Occurrence of monoethylmercury in the Florida Everglades: Identification and verification

A few studies have reported the occurrence of monoethylmercury (CH3CH2Hg+) in the natural environment, but further verification is needed due to the lack of direct evidence and/or uncertainty in analytical procedures. Various analytical techniques were employed to verify the occurrence of CH3CH2Hg+ in soil of the Florida Everglades. The identity of CH3CH2Hg+ in Everglades soil was clarified, for the first time, by GC/MS. The employment of the recently developed aqueous phenylation-purge-and-trap-GC coupled with ICPMS confirmed that the detected CH3CH2Hg+ was not a misidentification of CH3SHg+. Stable isotope-tracer experiments further indicated that the detected CH3CH2Hg+ indeed originated from Everglades soil and was not an analytical artifact. All these evidence clearly confirmed the occurrence of CH3CH2Hg+ in Everglades soil, presumably as a consequence of ethylation occurring in this wetland. The prevalence of CH3CH2Hg+ in Everglades soil suggests that ethylation could play an important role in the biogeochemical cycling of Hg.