A review of gold production, mercury consumption, and emission in artisanal and small-scale gold mining (ASGM)

Artisanal and small-scale gold mining (ASGM) is one of the largest sources of Hg emissions and is critical for addressing the Hg problem. Due to scarce and punctual statistics provided by governments and agencies, there is almost no accurate data on ASGM production, Hg use, and emissions. In this study, we surveyed different approaches to estimate ASGM production and collected data from different sources, including academic papers and technical reports. Globally, 380–870 tonnes of gold is produced by ASGM each year, with a median value of 520 tonnes. The Hg use in the ASGM sector was estimated to be 640–1000 tonnes each year, with a median value of 892 tonnes. Consequently, 248–838 tonnes of Hg are emitted from the ASGM sector each year, with a median value of 615 tonnes. However, significant discrepancies were found in the data calculated using different approaches, particularly in countries where the estimates were large, such as China. To obtain a more accurate picture of global ASGM activities, a general estimation approach combining specific studies of dominant countries is necessary. For better management of ASGM in the future, developing a solid baseline and comprehensive future projection scenarios and establishing international collaboration to construct guidance on ASGM are recommended.