The Embassy Science Fellows Program (ESF), organized by the U.S. Department of State, extends expertise of U.S. federal scientists to partners abroad to assist with issues pertaining to science and technology. In early 2024, the U.S. Embassy in Accra, Ghana, solicited an Embassy Science Fellow to assess baseline mercury concentrations in waters and other matrices within Western Ghana in response to concerns of potential mercury releases related to illegal artisanal-scale gold mining (ASGM). With joint funding from the U.S. Department of State and the U.S. Geological Survey’s Ecosystem Mission Area, Environmental Health Program, Grace traveled to Ghana in October 2024 to connect with Ghanaian scientists and other stakeholders to facilitate collaboration and transfer of knowledge and conduct a mercury baseline assessment targeting pathways of human exposure in two key rivers in Western Ghana.

Mercury is a contaminant of global concern and potent neurotoxin that affects human and wildlife health predominantly through the consumption of fish with elevated mercury concentrations. Mercury is used in ASGM practices to extract gold using amalgamation. However, this mercury-gold amalgam is heated to remove the mercury, releasing the contaminant into the air where it can deposit into local aquatic and terrestrial environments (e.g., soil, trees, crops) or be transported worldwide. Once deposited, mercury can bioaccumulate rapidly in the food web leading to fish consumption concerns. 

Throughout two-week trip to Ghana, Grace met with local partners (academic, private industry, government) to explore potential areas of collaboration, learn about ongoing research efforts, and understand the context around ASGM in Ghana. Collaborative discussions were held with scientists from the Council for Scientific and Industrial Research-Water Research Institute (CSIR-WRI), the International Water Management Institute (IWMI), the Centre for Remote Sensing and Geographic Information (CERSGIS, University of Ghana), and the University of Mines and Technology (UMAT) in Tarkwa, Ghana. These meetings were constructive and informative, and many groups were interested in using the prospective mercury concentration data, developing an inter-laboratory comparison to evaluate method performance, and potential future collaborations. 

To assess mercury baselines in aquatic systems, samples were collected based on a One Health approach. One Health aims to sustainably balance and optimize the health of people, animals, and the ecosystems they reside. Samples were collected in targeted areas within Western Ghana, focusing on pathways of human exposure including waters (environmental surface water and community drinking water), fish, sediment, and important Ghanaian crops: cocoa and cassava. This fieldwork was completed in partnership with Hen Mpoano, a Ghanaian non-governmental organization with grass-roots connections to the local coastal communities. Samples were collected from two prominent rivers in Western Ghana, the Ankobra River and the Pra River, at 8 communities downstream from gold mining activity. Notably, although the sample collections represent a “snapshot” of mercury concentrations (i.e., one-time measurement of select matrices at a few sites), the targeted field campaign provides valuable baseline data that the Ghanaian government can use to inform future monitoring and management efforts.

While this work centers on regional mercury concerns in Ghana, ASGM is a major focus of global efforts to mitigate mercury releases to the environment as part of the Minamata Convention on Mercury. Mercury emissions from ASGM can have far-reaching impacts on mercury deposition due to long range transport of the contaminant, impacting protected lands and waterways on a global scale. Ultimately, this ESF experience provided a valuable opportunity to share expertise with international scientists, but to also understand factors governing mercury release to the environment.