillation at 40 °C and 6 μm Hg pressure followed by hydride derivatization and atomic fluorescence spectrometric detection. Concentrations of MeHg+ in Great Bay Estuarine sediments ranged from 2.2 to 7.3 ng g-1 (dry weight) with a 4.7 ng g-1 average for samples taken over nine weeks of the 1996 summer. The RSD for replicate determinations of a homogenized estuarine sediment is typically less than 6%. The detection limit for the routine determinations on MeHg+ is 0.2 ng g-1 dry weight of sediment. We validated the method by determining MeHg+ concentration in reference sediment S-19, by confirming our method against an established extraction method, and by recovering 85% of 10 ng MeHgCl spiked into estuarine sediments. This paper also includes significant improvements in the hydride derivatization method for mercury compounds relative to previous work with respect to faster analysis time and lower detection limits. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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