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Cycle 6 (2017 Deadline)

Exploring the fate of mercury in artisanal gold mining of the Lake Victoria Gold Field

PI: Clavery Tungaraza,, Sokoine University of Agriculture
U.S. Partner: Mark Cohen, National Oceanic and Atmospheric Administration (NOAA)
Project Dates: December 2017 - June 2023

Project Overview:

6-263_Tungaraza processing site
A typical artisanal gold extraction site at one of PEER study area. Photo credit: Clavery Tungaraza, Sokoine University of Agriculture
This study will investigate quantitative and qualitative mercury availability in the environment surrounding artisanal and small-scale gold mining (ASGM) locations in Tanzania, where mercury contamination is of concern with regard to the health of community members and others who consume food products originating from the area. Although mercury contamination can be lessened by appropriate controls and proper handling methods, such measures are not routinely applied in Tanzania, where mercury has been documented in different environments and studies. Mercury can be transported away from emission sources by riverine systems to large water bodies like Lake Victoria. The resulting fish contamination can be significant, which is a particularly serious issue as fish are the major protein source in the region and the whole country. In Tanzania, very little data is available on levels of methylmercury in biota and sediments and on the contribution that ASGM activities make to these levels. Further, there is little information on the relative importance of riverine and atmospheric processes in transporting mercury from sources to ecosystems.

All these aspects must be taken into account in order to understand the magnitude of mercury impacts on the environment and on human beings. This project will develop data on levels of mercury downwind and downstream from ASGM activities in water, suspended particulate matter, sediments, and fish and improve understanding of spatiotemporal variations of mercury levels. Inclusion of methylmercury in the analysis represents a significant extension of the PI’s earlier work.

Tanzania is now in the process of ratifying the Minamata Convention, a key goal of which is to raise awareness of health concerns, especially in developing countries, resulting from mercury exposure of vulnerable populations, especially women and children. Mercury emissions from ASGM activities in Tanzania cause food chain contamination that poses direct threats to vulnerable populations under the Convention.

In preparation for ratifying the Minamata Convention, Tanzania needs to establish country-based information on the sources and extent of mercury contamination. The data and analysis generated in this project will help inform policies for protection of water quality and foodstuff safety, as well as provide scientific information to aid the formulation of the legal framework on mercury that will be needed for government regulations.

Summary of Recent Events

During the most recent reporting period (July – September 2022), major activities included water and sediment sample analyses, fish sample treatment for long-term storage, and manuscript preparation. These involved samples that were collected during April through June 2022. Both sediments and water samples were analyzed for total mercury (THg) concentration. The samples were also stored for future analysis of methyl mercury (MeHg) concentrations. Fish samples that were sampled during April and May 2022 were freeze-dried and stored for future THg and MeHg analyses.

During this period, one manuscript on THg levels in water bodies and areas under the influence of artisanal and small-scale gold mining (ASGM) activities in Tanzania was finalized and is ready for submission. Another manuscript explaining the possible long-lasting burden of mercury misuse by artisanal gold miners in Tanzania is at an advanced stage of preparation.

On the outreach side, the project has succeeded in establishing collaboration with other research groups. The project facilitated registration of the Sokoine University of Agriculture as a member of the Global Observation System for Mercury (GOS4M), an endeavor that was endorsed by the University Vice Chancellor. The project has also joined the Global Mercury Passive Network (Canada), which will be involved in atmospheric mercury sampling. During this reporting period, the project received two sets of passive samplers for air mercury sampling. In the first half of 2023, as the project approaches its extended end date of June 30, the team plans to finalize the analysis of fish samples for MeHg as soon as they receive the required supplies. The fish sample analyses will be preceded by customization of the methyl-mercury analytical methodology in Dr. Tungaraza's laboratory.

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