Deforestation as an Anthropogenic Driver of Mercury Pollution

Deforestation
reduces the capacity of the terrestrial biosphere
to take up toxic pollutant mercury (Hg) and enhances the release of
secondary Hg from soils. The consequences of deforestation for Hg
cycling are not currently considered by anthropogenic emission inventories
or specifically addressed under the global Minamata Convention on
Mercury. Using global Hg modeling constrained by field observations,
we estimate that net Hg fluxes to the atmosphere due to deforestation
are 217 Mg year–1 (95% confidence interval (CI):
134–1650 Mg year–1) for 2015, approximately
10% of global primary anthropogenic emissions. If deforestation of
the Amazon rainforest continues at business-as-usual rates, net Hg
emissions from the region will increase by 153 Mg year–1 by 2050 (CI: 97–418 Mg year–1), enhancing
the transport and subsequent deposition of Hg to aquatic ecosystems.
Substantial Hg emissions reductions are found for two potential cases
of land use policies: conservation of the Amazon rainforest (92 Mg
year–1, 95% CI: 59–234 Mg year–1) and global reforestation (98 Mg year–1, 95% CI:
64–449 Mg year–1). We conclude that deforestation-related
emissions should be incorporated as an anthropogenic source in Hg
inventories and that land use policy could be leveraged to address
global Hg pollution.