Small-scale Gold Mining Operations Research Articles

Assessment of Mercury Contamination in Water and Soil from Informal Artisanal Gold Mining: Implications for Environmental and Human Health in Darmali Area, Sudan

Mercury contamination stemming from artisanal and small-scale gold mining (ASGM) operations poses significant environmental and health concerns. This study focuses on the Darmali area in River Nile State, Sudan, where the reprocessing of amalgamation tailings has led to mercury contamination. This study assessed the mercury content in soil and tailings samples, as well as in tap and groundwater, to evaluate the human health risks from ASGM activities and assess contamination levels within the study area. Soil and water samples were collected from various locations, including agricultural, residential, and tailings sites, as well as groundwater and tap water from the Nile. Mercury analysis was conducted using MA-3000 (NIC), and geo-accumulation index analysis revealed extreme pollution levels in areas with tailings and moderate pollution levels in agricultural and residential areas. Hazard quotients were applied to assess health risks, with inhalation of mercury vapor identified as the primary exposure route. The results indicated that tailings pose significant health risks, particularly for children, while water samples and soil from agricultural and residential areas did not pose significant risks. These findings underscore the urgent need for authorities and local communities to address mercury contamination by removing and treating tailings from affected areas to mitigate health risks.

Contentious environmental governance in polluted gold mining geographies: The case of La Toma, Colombia

Amid the expansion of the gold mining frontier in Latin America over the last three decades, competing property schemes and divergent visions over resource-rich territories have upscaled water and environmental conflicts. In the expansion of the gold mining frontier, mercury contamination from Artisanal and Small-Scale Gold Mining has called the attention of governments, international agencies and scholars across disciplines, who have ranked Colombia as the world’s highest per capita mercury polluter. Despite the efforts by diverse parties to reduce mercury emissions and reach long-standing comprehensive policies to tackle the harming consequences of pollution, there are still significant gaps in understanding the disputed environmental governance of gold mining geographies. By examining the case of La Toma in Colombia, this article highlights some lessons to be learned from transdisciplinary research on mining conflicts and mercury contamination over the last decade. We discuss pathways and schemes of state-led corporate dispossession, probe incomplete and selective governmental research and control of mercury contamination, and illustrate the on-going intracommunal challenges faced by traditional miners to ban mercury use in small-scale gold mining operations. We argue that mercury pollution is a political phenomenon that needs to be critically addressed from the entanglement of colonial trajectories of oppression and marginalization to ethnic communities, and the structural violence and environmental racism that capitalist extractivism wreaks in rural commodity frontiers.

Characterisation of Small-Scale Gold Mining Tailings in the Western Region of Ghana

On average, small-scale miners can recover gold ranging from 20% to 70% of the total available gold by the conventional gravity separation methods only. As a result of this, tailings materials from Artisanal Small-Scale Gold Mining (ASGM) operations contain a significant amount of gold, and characterisation of these materials would inform metallurgical decisions concerning reprocessing of the tailings from ASGM. In this study, size-by-size analysis, gold grade, gold deportment, and cyanidation studies were carried out on ASGM tailings samples collected from five different locations (Asankragua, Bogoso, Prestea, Wassa-Akropong, and Tarkwa) in the Western Region of Ghana. Head grades of tailings samples from Asankragua, Bogoso, Prestea, Wassa-Akropong, and Tarkwa were 1.84 g/t, 4.12 g/t, 0.45g /t, 0.17 g/t, and 5.97 g/t, respectively. The 80% (P80) of the tailings materials passed through 1.797, 0.578, 1.636, 3.210, 0.380 mm screen sizes for samples from Asankragua, Wassa-Akropong, Tarkwa, Prestea and Bogoso, respectively, with an average of 1.52 mm. Also, the gold deportment analysis revealed that the highest metal distribution of 42.03% in -106 µm size fraction for samples from Bogoso, followed by 31.0% for Wassa-Akropong, 29.7% for Tarkwa, 27.0% for Prestea, and 22.0% for Asankragua. It was shown after cyanidation test works that the highest gold recovery was 81.5%, 72.3%, 75.3%, 65.6%, and 38.5% for samples from Wassa-Akropong, Asankragwa, Prestea, Tarkwa, and Bogoso, respectively. Cyanidation can thus be employed to get higher gold recovery in ASGM.

Impacts of Illegal Small-Scale Mining (Galamsey) on Manse and Ankobra Rivers in the Prestea Huni-valley Municipality of Ghana

Water samples from four sampling sites (Ankobra upstream (AUS), Ankobra downstream (ADS), Manse upstream (MUS) and Manse downstream (MDS) along the profile of Ankobra and Manse rivers in PresteaHuni-Valley Municipality in the Western Region of Ghana were collected and analysed for a period of six months with the aim of assessing the effects of illegal small-scale mining (galamsey) on the water quality. Levels of physicochemical parameters such as Potential of Hydrogen ( pH), Temperature, Dissolved Oxygen (DO), Electrical Conductivity (EC), Turbidity, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), True Colour and heavy metals such as Iron (Fe), Lead (Pb), Copper (Cu), Arsenic (As), Cadmium (Cd) and Mercury (Hg) were determined. The levels of the parameters studied suggest that illegal small-scale gold mining operations have impacted negatively on the water quality of the Ankobra and Manse rivers looking at the high levels of true colour, turbidity, total suspended solids, iron and mercury which exceeded the WHO recommended guideline values, the clayey undrinkable water from the two rivers, the fishes and other aquatic creatures that have died and the pits that have been dug along the banks of the rivers which now serve as breeding places for mosquitoes.

Heavy Metals in the Soils of Placer Small-Scale Gold Mining Sites in Myanmar.

Background.Artisanal and small-scale mining activities are widely practiced globally. Concentrations of heavy metals associated with gold, such as copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) can increase in the environment as a result of mining activities, leading to environmental pollution and pose toxicity risks to humans and animals.Objectives.The aim of the present study was to investigate soil concentrations of toxic heavy metals in placer small-scale gold mining operations in Myanmar.Methods.Soil samples were collected from three placer small-scale gold mining sites: Site A located in the Hmawbon public protected forest, Site B and Site C, situated in the Nant-Kyin reserved forest around Nar Nant Htun village. At each site, soil samples were collected from four gold mining stages (ore processing, sluicing, panning, and amalgamation). Atomic absorption spectroscopy was utilized to examine the concentrations of As, Cd, Pb, and Hg.Results.The highest heavy metal concentrations were generally found in the amalgamation stages across all the gold mining sites. Across the three mining sites, the maximum heavy metal concentrations in the amalgamation stage were 22.170 mg.kg−1 for As, 3.070 mg.kg−1 for Cd, 77.440 mg.kg−1 for Hg, and 210.000 mg.kg−1 for Pb.Conclusions.The present study examined the concentrations of As, Cd, Hg and Pb in the soil of several small-scale gold mining sites in Banmauk Township, Myanmar. The results demonstrated the presence of high concentrations of heavy metals in the soil of the gold mining sites. Miners in this area work without proper personal protective equipment, and frequent exposure to heavy metals in the soil may cause adverse health effects. The present study provides baseline data for future risk assessment studies of heavy metal contamination in gold mines.Competing Interests.The authors declare no competing financial interests

Changes in surface water quality from small-scale gold mining operations in the Surinamean rainforest

Small-scale miners often engage in environmentally damaging activities, are subject to poor safety conditions, and utilize inefficient mineral extraction technologies. Here, we explore environmental impacts to surface waters from regional artisanal small-scale gold placer mining operations conducted in iron and aluminum-rich saprolites found within the lateritic, interior Amazon rainforest of Suriname. Heavy equipment was utilized to release gold from its host material followed by amalgamation and gravity separation. In contrast with background tributary recordings, streams adjacent to these gold mining operations consistently contained turbidity measurements that exceeded United States’ EPA guidelines for aquatic species of 50 nephelometric turbidity units and were typically in the hundreds to thousands of units. Turbidity was further heightened in association with precipitation events. Mercury played a prominent role in whole ore amalgam concentration practices. Freshwater fish from the region were found to harbor mercury that encroached upon public health criteria. Dissolved phase metals present further ecotoxicological challenges to the region, but their association with mining activities was less clear. These findings collectively reveal that small-scale placer gold mining practices in the Surinamese rainforest result in an increase of suspended sediments and release of mercury into waterways that could impact communities that depend upon local fisheries.

Solid-phase partitioning and release-retention mechanisms of copper, lead, zinc and arsenic in soils impacted by artisanal and small-scale gold mining (ASGM) activities

Artisanal and small-scale gold mining (ASGM) operations are major contributors to the Philippines’ annual gold (Au) output (at least 60%). Unfortunately, these ASGM activities lacked adequate tailings management strategies, so contamination of the environment is prevalent. In this study, soil contamination with copper (Cu), lead (Pb), zinc (Zn) and arsenic (As) due to ASGM activities in Nabunturan, Davao de Oro, Philippines was investigated. The results showed that ASGM-impacted soils had Cu, Pb, Zn and As up to 3.6, 83, 73 and 68 times higher than background levels, respectively and were classified as ‘extremely’ polluted (CD = 30–228; PLI = 5.5–34.8). Minerals typically found in porphyry copper-gold ores like pyrite, chalcopyrite, malachite, galena, sphalerite and goethite were identified by XRD and SEM-EDS analyses. Furthermore, sequential extraction results indicate substantial Cu (up to 90%), Pb (up to 50%), Zn (up to 65%) and As (up to 48%) partitioned with strongly adsorbed, weak acid soluble, reducible and oxidisable fractions, which are considered as ‘geochemically mobile’ phases in the environment. Although very high Pb and Zn were found in ASGM-impacted soils, they were relatively immobile under oxidising conditions around pH 8.5 because of their retention via adsorption to hydrous ferric oxides (HFOs), montmorillonite and kaolinite. In contrast, Cu and As release from the historic ASGM site samples exceeded the environmental limits for Class A and Class C effluents, which could be attributed to the removal of calcite and dolomite by weathering. The enhanced desorption of As at around pH 8.5 also likely contributed to its release from these soils.

Mercury concentration in hair collected from women in artisanal small-scale gold mining areas in Camarines Norte, Philippines

After the conclusion of the Minamata Convention on Mercury, the use of mercury (Hg) has been prohibited worldwide, except in some developing countries. The Republic of the Philippines is one of the 128 signatories of the Convention. There are many artisanal and small-scale gold mining (ASGM) operations in the Philippines that still use Hg to amalgamate gold. In order to know the direct effect of exposure to Hg on women’s hair, we performed the proton-induced X-ray emission analysis of Hg concentrations in the hair samples collected from women at risk of Hg contamination, in both ASGM and non-ASGM areas in Camarines Norte, Philippines. At the same time of the hair sampling, we also conducted interviews with the women about their lives. From the analysis results, we found that the range of Hg concentrations in the hair samples was at a safe level, with no significant difference between the ASGM and non-ASGM areas. An analysis of the effect of diet on Hg concentrations in the hair samples showed a tendency toward higher Hg concentrations in women who ate more fish. Our results through hair analysis did not show a direct effect of exposure to atmospheric Hg, but further survey of local people should be necessary to reduce the risk of Hg contamination in women even after the use of Hg in ASGM eventually comes to an end.

Mercury contamination of soil and water media from different illegal artisanal small-scale gold mining operations (galamsey)

Environmental media contamination with mercury, because of illegal artisanal small-scale gold mining (popularly called galamsey), is a major concern in Ghana; yet specific details as to how such contaminations are influenced or distributed across different galamsey operations have been lacking. We monitored mercury levels across nine different galamsey operations (Washing Board, Washing Plant, Anwona, Dig and Wash, Dredging, Underground Abandoned Shaft, Underground Sample Pit, Chamfi and Mill House) in three hotspot assemblies (Tarkwa Nsuaem, Amenfi East and Prestea Huni Valley) of the Western Region of Ghana. Triplicate samples each of background soil, surface water/drainage, slurry/sludge and galamsey waste materials (totaling 160) were obtained and analyzed using Atomic Absorption Spectrophotometer (AAS) to determine total Hg concentrations. From the comparison of mean ranked concentration of mercury, using the Kruskal-Wallis Test, it was realized that the observed differences in ranking was significant for all four environmental media considered. Thus, the poor handling, usage and disposal of mercury from the different galamsey activities did result in elevation of harmful quantities of mercury into the environment. Overall, the highest median value obtained for mercury was recorded at the Mill House galamsey sites and within slurry/sludge medium. This was followed by Chamfi, Washing Board, Washing Plant, Anwona, Dig and Wash and Dredging in descending order, with the Underground Abandoned Shaft and Underground Sample Pit galamsey types recording values below detection limit. In terms of their contribution to mercury contamination to the environment, Mill House, Chamfi, Anwona, Washing Board and Washing Plant galamsey types recorded the highest mean rankings. Overall, key priority information required for influencing reclamation and cleanup policy decisions for mercury, for the many affected wastelands across the country, can be derived from this paper.

Exposure to total and methylmercury among pregnant women in Suriname: sources and public health implications.

Previous research has found that women and children living in rural, interior communities in Suriname have high concentrations of mercury in hair. Freshwater fish from these areas also have high concentrations of mercury. Artisanal and small-scale gold mining operations in parts of the country use elemental mercury to extract gold from soils and sediments. Total mercury and methylmercury concentrations have been determined in hair and blood from pregnant women across the country. Pregnant women from interior communities have significantly higher concentrations of both total and methylmercury in hair (median total mercury in hair 3.64 μg/g) compared with pregnant women from two urban coastal cities, Paramaribo (0.63 μg/g) and Nickerie (0.74 μg/g). Total and methylmercury concentrations in blood and hair are highly correlated (r=0.986, r=0.974) with methylmercury making up 86% of the total in blood and 97% of the total in hair. Most women in the interior regions rely heavily on local fish as part of their regular diet, and many live outsides of areas with active ASGM operations. This study demonstrates that diet and fish consumption largely govern mercury exposures in pregnant women in Suriname.

Influence of illegal artisanal small-scale gold mining operations (galamsey) on oil and grease (O/G) concentrations in three hotspot assemblies of Western Region, Ghana

This study determined the contamination levels of oil and grease (O/G) across nine (9) galamsey operations under different environmental media (background soil, surface drainage, slurry/sludge and galamsey wastes) in three galamsey hotspot assemblies (Tarkwa Nsuaem, Amenfi East and Prestea Huni Valley) within the Western region of Ghana. Triplicate samples each of the four environmental media for the nine galamsey types (Washing Board, Washing Plant, Anwona, Dig and Wash, Dredging, Underground Abandoned Shaft, Underground Sample Pit, Chamfi and Mill House) were collected and analysed using n-hexane extractable materials in acidic medium by extraction and gravimetry to determine O/G concentrations. From the comparison of mean ranked concentration of O/G, using Kruskal-Wallis Test, the observed differences in the ranking was significant across all four media. The O/G concentrations for Anwona, Chamfi, Mill House, Washing Board and Washing Plant galamsey recorded exceedances when compared to the Ghana EPA Effluent Guideline Value of 100 mg/L for water and The New Dutch Lists’ Target and Intervention Value of 50 mg/kg and 500 mg/kg for solid/semi-solid materials. Consistently and for all environmental media types, the levels of O/G across the galamsey types were in the descending order of: Washing Board, Chamfi, Anwona, Mill House, Washing Plant, Underground Sample Pit, River Dredging, Dig and Wash, Underground Abandoned Shaft and Control Sample (non-galamseyed areas). In general, the surface drainage medium was predominantly found to be the most impacted upon medium from hydrocarbons by seven of the nine galamsey operations (Washing Board, Anwona, Chamfi, Mill House, Dredging, Dig and Wash and Underground Sample Pit). This was followed by slurry/sludge, background soil and waste media in that order. Expectedly, there were no exceedances for the Reference or Control Samples (non-galamseyed areas).

Effects of the government's ban in Ghana on women in artisanal and small-scale gold mining

Artisanal and small-scale gold mining operations have been conducted in Ghana for centuries. Over time, technological advances in the industry occurred and miners separated from large-scale mining and applied this knowledge to small-scale or individual mining practices. In March 2017, the government responded to a media campaign against environmental degradation and placed a ban against water pollution; this ban affected all informal gold mining operations because of the chronic use of mercury in gold extraction, which contributes to water contamination. The unintended consequences of this ban were that approximately 1 million people lost their jobs. A qualitative study was conducted to understand how small-scale gold mining affected female miners and in turn, the implications of the ban on these women and their families. There were 21 illegal female miners interviewed in Akwatia, Ghana. The results from this study confirmed that many female miners used their mining money to support their families. Because the ban blocked mining employment opportunities, the women were forced into unreliable and low-paying alternative jobs and were unable to pay for school fees and food. Unfortunately, while the ban may have improved the environment, it also contributed to adverse outcomes related to women and children's development, like inadequate nutritional needs and school dropout rates; thus, bans like this need to be reconsidered and readapted to address these immeasurable consequences.

The Political Ecology of Landscape Change, Malaria, and Cumulative Vulnerability in Central Ghana’s Gold Mining Country

Following the 2008 global financial crisis, small-scale gold mining operations proliferated worldwide. Along Ghana’s Offin River, the landscape has been radically transformed by mining, including disruptions to agriculture and surface hydrology, with adverse health outcomes. Yet, health research on small-scale mining tends to focus on miners’ mercury exposure. Further, studies on the relationships between disease and landscape change typically examine disease clustering and risk factor identification, rather than complex nature–society dynamics shaping infection and uneven vulnerability. Combining ethnographic, remote sensing, and quantitative methodological approaches, we detail how the socioecological outcomes of mining—from food insecurity and water-logged pits to profound anxiety and mercury contamination—combine to increase local malaria incidence. We argue that these changes interact with existing sociostructural conditions and Plasmodium falciparum’s unique biological capacities to render women and children most vulnerable to the disease. We suggest that mental health profoundly shapes malaria incidence and, countering individualized constructions of risk, family members’ health is deeply interconnected. This article contributes to current geographic debates in several ways. First, a cumulative vulnerability approach helps scholars conceptualize how biological, psychological, structural, and social conditions interrelate to shape humans’ conjunctural vulnerabilities along axes of difference, particularly in health contexts. We also highlight the importance of materiality in mediating vulnerability and malaria dynamics. Finally, we argue for more scholarly attention to familial relationships of care and mental health, heretofore unexplored topics in political ecologies of health.

A comparison of factors affecting the small-scale distribution of mercury from artisanal small-scale gold mining in a Zimbabwean stream system

Artisanal small-scale gold mining (ASGM) operations use mercury liberally in the gold extraction process and account for approximately one quarter of the anthropogenic mercury consumption worldwide. ASGM activities are concentrated in many impoverished and poorly regulated countries such as Zimbabwe, resulting in a number of negative impacts to health and the environment. To examine levels of mercury contamination in one such geographic locality, sediment and tailing samples were collected in a heavily mined watershed in southern Zimbabwe from May–June 2015. Samples were collected from multiple points within the stream system, as well as from around six stamp mills and a single industrial mine in the watershed. GPS point location data were taken for mining operations and sampling sites to examine the spatial patterns of mercury concentration. Data were first analyzed using linear regression and development of a MARS model, followed by application of an ANCOVA model to assess the relationship among mercury concentrations and percent organic material, distance downstream, and distance from potential contamination source. Mercury concentrations within the study area ranged from 6 to 1541 μg/kg dw (mean 142 μg/kg dw). Analyses of mercury concentrations indicated a positive relationship with percent organic material but a negative relationship with distance downstream and distance from potential contamination source. Results from this study help elucidate the relationship between gold production and the spatial scale of mercury contamination in aquatic ecosystems in Africa. These data may lead to a better understanding of the relationship between mercury use and community health, which may aid both the local and global communities in regulating mercury contamination of the environment.

Proof of concept for a passive sampler for monitoring of gaseous elemental mercury in artisanal gold mining

Mercury emissions from artisanal gold mining operations occurring in roughly 80 developing countries are a major workplace health hazard for millions of people as well as the largest contributor to global mercury pollution. There are no portable, cheap, and rapid methods able to inform workers or health practitioners of mercury exposure on site in remote locations. In this work, a proof of concept for a miniaturized mercury sampler, prepared by the direct reduction of gold into the porous nanostructures of Vycor glass (PVG), is introduced. Mercury retention on the PVG/Au sampler induces significant color changes, due to the formation of Au-Hg amalgam that affects the surface plasmon resonance characteristics of the material. The color change can potentially be quantified by the analysis of pictures obtained with a cell phone camera rapidly and onsite. Laboratory experiments showed the viability of using PVG/Au as passive sampler for monitoring of Hg°. PVG/Au samplers were then deployed in an artisanal and small-scale gold mining (ASGM) operations in Burkina Faso and it was able to indicate personal mercury exposures. The amount of mercury quantified in the samplers for all miners was higher than the current personal exposure limit set by the US Occupational Safety & Health Administration (OSHA).

Knowledge of and Adherence to the Cyanide Code Among Small-scale Gold Miners in Northern Tanzania.

Background.Tanzania has seen explosive development in small scale gold mining (SGM) operations. Recently, the use of cyanide has become more common in SGM, especially in the reprocessing of mercury-amalgamated tailings from artisanal mining sites.Objectives.The primary objective of this study was to examine the level of knowledge and adherence to the Cyanide Code among workers and managers at SGM operations in northwestern Tanzania that use cyanide for gold extraction, focusing on workers' safety.Methods.A cross-sectional study of workers and managers at 17 selected SGM sites was conducted. A random-cluster approach was used to recruit 215 mine workers and 23 mine managers who worked at the same sites for more than three months. Individuals participated in structured face-to-face interviews. Site evaluation checklists were also administered to assess adherence.Results.The majority of the SGM workers (61.4%, n=132) were not aware of the Cyanide Code. Among the mine managers, 64.2% (n=15) were aware of the Cyanide Code. Fifty-four percent of workers and 39.1% of managers did not adhere to the Cyanide Code. Workers who reported being trained on the Cyanide Code were significantly more likely to have knowledge about the Cyanide Code guidelines compared to untrained workers (adjusted odds ratio =20.3, confidence interval: 7.5 – 54.8).Discussion.Wide variations in knowledge of and adherence to the Cyanide Code were found. A manager's knowledge of Cyanide Code was significantly associated with workers' knowledge. High worker and manager knowledge was associated with increased site safety performance. Even though all the SGM sites were physically visited, some potentially hazardous practices may not have been revealed by managers and workers because of fear of possible regulatory actions due to disclosure of concerns related to their operation's safety compliance.Conclusions.The limited knowledge of the Cyanide Code among workers and managers, combined with poor adherence to cyanide waste management practices, indicates that there is a need for education, health promotion and sensitization among workers and managers to improve worker safety and minimize environmental health impacts.Participant Consent:ObtainedEthics Approval:Ethical approval was obtained from the Conjoint Catholic University of Health and Allied Sciences and Bugando Medical Centre Research Review and Ethics Committee (Ref. BREC/001/35/2014). Permission to conduct research in Geita District was obtained from the respective authorities at the regional and district levels and from owners of the SGM sites.

Green Gold—Dirty Gold, Tadó, Dept. Chocó, Colombia

In place of mercury, small-scale alluvial gold miners in Tadó, Dept. Chocó, Colombia produce “green gold” (oroverde) using locally available plant extracts. The leaves of Balso (Ochroma pyramidale) and Malva (Hibiscus furcellatus) are crushed by hand and are mixed with water to make a foamy liquid that is added to the gold pan (batea) instead of mercury. After the plant extract is added, the gold, magnetite, and other heavy minerals sink and the lighter minerals are floated out of the gold pan. For final clean-up, a combination of other methods may be used. However, ICP (Inductively Coupled Plasma) analyses indicate that even green gold contains 208 - 4530 ppm Hg—this mercury may have been released from dragas or other small-scale gold mining operations that continue to use mercury; coal burning; volcanism; or native mercury released from cinnabar occurrences. ICP also indicates 308 - 106,000 ppm Ag and 452 - 585 ppm Pt.

A review of mercury concentrations in freshwater fishes of Africa: patterns and predictors.

The methylated form of mercury (methylmercury) is a potent neurotoxic chemical and a contaminant of concern for fisheries because of its potential effects on ecosystem and human health. In Africa, inland fisheries are a crucial component of food and economic security, yet little information is available on mercury (Hg) contamination trends. The authors compiled published data on Hg contamination in African freshwater fishes, invertebrates, and plankton, as well as on potential drivers of Hg concentrations in these organisms. From 30 identified studies the authors assembled 407 total Hg concentrations from 166 fish species, 10 types of invertebrates, and various plankton, distributed across 31 water bodies in 12 countries. In fishes, total Hg concentrations, expressed as mean (± standard deviation) per location, averaged 156.0 ± 328.0 ng/g wet weight and ranged from 5.5 ng/g wet weight to 1865.0 ng/g wet weight. Only locations with nearby artisanal and small-scale gold mining operations had mean Hg concentrations above the World Health Organization/Food and Agriculture Organization's recommended guideline for fish (500 ng/g wet wt). The authors used mixed models to detect relationships between fish Hg concentrations and trophic level, mass, latitude, and chlorophyll a. Mass, trophic level, and latitude were all positive predictors of Hg concentration, confirming the presence of Hg bioaccumulation and biomagnification in African fishes. Although strong trends in Hg concentrations were evident, the present study also highlights limited availability of Hg data in Africa.

Pilot Assessment of Hazards and Health Effects in a Small-Scale Artisanal Gold Mining Community in Ghana

Background: Small-scale artisanal gold mining (SAGM) operations contribute a substantial fraction to the exports of some countries – for example, as much as 40% in the West African nation of Ghana....

A Lantern Retort for Small-Scale Gold Extraction

Two major retorts used in small-scale gold mining operations to reduce mercury emissions, during amalgam distillation are the steel and thermex retorts. Steel retorts are not very popular due to the reported darkening of gold after retorting. In addition, its opaque nature prevents miners from observing the process directly. The Thermex glass retort introduced by the United Nations Industrial Development Organisation (UNIDO) is also not patronised due to the extended heating periods resulting from the low thermal conductivity of glass. This paper describes a new retort, the Lantern retort, a combination of highly conductive steel with transparent glass, and therefore, a potential solution to the above concerns. The Lantern retort has a shorter warm-up and amalgam distillation time, and the rate of heating is 1.81oC/s while that of the Thermex is 1.49oC/s. For an amalgam of mass 20 g, 900 s was required to carry out complete distillation in the Lantern retort as against 2100 s in the Thermex. The height of the distillation column of the Lantern retort required to reduce mercury loss to below 1%, as it is with the Thermex retort, is 2.5 cm. Other advantages of the Lantern retort are that, it is less expensive and can withstand the harsh terrain of small-scale gold mining.