Assessment of heavy metal levels in cow's milk and associated health risks in the vicinity of the MIDROC Laga Dambi gold mine in Ethiopia.

INTRODUCTION: The possible health effects of consuming milk contaminated with heavy metals have been the subject of considerable concern worldwide. OBJECTIVE: The aim of this study was to determine the level of heavy metals in cow's milk in the vicinity of MIDROC Laga Dambi gold mine and to assess their possible health risks for consumers. METHODS: Nine composite samples were formed by aggregating 243 milk samples obtained in triplicates from 81 domestic milk-producing households. Inductively coupled plasma-optical emission spectroscopy was used to measure the amount of heavy metals after samples digestion under optimal conditions. RESULTS: The heavy metals concentrations obtained were 13.913-7.843, 9.505-3.589, 5.972-3.147, 2.288-1.851, 0.403-0.143, 0.436-0.128, 0.26-0.153, 0.143-0.048, 0.160-ND (not detected), and 0.140-ND mgkg-1for Fe, Zn, Pb, Mn, Hg, Cr, Cd, As, Ni, and Co, respectively. Of the heavy metals identified, the levels of Pb, As, Cd, and Hg exceeded the recommended value. Based on the estimated daily intake (EDI), the total health quotient (THQ) is higher than unity even for Pb alone. It has been found that the consumption of cow milk increases the health index (HI) by 2.972. Ninety five percent of the HI in the study area was explained by the toxic heavy metals (Pb, Cd, As, and Hg) in the cow milk, which were found to be beyond the safe limit. CONCLUSION: This demonstrates that there is a health risk to the population who consume cow's milk sourced from the vicinity of MIDROC Laga Dambi gold mine. To safeguard the public's health, we advised strict monitoring and legislative control for the safety of cow's milk originating from study area.

The impact of gold mining activities: understanding the dynamics of cyanide in river ecosystems in Ecuador.

Understanding the behavior of cyanide in rivers is of utmost importance as it has a direct impact on the health of people who depend on these water sources. Cyanide contamination from gold mining activities poses a significant environmental threat to river ecosystems, particularly in southern Ecuador. This study aimed to investigate the behavior of cyanide when it enters contact with other metals in these rivers. Simulations were conducted to determine the speciation of cyanide, mercury, arsenic, lead, and manganese in a study area, taking into account the water temperature and pH at four locations. The findings revealed that CN-and HCN(aq) species were present in the research area. Additionally, mercury-cyanide (Hg(CN)2(aq), Hg(CN)3-), and manganese-cyanide (MnCN+) complexes were identified 3 km downriver from the site where the mining activity is higher. These metal-cyanide complexes tend to dissociate quickly under weak acidic conditions, making them hazardous to the environment. This research is crucial, not only for the environment but also for human health, as it allows to predict toxicity risks for people supplied with this water source, emphasizing the potential harm to human health. This study highlights the importance of stringent regulations and effective monitoring practices to mitigate cyanide contamination and safeguard environmental and occupational health.

Mercury Dynamics and Bioaccumulation Risk Assessment in Three Gold Mining-Impacted Amazon River Basins.

Mercury contamination from gold mining in the Amazon poses significant environmental and health threats to the biome and its local populations. The recent expansion of non-industrial mining areas has severely impacted territories occupied by traditional communities. To address the lack of sampling data in the region and better understand mercury dynamics, this study used the probabilistic model SERAFM to estimate the mercury distribution and bioaccumulation in fish. The analysis covered 8,259 sub-basins across three major Amazonian basins: the Branco, Tapajós and Xingu rivers. The findings revealed increasing downstream mercury levels, with notable accumulations in the main watercourses influenced by methylation processes and mining releases. The projected concentrations showed that an average of 27.47% of the sub-basins might not comply with Brazilian regulations, rising to 52.38% in the Branco and Tapajós river basins separately. The risk assessment of fish consumption based on the projections highlighted high mercury exposure levels among traditional communities, particularly indigenous populations, with an average of 49.79% facing an extremely high risk in the Branco and Tapajós river basins. This study demonstrated SERAFM's capacity to fill information gaps in the Amazon while underscoring the need for enhanced data collection, culturally sensitive interventions and regulatory updates to mitigate mercury contamination in gold mining-affected areas.

Health and environmental risk assessment of mercury in outdoor and indoor dust in artisanal and small-scale gold mining area in Amansie-west district in the Ashanti Region of Ghana.

Mercury (Hg) pollution around artisanal and small-scale gold mining (ASGM) areas has been of much concern. Many studies have reported elevated Hg concentrations in environmental media, but studies on dust relating to inhalation exposure of Hg around ASGM area are limited. In this study, we investigated Hg in indoor and outdoor dust to reveal environmental and human health risk around ASGM in Amansie West district, Ghana. Indoor and outdoor dust samples were collected from Manso Abore and Manso Nkwanta in Ashanti Region. Concentration of Hg in the samples were analyzed using a direct Hg analyzer. The mean and median value of Hg concentration in the indoor dust (n = 31) were 2.2 ± 3.6 mg/kg and 0.72 mg/kg respectively while that of the outdoor dust (n = 60) were 0.19 ± 0.48 mg/kg and 0.042 mg/kg, respectively. The mean and median Hg concentration in indoor dust were about 11 and 17 times higher respectively than that in the outdoor dust. The Hg concentration in the indoor dust was statistically significantly higher than that of the non-miner in Manso Abore (p < 0.05) but was not significant in Manso Nkwanta, probably due to higher mining activity. The geo-accumulation index of the outdoor dust ranged from unpolluted to extremely polluted while that of the indoor dust ranged from moderately polluted to extremely polluted. Health risk assessments suggested that there was no potential non-carcinogenic health effect for Hg exposure relating to the dust to residents living in rooms of miners and non-miners.

Soil amendment-assisted phytoremediation with ryegrass offers a promising approach to mitigate environmental health concerns.

This study aimed to examine the potential of soil amendment-assisted phytoremediation using ryegrass in reclaiming abandoned gold mine soil in southwestern Ghana, with a specific focus on the soil contamination hazards associated with metals and metalloids. A pot experiment lasting 60 days was carried out to assess the efficacy of soil amendments, such as compost, iron oxide, and poultry manure, in mitigating environmental hazards. Three soil contamination indices (soil contamination = CF, enrichment factor = ER, and pollution load index = PLI) were used to calculate the extent of soil contamination, enrichment, and pollution of the sites with Co, Hg, Ni, Mo, Se, Sb, and Pb. The findings show that Hg made the greatest contribution (with a maximum soil CF of 18.0) to the overall PLI, with a maximum value of 74.4. The sites were averagely and consequently enriched with toxic elements in the decreasing order: Ni (ER = 33.3) > Mo (20.5) > Sb (14.1) > Pb (11.0) > Hg (7.9) > Se (2.1). The bioaccumulation factor (BCF > 1) suggests that ryegrass has the ability to phytostabilize Co, Hg, Mo, and Ni. This means that the plant may store these elements in its roots, potentially decreasing their negative effects on the environment and human health. Ultimately, the addition of combined manure with iron oxides might have augmented the sequestration of these metals in the root. The elements may have accumulated through sorption on manure or Fe surfaces, dissolution from watering the plants in the pot, or mineralization of organic manure. Thus, ryegrass has shown potential for phytostabilisation of Co, Hg, Mo, and Ni when assisted with a combination of manure and iron oxides; and can consequently mitigate the environmental and human health impacts.

Gold mining in Ghana has caused significant environmental damage and political unrest. Research on environmentally friendly solutions to land degradation is crucial for restoring degraded lands, preserving ecosystem integrity, restoring livelihoods, and protecting public health in gold mining hotspots. However, previous studies have often overemphasized the use of trees in improving soil quality. Other past studies have merely collected plant species for heavy metal analysis without concrete pots or field experiments. Ryegrass has only been limited to arsenic remediation, and its phytoremediation ability for other toxic elements like Co, Hg, Mo, Ni, Pb, Sb, and Se has not been investigated. This work reports for the first time the phytostabilisation ability of ryegrass for potentially toxic elements in a Ghanaian context. Consequently, recommendations are made for reclaiming gold-mine-affected sites while at the same time providing evidence for widening the choice of plant species available for restoring mine-derelict lands. Ultimately, the study fills the gap in phytoremediation research within the global scientific community and Ghana in particular.

Comprehensive assessment of heavy metal pollution of agricultural soils impacted by the Kalsaka abandoned gold mine and artisanal gold mining in northern Burkina Faso.

In this study, the environmental quality of agricultural soils around the Kalsaka abandoned gold mine was evaluated. A total of 117 samples including industrial mine wastes, topsoil, and control soil were collected in and around the mine, and their heavy metal concentrations were determined using ICP-MS after aqua regia digestion. Except for Zn, the average concentrations of the metals were higher in mine wastes and the agricultural soils than their average upper continental crust (UCC) counterpart, whereas those of Ag, As, and Hg exceeded the UCC in the control soils. The control soils had the lowest contaminations and the lowest pollution levels for all metals except for Hg. Based on the average concentrations and coefficients of variation, it can be concluded that Cr, Ni, and Zn abundance in the agricultural soils was controlled by natural factors, whereas that of Ag, As, Hg, Co, Cu, and Mn was mainly associated with mining. The absence of Hg in industrial mine wastes and its high contents in agricultural and control soils reflected the artisanal gold mining source of this metal. Thus, single and integrated pollution indices showed that ecological risk and toxicity are much higher when Hg is included in the index calculation, suggesting cumulative effects of industrial and artisanal gold mining on the agricultural soil quality. The results also showed that Hg and As are the pollutants of major concern in the Kalsaka abandoned gold mine. Because of its proximity to human settlements, the Kalsaka abandoned gold mine necessitates an immediate rehabilitation.

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.

Characterization of medium and small-scale gold processing operations, wastewaters, and tailings in the Arequipa region of Peru.

Gold cyanidation facilities in the Arequipa Region of Peru are challenged by the availability and quality of water for processing in an arid environment. The facilities reuse decant water which recycles residual cyanide but also undesirable constituents. To understand the impact of intensive water recycling on cyanide and metals concentrations, we collected barren water, decant water, and tailings samples from six gold cyanidation facilities with ore capacities of 10-430 tons per day. Processing facilities in Arequipa recycle all effluents, with decant waters making up 58 ± 11 % of process waters. Decant water contained non-target metals: copper (394 ± 161 mg/L), iron (59 ± 34 mg/L), and zinc (74 ± 42 mg/L). In addition, decant water mean free and complexed cyanide concentrations were 534 ± 129 mg/L and 805 ± 297 mg/L, respectively. Complexed cyanide concentrations remained more constant than free cyanide concentrations with 786 ± 299 mg/L for barren water and 805 ± 297 mg/L for decant water. Cyanide mass balances showed between 21 % and 42 % of unaccounted free cyanide from the start of gold cyanidation and discharge to the tailings storage facility (TSF). Free cyanide estimated losses due to volatilization were 0.8 kg and 2.5 kg of hydrogen cyanide per ton of ore processed at barren water pH of 10.1 and 9.7. Together these results indicate two acute hazards: 1) volatilization of free cyanide during processing and 2) loading and retention of cyanides and metals into TSFs. This study elucidates the extent of uncontrolled vapor phase cyanide release during gold processing operation and contaminant concentrations in the tailings storage facilities. The data highlights the need for improvement oversight, accountability, and regulation of gold processing facilities practicing intensive recycling and zero discharge.

Legacy effects of historical gold mining on floodplains of an Australian river.

The gold rush at the end of the nineteenth century in south-eastern Australia resulted in the mobilization and re-deposition of vast quantities of tailings that modified the geomorphology of the associated river valleys. Previous studies of contamination risk in these systems have either been performed directly on mine wastes (e.g., battery sand) or at locations close to historical mine sites but have largely ignored the extensive area of riverine alluvial deposits extending downstream from gold mining locations. Here we studied the distribution of contaminant metal(loids) in the Loddon River catchment, one of the most intensively mined areas of the historical gold-rush period in Australia (1851-1914). Floodplain alluvium along the Loddon River was sampled to capture differences in metal and metalloid concentrations between the anthropogenic floodplain deposits and the underlying original floodplain. Elevated levels of arsenic up to 300 mg-As/kg were identified within the anthropogenic alluvial sediment, well above sediment guidelines (ISQG-high trigger value of 70 ppm) and substantially higher than in the pre-mining alluvium. Maximum arsenic concentrations were found at depth within the anthropogenic alluvium (plume-like), close to the contact with the original floodplain. The results obtained here indicate that arsenic may pose a significantly higher risk within this river catchment than previously assessed through analysis of surface floodplain soils. The risks of this submerged arsenic plume will require further investigation of its chemical form (speciation) to determine its mobility and potential bioavailability. Our work shows the long-lasting impact of historical gold mining on riverine landscapes.

"Hg distribution and accumulation in soil and vegetation in areas impacted by artisanal gold mining in the Southern Amazonian region of Madre de Dios, Peru."

Artisanal and small-scale gold mining (ASGM) is the primary global source of anthropogenic mercury (Hg) emissions. It has impacted the Amazon rainforest in the Peruvian region of Madre de Dios. However, few studies have investigated Hg's distribution in terrestrial ecosystems in this region. We studied Hg's distribution and its predictors in soil and native plant species from artisanal mining sites. Total Hg concentrations were determined in soil samples collected at different depths (0-5 cm and 5-30 cm) and plant samples (roots, shoots, leaves) from 19 native plant species collected in different land cover categories: naked soil (L1), gravel piles (L2), natural regeneration (L3), reforestation (L4), and primary forest (L5) in the mining sites. Hg levels in air were also studied using passive air samplers. The highest Hg concentrations in soil (average 0.276 and 0.210 mg kg-1 dw.) were found in the intact primary forest (L5) at 0-5 cm depth and in the plant rooting zones at 5-30 cm depth, respectively. Moreover, the highest Hg levels in plants (average 0.64 mg kg-1 dw) were found in foliage of intact primary forest (L5). The results suggest that the forest in these sites receives Hg from the atmosphere through leaf deposition and that Hg accumulates in the soil surrounding the roots. The Hg levels found in the plant leaves of the primary forest are the highest ever recorded in this region, exceeding values found in forests impacted by Hg pollution worldwide and raising concerns about the extent of the ASGM impact in this ecosystem. Correlations between Hg concentrations in soil, bioaccumulation in plant roots, and soil physical-chemical characteristics were determined. Linear regression models showed that the soil organic matter content (SOM), pH, and electrical conductivity (EC) predict the Hg distribution and accumulation in soil and bioaccumulation in root plants.

Highly Sensitive Whole-Cell Mercury Biosensors for Environmental Monitoring.

Whole-cell biosensors could serve as eco-friendly and cost-effective alternatives for detecting potentially toxic bioavailable heavy metals in aquatic environments. However, they often fail to meet practical requirements due to an insufficient limit of detection (LOD) and high background noise. In this study, we designed a synthetic genetic circuit specifically tailored for detecting ionic mercury, which we applied to environmental samples collected from artisanal gold mining sites in Peru. We developed two distinct versions of the biosensor, each utilizing a different reporter protein: a fluorescent biosensor (Mer-RFP) and a colorimetric biosensor (Mer-Blue). Mer-RFP enabled real-time monitoring of the culture's response to mercury samples using a plate reader, whereas Mer-Blue was analysed for colour accumulation at the endpoint using a specially designed, low-cost camera setup for harvested cell pellets. Both biosensors exhibited negligible baseline expression of their respective reporter proteins and responded specifically to HgBr2 in pure water. Mer-RFP demonstrated a linear detection range from 1 nM to 1 µM, whereas Mer-Blue showed a linear range from 2 nM to 125 nM. Our biosensors successfully detected a high concentration of ionic mercury in the reaction bucket where artisanal miners produce a mercury-gold amalgam. However, they did not detect ionic mercury in the water from active mining ponds, indicating a concentration lower than 3.2 nM Hg2+-a result consistent with chemical analysis quantitation. Furthermore, we discuss the potential of Mer-Blue as a practical and affordable monitoring tool, highlighting its stability, reliance on simple visual colorimetry, and the possibility of sensitivity expansion to organic mercury.

Risks to Human Health from Mercury in Gold Mining in the Coastal Region of Ecuador.

Artisanal and small-scale gold mining (ASGM) plays a crucial role in global gold production. However, the adoption of poor mining practices or the use of mercury (Hg) in gold recovery processes has generated serious environmental contamination events. The focus of this study is assessing the concentration of Hg in surface waters within the coastal region of Ecuador. The results are used to conduct a human health risk assessment applying deterministic and probabilistic methods, specifically targeting groups vulnerable to exposure in affected mining environments. Between April and June 2022, 54 water samples were collected from rivers and streams adjacent to mining areas to determine Hg levels. In the health risk assessment, exposure routes through water ingestion and dermal contact were considered for both adults and children, following the model structures outlined by the U.S. Environmental Protection Agency. The results indicate elevated Hg concentrations in two of the five provinces studied, El Oro and Esmeraldas, where at least 88% and 75% of the samples, respectively, exceeded the maximum permissible limit (MPL) set by Ecuadorian regulations for the preservation of aquatic life. Furthermore, in El Oro province, 28% of the samples exceeded the MPL established for drinking water quality. The high concentrations of Hg could be related to illegal mining activity that uses Hg for gold recovery. Regarding the human health risk assessment, risk values above the safe exposure limit were estimated. Children were identified as the most vulnerable receptor. Therefore, there is an urgent need to establish effective regulations that guarantee the protection of river users in potentially contaminated areas. Finally, it is important to continue investigating the contamination caused by human practices in the coastal region.

Public health assessment of Kenyan ASGM communities using multi-element biomonitoring, dietary and environmental evaluation.

The Kakamega gold belt's natural geological enrichment and artisanal and small-scale gold mining (ASGM) have resulted in food and environmental pollution, human exposure, and subsequent risks to health. This study aimed to characterise exposure pathways and risks among ASGM communities. Human hair, nails, urine, water, and staple food crops were collected and analysed from 144 ASGM miners and 25 people from the ASGM associated communities. Exposure to PHEs was predominantly via drinking water from mine shafts, springs and shallow-wells (for As>Pb>Cr>Al), with up to 366 µg L-1 arsenic measured in shaft waters consumed by miners. Additional exposure was via consumption of locally grown crops (for As>Ni>Pb>Cr>Cd>Hg>Al) besides inhalation of Hg vapour and dust, and direct dermal contact with Hg. Urinary elemental concentrations for both ASGM workers and wider ASGM communities were in nearly all cases above bioequivalents and reference upper thresholds for As, Cr, Hg, Ni, Pb and Sb, with median concentrations of 12.3, 0.4, 1.6, 5.1, 0.7 and 0.15 µg L-1, respectively. Urinary As concentrations showed a strong positive correlation (0.958) with As in drinking water. This study highlighted the importance of a multidisciplinary approach in integrating environmental, dietary, and public health investigations to better characterise the hazards and risks associated with ASGM and better understand the trade-offs associated with ASGM activities relating to public health and environmental sustainability. Further research is crucial, and study results have been shared with Public Health and Environmental authorities to inform mitigation efforts.

Arsenic, cadmium, lead, antimony bioaccessibility and relative bioavailability in legacy gold mining waste.

Bioaccessibility and relative bioavailability of As, Cd, Pb and Sb was investigated in 30 legacy gold mining wastes (calcine sands, grey battery sands, tailings) from Victorian goldfields (Australia). Pseudo-total As concentration in 29 samples was 1.45-148-fold higher than the residential soil guidance value (100 mg/kg) while Cd and Pb concentrations in calcine sands were up to 2.4-fold and 30.1-fold higher than the corresponding guidance value (Cd: 20 mg/kg and Pb: 300 mg/kg). Five calcine sands exhibited elevated Sb (31.9-5983 mg/kg), although an Australian soil guidance value is currently unavailable. Arsenic bioaccessibility (n = 30) and relative bioavailability (RBA; n = 8) ranged from 6.10-77.6% and 10.3-52.9% respectively. Samples containing > 50% arsenopyrite/scorodite showed low As bioaccessibility (<20.0%) and RBA (<15.0%). Co-contaminant RBA was assessed in 4 calcine sands; Pb RBA ranged from 73.7-119% with high Pb RBA associated with organic and mineral sorbed Pb and, lower Pb RBA observed in samples containing plumbojarosite. In contrast, Cd RBA ranged from 55.0-67.0%, while Sb RBA was < 5%. This study highlights the importance of using multiple lines of evidence during exposure assessment and provides valuable baseline data for co-contaminants associated with legacy gold mining activities.

The global challenge of reducing mercury contamination from artisanal and small-scale gold mining (ASGM): evaluating solutions using generic theories of change.

Mercury contamination from artisanal and small-scale gold mining (ASGM) currently accounts for 37% of the global total, often affecting tropical regions where regulations, if they exist, are often poorly enforced. Ingestion by people and other animals damages the nervous, reproductive, and cognitive systems. Despite the efforts of many organizations and governments to curb mercury releases from ASGM, it is increasing globally. There are many possible interventions, all with significant complexity and cost. Therefore, we recommend taking an established systematic approach to articulate the current situation and construct theories of change (ToC) for different possible interventions for any government or organization trying to solve this problem. Here we present a high-level situation analysis and generic ToC to support a more coordinated approach that explicitly builds upon previous experience to identify organization- and situation-appropriate engagement on this issue. We then illustrate the use of these generic models to construct a specific ToC with a policy-focused entry point. This includes interventions through (1) engagement with the global Minamata Convention on Mercury; (2) support for existing national laws and policies connected to ASGM and mercury contamination; and (3) engagement of indigenous people and local communities with governments to meet the governments' legal obligations. By methodically articulating assumptions about interventions, connections among actions, and desired outcomes, it is possible to create a more effective approach that will encourage more coordination and cooperation among governments and other practitioners to maximize their investments and support broad environmental and socio-political outcomes necessary to address this pernicious problem.

Trends in Mercury Contamination Distribution among Human and Animal Populations in the Amazon Region.

Mercury contamination in the Amazon arising from both natural sources and intensive mining activities in the region is a significant public health concern. This metal is used to separate Au from sediments. Accordingly, this study aimed to assess the impact of mining on mercury contamination in the animal and human populations of the Amazon. This overall objective was pursued through a systematic review of the existing literature to assess the impact of Hg and identify gaps in geographic coverage arising from this assessment. Herein, we employed PECO and PRISMA-ScR protocols to select articles published between 2017 and 2023 based on projected points on a map within the biogeographic boundaries of the Amazon. We found that mercury concentrations increase with trophic levels, reaching high values of 3.7 µg/g in the muscles of predatory fish and 34.9 µg/g in human hair. The mean level of mercury in human hair in the whole (Amazon) region exceeds 6 µg/g, surpassing tolerance levels. Although mining regions show high concentrations of Hg, the highest incidence was observed among populations with fish-based diets. It was concluded that continuous research and monitoring of fish in the region are required in order to accurately assess the risk associated with Hg contamination, especially since fish are the main source of protein in this region.

Elevated mercury exposure in bird communities inhabiting Artisanal and Small-Scale Gold Mining landscapes of the southeastern Peruvian Amazon.

Artisanal and Small-Scale Gold Mining (ASGM) represents a significant source of anthropogenic mercury emissions to the environment, with potentially severe implications for avian biodiversity. In the Madre de Dios department of the southern Peruvian Amazon, ASGM activities have created landscapes marred by deforestation and post-mining water bodies (mining ponds) with notable methylation potential. While data on Hg contamination in terrestrial wildlife remains limited, this study measures Hg exposure in several terrestrial bird species as bioindicators. Total Hg (THg) levels in feathers from birds near water bodies, including mining ponds associated with ASGM areas and oxbow lakes, were analyzed. Our results showed significantly higher Hg concentrations in birds from ASGM sites with mean ± SD of 3.14 ± 7.97 µg/g (range: 0.27 to 72.75 µg/g, n = 312) compared to control sites with a mean of 0.47 ± 0.42 µg/g (range: 0.04 to 1.89 µg/g, n = 52). Factors such as trophic guilds, ASGM presence, and water body area significantly influenced feather Hg concentrations. Notably, piscivorous birds exhibited the highest Hg concentration (31.03 ± 25.25 µg/g, n = 12) exceeding known concentrations that affect reproductive success, where one measurement of Chloroceryle americana (Green kingfisher; 72.7 µg/g) is among the highest ever reported in South America. This research quantifies Hg exposure in avian communities in Amazonian regions affected by ASGM, highlighting potential risks to regional bird populations.

Data on investigation of potential gold mineralization sites in Tchollire and Environs (North Cameroon).

Fresh and altered rock samples were collected and analyzed during field and laboratory studies in Tchollire and Environs. This approach aimed at the delineation of hydrothermal alteration minerals which according to the geological and mining settings of Tchollire and Environs, may be associated with gold mineralizations sites. Field investigations were achieved during the dry season to ensure the representativeness and reliability of our samples whose collections were constrained by earlier remote sensing and geophysical studies as expressed in [1]. An optical microscope both in reflected and transmitted light was used for petrographic analyses of thin and polished sections of rock samples. Other rock samples were prepared for spectral measurements which were achieved using an analytical spectral device spectrometer. The data presented here are further interpreted and discussed in [1].

Assessment of mercury distribution and bioavailability from informal coastal cinnabar mining - Risk to the marine environment.

Coastal cinnabar mining commenced in 2010 around Luhu on Seram (Ceram) Island, Indonesia. This study investigates the ore characteristics and environmental distribution and bioavailability of mercury in coastal sediments from eight sites adjacent to, and north and south of the mining area. Sediment and ore samples were digested using 1:3 HNO3:HCl for total extractable metal determination and separate samples were extracted with 1.0 HCl for bioavailable metals (Hg, Cu, Zn, Cr, Ni and Pb). Analysis was completed using inductively coupled plasma-mass spectrometry. Ore defined by miners as 'first class ore' was around 50 % cinnabar. Mercury concentrations were extremely elevated in near coastal sediments (up to 2796 mg/kg) with bioavailable concentrations exceeding 450 mg/kg. Marine sediments elevated in mercury extend to the north and south of the coastal mine site and cover in excess of 14 km. Total organic carbon in marine sediments was relatively low (predominately <0.6 %) suggesting mercury methylation will likely be slow, however, inorganic mercury is a known toxicant. Other metals of environmental concern (Cu, Zn, Cr, Ni and Pb) in sediments were not strongly associated with the mining operations, rather were elevated around coastal villages, but not at concentrations that raise immediate concerns.

Prenatal arsenic and mercury levels among women practicing geophagy in areas with artisanal and small-scale gold mining activities, Northwestern Tanzania.

BACKGROUND: Artisanal and small-scale gold mining (ASGM) areas potentially pose increased exposure to arsenic and mercury through community contamination, occupations at gold mines, and/or geophagy when soil is locally sourced. This study examined the effects of geophagy, a deliberate soil eating practice, along with community and occupational exposures in ASGM areas on urinary arsenic and blood mercury levels among pregnant women in the Mining and Health Longitudinal Cohort in northwestern Tanzania. METHODS: Data on maternal arsenic and mercury levels were captured for 1056 pregnant women using an unprovoked morning urine samples and dried blood spots respectively. We used a step-wise generalized linear regression model to retain the most relevant covariates for the model. A generalized linear regression model with identity link function was used to predict the effect of geophagy practices on arsenic and mercury levels separately. The model was adjusted using sociodemographic correlates, including maternal age, education level, whether respondents lived in mining or non-mining area, years of residence, marital status, maternal occupation, individual partner's education, and occupational, and socioeconomic status. RESULTS: In the adjusted regression model, eating soil during pregnancy increased arsenic concentration by almost 23% (ß = 1.229, 95% CI: 1.094, 1.38, p < 0.001) and living in mining areas had a 21.2% (ß = 1.212; 95% CI: 1.039,1.414, p = 0.014) increased risk. Geophagy significantly increased mercury levels by 13.3% (ß = 1.133, 95% CI: 1.022, 1.257, p = 0.018). Living in areas with ASGM activities was associated with a 142% (ß = 2.422, 95% CI: 2.111, 2.776, p < 0.0001) increase in blood mercury. CONCLUSION: Geophagy practices increased urinary arsenic and blood mercury levels in pregnant women, which was especially true for arsenic when living in areas with ASGM activities. Working in mining = increased risk for blood mercury levels. Community-based environmental health policies should address reductions in occupational and community exposures, along with strategic geophagy reduction interventions.