Search Results (227)

Artisanal and small-scale mining (ASM) is expanding across West Africa, driving deforestation, water contamination, and land degradation that require scalable monitoring approaches. Deep learning (DL) models applied to Sentinel imagery have shown acceptable performance for ASM mapping within individual countries, but their ability to transfer across national boundaries remains poorly understood. This study evaluates four DL segmentation models for ASM mapping in Ghana and Côte d’Ivoire, two major gold-producing countries with contrasting mining landscapes. The models were trained under three geographic scenarios of Ghana only, Côte d’Ivoire only, and both countries combined, using the SmallMinesDS benchmark dataset for Ghana and a newly compiled dataset for Côte d’Ivoire, both combining Sentinel-1 SAR and Sentinel-2 optical imagery. Models performed best when trained and tested on the same country, with U-Net++ (EfficientNet-B3) reaching IoU = 0.748 (F1 = 0.856) on Ghana. On the harder Côte d’Ivoire domain, models trained on Ghana alone transferred poorly (IoU = 0.488, F1 = 0.656), but training on both countries together gave the best result (IoU = 0.568, F1 = 0.724). Overall, the geography of the training data, rather than the model architecture or the use of SAR data, was the main factor driving performance, though some differences may also reflect the datasets being collected at different times. Full article

Despite decades of intervention efforts, mercury amalgamation remains widespread in artisanal gold mining (AGM), yet no prior study has presented an integrated metallurgical balance quantifying gold (Au), silver (Ag), and mercury (Hg) simultaneously across both the amalgamation and cyanidation stages of a single processing circuit. This study addresses this gap by evaluating an artisanal amalgamation–cyanidation operation in Pernambuco, Brazil, through systematic sampling, fire assay and ICP-OES analyses, grain size distribution, and SEM-EDS mineralogical characterization. The whole-ore amalgamation (WOA) stage recovered 44.7% ± 11.7% of Au and 11.5% ± 15.4% of Ag from a feed grading 2.96 ± 1.53 ppm Au and 8.09 ± 1.65 ppm Ag. Subsequent vat cyanidation of the Hg-contaminated tailings recovered 75.8% ± 4.32% of the remaining Au and 32.9% ± 9.24% of Ag, raising overall recoveries to 86.6% ± 2.89% for Au and 40.6% ± 4.58% for Ag. Although both stages contribute meaningfully to gold recovery, under the operating conditions evaluated, cyanidation contributed more substantially to overall Au recovery than whole-ore amalgamation. SEM-EDS identified free amalgamated electrum particles in the tailings, attributed to excessive pulp density (≈43% solids) impairing particle settling on the amalgamation plates. These inefficiencies led to estimated mercury losses of 262 g/day, yielding a Hg_(lost):Au+Ag_(produced) ratio of 5.5. Based on this diagnostic evidence, replacing whole-ore amalgamation with optimized comminution followed by gravity concentration is identified as a technically promising mercury-free pathway requiring pilot-scale validation. Full article

Gold’s price reflects currency, opportunity-cost, and safe-haven channels whose strength shifts across regimes, motivating an empirical, data-driven forecasting approach. This study develops a monthly gold price forecasting system for ASM sales-timing decisions in Peru (January 2020–June 2026) using macro-financial predictors including a geopolitical risk index and three U.S. monetary indicators, none of which were Granger-causal and were therefore excluded from the production set. After confirming non-stationarity and Johansen cointegration (four vectors), thirty-two model-feature-set combinations, including Elastic Net, Bayesian Ridge, and a PCA factor, were compared under strict temporal validation with bounded hyperparameter search. The selected model, Ridge regression on the CONTROL feature set, achieved a cross-validation MAPE of 2.29% and test MAPE of 3.62% (official)/3.15% (extended sensitivity window). It was benchmarked against random walk, historical mean, and exponential smoothing and evaluated via the Diebold–Mariano, Clark–West, encompassing, and Model Confidence Set tests (low-power caveats given the small sample). A dual-horizon Monte Carlo simulation, robust to heavy-tailed shocks, projected USD 4482/oz (December 2026) and USD 5106/oz (December 2027). A sales-timing backtest showed a statistically significant result (−0.67%) versus a passive strategy, indicating calibrated price information alone does not yet yield a reliable trading edge, supporting the model’s role as decision support rather than an autonomous trading signal. Full article

Background: The global nutrition crisis continues to disproportionately affect vulnerable populations’ health in regions where artisanal mining is high. Objective: This study assessed the nutritional status of children, adolescents, and women living in the Revuè sub-basin, who are potentially exposed to heavy metal contaminants. Methods: An observational and cross-sectional design was used to combine anthropometric and sociodemographic data with laboratory analysis for the assessment of heavy metal contaminants in drinking water sources. Results: Results indicated a high prevalence of stunting among children under five (28.4% of boys and 19.9% of girls) while female adolescents were underweight (25.7%), particularly during the rainy season. In contrast, 19% of women were overweight and 3.1% were obese. A modified Poisson regression analysis revealed a significant negative association between mercury exposure (RR = 0.77, p = 0.02) and stunting in children, whereas higher educational attainment among husbands was protective for women (RR = 0.76, p = 0.03). The assessment of mercury exposure through water consumption showed statistically significant variations across regions and seasons (p < 0.001). Water analyses identified high concentrations of arsenic (0.03 mg/L, 95% CI: 0.02–0.10) and mercury (0.09 mg/L (95% CI: 0.003–0.009), exceeding safety standards. Conclusion: Overall, these findings highlight the nutritional and health risks potentially linked to artisanal mining. Full article

This study examines the role of microfinance institutions (MFIs) in promoting environmental sustainability in Zimbabwe’s artisanal gold mining (AGM) sector, a context characterised by significant ecological degradation and weak regulatory enforcement. While previous studies have focused on MFIs’ role in financial inclusion, their potential to promote environmental sustainability in the informal AGM sector remains underexplored in sub-Saharan Africa. Using an interpretivist qualitative case study design, the study draws on in-depth interviews with MFI personnel operating in AGM regions. The findings of this study suggest that MFIs have the potential to influence environmental sustainability through mechanisms such as conditional lending, financial incentives, and environmental awareness programs within AGM sectors in which they operate. The effectiveness of MFIs in advancing environmental sustainability, however, is constrained by weak regulatory frameworks, limited resources, and the sector’s informal nature. The study contributes to the emerging literature on green microfinance by providing context-specific insights into how financial institutions function as intermediaries of environmental governance. Practically, the findings highlight the need for policy frameworks that integrate environmental considerations into microfinance operations and strengthen institutional coordination among stakeholders. Full article

African soils face increasing levels of metal pollution due to industrialization, artisanal mining activities, improper waste management, and enhanced agricultural productivity. However, unlike many organic pollutants, heavy metals do not degrade naturally and therefore persist in environmental systems for prolonged periods. Heavy metals accumulate over many decades in the soil and bioaccumulate through the food chain causing severe health complications such as cancer, kidney problems, and neurological impairment. This paper reviews the current literature on the origin, prevalence, and behavior of the main pollutants Pb, Cd, Cr, As, Hg, and Cu. The major phytoremediation methods including phytoextraction, rhizofiltration, phytostabilization, and phytovolatilization are highlighted alongside in planta screening methods for hyperaccumulating plants including Berkheya coddii (Ni) and Haumaniastrum robertii (Co). The paper evaluates various enhancement techniques such as the use of chelators, Rhizobium inoculations, and genetic modifications. The significance of these approaches in tropical and subtropical climates is discussed. The paper suggests a holistic framework involving empirical kinetic modeling, geospatial machine learning (random forest, kriging), and molecular omics in prediction modeling. Major hurdles in such predictions include lack of field-based verification of the models, biotechnology safety of genetically modified (GM) organisms, and inadequate regulations. Future perspectives emphasize community-driven phytomining, biomass recycling, and resilient phytoremediation solutions. Full article

Artisanal and small-scale gold mining (ASGM) generates complex metal mixtures, yet their biological effects remain poorly characterized in high-altitude populations, where occupational exposure occurs against a hypoxic environmental background. This study evaluated 49 occupationally exposed gold miners from the Vetas–California mining district, near the Santurbán páramo in Colombia, and 25 non-exposed individuals from a comparable high-altitude area. Hair concentrations of essential and toxic elements were quantified by ICP-MS, and serum catalase (CAT), superoxide dismutase (SOD), reduced glutathione (GSH), oxidized glutathione (GSSG), and the GSH/GSSG ratio were assessed. Miners showed a distinct multielement profile, with a higher toxic-metal burden and a dominant mixture mainly characterized by Fe, Mn, As, Pb, Cd, and Hg. CAT and SOD activities did not differ markedly between groups, although SOD activity decreased along the main exposure gradient among exposed workers. In contrast, glutathione-related biomarkers showed a more consistent exposure-related pattern, with higher GSSG and a lower GSH/GSSG ratio, suggesting a shift toward a more oxidized glutathione redox status. Together with positive within-group associations between selected elements and the GSH/GSSG ratio, these results are consistent with a mixture-associated perturbation of glutathione redox homeostasis, with heterogeneous adaptive responses. Overall, this study supports the use of integrated biomonitoring strategies and highlights glutathione-related markers as potential indicators of early redox perturbation in high-altitude mining populations. Full article

Maternal anemia and prenatal exposure to neurotoxic metals are widespread in low- and middle-income countries and may affect early childhood development. In Suriname, where mercury contamination from artisanal gold mining and social disparities coexist, we examined associations between maternal anemia, prenatal exposure to mercury (Hg), lead (Pb), manganese (Mn), selenium (Se), and cadmium (Cd), and early neurodevelopment. The study included 755 pregnant women and 644 children (10–26 months) from the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH) cohort. Maternal anemia was defined using WHO criteria for Hb, metals were measured in maternal blood, and child development was assessed using the Bayley Scales of Infant and Toddler Development, third edition (BSID-III-NL). Analyses used non-parametric tests, correlations, and multivariable regression. Anemia, though common (34%), was not independently associated with cognitive, language, motor, or social–emotional outcomes. However, iron status was not directly measured; therefore, the absence of an observed association should not be interpreted as evidence that maternal iron deficiency is unrelated to early neurodevelopment. Pb showed the most consistent associations, with higher prenatal levels predicting poorer cognitive, motor, and language scores. Hg demonstrated weaker but significant negative associations with several domains, while Mn and Cd showed limited direct effects. Interaction analyses suggested a potential modifying role of Se in certain metal-neurodevelopment associations; however, these findings require confirmation in future studies. Overall, these results suggest that prenatal exposure to neurotoxic metals and sociodemographic disparities may be important contributors to variation in early neurodevelopment in this population, but causal inferences cannot be made from this cross-sectional analysis. Full article

Mercury pollution from artisanal and small-scale gold mining remains one of the most persistent environmental threats due to the high toxicity, mobility, and bioaccumulation of Hg(II). In this work, Colombian banana pseudostem waste is valorized into a lignocellulosic carbocatalyst through pyrolysis at 500 °C followed by MnCO₃-derived MnOx functionalization, producing a sustainable material for Hg(II) remediation. The transformation of the biomass leads from a fibrous structure (~25 µm) to a pyrolyzed carbon matrix (9.56 µm), and finally to a heterogeneous Mn-modified system with bimodal particle distribution (~25 µm and ~0.85 µm), the latter being associated with highly dispersed MnOx redox-active domains. Structural and textural analyses reveal that Mn incorporation significantly enhances surface properties, increasing the BET surface area from 140.8 to 213 m² g⁻¹ while reducing pore size to the meso–microporous range (~1.9 nm). Importantly, the material retains intrinsic minerals such as Ca, Mg, K, and Si, which contribute to surface basicity and ion-exchange capacity, supporting additional Hg(II) interaction pathways. Optical and electronic characterization shows a wide band gap semiconductor behavior (≈3.4 eV) and a conduction band position at −0.892 V vs. NHE, sufficiently negative to thermodynamically drive Hg²⁺ reduction to Hg⁰ under UV-A irradiation. Hg(II) quantification was validated using a UV–Vis method based on the Hg²⁺–dipicolinic acid (DPA) complex, confirming stable complex formation with 1:2 stoichiometry (Hg²⁺:DPA) and high analytical reliability (R² = 0.948, LOD = 1.85 mg L⁻¹). Photocatalytic experiments demonstrated negligible Hg(II) reduction under UV-A light in the absence of catalyst, whereas the carbon-based materials enabled significant Hg transformation through adsorption-assisted photoinduced electron transfer. Electrochemical analyses (Rct ≈ 11 Ω) confirmed efficient charge transport, while cyclic voltammetry evidenced reversible Mn(IV)/Mn(III)/Mn(II) redox cycling, which sustains electron mediation during photocatalysis. Overall, pristine biochar acts primarily through adsorption driven by oxygenated functional groups and porous structure, whereas Mn-functionalized biochar operates via a synergistic adsorption–photocatalytic mechanism. In this system, MnOx species function as redox-active centers that facilitate electron transfer from the carbon matrix to Hg(II), while the conductive lignocellulosic-derived framework enhances charge mobility. The combination of structural carbon stability, dispersed Mn active sites, and inherent mineral functionality establishes a highly efficient and sustainable carbocatalyst, demonstrating a green and scalable approach for mercury remediation in mining-impacted regions. Full article

Despite the proliferation of mining and industrial activities within the Mano River Union member states, sediment quality assessment remains limited due to the lack of a comprehensive geochemical dataset. To narrow this knowledge gap, we evaluated heavy metal(loid) concentrations in stream sediments from Lofa County, Liberia. A total of 313 samples were collected and analyzed for eight metal(loid)s (Cu, Pb, Zn, Cr, Cd, Ni, As, and Hg). The contamination factor (CF), enrichment factor (EF), geoaccumulation index (Igeo), and potential ecological risk index (PERI) were calculated independently against two background values: the average shale and upper continental crust (UCC) values. The UCC background values proved more appropriate than average shale for Liberia’s geographic location and geological setting, providing results that align with the empirical data. The results show that zinc concentrations were consistently low across all sampling sites, indicating regional depletion of the micronutrient. Despite variations in the methodological approaches, assessment results from all four indices identified mercury and arsenic as the contaminants of primary concern. The varying degrees of metal(loid) enrichment and depletion necessitate further research in the study area. This study should guide policymakers in devising a sustainable plan for tackling site-based contamination and delivering on the United Nations Sustainable Development Goal 6.3. Full article

Mining activities are characterised by a multiplicity of inherent occupational hazards. Exposure to mineral dust such as silica, asbestos, and coal dust is common in mining, leading to pneumoconiosis. Exposure to respirable silica-containing dust is one of the common respiratory hazards associated with adverse health effects such as silicosis, lung cancer, renal failure, scleroderma, systemic lupus erythematosus (SLE) and chronic obstructive pulmonary disease (COPD), to mention but just a few. In southern Africa, there is a rising epidemic of silicosis, human immunodeficiency virus (HIV) and tuberculosis (TB). Excessive exposure to silica-containing dust exacerbates the TB and silicosis epidemic in mining areas. There is poor control of dust exposure and a lack of occupational hygiene assessments of silica dust in mining in southern Africa. In southern Africa, there remains a persistent knowledge gap regarding the extent of occupational exposures to respirable chemical substances, such as silica dust. Consequently, occupational hygiene air monitoring was conducted in mining companies across four low-income Southern Africa Development Community (SADC) countries, Lesotho, Mozambique, Malawi and Zambia, to provide a baseline exposure dataset. The hazardous nature of work associated with mining activities still persists in these low-income countries, with 53% (n = 72) of quarries and 20% (n = 19) of coal mines having respirable quartz exposures exceeding the reference occupational exposure limit (OEL) of 0.1 milligrams per cubic meter (mg/m³). The highest exposure ranges for quartz were recorded in surface aggregate quarries, with the maximum concentration recorded at 2.739 mg/m³. The highest number of air samples (93%, n = 111), which were in compliance with the OEL of 3 mg/m³ for respirable dust, were recorded in the copper, diamond, ruby, cement quarry and gold mines. This exploratory study confirms the variable extent of mineworker exposure to respirable dust and corresponding quartz fractions emanating from different mining activities. The collected exposure data provides a baseline overview of exposures within the mining industry in the SADC region. It also serves as a vital input for future regional exposure surveillance databases, as well as preliminary data for directing future research towards regional exposure prevention initiatives. Full article

Artisanal gold mining (AGM) activities are increasing globally and rely on rudimentary methods, such as amalgamation, to recover gold. In this study, mercury (Hg) metallurgical balances were conducted in 18 operations and gold (Au) balances in 35 operations, at a processing site serving approximately 4000 miners in the Korokpa mining area in Minna, Niger State, Nigeria. Ore processing involves grinding ore in hammer mills to below 1 mm, concentrating gold in sluice boxes, followed by amalgamating free gold particles in the concentrate. The results showed an average Au feed grade of 1.74 g/t and an average Au recovery from gravity concentration of 42.7%. Chemical analysis of the gravity separation tailing size fractions indicates that Au is lost in coarse fractions due to poor Au liberation and in fine fractions due to inefficiency in the sluicing process. Hg lost in the tailings was calculated as the mass balance difference between Hg added and the sum of Hg recovered through filtration and volatilized Hg in bonefires. It was found that 34% of Hg was lost during amalgamation, by volatilisation (18%) and with tailings (17%). The Hg lost-to-Au produced ratio was 2.6. By optimising procedures for grinding, classification, and concentration, the efficiency of recovery can be improved. Implementing a simple Hg recovery method, such as using a retort for condensation, and improving amalgam heating time can help miners minimise environmental loss. Full article

Illegal artisanal and small-scale mining (galamsey) and climate stress jointly degrade ecosystems and livelihoods in Ghana. This paper demonstrates how community-driven governance can realign incentives toward environmental stewardship and inclusive livelihoods. Using an explanatory sequential mixed-methods design—quantitative difference-in-differences followed by qualitative case analysis and Participatory Action Research—we evaluate a structured program combining vocational training, financial literacy, environmental stewardship, and governance alignment. We operationalize Environmental, Social, and Governance (ESG) outcomes via transparent composite indices and triangulate survey, administrative, and focus group evidence. The study identifies conditions under which alternative livelihoods reduce participation in illegal mining, strengthen women’s economic agency, and improve adoption of climate-smart practices. Implications include practical guidance for program design (community delivery, matched incentives, oversight), policy (local climate finance and accountability mechanisms), and research (scalable indicators and rigorous impact evaluation in resource-dependent communities). Full article

The use of agricultural-grade ammonium nitrate without fuel oil as an explosive has been empirically observed in underground artisanal mining in Ecuador. Despite its practical adoption, the explosive behaviour of this material has not been adequately characterized through experimental measurements. This study presents an experimental evaluation of agricultural ammonium nitrate used as an explosive in underground artisanal mining, with velocity of detonation (VOD) employed as the main control variable. Field-scale experiments were conducted under confined conditions and through in situ measurements in underground production tunnels, using configurations involving ammonium nitrate and commercial emulsion explosives. VOD measurements were performed using a high-sensitivity recording system suitable for short charge lengths. The results show that the emulsion explosive detonated reliably, whereas detonation transferred to the ammonium nitrate column rapidly weakened and collapsed. Detonation propagation within the ammonium nitrate was limited to short distances or extinguished entirely, indicating a non-ideal detonation regime in which sustained propagation cannot be maintained under underground artisanal mining conditions. The study provides rare field-scale data on the physical limits of detonation in low-sensitivity energetic materials, obtained under realistic underground artisanal mining conditions. Full article

Workers’ exposure to silica dust is a global occupational and public health concern and is particularly prevalent in Southern Africa, mainly because of inadequate dust control measures. It is worsened by the high prevalence of HIV/AIDS, which exacerbates tuberculosis and other occupational lung diseases. The prevalence of silicosis in the region ranges from 9 to 51%; however, silica dust exposure levels and controls, especially in the informal mining sector, particularly in artisanal small-scale mines (ASMs), leave much to be desired. This is important because silicosis is incurable and can only be eliminated by preventing worker exposure. Additionally, several studies have indicated inadequate occupational health and safety policies, weak inspection systems, inadequate monitoring and control technologies, and inadequate occupational health and hygiene skills. Furthermore, there is a near-absence of silica dust analysis laboratories in southern Africa, except in South Africa. This protocol aims to systematically evaluate the effectiveness of respirable dust and respirable crystalline silica dust exposure evaluation and control methodology for the mining industry. The study will entail testing the effectiveness of current dust control measures for controlling microscale particles using various exposure dose metrics, such as mass, number, and lung surface area concentrations. This will be achieved using a portable Fourier transform infrared spectroscope (FTIR) (Nanozen Industries Inc., Burnaby, BC, Canada), the Nanozen DustCount, which measures both the mass and particle size distribution. The surface area concentration will be analysed by inputting the particle size distribution (PSD) results into the Multiple-Path Particle Dosimetry Model (MPPD) to estimate the retained and cleared doses. The MPPD will help us understand the sub-micron dust deposition and the reduction rate using the controls. To the best of our knowledge, the proposed approach has never been used elsewhere or in our settings. The proposed approach will reduce dependence on highly skilled individuals, reduce the turnaround sampling and analysis time, and provide a reference for regional harmonised occupational exposure limit (OEL) guidelines as a guiding document on how to meet occupational health, safety and environment (OHSE) requirements in ASM settings. Therefore, the outcome of this study will influence policy reforms and protect hundreds of thousands of employees currently working without any form of exposure prevention or protection. Full article