Abstract: As a global pollutant, mercury (Hg) can be transported for a long distance in atmosphere. Methyl-mercury (MeHg), an extremely toxic organic form of Hg formed by the methylation from inorganic Hg in aquatic environment, can be bio-accumulated and biomagnified along food chains, potentially threatening human health. Isotopes can trace the behaviors of elements in the environment. Adding Hg isotope to the environment or using Hg isotopic labeling technique is a powerful tool for the studies of Hg biogeochemical behaviors, including the transportation and transformation of Hg in the environment. This paper reviewed the basic theory of Hg isotopic labeling technique, the applications of this technique in sample Hg species analysis, and the Hg transportation/transformation in soilplantatmosphere system and in aquatic ecosystem, and prospected the applications of Hg isotopic labeling technique in the studies of Hg environmental geochemistry.

Key words: black and odorous water body, VOSCs, Geosmin, formation mechanism, assessment methodology.