Gold Mining Operations Research Articles

Causes and Consequences of Inefficient Drilling and Blasting in Mine Development Headings: A Case Study of Hard Rock Gold Mining Operations in Northern Tanzania

Causes and Consequences of Inefficient Drilling and Blasting in Mine Development Headings: A Case Study of Hard Rock Gold Mining Operations in Northern Tanzania

Index of heavy metal pollution and health risk assessment with respect to artisanal gold mining operations in Ibodi-Ijesa, Southwest Nigeria

BackgroundArtisanal gold mining can help reduce poverty while creating job possibilities for many low-income and unskilled workers. However, it is an activity with several detrimental societal consequences. Miners are exposed to chemical toxins that have long-term health consequences. ObjectivesThis study examined soil degradation, pollution, and environmental hazards from artisanal gold mining in Ibodi-Ijesa, Osun State, Nigeria. The aim is to assess the levels of Cu, Co, Cd, Pb, As, and Ni in the study area as potential indicators of environmental concerns. MethodsSoil samples were systematically collected from 66 distinct locations surrounding the gold mining site, at depths ranging from 0 to 15 cm, within distances of 0 to 500 m, and at intervals of 100 m. These samples underwent standard laboratory procedures for heavy metal analysis using Atomic Absorption Spectroscopy (AAS).Results: The findings showed that copper (Cu), cobalt (Co), lead (Pb), and nickel (Ni) concentrations ranged from 80.17 to 100.11 mg.kg−1, 42.11 to 50.07 mg.kg−1, 30.93 to 54.00 mg.kg−1, and 35.30 to 44.20 mg.kg−1, respectively. Nickel (Ni), cadmium (Cd), and arsenic (As) were all below the detection limit. Although all analysed heavy metal concentrations were lower than the control samples, they outperformed the control values. The contamination index showed no distinct distribution pattern, but all values surpassed those of the control samples. Furthermore, the Health Risk Index was greater than one, indicating possible health hazards for inhabitants. ConclusionThe study indicated that artisanal gold mining operations in Ibodi-Ijesa substantially influenced soil quality, raising heavy metal concentrations and posing health hazards to adjacent populations.

Hydrogeochemical characteristics and air quality risks associated with gold mining operations in Egypt using geochemical modeling and risk indices

The success of industrial operations depends on the effective identification, appraisal, and mitigation of possible hazards and associated environmental concerns. This report provides a complete review of environmental management techniques at the Sukari Gold Mine (SGM), located in the southeastern desert of Egypt. Extensive environmental measurements were taken to assess air and water quality, identify hazards, and analyze risks on the SGM premises. Air quality and noise intensity levels were measured at 39 places around the mine's working region. The findings found noncompliance with the Egyptian Environmental Law's (EEL4/94) noise exposure limitations, with the Power Generator House having the maximum noise levels at 107 dB. Remedial measures such as personal protective equipment (PPE) and exposure limit reduction strategies are being considered to address elevated noise levels. Measurements of particulate matter (PM10) and noxious gases (e.g., CO, SO2, NO2, HCN, and NH3) were conducted in workplace and ambient environments. Elevated PM10 concentrations were particularly concerning in underground regions, forcing the deployment of water depression techniques and improved PPE measures. While gas emissions from most activities remained under regulatory limits, select zones showed hydrogen cyanide (HCN) levels that exceeded permitted thresholds, necessitating specific control actions. Using hazard index (HI) and risk rating assessments, this study found different risk profiles across SGM's workplaces, focusing on high-risk regions for focused intervention. Additionally, a water assessment near a Tailing Storage Facility (TSF) was conducted to monitor the impact of mining activities on groundwater quality. The study revealed that groundwater in the region belongs to the Na–K–Cl–SO4 and Ca–Mg–Cl–SO4 water classes, with potential degradation attributed to high mineralization processes induced by aquifer materials and seawater intrusion. The findings underscore the importance of ongoing monitoring, control measures, and implementation of programs to ensure environmental sustainability and minimize risks associated with mining activities in the Sukari Gold Mines. This research highlights the imperative of continuous monitoring, proactive control measures, and the implementation of environmental initiatives to ensure the sustainability of mining operations within the Sukari Gold Mines.

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.

GEO-ECONOMIC EXPLORATION OF GOLD DEPOSITS IN UZBEKISTAN'S AKBA SITE

This article presents a comprehensive study of the Akba site in Uzbekistan, focusing on its geological structure, ore-containing rocks, and the economic feasibility of gold mining operations. Through a multidisciplinary approach combining geological surveys, sample analysis, and economic evaluations, we have identified significant gold reserves accessible for extraction. Our findings reveal the potential for profitable mining, supported by detailed geological mapping and financial projections under current market conditions. The study emphasizes the importance of integrating geological data with economic analyses to optimize mining strategies, considering both profitability and environmental sustainability. Recommendations for future research include advancing exploration techniques and expanding economic evaluations to ensure the sustainable development of Uzbekistan's gold mining industry.

Determination of Bioavailability, Potential Ecological and Human Health Risks, and Biomonitoring of Potential Toxic Elements in Gold Mine Tailings from Four Areas of Antioquia, Colombia

Gold mining has helped many countries and regions grow and prosper. Yet, because of the significant environmental effects produced, waste management (mine tailings) has emerged as a crucial issue for the sector. In this study, the concentrations of several potential toxic elements (PTEs) (Fe, Zn, Cu, As, Hg, Pb, Cr, Cd, and Ni) in mine tailings from four gold mining operations (Yalí, Puerto Berrio, Buriticá 1, and Buriticá 2,) were quantified. A biomonitoring system has also been suggested, along with two environmental risk indexes for ecosystems and human health. To do this, composite samples of tailings were collected from the four regions. A PTEs analysis using an ICP-OES as well as physicochemical characterization (pH, electrical conductivity, cation exchange capacity, organic matter) have been performed. Indicators such as antioxidant activity and H2O2 content in Phaseolus vulgaris plants have been used to estimate the bioavailability of PTEs. In contrast to the pseudo-total concentration, the data showed that the bioavailable concentration of PTEs correlated with the risk. The ecological system and public health are more at risk from the mine tailings in Buriticá and Puerto Berrio. It has been demonstrated that P. vulgaris is a quick and effective technique to assess the danger to the environment and public health connected with mining regions, according to the suggested biomonitoring system. The findings of this study can assist the relevant authorities in taking quick action to improve environmental protection and risk management of hazardous waste in gold mining areas.

Security issues of the gold industry chain based on smart blockchain in the context of the Internet of Things

The purpose is to solve the safety production and management problems of the gold Industrial Chain and give early warning of the safety situation of the gold Industrial Chain. According to the theory of industrial chain security governance and the basic situation of the gold Industrial Chain, this work establishes a gold Industrial Chain model based on smart blockchain and system dynamics (SD), and discusses the application of the gold Industrial Chain in the Internet of Things (IoT) environment. The overall goal of the application of IoT technology to the safety management of intelligent gold mines is to take the gold mine production demand as the driving force. The digitalization of production, electromechanical, safety, dispatching, and other information realizes intelligent digital perception, assists decision-making, guides the safety management of gold mining operations, continuously improves the operation efficiency of the gold mining industry, and drives the development of the industry. Finally, it takes the resource reserve of China’s gold industry from 2011 to 2021 as the research data introduces the weighting method to assess the security situation of China’s gold Industrial Chain from 2011 to 2021. The safety performance of China's environmental industry chain is evaluated through the detailed introduction of the basic information of the gold Industrial Chain. The result shows that the security situation of China’s gold Industrial Chain from 2011 to 2021 shows an overall growth trend, 88.42% higher than in 2014. The security situation of China’s gold Industrial Chain from 2011 to 2021 positively impacted the opening of the domestic gold market and entering the international gold market, improving the security level of China’s gold Industrial Chain. In this work, a gold Industrial Chain security model based on smart blockchain and SD is established to solve the safety problem of the gold Industrial Chain, which can improve the safety level of the gold industry and promote its sustainable development.

Localization conditions of apometaterrigenous non-carbon the Sarykul deposit of the Karatyubinsky ore district in Uzbekistan

This article explores the occurrence of apometaterrigenous non-carbon tungsten mineralization at the Sarykul deposit in the Karatyubinsk Mountains. Initially considered unpromising, this newly discovered tungsten mineralization was found during gold mining operations. The prospecting activities targeting calcification zones in metaterrigenous rocks revealed their tungsten-bearing nature. This discovery has reshaped the understanding of tungsten mineralization genesis, lithological and structural conditions, and the overall minerogenic potential of the Karatyubinsky ore field.Apometaterrigenous tungsten mineralization originates from coarse flysch rocks transformed into shale rocks in the contact zone with a tungsten-specialized granitoid intrusive. The mineralization is associated with multicomponent metasomatites formed on aluminosilicate metaterrigenous rocks. Significant correlations exist between tungsten and elements such as Pb, Ag, Au, Be, Cu, Mo, V, and Mn. Scheelite mineralization forms autonomously, followed by the combination of different stages within mineralized zones. The regional trog structure, characterized by the formation of an olistostromic stratum due to high granulometric dispersion, is also linked to the apometaterrigenous mineralization.

Historical gold mining increased metal(loid) concentrations in lake sediments from Nova Scotia, Canada

Historical gold mining operations between the 1860s and 1940s have left substantial quantities of arsenic- and mercury-rich tailings near abandoned mines in remote and urban areas of Nova Scotia, Canada. Large amounts of materials from the tailings have entered the surface waters of downstream aquatic ecosystems at concentrations that present a risk to benthos. We used paleolimnological approaches to examine long-term trends in sedimentary metal(loid) concentrations, assess potential sediment toxicity, and determine if geochemical recovery has occurred at four lakes located downstream of three productive gold-mining districts. During the historical mining era, sedimentary total arsenic and mercury concentrations and enrichment factors increased substantially at all downstream lakes that received inputs from tailings. Similarly, chromium, lead, and zinc concentrations increased in the sediments after mining activities began and the urbanization that followed. The calculated probable effects of concentration quotients (PEC-Qs) for sediments exceeded the probable biological effects threshold (PEC-Q > 2) during the mining era. Although sedimentary metal(loid) concentrations have decreased for most elements in recent sediments, relatively higher PEC-Q and continued exceedance of Canadian Interim Sediment Quality Guidelines suggest that complete geochemical recovery has not occurred. It is likely that surface runoff from tailing fields, urbanization, and climate-mediated changes are impacting geochemical recovery trajectories.

New Approach Towards Sustainability – The Global Efficiency Concept (GEff)

In the actual economical environment, business sustainability requires high-efficiency technological processes and new innovative developments. That is why the efficiency concept has to be present at all levels of industrial and financial activities. The proposed concepts in this paper could be further developed as a model for improving companies’ corporate energy policies.
 Nowadays, some purchase decisions for equipment are still driven predominately by the purchase price, and the full consequences of energy efficiency and the impact on the environment are not always considered.
 In general relatively “low value equipment” purchase policy is still driven by purchase price only, in spite of the evidence that such price represents a maximum of 5 % to 7 % of the total expenses related to the total costs of ownership. In the minerals industry “low value equipment”, like low-voltage motors (up to 1100 volts, 50/60 Hz), are found many times and in very large numbers, their efficiency and reliability influencing dramatically specific costs of technological processes.
 Although with “major equipment” energy savings are considered more in the purchase decision, every growing importance on the environment of “Green House Gas” (GHG) emissions is still not a major factor when selecting equipment. Often more traditional equipment is purchased at the expense of new innovative technologies that in addition to providing energy savings can also be used as a tool for trading Carbon Credits in the financial marketplace. An example of such a technology is the IsaMill™ comminution machine, which is becoming more widely used in gold and general mining operations in South Africa and throughout the world. Comminution in the mining industry is one of the most energy intensive activities in the world, and the innovative use of “major equipment” saving power can also have a positive effect on the environment.
 The paper presents descriptions of the essentials of the Global Efficiency (GEff) concept that has been promoted over the last years in South Africa. Price-efficiency criteria (as a corollary of GEff) are investigated for applications incorporating equipments that are driven by low and high voltage motors.
 The paper presents theoretical and technical aspects analysing the economic and environmental impact, by reducing total cost of ownership with energy savings, for one “low value equipment” in typical applications largely used in mineral processing in the gold mining industry, and one “major equipment” purchase at a current operating gold mine where the innovative IsaMill™ comminution technology was installed as an alternative to traditional older technologies.
 Besides the impact of energy savings with high-efficiency technological processes and new innovative developments, this paper suggests the general impacts of:
 
 Technical and economical performance improvements and competitiveness of mining corporations to international standards;
 Defusing incipient energy crisis in the gold mining sector;
 Improving environmental conditions;
 Creating new job opportunities in the gold mining sector.

Unearthing Hazards: Investigating the Root Causes of Workplace Accidents at PT Indo Muro Kencana's Gold Mines

Objective: This study seeks to dissect the occurrences of work-related accidents at PT Indo Muro Kencana (PT IMK) over a period spanning from 2018 to 2023. It aims to pinpoint the contributing factors to these mishaps, analyzing them to forge actionable recommendations and preventive strategies aimed at mitigating accident risks and enhancing workplace safety and health. Design/Methods/Approach: Employing a quantitative descriptive methodology, this research adopts an observational descriptive design to catalog and scrutinize work accident incidents. The Loss Causation Model serves as the analytical framework, facilitating a thorough evaluation of accident causatives. The study encompasses all PT IMK employees during the specified timeframe, utilizing a total sampling approach. Data compilation hinges on secondary sources, including company accident reports and relevant literature, with SPSS Statistics 25 software facilitating cross tabulation for data analysis. Findings: Analysis reveals a fluctuating pattern of work accidents over the years, with a significant portion resulting from direct physical interactions such as collisions and strikes. Predominantly occurring in excavation and roadway sectors, these incidents frequently involve heavy machinery and service vehicles. Notably, accidents disproportionately affect younger employees with limited tenure, though veterans are not exempt from risk. Primary accident triggers are identified as unsafe acts—including procedural breaches and poor decision-making—and unsafe conditions like slippery surfaces and subpar equipment. Underlying causes are attributed to human elements, notably inadequate judgment skills, and occupational hazards, including poor hazard awareness and deficient job safety analysis. Originality/Value: This research pioneers in its focused examination of work accident causatives within PT Indo Muro Kencana's gold mining operations, marking a novel contribution to occupational safety and health literature in the mining sector. Practical/Policy implication: The insights garnered herein are poised to inform the development of targeted safety programs, underlining the study's utility in propelling occupational safety and health consciousness, alongside facilitating accident risk reduction initiatives.

Gold mining's environmental footprints, drivers, and future predictions in Ghana

The last two decades have seen a surge in gold mining operations around the world. Despite mining occupying a smaller geographical area compared to other land use/land cover (LULC) classes, it exhibits strong interconnections with various land uses and serves as a major driver for changes in mining landscapes. Understanding and evaluating historical and potential future LULC changes in these landscapes are crucial in assessing the environmental impact of mining. Traditionally, these assessments heavily rely on geospatial techniques, with limited emphasis on projecting future LULC trends. This research aims to monitor, analyse the drivers of change, and predict future changes in LULC under two scenarios: the “business as usual” scenario and the "remedial measures" scenarios. Utilising the CA-Markov model, this article predicts LULC changes and offers comprehensive insights into the environmental impacts of mining, combining geospatial and social research methodologies. The investigation spanned a 34-year period (1986–2020) and employed a blend of supervised and unsupervised image classification methods, complemented by interviews, focus groups, and field observations. The findings reveal substantial land degradation, water pollution, and a significant loss of forest cover, accounting for 27,333 ha (36%). Continuation of current mining practices is predicted to lead to further ecological deterioration.

A Statistical Study of Price of Gold

Gold has long been considered one of the most precious metals, and its value has been used as the standard for many currencies (known as the gold standard) in history. Ancient India accumulated gold through trade of Indian spices with Roman Empire and by gold mining operations, predominantly in the regions of Hatti and Kolar of modern-day Karnataka. 1. There has been drastic increase in the prices of gold since 2001. Gold prices have been increased by 90% during last 10 years. 2. The Bank of India has one of the largest stores of gold in the world. India is the second largest consumer of gold in the world and is one of the most reliable drivers of global demand. Gold accounts for nearly 5.5% of the total foreign reserve holdings of India. India’s festival and wedding season, which runs from October to December, has historically been a huge boon to gold trade. 3. Gold has always been used as a monetary standard. Gold has a profound impact on the value of world currencies. Even though the gold standard has been abandoned, gold as a commodity can act as a substitute for fiat currencies and be used as an effective hedge against inflation. There is no doubt that gold will continue to play an integral role in the foreign exchange markets. Gold consumption observed a sharp acceleration during the 1990s amidst liberalization of gold import policy, strong economic growth and favourable movements in gold prices. Gold is now being used as an alternative for dollar since its collapse. Monetary and Non- Monetary demand for gold is steeply rising. It has been demanded by individual buyer, institutional buyer as well as he Countries too.

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.

The Implications of The Tanzania New Mining Legislation in Enhancing Revenue: A Case of Geita Gold Mine.

Purpose: The purpose of this study is to investigate the implications of these reforms from a revenue collection perspective in Geita District using Geita Gold Mine Limited (GGML) as a case study.
 Design/Methodology/Approach: This study utilizes a mixed-method approach, by using both qualitative and quantitative approaches. The study population consisted of individuals from sampled households in six wards around GGML with a sample size of 384 respondents. The study used both stratified and simple random sampling methods in selecting respondents. The qualitative data were collected through in-depth interviews, focus group discussion and documentary analysis while the quantitative data were collected through the survey method. Qualitative data were analysed using content analysis and quantitative data from households were analysed using descriptive statistics.
 Research Implications/Limitations: This study is limited to GGML and Geita District only, which may not fully capture the diverse range of other mining companies operating outside the district within Tanzania.
 Findings: Study findings indicated that the mining legislation helped to improve the quality of institutions as well as resource governance. For instance, due to improvements in resource governance such as the increase in royalty and mining supervision the revenue from mining activities almost tripled to a total of TZS 664 billion as compared to TZS 196 billion that was collected four years back from 2017.
 Practical Implications: The findings are expected to have a significant on improving the traceability of gold production and reporting their activities more transparently. Additionally, reforms can lead to more efficient and effective collection of royalties, taxes, and fees related to gold mining operations, resulting in increased government revenue
 Social Implications: The social implications of this research are essential, as the increase in mining revenue through taxes, royalties, service levies and other fees can help to improve social services such as education and health services. The mining sector can also contribute to the provision of employment to host communities which has a direct impact on improving social welfare.
 Originality/Value: The novelty of this research lies in its holistic and sector-specific examination of revenue collection reforms in the gold mining industry, considering economic, environmental, social, and governance dimensions. It offers a comprehensive understanding of how reforms in this critical sector can impact both individual nations and the global resource landscape.

Socioeconomic and Environmental Effects of Gold Mining in Paring Lahung, Montallat District, North Barito Regency

This study aims to assess the impact of gold mining operations on the socioeconomic well-being of the Paring Lahung Village community in the Montallat District of North Barito Regency. The research utilizes both secondary and primary data sources. Secondary data is collected from many sources, such as the Central Bureau of Statistics (BPS), sub-district offices, villages/districts, and private entities. On the other hand, primary data is directly received from respondents residing in Paring Lahung Village, Montallat District, North Barito Regency. For a sample size of 30 participants. The research findings indicate that there is a discernible public impression regarding the presence of unauthorized gold mining operations in Paring Lahung Village. The findings indicate that the residents of Paring Lahung Village have a predominantly neutral stance towards gold mining operations. Out of the total number of respondents, 14 individuals (46%) expressed a positive attitude towards gold mining activities in the vicinity of the Paring Lahung Village forest area. Additionally, 9 respondents (30%) had a neutral view, while 7 respondents (24%) exhibited a negative attitude towards such activities. The present study examines the social, economic, and environmental conditions associated with the presence of gold mining activities in Paring Lahung Village. The analysis of social situations reveals that individuals distribute their wealth towards several sectors, including education, health, and housing. The economic conditions demonstrate a tendency towards above-average performance and have exhibited growth subsequent to the implementation of gold mining operations. This can be attributed to the augmentation of respondents' primary income, as well as the acquisition of supplementary sources of revenue. In Paring Lahung Village, the prevailing environmental conditions indicate the utilization of a method to separate combined gold and sand, alongside a minority engaging in conventional processing techniques. As per the accounts of certain inhabitants, the procedure of gold extraction involves the utilization of quicksilver, often known as mercury. Mercury is categorized as a heavy metal with the capacity to be designated as B3 trash

Assessing the environmental impact of gold production from double refractory ore in a large-scale facility

Despite the strict environmental management regulations, there is still a considerable adverse impact on the ecosystem and human health when it comes to large-scale gold mining operations. Gold mining is an energy-intensive process that can discharge substantial quantities of chemicals combined with gaseous emissions into the environment. Considering gold mining's significant role in Nevada's economy and the growing concern about climate change, it's necessary to investigate the environmental burdens of this sector. To provide a comprehensive environmental perspective on the large-scale gold mining operations in Nevada, this study used a life cycle assessment (LCA) approach to evaluate the environmental burdens of gold production from double refractory ores in the roasting process. The Tool for Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI) method was used to evaluate the categories of acidification, ozone depletion, global warming, smog, carcinogenics, non-carcinogenics, respiratory effects, and fossil fuel depletion. Results showed that major contributors to greenhouse gas (GHG) emissions were grinding and off-gas treatment stages being responsible for 34.80 % and 56.10 % of the total global warming, respectively. The carbon footprint for producing one kg of gold was 12,200 kg CO2-eq. Sensitivity analysis was also employed on electricity to observe the influence of electricity on key contributor stages. A 10 % change in electricity reduced the GHG emissions in crushing and grinding by 12.2 % and 7.10 %, respectively, while delivering an insignificant effect on the off-gas treatment. Significantly, this study stands as the first initiative to apply LCA in the North American mining industry, with a unique focus on the off-gas treatment post-roasting and its associated emissions. Our findings can serve as a foundational database, aiding stakeholders in making informed decisions and enhancing sustainable practices in the gold mining industry.

Contrasting mercury contamination scenarios and site susceptibilities confound fish mercury burdens in Suriname, South America

In Suriname, mercury (Hg) use has recently increased because of gold mining, which has put fish-reliant communities (e.g., Indigenous and Tribal) at risk of enhanced Hg exposure through the riverine fish these communities consume. To quantify how the magnitude of these risks change according to location and time, we measured total mercury (HgT) in fish at sites downstream and upstream of an artisanal and small-scale gold mining (ASGM) operation in 2004–2005 and in 2017–2018. We tested whether fish HgT burdens over dynamic ranges were increased. Surprisingly, our findings did not support broadly increased fish Hg burden over time or that proximity to ASGM was diagnostic to fish HgT-burden. Subsequently, we elected to test the HgT stable isotope ratios on a set of freshly collected 2020 fish to determine whether differences in Hg source and delivery pathways might cofound results. We found that remote unmined sites were more susceptible to gaseous elemental Hg deposition pathways, leading to enhanced risk of contamination, whereas ASGM proximate sites were not. These results highlight that elemental mercury releases from ASGM practices may have significant impact on fish-reliant communities that are far removed from ASGM point source contamination.

Investigation of techniques to replace amalgamation in artisanal gold mining operations

Artisanal gold mining is the leading source of anthropogenic mercury emissions worldwide. This article explores cost-effective gold leaching methods for skilled miners to address mercury's environmental and health impacts in this sector. A sample from Colombia's La Maria deposit, containing 48.87 ppm gold, ground to 80% below 0.13 mm, served as the basis for comparison. The standard whole ore amalgamation approach, commonly used by miners, resulted in less than 19% gold extraction. However, employing cyanidation with 1g/L of free cyanide extracted 84% of the gold within 24 hours. Among the unconventional processes investigated, using effluent from a local cassava processing plant as a lixiviant demonstrated promise. Two cassava varieties produced liquids with 267 and 600 mg/L of free cyanide, leading to 50.9% and 82.4% gold extraction from the ore in 24 hours, respectively. Another alternative method involved employing Dimethyl sulfoxide, a water-free reagent, as a gold-leaching lixiviant, resulting in a remarkable 96.5% gold extraction in just 2 hours. The researchers also modified the Merrill-Crowe cyanidation process by eliminating filtration and vacuum, instead utilizing bags filled with zinc (or aluminum) in the pulp. With reduced agitation to prevent aeration, over 99% of the gold precipitated on the zinc shavings within 2 hours. Furthermore, testing a hydrochloric solution (50%) with an oxidant demonstrated 83.9% and 100% gold extraction in 8 hours at ambient temperature and 50°C, respectively. It is crucial to note that successful implementation of these alternative strategies necessitates knowledge, investment, and customization to suit specific site conditions.

Exogenous thiocyanate inhibits sulfurtransferase pathway and induces β-cyanoalanine synthase pathway to enhance exogenous cyanide assimilation in rice plants

Cyanide (CN−) assimilation in plants takes place by β-cyanoalanine synthase (β-CAS) and sulfurtransferase (ST), in which the ST pathway converts CN− into thiocyanate (SCN−). Both chemicals (CN− and SCN−) are frequently detected in the effluent of gold mining operations. In this connection, exogenous SCN− was applied to rice plants with CN− and compared with CN− alone to investigate its effects on CN− assimilation and degradation pathways. Interestingly, the CN− and SCN− content in both roots and shoots were increased with the increase in “CN−” treatments, but surprisingly their content under “SCN−+CN−” treatments did not show the similar trend. The increasing trend remained the same for CN− but the SCN− content was constant with increasing CN− concentrations in comparison with the control (SCN− alone). Additionally, the assimilation rates of CN− in rice plants under “SCN−+CN−” treatments were significantly higher than “CN−” treatments. The application of SCN− with CN− mostly alters the expression of both β-CAS and ST-associated genes. On one side, the application of SCN− significantly repressed the expression of genes encoded with ST in rice plants, but on the other side, it significantly up-regulated the expression of the β-CAS gene located in mitochondria. These results reveal that the application of exogenous SCN− increases CN− assimilation rates by inhibiting the ST pathway and stimulating the β-CAS pathway. This study would provide new insight into the positive effects of exogenous SCN− in increasing CN− assimilation by altering the degradation pathways in rice plants.