Artisanal and small-scale gold miners in developing nations often utilize large amounts of elemental mercury to separate gold from gangue minerals, and then heat the resulting amalgam to isolate the gold. As the price of gold has increased over the last ten years, so have ASGM activities. As a result, ASGM has recently been recognized by the United Nations as being the largest source of mercury emissions to the air and water combined. For example, in El Oro province, Ecuador over 100 gold processing plants and an unknown number of legal and illegal gold shops emit mercury vapor directly into the urban environment. A Lumex RA-915M portable mercury analyzer and a Mercury Instruments VM-3000 CV-AAS were coupled with GPS to map the cities of Portovelo and Zaruma in El Oro province for air mercury contamination. This technology allowed researchers to provide accurate maps to the local community, and locate gold shops in the region. These gold shops are located next to restaurants, children’s bookstores and schools. The concentration of Hg on the street outside these goldshops can exceed 1,000,000 ng/m3, and while monitoring a goldshop over an 8 hr workday, it was determined that the average concentration of mercury in the gold shop during this time period exceeded 200,000 ng/m3, with spikes of greater than 2,000,000 ng/m3 during burning. The Agency for Toxic Substances and Disease Registry (ASTDR) minimal risk level (MRL) for elemental mercury is 200 ng/m3.

Monitoring metal contamination from artisanal and small-scale gold mining (ASGM) communities in Ecuador Part I: Mercury emissions to air

249th National Meeting (2015)

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