ICMGP - Conference Presentation

Abstract Information :

Mercury emissions from ASGM are probably set to definitively surpass those from coal combustion in the coming years. This is in part due to the declining use of coal in power production, and in part to the steady or increasing price of gold which makes ASGM an attractive source of income where there is a lack of alternative employment. A caveat should be added here, as instability in gas and oil supplies could prompt a return to coal, in the short term, as nations seek to ensure their energy security. Unfortunately the economic inducement to operate illegal or informal mines is such that despite potentially fatal working conditions, long-term repercussions on human health, and grave consequences for the local ecosystems, ASGM continues.
The proportion of atmospheric emissions of Hg which are deposited locally or which join the global atmospheric pool and are subject to long distance transport depends on a number of factors, one of which is location. Most ASGM occurs in the tropics and subtropics, where there is often an abundance of vegetation, and in many areas, frequent convective precipitation events. Both of these characteristics represent significant deposition pathways, and render the fate of mercury emissions from ASGM generally very different from that of the more intensively studied and monitored emissions from coal combustion for power generation in northern mid-latitudes. This study presents a simplified chemical transport model to examine the fate of Hg emissions from ASGM, and determine their relative local and long-range impact.