Analytical Methods, Occurrence, Fate, and Toxicity of Ethylmercury in the Environment: Review and Outlook

Abstract

Studies on the environmental fate and risk of mercury (Hg) have been mostly focused on total mercury and a very toxic species methylmercury (MeHg). However, another organic Hg species, ethylmercury (EtHg), has long been neglected, partly due to the analytical limitations. The generally used aqueous ethylation for analyzing MeHg converts both Hg2+ and EtHg into diethylmercury, making it impossible to distinguish EtHg from Hg2+. Thanks to the emerging methods other than ethylation derivatization, EtHg has been identified in soils and sediments from a variety of sites, with a similar concentration to MeHg in some cases (e.g., the Florida Everglades). More importantly, results from recent studies also suggested that EtHg in the environment is derived not only from anthropogenic input (as bactericide, etc.), but also possibly from unknown natural formation pathways. Unfortunately, the environmental aspects, including formation, transport, transformation, bioaccumulation, and toxicity of EtHg, are still not well understood, limiting our understanding of this “new” organic Hg species. In this review, the current analytical methods focusing on gas/liquid chromatography coupled with atomic spectrometer for EtHg are summarized. Then, the occurrence of EtHg and its possible natural sources in the environment are discussed. Finally, the environmental transport, degradation, bioaccumulation, and toxicity of EtHg are discussed. It is expected that this review would provide comprehensive background and important clues to understand the natural occurrence and fate of EtHg.