Assessing Global Mercury Cycling and Trends in the Context of the Minamata Convention

Abstract:

We draw upon recent modeling work to reassess the global biogeochemical cycle of mercury in the context of scientific and monitoring challenges in implementing the Minamata Convention. Mercury that cycles between the atmosphere and the land and ocean surface originates from anthropogenic activities (both present and historical) and from natural sources. The timescales of mercury cycling are poorly constrained, and better knowledge of these would allow us to understand trends and responses to policies. We synthesize information from a global suite of observations to provide improved constraints on the global (past and present) mercury cycle and trends. We project future mercury emissions under policy scenarios consistent with the Minamata Convention, and assess their impacts on atmospheric concentrations, deposition, and the global biogeochemical cycle. We examine the importance of uncertainties, and identify key uncertainties in measurements and our understanding of atmospheric chemistry, ecosystem processes and human responses that affect our ability to link emissions to impacts. Finally, we draw conclusions about the ability for currently-available measurements and networks to evaluate levels and trends, and draw lessons for policy implementation.