The Challenge and Its Solution When Determining Biogeochemically Reactive Inorganic Mercury (RHg): Getting the Analytical Method Right

Biogeochemially, reactive inorganic mercury (RHg) is an important fraction of Hg. Researchers have attempted to measure RHg when characterizing Hg-impacted sites, conducting research and development of remediation practices, or evaluating remediation efficiency. In these uses, RHg will be the best choice for analysis in ways that total methyl, and other species of Hg cannot duplicate. In this paper, the problems of using a Sn super( 2+) reduction method were discovered to be generating irreproducible and negatively biased results. Negative bias from 20% to 99% was found in different types of waters. To obtain reliable results, an ethylation-based GC-CVAFS method was used to determine RHg. The performance of the method was evaluated by comparing it to the Sn super( 2+) reduction method. Biogeochemically, meaningful results have been obtained in the application of the method to determine RHg in mercury mine-impacted waters from the Idrijca River in Slovenia.