Mercury cycle in a typical Artisanal and Small-Scale Gold Mining process

Numbers represent key steps in the ASGM process: 1—excavation, 2—crushing and grinding, 3—sifting/shanking, 4—washing/sluicing, 5—amalgamation, and 6—burning. Letters represent key steps in the mercury cycle: A—residual mercury from amalgamation may be discarded in local soil and water; B—volatilization of elemental mercury into the atmosphere; C—oxidation of elemental mercury; D—deposition onto local terrestrial systems; E—deposition onto local aquatic systems; and F—methylation of inorganic mercury to methylmercury. (Source: Rajaee M, Obiri S, Green A, et al. Integrated assessment of artisanal and small-scale gold mining in Ghana-part 2: natural sciences review. Int J Environ Res Public Health 2015;12[8]:8971-9011. Creative Commons Attribution 4.0 International [CC BY 4.0] license, creativecommons.org/licenses/by/4.0.)