|Abstract Title:||Mercury in the Southern Hemisphere Biota: More Diversity than Trends|
|Presenter Name:||Jean Guimaraes|
|Session:||Special Session - Mercury in the Southern Hemisphere|
|Co-Authors:||Jean Guimaraes, Maria Dieguez, Larissa Schneider, Anne Helene Fostier, Jenny Fisher, Saul Guerrero|
Abstract Information :
The Southern Hemisphere (SH) has many distinctive features, such as high bio and geo diversity, poor infrastructure, high prevalence of poverty and of ASGM, abundance of large hydroelectric reservoirs, among others. Research on mercury in the SH has been irregular in space and time, but has highlighted some points. Among these, is the discovery of high mercury levels in piscivore fish in the Amazon basin, a consequence of long food chains that, in combination with a high fish intake, result in human exposure to mercury that is among the highest in the world, but has no clear relation with ASGM activity. Not far from the Amazon, in the Southern Patagonian Andes, freshwaters show moderate to high inorganic mercury levels due to enhanced deposition of Hg in catchments from natural processes related with volcanism and forest fires. Although Hg availability is high due to extremely low dissolved organic matter in natural waters, total Hg and MeHg reach moderate levels in fish, benthic feeders being the most affected. In the African continent, despite the presence of many active ASGM fields, mercury in fish and hence in humans is notably low, leading to the coining of the expression. ?low-Hg African paradox?. In Australia, mercury emissions and atmospheric deposition are low, which in combination with shorter food chains contribute to the moderate mercury levels recorded in the aquatic biota.