Artisanal Gold Mining Research Articles

Assessment of human health risks through the consumption of mercury contaminated fish from gold and platinum mining areas

ABSTRACTMining activities can pollute freshwater systems with toxic contaminants that can damage the environment and cause risks to human health. In South Africa, mercury is a contaminant of major concern due to it being released into the environment through artisanal gold mining and the coal combustion process at power stations. Mercury accumulates in the liver and more importantly the muscle tissue of fish. Mercury can then be transferred to humans through the consumption of contaminated fish and can affect the nervous system and cause permanent damage. Although South Africa is a major contributor to global mercury emissions, there are very few papers published on mercury concentrations and the risks to human health associated with consuming contaminated fish. This study aimed to determine the mercury concentrations in environmental matrices (water, sediment and two fish species (Cyprinus carpio and Clarias gariepinus)) from five sites and determine the risks to human health associated with the consumption of these fish. The mercury concentrations in muscle and liver tissues of C. carpio (1.2 and 0.8 mg/kg) and C. gariepinus (1.6 and 0.9 mg/kg) from Boskop Dam were the highest across all sites. Clarias gariepinus had higher mercury concentrations and a higher risk to human health compared to C. carpio across all sites. Both species from Boskop Dam and the Vaal River, while C. gariepinus from Olifantsnek and Modder Dam all had a hazard quotient of > 1 which shows these fish had a high possibility for adverse health effects to humans.

Assessing the impact of artisanal gold mining on the environmental sustainability of groundwater resource for water security in southwestern Ghana

The increase in illegal gold mining (galamsey) activities that harm the environment by polluting water sources necessitates the need to take meaningful steps towards protecting the environment.The Jacobu water system in the Amansie Central district was selected as a case study. The purpose of the work is to assess the environmental sustainability of groundwater resource and whether surface water pollution has seeped into the water table to pollute groundwater resource. Methodologically, the study employed groundwater sustainability assessment framework, involving both linear and non-linear sustainability index functions, as well as analytical hierarchy process (AHP). Four groundwater sustainability aspects of quantity, quality, ecosystem and management were assessed. Also, thirteen groundwater sustainability indicators were created for the study. Using the linear sustainability index function, the environmental sustainability index was 0.845, which indicates an excellent level. For the assessment to properly reflect the reality in the study area, the combined linear and non-linear sustainability index function revealed a good level, 0.765, showing an environmentally good overview of Jacobu groundwater resource. This, therefore, suggests the need to ensure continuous protection of groundwater resource. Generally, the study area has not yet experience hydromorphic dispersion of polluted surface water into groundwater resources. For a sustainable groundwater in the future, strict control measures by enforcing environmental laws and regulations to prevent possible pollution of groundwater resource due to ‘‘galamsey’’ activities is critical to protect the invisible resource. This can be done through community engagement, and innovative approaches to monitoring and controlling illegal mining activities. This is to help sustain future generation's security of the ‘invisible’ groundwater resource in Ghana and contributes to Goal 6 (Ensuring Access to Clean Water and Sanitation) of the Sustainable Development Goals set by the United Nations.

Informal gold miners with mercury toxicity: Novel asymmetrical neurological presentations

Mercury is a highly toxic heavy metal that may cause neurological, respiratory, gastrointestinal and dermatological illnesses. Previously described neurological manifestations of mercury toxicity are symmetrical, and include a pancerebellar syndrome, generalised seizures and encephalopathy. Mercury is used in the gold mining process, and in artisanal or illicit gold mining, often without necessary protection. Here we describe the cases of two artisanal gold miners from western Johannesburg, South Africa, who presented with atypical neurological manifestations of mercury toxicity. Patient 1 presented with focal seizures, an asymmetrical cerebellar syndrome and an acute encephalopathy. Patient 2 had unilateral cerebellar ataxia. Both patients had toxic mercury levels, with no other cause identified for their symptoms. Patient 1 responded well to chelation therapy, but patient 2 refused admission and further medical treatment. The neurological manifestations of mercury toxicity are typically symmetrical, whereas our two patients presented with markedly asymmetrical features. It is important to maintain a high index of suspicion for mercury poisoning, even in patients with atypical and unilateral or asymmetrical presentations. A prompt diagnosis and the commencement of early chelation therapy have the potential to produce good outcomes.

Social determinants of health among people working on informal gold mines in French Guiana: a multicentre cross-sectional survey

IntroductionSocial determinants of health, such as living and working conditions, economical and environmental context and access to care, combine to impact the health of individuals and communities. In French Guiana...

Pollution of Surface Water Close to an Artisanal Gold Mining Area: the Case of Macalder Mine, Kenya

Pollution of Surface Water Close to an Artisanal Gold Mining Area: the Case of Macalder Mine, Kenya

LIPTAKOR, a participatory approach for increasing risk awareness and facilitating operational changes at artisanal gold mines

The literature highlights the importance of engaging local communities when attempting to raise awareness of environmental and human health-related risks at artisanal gold mines. There are, however, few reliable and tested methodologies available to achieve this or which can be adapted for use in a number of contexts. To help bridge this gap, we developed a tangible tool that takes the form of a game, which provides a space for participatory exploration of risk perceptions associated with artisanal gold mining. We present the results of this study, which was conducted in 2021 in the Nigerien Liptako–Gourma Region, and compare them to findings shared in the literature on risk perceptions related to artisanal gold mining.

Identification of Gold Mining Vessels based on Classification Algorithms using Sentinel-2 Images

Artisanal and small-scale gold mining can occur on land or in riverbeds. However, the activity needs to be supported by a Mining Permit, issued by the Agência Nacional de Mineração, and the appropriate environmental license from the competent environmental agency. The use of images from Sentinel-2 satellites presents itself as a potential tool for identifying gold mining vessels due to the temporal resolution, free imagery, global coverage, and more refined spatial resolution. So, this study aimed to identify gold mining vessels on the Madeira River near Porto Velho city, Rondônia state, located at Brazilian Amazon, in 13 Sentinel-2 images from 2018 to 2021 using the classifiers: Support Vector Machine (SVM), K-Nearest Neighbors (KNN) Random Forest (RF) and Spectral Angle Mapper (SAM). The results showed that machine learning classifiers obtained the best performance, especially the object-oriented SVM classifier, which had the best average F1 score (0.91). In addition, the detection percentage of gold mining vessels originated by this classifier was satisfactory, with only 0 to 4 active gold mining vessels with sediment plumes being omitted per image. Therefore, based on the results obtained, it was concluded that the use of machine learning classifiers proved to be effective in identifying gold mining vessels.

Survival, Reproduction, and Life History Traits Evaluation of Heterocephalobellus sp. and Cephalobus sp. from an Artisanal and Small-scale Gold Mine Site, Davao de Oro, Philippines as Bioindicators of Heavy Metal Contamination

Survival, Reproduction, and Life History Traits Evaluation of Heterocephalobellus sp. and Cephalobus sp. from an Artisanal and Small-scale Gold Mine Site, Davao de Oro, Philippines as Bioindicators of Heavy Metal Contamination

Education and equipment distribution lead to increased mercury knowledge and retort use in artisanal and small-scale gold mining communities in Senegal

Artisanal and small-scale gold mining is an important livelihood, but also the largest contributor to anthropogenic mercury emissions globally. Two key persistent challenges in reducing mercury use in artisanal and small-scale gold mining communities are effective educational interventions and accessibility to improved technologies. This study evaluates the efficacy of education and equipment distribution interventions to reduce mercury use in artisanal gold mining in Senegalese mining communities. We analyzed the effects of education and retort (mercury-capture devices) distribution through pre- and post-intervention surveys in nine Senegalese mining communities, divided into control, education-only, and education + retort distribution. Educational sessions were conducted in local languages using simple graphics by trusted community members. Retorts were constructed by local metalworkers using locally available materials. The combination of education and retort distribution increased knowledge about the efficacy of retorts and dangers of mercury (94% post-intervention). The combination also increased retort use, from 3% to 64% post-intervention. Retort use in the other two groups also marginally increased. The increased knowledge and retort use observed in control villages suggests a potential social overflow effect of the intervention, extending beyond the locations in which they occurred. Our results indicate that the graphics-based and community-oriented educational approach accompanied by increased access to retorts provides a strong foundation for reducing mercury emissions and exposure to artisanal and small-scale gold mining communities.

Mercury and CO2 emissions from artisanal gold mining in Brazilian Amazon rainforest

AbstractThe Tapajós River basin in Brazil is one of the world’s regions most affected by artisanal gold mining (ASGM), which is responsible for the release of mercury and high energy consumption. Mercury, mixed with gold-containing materials and then released through heating to extract the gold, can be recovered using a simple distillation device called a retort. Use of these tools has now become standard. In a comprehensive study, we investigated the use of mercury and energy at 47 mining sites in the Tapajós River basin. These included numerous mines that were operated informally or in some cases even illegally and are therefore not accessible to outsiders. Our survey shows that 1.7 kg of mercury are used per kg of gold extracted, of which only about 0.19 kg of mercury is released into the environment when retorts are used. Overall, this means an annual release of at least ≈2.5 tonnes of mercury in the region, even when retorts are used. We also find that ASGM contributes to climate change through energy consumption responsible for the release of about 16,000 kg of CO2 equivalent per kilogram of gold. This means that even artisanal gold mining, which uses retorts, has a major environmental impact.

Does the use of cocoa farmlands for artisanal small-scale gold mining really increase household food insecurity? Evidence from Ghana

In recent years, the use of cocoa farmlands for artisanal small-scale gold mining (ASGM) in mineral rich countries in sub-Saharan Africa has been on ascendency. Previous studies have examined the environmental, health and livelihood implications of the land use decision. Notably, studies on the indirect effects of the food security implications of the nexus between ASGM and agriculture abounds but limited attention has been given to the direct effect of using farmlands for ASGM on household food security. Using a primary cross-sectional data on 400 cocoa farmers in the Amansie West District of Ghana and an endogenous switching regression model, this study analyzes the impact of using cocoa farmlands for ASGM on household-specific food security indicators. The study finds that farmers who use their farmlands for ASGM; 1) increase their household food insecurity, 2) increase their household dietary diversity, but in the short-run due to income effect, 3) increase their inability to use effective coping mechanisms to fight household food insecurity. Policy efforts geared toward the use of farmlands for ASGM to address food insecurity among smallholder farmers in mineral-rich countries in sub-Saharan Africa should focus on: 1) reducing liquidity constraints of smallholder cocoa farmers, 2) promoting stakeholder-driven productivity enhancing interventions, and 3) creating attractive policy environments for the youth to enter into farming.

Mercury presence in cassava farming, Manihot esculenta Crantz, in the vicinity of artisanal gold exploration areas in Southern Amazonia

Cassava, Manihot esculenta Crantz (Euphorbiaceae), a native plant to Brazil, is one of the main sources of carbohydrate in the diet of Brazilians. In gold-mining regions, such as the south of the Amazon, it is inevitable that crops will come closer to Artisanal and Small-scale Gold Mines (ASGM), creating risks of production contamination by mercury (Hg). Due to the importance of cassava in the population’s diet, the present study aimed to evaluate the effect of the proximity of ASGM on Hg concentrations in soil and cassava samples and to assess the risk of human exposure to Hg through consumption of this food. Samples were collected in two areas along the BR-163 highway, in the State of Mato Grosso, Brazil. Forty-two samples of cassava (roots, stems and leaves) and soil were collected. It seems there is no effect of ASGM on Hg soil concentrations. The highest concentrations of Hg in the leaves were observed in the area close to ASGM, indicating higher atmospheric deposition. In the mining area, the higher bioconcentration factor indicates the outcome of Hg from the atmosphere also on the concentrations in the roots. Daily intake and health risk quotient estimation were performed for cassava and cassava flour, with the highest values observed in the vicinity of ASGM, however, all below the established limits, indicating that, currently, the consumption of these foods by the population is safe. The cassava crop can be used as a bioindicator of atmospheric pollution by Hg caused by ASGM.

Groundwater characterization including prediction of the quality, fluoride, and nitrate occurrence in a typical artisanal mining area in Ghana: A hydrochemical and multivariate statistical approach

Groundwater quality has been compromised by both geogenic and anthropogenic activities. Also, the negative impact of the intake of groundwater with high fluoride and nitrate content has been well established. Artisanal gold mining operations within the Tinga-Maluwe areas go beyond a decade with no knowledge of the level of impact these activities have on the groundwater quality. Hence, this study aims to characterize the groundwater with emphasis on the quality for usage as well as the controls of fluoride and nitrate occurrence in the area using hydrochemistry and multivariate linear regression modeling techniques. This is to enhance groundwater monitoring and stakeholder decision-making processes in the catchment. The concentration order of the cations is Ca2+ > Na+ > Mg2+ > K+ and that of the anions is HCO3− > NO3− > Cl− > SO42− > CO32− > F− with a Na – Cl dominant water type. Apart from F−, NO3−, and TDS exceeding their acceptable limits in Tinga, the overall pollution, water quality, and percentage of pollution indices show that the groundwater is slightly to heavily polluted in Daklupe, Seripe, Tinga, Kablima, Maluwe, Sakpa, and Bekwa-kura communities. Mineral dissolution, especially carbonate minerals, is the dominant process controlling groundwater mineralization from the discriminant diagrams used, and the saturation indices. However, anthropogenic activities impact on the groundwater cannot be precluded from the MLRMs of OPI, WQI, and PPI. The MLRMs show that pH, SO42−, Na+, K+, Ca2+, and Mg2+ are the controls of F− occurrence while that of NO3− is by TDS and pH.

Investigation of Gold Recovery and Mercury Losses in Whole Ore Amalgamation: Artisanal Gold Mining in Nambija, Ecuador

Mercury is a highly toxic pollutant that can negatively affect human health and the environment; informal mining is one of the main sources of anthropogenic mercury release due to the separation or concentration by amalgamation that is still used to recover gold directly from ore. In the Nambija mining district, there is still informal mining based on practically no technical knowledge, which uses amalgamation as a processing technique for gold recovery. The production tasks that directly affect the handling of mercury during the in situ grinding–amalgamation process are monitored here. Experimental grinding tests were initially carried out in a “chancha” bar mill for a range of ore sizes and as a function of time; then, experimental tests were performed at the macro-level on grinding cycles in Chilean mills. Considering the characteristics of the ore mineral and the operation of the Chilean mills, it was determined that it is possible to reduce the Hg input to mill by up to 20% (at source). Experimental grinding–amalgamation tests were carried out at different times along with a grain size analysis of the ore; the recovery establishes the grinding time and the fraction in which the gold is extracted in a greater proportion, which affects the control of the amalgamation times. The mercury dosage used by the miners in the amalgamation process should be reduced, considering trials where there is better gold recovery and with the purpose of also reducing mercury losses; eventually, it is possible to jointly achieve an increase in gold recovery.

Mercury Levels in Groundwater near Artisanal Small-Scale Gold Mines in Migori County, Kenya

In Migori County, artisanal and small-scale gold mining (ASGM) is an economic activity that uses mercury during the amalgamation process to obtain gold. The waste generated in the form of soil tailings and pan-pond water contains mercury and is located close to community boreholes. The proximity may predispose groundwater to mercury contamination. Boreholes are one of the main water sources in Migori County. Ingestion is one of the ways mercury can get into the human body. This study was conducted to establish mercury concentration in groundwater from boreholes, soil tailings and pan-pond water located near five mine sites in Migori County during dry and wet seasons in comparison with drinking water standards required by KEBS and NEMA effluents discharge standards. The five mines were: -Masara, Osiri Matanda, Macalder, Kitere and Kehancha. The study used a cross-sectional-analytical study design and focused on boreholes found within a distance of 6 km from each of the five mines. Fifteen boreholes were proportionately sampled to obtain groundwater samples. 20 pan-pond water and soil tailing samples were collected in both dry and wet seasons as per the respective sampling protocols applied. Inductively Coupled Plasma –Mass Spectroscopy (7900 ICP-MS) was used to measure mercury levels. A paired t-test was used to compare the means of the levels of mercury in groundwater obtained within the two seasons. The study established that during the dry season, all of the boreholes had groundwater mercury levels higher than the recommended limit by KEBS of 0.001 mg/L. There was a decrease in the levels of mercury in groundwater as distances from the mine increased. However, during the wet season, all of the boreholes had mercury levels below the limit of detection. The study established a significant difference in the levels of mercury in groundwater between wet and dry seasons at a 95% confidence level. Mercury levels in soil tailings and pan-pond water were above the NEMA effluents discharge standards of 0.05 mg/kg and 0.05 mg/L, respectively, in the dry season. During the wet season, all pan-pond water achieved the recommended mercury level of NEMA effluent discharge limits, while the soil tailings had mercury levels above the recommended limit. This study recommends that there is a need to implement mine waste remediation. Communities near the mines continuously conduct groundwater heavy metal analysis during the dry season to protect their health

Air Quality Indices Assessment in Artisanal Gold Mining Areas of Zamfara State, Nigeria

Mining processes contribute significantly to air pollution which has been identified as the largest cause of human deaths worldwide. This research was therefore conducted to assess air pollution of three gold mining areas: Kwali, Maraba, Duke and a non–mining area: Kadauri in Zamfara State, Nigeria. Monthly measurements of CO, SO2 and NO2 wasdone using Gasman detection instrument (Crowcon–EExias IIC T5), particulates were determined using optical counter, buffered KI solution was used to measure O3 while temperature, humidity and pressure were measured using their respective meters over a period of one year. Air quality indices were calculated using the USEPA (1999) AQI formula, pollutants and meteorological factors relationships were determined using Pearson’s correlation and seasonal variation was measured using T–test. Highest and lowest CO were 25.85±7.42 µg/m3 in Kwali and 12.08±3.32 µg/m3 in Kadauri respectively, SO2 was also highest (48.15±12.42 µg/m3) and lowest (31.74±6.67 µg/m3) in Kwali and Kadauri respectively. O3 was highest (151.29±29.74 ppb) and lowest (107.38±21.95 ppb), while PM10 was highest (498.37±48.49 µg/m3) and lowest (319.31±44.86 µg/m3) in Duke and Kadauri respectively. Air quality parameters generally exceeded the WHO limit while CO, SO2, and PM2.5 had significant difference (P<0.05) across sampling stations. Mining areas had hazardous AQI with Duke being the highest (392) and Kadauri had 248 implying very unhealthy atmosphere. Pollutants correlated negatively with humidity and positively with pressure, temperature inversely correlated with NO2, SO2 and PM2.5 while pollutants’ dry season concentrations were significantly higher. Information and regulation of mining activities is suggested as well as the use of PPEs.

Elemental composition and speciation trends in Upper Mazowe River, a typical sub-tropical river ecosystem impacted by gold mining and agriculture in Zimbabwe

This study was carried on Upper Mazowe River in Zimbabwe which connects with Luenha River in Mozambique, which is a tributary of the Zambezi River. Zambezi River is the fourth longest river in Africa flowing into the Indian Ocean, which makes the study of regional and global interest. Heavy metal aqueous speciation has received relatively little attention compared to sediment speciation in the Upper Mazowe River, and yet heavy metal behaviour and fate in surface waters are greatly affected by the heavy metal chemical form in solution. The aim of the study was to determine the elemental composition and speciation of heavy metal(oid)s. This study focused on water and sediment speciation of Al, As, Cu, Hg, Mn, Fe, and Pb using Visual MINTEQ Version 3.1 computer modelling and sequential extraction techniques. Twenty-eight different water column elemental species, comprising 3, 2, 3, 1, 7, 7 and 5 species each, and 35 sediment phase elemental species, comprising 6, 6, 6, 2, 6, 5, and 4 species each for Al, As, Cu, Hg, Mn, Fe, and Pb respectively, were identified. Of note is the fact that Hg, mainly derived from artisanal gold mining activities, exists entirely as the fulvic acid complex, FA2Hg (aq), and As exists as H3AsO3 and H2AsO3− in the water phase. Exchange equilibrium reactions across the water-sediment interface were observed for Mn2+, Fe2+, Cu2+, and Pb2+. Reactions leading to the formation of the species were identified. Species interactions within the water column and sediment phase and species interrelationships with physicochemical parameters are discussed. H3AsO3 formation is predicted to be temperature sensitive and the aluminium hydroxide-fulvic acid complex /FA2(AlOH) (aq) is oxic favourable.

An analysis of the foremost issues with artisanal and small-scale gold mining from Ghana's perspective.

Ghana has abundant mineral reserves in many of its regions, and gold mining remains one of the country's main sources of revenue. Given Ghana's current position in the global gold market, this review provides insight into the ASGM sector to give an understanding of the pertinent issues in the sector and its role in the socio-economic development of the country. This review assesses the effects of ASGM operations in economic, social, health, and environmental contexts to raise awareness of issues related to ASGM. It evaluates the measures taken to lessen the consequences of ASGM and maintain the sector's long-term viability. This review considers the foremost issues, including continued Hg use in ASGM, recent use of cyanide in ASGM, pollution of water bodies, and toxic metal contamination. It takes into account sustainable measures and remedial techniques that Ghana has implemented to alleviate the negative effects and support best mining practices. The primary factors influencing people to participate in ASGM are the need for quick sources of income, the scarcity of jobs in rural areas, the economic hardship, the need to supplement earnings from other activities like trading, and the comparatively meager profits from agricultural activities. Findings indicated that to gain more traction in addressing the challenges in the ASGM sector, the involvement of the community and direct stakeholders is essential to promoting responsible mining and environmentally sustainable practices. This review will increase awareness and pressure on decision-makers, researchers, and ASGM communities about the relevance of environmental conservation and sustainability.

Environmental Geochemical Analysis in the Yanomami Indigenous Land, Mucajaí River Basin, State of Roraima, Brazil.

The Yanomami Indigenous Land in the Amazon has a long history of illegal artisanal gold mining, leading to concerns about mercury (Hg) contamination. This study has conducted a geochemical analysis to assess Hg contamination from these mining activities. Geological materials, including river water and stream sediments, were collected from 14 predetermined points based on the Geological Survey of Brazil's methodology. The results revealed that water samples did not show Hg contamination above the limits set by the National Council of the Environment (Conama) Resolution 357. However, two stream sediment samples, particularly PJS009 and PJS010 collected from the Mucajaí River, exceeded the Conama Resolution 454's limit of 0.17 mg/kg. A Hg content of 0.344 mg/kg was found in the sediment sample PJS009, the one collected further upstream in the Mucajaí River, and 1.386 mg/kg was found in sample PJS010, also in the Mucajaí River in the region shortly before the Fumaça Waterfall, indicating that the sediments of the Mucajaí River may be contaminated with Hg from the Fumaça Waterfall upstream.

Evaluation of biosorbents as an alternative for mercury cyanide removal from aqueous solution

Worldwide, artisanal gold miners currently use and lose over 2000 t/year of mercury, which causes massive social and environmental problems. The combined use of mercury and cyanide by artisanal processing centers have exacerbated the bioavailability of the pollutant. Biosorbents have the capability to adsorb mercuric species in solution, and due their low cost and extensive availability close to mines, they can be used to detoxify effluents. In this study, four biosorbents were evaluated for mercury cyanide removal from simulated gold mining effluents: banana peel, passion fruit peel, eggshells, and chicken feathers. For each treatment, the adsorption capacity, equilibrium isotherms, and kinetic modeling were studied. Only banana peel showed favorable adsorption of Hg(CN)2, with a 94 % removal percentage within 90 min. The pseudo-first order model resulted in the same adsorption capacity as the experimental data (0.47 mg/g). The Sips isotherm model fitted the experimental data, indicating that the adsorption was monolayer-based. Banana peel was found to be more selective for mercury than for gold cyanide. Conversely, the excess of free cyanide had a negative effect on the adsorption efficiency.