Cycling of mercury between water,air, and soil compartments of the environment

The propensity to resist chemical, photo-chemical or biological degradation processes, coupled with a high degree of mobility — due to favorable physical-chemical properties such as relatively high vapor pressure and low solubility in water - bestows upon some chemical substances the necessary pre-requisites for extensive cycling among environmental compartments. Certain inorganic and organometallic species of Hg exhibit the aforementioned characteristics. This paper presents field measurement data, collected in Canada and Sweden, that provide information concerning the direction and magnitude of the material fluxes associated with transfer processes of Hg in the natural environment. The results of the field measurements reported here point to the importance of the natural phenomena of emission or re-emission (i.e., volatilization processes) involving the release of volatile Hg species from lake and soil surfaces into the overlying air, at least under warm weather conditions. Consequently, volatilization fluxes of Hg from natural surfaces should be taken into account when constructing biogeochemical cycles for this element and when calculating mass balances or budgets for Hg on local, regional and global scales.