Methylmercury Generation in Seawater by Transmethylation Reactions of Organolead and Organotin Compounds With Inorganic Mercury as Monitored by Multinuclear Magnetic-Resonance and Electrochemical Techniques

Abstract

The generation of methylmercury species by reactions between inorganic mercury and methylated forms of lead and tin in seawater and other matrices is described. The reactions were investigated by 119Sn, 199Hg and 207Pb multinuclear Fourier transform magnetic resonance spectroscopy and by differential pulse polarography and anodic stripping voltammetry. Methylmercury chloride is shown to be produced from mixtures of inorganic mercury with methyltin or methyllead species over the 10-2-10-8 M concentration range at ambient temperatures in seawater and artificial seawater.

Formation of Artifact Methylmercury during Extraction from a Sediment Reference Material

“…Carboxylic acids, including acetic and other acids that have a methyl group in the α position, also have been implicated as potential methyl donors for MMHg formation . Trimethyllead and methylated compounds of tin(IV) can methylate Hg 2+ to MMHg in seawater, , and these compounds also would have been soluble in our acid leachates. If transmethylation is the source of artifact MMHg, then future work might include examining alternative methyl acceptors that can be added to samples before extraction to minimize methylation of ambient inorganic Hg.…”

Geochemistry of mercury in an intertidal flat of the Scheldt estuary

“…It is thus very difficult to make a distinction between biomethylation (a reaction occurring in the cell through the interception of Hg in an active enzyme system) and abiotic methylation (where Hg reacts with a product of the destroyed enzymatic system to form methylmercury). Besides this reaction with methylcobalamine, Hg can also be methylated by reactions with humic and fulvic complexes (CRAIG and MORETON, 1985;NAGASE et aL, 1982;1984) as well as by transalkylation reactions with alkyllead and alkyltin compounds (BELLAMA et aL, 1988;HOWELL et aL, 1986). These reactions should not be neglected in the sediments of the Groot Buitenschoor due to the high humic matter contents (autoclavation also increases the solubilisation of humic matter) as well as the high heavy metal load.…”

Stand und Trends der Quecksilberspurenanalytik

“…Die Nachweisgrenze betragt 1 ng Quecksilber bei eiiiem linearen MeBbereich bis 100 ng und einem nichtlinearen MeBbereich bis 500 ng. Diese Methode IliBt sich durch Kopplung init einem ReduktionsgefliR auch erfolgreich fur wiiBrige Proben und Proben rnit hohem Anteil organischer Losungsmittel, die bei der AAS storen, einsetzen [146]. Pntterson [138] verwendet einen photoakustischen Quecksilberdetektor und nutzt ebenhlls die Kaltdampftechiiik.…”

“…Xine sehr erfolgreiche Analysentechnik ist die Kopplung der Gaschromatographie niit der niIassenspektrometrie (GC/MS). Die Bedeutung dieser Methode liegt in der besseren Identifizierungsmoglichkeit der einzelnen queeksilberorgaiiischen Verbindungen Schwedt und Lippmnnn publizierten eineii dunnschichtchromatographischen Schnelltest auf toxische Metalle (u. a. Hg) [146]. Metallionen aus Wasserproben werden dunnschichtchromatograpliisch als Diethyldithiodicarbaminate getrentit,.…”