Discovery of a transalkylation mechanism - Identification of ethylmercury(+) at a tetraethyllead-contaminated site using sodiumtetrapropylborate, GC-AED and HPLC-AFS

Although organolead as a gasoline additive is banned in most countries, con tamination by organolead compounds is still present. Little is known about transformation reactions of organolead compounds and especially transalkyla tion reactions with other metals. Laboratory experiments to clarify transal kylation reactions between organolead and inorganic mercury, and investigat ions of sites, where organolead compounds were emitted, are reported. Under laboratory conditions, inorganic mercury is ethylated to ethylmercury(+) i n presence of tetraethyllead. These transalkylations take place very fast a nd almost completely. Tn soil samples from an industrial site contaminated with organolead compounds and inorganic mercury, EtHg+ was clearly identifi ed in high concentrations (up to 46 mg Hg/kg dw). Furthermore, methylmercur y(+) was found in concentrations up to 27 mg Hg/kg dw. It is the first time , that a transethylation of an organolead compound to an organomercurial co mpound in the environment is reported. It must be assumed, that this transa lkylation takes place at sites, where organolead compounds occur and Hg2+ i s available. Thus, it will be necessary to assess the risk of these sites.