Abstract: Earth surface natural mercury (Hg) emission includes the Hg emission from natural sources and the re-emission from previously deposited Hg. It was demonstrated that the total amount of natural Hg emission from earth surface could be far larger than that of the direct emission from human activities. It is of great importance to quantify the natural Hg emission, not only for the evaluation of the effects of reducing anthropogenic Hg emission on the global environment, but also for providing guidance on the policy-making in global Hg-reduction strategy. Due to the lack of reliable methodologies in quantifying the Hg emission from natural sources, we still don’t have a clear understanding about the processes and mechanisms of Hg exchange between earth surface and atmosphere as well as the effects of atmospheric Hg deposition on the processes of earth surface natural Hg emission, and thereby, we are hard to accurately quantify the Hg emission from natural sources. However, with the development of new technologies, we have the feasibility to study the processes, mechanisms, and fluxes of Hg emission from natural sources. To quantify the Hg emission from natural sources would be one of the research frontiers about the biogeochemical cycling of Hg in the environment.

Key words: Chlorophyll a, Phaeopigments, Sediment