Mercury emissions from global biomass burning: spatial and temporal distribution

This chapter represents a new addition to the UNEP global mercury budget: the mercury emissions from biomass burning, here defined as emissions from wildfires and prescribed burns, and excluding contributions from bio-fuel consumption and charcoal production and use. The results cover the 1997-2006 timeframe. The average annual global mercury emission estimate from biomass burning for 1997-2006 is 675 ± 240 Mg/year. This accounts for 8% of all current anthropogenic and natural emissions. By season, the largest global emissions occur in August and September, the lowest during northern winters. The inter-annual variability is large and region-specific, and responds to dry seasons, i.e. to El Nino regimes. The largest Hg emissions are from tropical and boreal Asia, followed by Africa and South America. They do not coincide with the largest carbon biomass burning emissions, which originate from Africa. Frequently-burning grasslands in Africa and Australia, and agricultural waste burning globally, do not contribute significantly to the mercury budget.