Heileen Hsu-Kim

Primary Theme: Energy & Environment

In 2013, Bass Connections helped launch one of the largest and most comprehensive studies of mercury exposure due to artisanal and small-scale gold mining (ASGM) anywhere on the planet, in Madre de Dios, Peru. ASGM is the largest source of global mercury (Hg) pollution and the leading cause of deforestation in the Peruvian Amazon. ASGM emits large amounts of Hg directly into atmospheric, terrestrial and aquatic ecosystems via burning of mercury-gold amalgams and disposal of mercury-laden tailings. Hg is a potent neurotoxin that impacts human and wildlife health. When Hg enters aquatic systems, it is transported downstream, and the concentration of Hg near mining and downstream should be higher than in upstream areas. However, Duke research in Madre de Dios suggests that average hair Hg concentrations (a standard biomarker of total Hg exposure) in communities more than 150 km upstream of ASGM are 115% that of mining communities and 145% that of downstream communities. These high concentrations upstream of ASGM are also apparent in top predators, as one study has shown elevated mercury concentrations in giant otters (a protected species) within Manu National Park in Peru. There are several viable hypotheses that could explain why human and wildlife mercury levels are high in a region that is otherwise physically, socially and economically disconnected from ASGM. These include fish migration, atmospheric deposition and land use/land cover change. Deforestation patterns due to ASGM, oil exploration and agricultural expansion may underlie many of these hypotheses, and, if true, forest conservation near ASGM could be crucial to protecting human and wildlife populations from high mercury concentrations and the resultant toxic impacts. Unfortunately, little is known about the influence of forest cover on mercury cycling.