The use of mercury for the mining of gold and other precious metals represents the largest anthropogenic source of mercury to the atmosphere. Much of these emissions originate from artisanal or small scale mining practices in developing regions of the world, including South America, Africa and Asia. In this research, we are investigating mercury contamination in sediments and soils stemming from current and historical mining activities in South American mining communities of Peru and Bolivia and the implications of this contamination for human health.
We are currently focused on the tropical Madre de Dios (MDD) region of Peru, a watershed in the lower Amazon Basin that is facing major emerging environmental and health threats due to rapid increases in artisanal gold mining, road development, and agricultural expansion. The region is the among the most economically disadvantaged in Latin America, though in the last few years it has seen much immigration as people are lured by the economic promise of participating in gold mining and processing, an illegal but rapidly growing sector of the economy. Artisanal mining has a potentially devastating impact on human and environmental welfare due to the use of mercury in the amalgamation of gold. To date, no research has delineated the extent of mercury contamination in the MDD watershed, nor the impact on fishing as an economic livelihood or on the overall health of indigenous and non-indigenous populations in the region. We aim to fill this gap by implementing three objectives: (1) measuring mercury accumulation in river sediment and fish; (2) evaluating the impact of human mercury exposure; and (3) developing sediment transport models to identify where conservation efforts can be focused.
In past work in the region, we also investigated mercury contamination within urban communities of the Andean mining region in South America. During the Spanish colonial period (from 16th to 19th centuries), mining towns such as Huancavelica (Peru) and Potosí (Bolivia) were the sites of the largest precious metals mines in the world. Mercury was mined in Peru and used extensively across the Andean region to extract silver and other metals from ore deposits. Mercury use continues today in artisanal (small-scale) mining practices. In our research, we studied historical mercury contamination in urban communities as a result of mining from centuries ago, a legacy that still persists today. This work involved review of archival maps and records from the colonial period, modeling of historical atmospheric mercury levels in area, and quantification of soil mercury levels and exposure to present-day residents of these communities.