MERCURY CONTAMINATION IN FOUR INDONESIAN WATERSHEDS AFFECTED BY ARTISANAL AND SMALL SCALE GOLD MINING

Artisanal and small scale gold mining (ASGM) accounts for almost half of anthropogenic mercury (Hg) emissions worldwide and causes widespread water pollution. Gold extraction by Hg amalgamation releases Hg-laden sediment and water into local watersheds where anaerobic organisms convert inorganic Hg into toxic organic methylmercury (MeHg). In Indonesia, several studies have identified harmful levels of Hg in fish, sediment, soil, crops, and human hair affected by ASGM; however, to our knowledge no study examines downstream transportation of total Hg and MeHg concentrations. We evaluated Hg contamination in four Central Java gold mining areas by collecting water samples along river transects. Preliminary results show elevated total Hg concentrations downstream of ASGM sites, with concentrations exceeding 250 ng/L. Adjacent to tailings sites, concentrations exceed 2500 ng/L. In future work, we will sample the same locations during the wet season to compare concentrations during high flows. This study provides important information to local government agencies in Indonesia seeking to improve water quality in their communities.