Artisanal And Small-scale Gold Mining Activities Research Articles

Mercury-free artisanal and small-scale gold mining: Proposing a community-business model canvas

The use of mercury in artisanal and small-scale gold mining (ASGM) is one of its least favourable applications. Although prior research about the formalisation of these mining systems has explored approaches to attaining sustainable development, studies that consider business models tailored to mining communities are absent. The question becomes, ‘what sort of business model could engage the ASGM community to eliminate the use of mercury and how sustainable ASGM activities could be achieved by the implementation of such a business model?’ This paper examines the relationships between ASGM, business models, and sustainability. We provide an analysis of managerial concepts applied to the ASGM field, emphasising a mercury-free transition. Through a case study of Barksanem mining company in Burkina Faso, we propose a novel framework for sustainable community-business models, which we call the community-business model canvas, to foster that transition. This canvas is meant to encourage more interdisciplinary research in the fields of management and mining and is an attempt to involve all the stakeholders in an enabling role in community-business models. The latter canvas has the potential to support mineral policy making, programmes, and business practices in building sustainable futures for artisanal and small-scale miners and their dependents.

Element Rich Area Associated with Human Health Disorders: A Geomedical Science Approach to Potentially Toxic Elements Contamination.

(1) Background: Geomedical science focuses on the relationship between environmental impact and human health. The abundance of elements in a geographic area is reflected accumulation of these elements in humans. This study aims to describe the relationship between concentrations of geologic elements and accumulations in the human body as well as element-related symptoms. (2) Methods: Geogenic sampling was conducted in an Artisanal and Small-Scale Gold Mining (ASGM) area and around residential areas in Indonesia, and samples were analyzed using particle-induced X-ray Emission (PIXE). Head hair was sampled, and health assessments were performed to determine heavy metal exposure, especially to copper and mercury. (3) Results: Results show that potentially toxic elements’ accumulation in the human body follows the abundance of these elements in the geographic area, which then affect health and manifest with specific signs and symptoms. East Tulabolo is an area rich in copper (hazard quotient (HQ) in dust = 152.8), and most of the population shows the sign of Kayser–Fleischer rings. Likewise, the Dunggilata area has the highest concentration of mercury, especially in the dust (HQ = 11.1), related to ASGM activity in residential areas. (4) Conclusions: This study concludes that the geogenic concentration of elements parallels the accumulation of human tissue and manifests with element-related signs and symptoms.

Formalization is just the beginning: Analyzing post-formalization successes and challenges in Peru's small-scale gold mining sector

In recent years, the formalization of artisanal and small-scale gold mining (ASGM) activities has become a key strategy for governments to better govern and regulate the sector. While scholars have focused on examining the viability of formalization itself, little is known about the outcomes once ASGM operations become formal, or whether formalization efforts are sustainable. Peru has made great strides on simplifying the formalization process and has formalized over 9600 artisanal miners. Drawing on a case study from one of these formalized operations, this research examines postformalization outcomes. Findings from interviews with government officials and members of the ASGM community in one of the most important ASGM regions of Peru, Puno, demonstrate that formalization has yielded mixed results. Formal ASGM operations have improved health and safety practices and labor conditions, and miners believe their environmental awareness has increased. Despite these changes, miners who have become formalized feel even more pursued and scrutinized than they did when they operated informally, and they continue to face challenges obtaining technical support and accessing capital. We argue that although some progress has been made in formalization efforts, the problems and weaknesses within the approach may inadvertently push miners back into informality.We conclude that in order for formalization to be more fruitful for governments and miners, governments working on formalizing ASGM activities would greatly benefit from the creation of a solid postformalization strategy focused on educating and supporting formal ASGM operations.

An Investigation of the Socio-Economic Benefits of Small-Scale Gold Mining in Malawi

In the recent years, there has been a surge in artisanal and small-scale gold mining (ASGM) in various districts of Malawi. Reports of a gold rush have emerged in various districts, including Mangochi, Lilongwe, Balaka, and lately in Kasungu. There has been persistence by many indigenous communities participating in ASGM activities, yet little is being done by the government to formalize and support the sub-sector. The purpose of this study was to investigate the benefits of artisanal small-scale gold mining in Malawi and expose the shortfalls so that key stakeholders and policy makers are well informed. A quantitative approach which used semi-structured questionnaires was used and the data was analyzed using Microsoft excel and Statistical Packages for the Social Sciences (SPSS). The study shows that ASGM is characterized by people with low literacy levels, who use traditional tools (low-tech) and use methods fueled by lack of capital, and deficiency of basic knowledge of mining and geology. The study found that the government could achieve substantial socio-economic development from the sector by: (1) revising the current artisanal and small-scale mining (ASM) legislation so that it embraces the customary practices whilst safeguarding the environment and improving the tax collection base; (2) providing support in form of mining related training and education to these communities; (3) leading in transfer of modern technologies for improved extraction; (4) supporting ASM cooperatives in securing credit facilities from financial institutions; and (5) closing the existing knowledge gap for ASM related issues through introduction of mining desk officers in district councils.

The effect of artisanal gold mining on aquatic insect communities: a case study in Costa Rica

Among the anthropogenic disturbances that affect rivers, artisanal and small-scale gold mining (ASGM) has recently generated great concern regarding the deterioration of aquatic ecosystems. This study aimed to evaluate the impact of ASGM on the assemblages of aquatic insects. For this, aquatic insects were sampled from two actively mined streams in the Osa Peninsula in Costa Rica. ASGM produces significant changes in the richness, abundance and assemblage’s composition of aquatic insects. These changes, however, are mitigated a few meters downstream, after encountering a seemingly undisturbed tributary, for which the stream seems to keep its stability through resilience. For ASGM activities that have low intensities of extraction and don’t use pollutant chemicals for amalgamation, keeping a low intensity of the activity and a considerable distance between goldmining sites could be an option for a more sustainable development of this activity, since it allows biodiversity to be partially restored.

Preponderance of Vaccine Preventable Diseases Hotspots in Northern Ghana: A Spatial and Space-Time Clustering Analysis from 2010 to 2014

Background: National immunization programs around the world have seen massive improvements in the last few decades especially, in vaccinations coverage. This notwithstanding, vaccine-preventable diseases (VPDs) have persisted globally with a disproportionately high burden in Low and Middle-Income Countries (LMICs). Perhaps, a more nuanced understanding of VPD transmission beyond vaccination coverage may help optimise VPDs control efforts. This study set out to first identify VPDs hotspots in Ghana, and subsequently, explore how ecology, ubanicity and land-use variations (Artisanal and Small-scale Gold Mining (ASGM) activities) may influence the spatial distribution hotspots. Methods: The study used district-level disease count data from 2010 to 2014 from the Ghana Health Service (GHS) and population data from the Ghana Population and Housing Census (PHC) in determining the clustering patterns for six VPDS (Measles, Meningitis, Mumps, Otitis media, Pneumonia and Tetanus). Purely spatial and space-time cluster analyses were implemented in SaTScan using the discrete Poisson model and the default settings which calculate pp = 0.045), incidence of the other five VPDs did not differ across the urban-rural divide. The relationship between ASGM activities and VPDs was ambivalent. Whereas spatial analysis suggested that some VPD hotspots (tetanus and otitis media) occur more frequently in mining districts in the southern part of the country, a Mann-Whitney U test revealed a higher incidence of meningitis in non-mining districts (p = 0.019). Interpretation: Taken together, this study presents evidence of a preponderance of VPDs hotspots in the northern parts of Ghana. It also highlights differences in VPD clustering patterns and its implications for integration VPDs control activities into a unified framework. Further studies will be needed to clarify the relationship between ASGM activities and VPD transmission in Ghana. Funding Information: This study was partly supported by funding from Pure Earth. Declaration of Interests: We declare no competing interests.

Assessment of Atmospheric Mercury Deposition in the Vicinity of Artisanal and Small-Scale Gold Mines Using Glycine max as Bioindicators

Artisanal and Small-scale Gold Mining (ASGM) is one of the main sources of global Hg emissions and is present over a wide territorial in the southern Amazonia. In this region, there is a rapid approximation between agricultural and livestock activities and the impact of this close proximity having little or no evaluation. Thus, we have determined the Hg concentration in soybean plants in an area with ASGMs activities. The concentration of Hg in plants was higher in the vicinity of the ASGMs, where the Hg leaf concentration was three times higher, suggesting a higher atmospheric metal deposition in this area. It is estimated that atmospheric Hg deposition in the vicinity of ASGMs of up to 6.94 g km−2 during the contact time between leaves and atmosphere. The translocation and bioaccumulation factors reinforce the effect of atmospheric Hg deposition, mainly, in the leaves. No impact was observed on the edible part of the plant due to the proximity of the ASGMs. It can be inferred that our results point to considerable rates of Hg emissions in the southern Amazon region and indicate the need to monitor these emissions so as to facilitate the taking of pollution mitigation actions. Soybean plants have a potential use as a bioindicator species of Hg contamination from ASGM, and the proposed method consists of an viable alternative, which can be used for the biomonitoring of long-term Hg emissions.

Application of the Quartz Crystal Microbalance Method for Measuring Mercury in the Air of Working Environments Involved to Artisanal and Small-scale Gold Mining (ASGM).

Artisanal small gold mining (ASGM) is responsible for approximately 40% of the total Hg emissions into the atmosphere worldwide. In developing countries, many people are engaged in ASGM activities. We developed a small, simple Hg measuring device, which detects Hg in the air based on the change of the oscillation frequency of an Au electrode on a quartz crystal microbalance (QCM). This device is called QCM-Hg. We tested the viability of the QCM-Hg in various work settings including a gold mining area and gold shops. In working environments with an airborne Hg concentration of several μg m-3, the changing rate of the oscillation frequency for either 2 or 3 min corresponded with the Hg concentrations measured using the conventional method of gold amalgamation and cold vapor atomic absorption spectrometer (CVAAS). The results revealed that the QCM-Hg is a useful device for real-time Hg monitoring in actual working environments related to ASGM activities and Hg treatment facilities.

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

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

Spatial Analysis of Artisanal and Small-Scale Mining in the Tarkwa-Nsuaem Municipality of Ghana

Abstract
 In recent times there have been lots of public outcry on the environmental and public health and safety effects of Artisanal and Small-scale gold Mining (ASM) and the need to monitor ASM activities for reclamation purposes. To effectively develop and deploy policy responses to the environmental and human health effects of ASM, knowledge of the locations and distribution of ASM sites is a prerequisite. However, information regarding ASM hotspots and spatial distribution, the scope and types of ASM operations are hard to find. Therefore, this research was designed to use satellite-based data to map out ASM sites, focusing on the Tarkwa-Nsuaem municipality as the study area. Several image processing techniques were applied on a Landsat 8 satellite image downloaded from the US Geological Survey website. The image processing resulted in the identification of 221 clusters of ASM sites, representing 12.72% of the total size of the study area. To further explore the effects of these ASM sites, Areas of Interest (AOI) including forest reserve, rivers, large-scale mines and urban settlements were defined. By selecting and analysing the location and distribution of the ASM sites in relations to the AOI, the study was effective in identifying environmentally sensitive and critical areas warranting the urgent attention of society to mitigate the health, safety and ecosystem service effects of ASM in the study area. By identifying the environmental sensitive areas being affected by ASM, the findings could support the prioritisation of reclamation efforts.
 
 Keywords: Artisanal Small-Scale Mining, Satellite Image, Environmental Effect, Public Health and Safety

Evaluation of selected heavy metals on the artisanal gold mining sites in North Rift Region, Kenya

ASGM activity significantly contributes to the economies of developing countries with a consequent impact on the socio-ecological systems. The impacts are largely due to the wide use of mercury in the extraction processes. It also deforestates the exploited areas with consequent loss of biodiversity and ecosystem functions. ASGM has varied impacts of adverse health effects and it is said that mercury has more significant health effects than other heavy metals (Cd, Pb, As, and Cr). Due to dearth in the studies on artisanal mining in Kenya, the study sought to evaluate the concentration levels of selected heavy metals on the artisanal mining sites in Nandi and West Pokot Counties of Kenya in order to determine their nature, concentration levels and suggest mitigation measure. The study was done in two artisanal gold mining sites in Kapsaos in Nandi County and Sekker in West Pokot County in Kenya and employed a comparative analysis to examine the attributes of these locational spaces. Thirteen samples were randomly collected from tailings at different points from the tailing disposal site in Kapsaos areas and Sekker site. The samples were transported prepared and stored at Environmental Chemistry Laboratory, the University of Eldoret where it was subjected to Atomic Absorption Spectroscopy (AAS). The laboratory analysis results showed that the samples from both artisanal gold mining sites contained several heavy metals which included Chromium, Cadmium, and Lead. Overall, the mining sites in Nandi County had the following concentration of Cr, 0.4195 ppm, Cd, 0.2470 ppm, and Pb, 0.6300 ppm, while the mining sites in West Pokot county had the following concentrations: Cr, 0.1790 ppm; Cd, 0.0050 ppm; and Pb, 0.7400 ppm. Besides, the concentrations levels of Lead and Cadmium were above the WHO guidelines. A casual look at the concentration levels indicates that the mining sites in Nandi County have higher concentration levels of selected heavy metals (Pb, Cd and Cr) that in West Pokot County which was attributable to the ASGM activities. The study concluded that ASGM activities excavates, destabilizes the stables states of elements and then concentrates them. Finally, the study recommends that ASGM be upscaled instead of being frowned upon. Further studies on the potential socio-economic impacts on the ASGM activities in Western Kenya because the activity is considered a complementary/supplementary economic activity. Keywords: Artisanal and small scale gold mining (ASGM), artisanal mining, selected heavy metals, mercury, heavy metal pollution DOI: 10.7176/JEES/10-6-12 Publication date: June 30 th 2020

A population-based mercury exposure assessment near an artisanal and small-scale gold mining site in the Peruvian Amazon.

Human exposure to mercury is a leading public health problem. Artisanal and small-scale gold mining (ASGM) is a major source of global mercury emissions. Although occupational mercury exposure to miners (via mercury vapor inhalation) is known, chronic mercury exposure to nearby residents that are not miners (via mercury-contaminated fish consumption) is poorly characterized. We conducted a population-based mercury exposure assessment in 23 communities (19 rural, 4 urban) around the Amarakaeri Communal Reserve, which is bordered on the east by heavy ASGM activity. We measured total mercury in hair (N = 2083) and blood (N = 476) from March-June 2015 and performed follow-up measurements (N = 723 hair and N = 290 blood) from February-April 2016. Mercury exposure risk was highest in communities classified as indigenous, or native, regardless of proximity to mining activity. Residence in a native community (vs. non-native) was associated with mercury levels 1.9 times higher in hair (median native 3.5 ppm vs. median non-native 1.4 ppm total mercury) and 1.6 times higher in blood (median native 7.4 ng/mL vs median non-native 3.2 ng/mL total mercury). Unexpectedly, proximity to mining was not associated with exposure risk. These findings challenge common assumptions about mercury exposure patterns and emphasize the importance of population-representative studies to identify high risk sub-populations.

Survey of Methylmercury Exposures and Risk Factors Among Indigenous Communities in Guyana, South America.

Background.Gold mining activities in forested areas across Guyana have been a common practice for more than a century. The intensification of artisanal and small-scale gold mining (ASGM) in recent decades caused by global market demand is contributing to the mobilization of mercury into aquatic systems. Indigenous populations who consume high levels of locally sourced fish are greater at risk for methylmercury poisoning from ingestion of contaminated fish.Objectives.The aim of the present study was to investigate the levels of mercury contamination and identify the risk factors associated with hair mercury levels in four indigenous communities in Guyana.Methods.Concentrations of total mercury were measured in hair samples from 99 participants from four indigenous communities in the south Rupununi region in Guyana. The findings of this study were compared with those of previous studies to assess the prevalence of mercury contamination in indigenous communities across Guyana.Results.Hair mercury levels were found to be above the World Health Organization (WHO) reference value for residents who live close to ASGM activities and who consume high quantities of locally sourced fish. Our results are not only consistent with those obtained in previous studies, but also evidence that mercury poisoning has become a generalized problem for indigenous communities in Guyana.Conclusions.Fish is the main source of protein for many riverine communities and consumption of mercury-contaminated fish poses a serious health hazard for these vulnerable populations. The situation is especially dire for community members of Parabara with 100% of participants showing elevated (>15 μg*g−1) hair mercury levels. It is therefore crucial that Parabara residents be evaluated by relevant health agencies for clinical symptoms related to mercury toxicity.Participant Consent.ObtainedEthics Approval.The study protocol was approved by the Institutional Review Board of the Ministry of Public Health, Guyana.Competing Interests.The authors declare no competing financial interests.

Deforestation Due to Artisanal and Small-Scale Gold Mining Exacerbates Soil and Mercury Mobilization in Madre de Dios, Peru.

Artisanal and small-scale gold mining (ASGM) is a significant contributor of mercury (Hg) contamination and deforestation across the globe. In the Colorado River watershed in Madre de Dios, Peru, mining and deforestation have increased exponentially since the 1980s, resulting in major socioeconomic shifts in the region and two national state of emergency (2016 and 2019) in response to concerns for wide-scale mercury poisoning by these activities. This research employed a watershed-scale soil particle detachment model and environmental field sampling to estimate the role of land cover change and soil erosion on river transport of Hg in a heavily ASGM-impacted watershed. The model estimated that observed decreases in forest cover increased soil mobilization by a factor of two in the Colorado River watershed during the 18 year period and by 4-fold in the Puquiri subwatershed (the area of most concentrated ASGM activity). If deforestation continues to increase at its current exponential rate through 2030, the annual mobilization of soil and Hg may increase by an additional 20-25% relative to 2014 levels. While, the estimated total mass of Hg transported by rivers is substantially less than the estimated tons of Hg used with ASGM in Peru, this research shows that deforestation associated with ASGM is an additional mechanism for mobilizing naturally occurring and anthropogenic Hg from terrestrial landscapes to aquatic environments in the region, potentially leading to bioaccumulation in fish and exposure to communities downstream.

Time variation in transfer amounts of mercury by a river system near an artisanal and small-scale gold mining area in West Java, Indonesia

To evaluate the impact of mercury released into a river system by artisanal and small-scale gold mining (ASGM) activity in West Java, Indonesia, the temporal variations in elemental mercury, mercury ions, dissolved total mercury and particulate mercury concentrations in river water were observed in March 2015 (rainy season) and August 2015 (dry season) at a fixed observation point, and the migrated amount of mercury was estimated. Variations for other metals, total organic carbon (TOC), and total nitrogen (TN) contents were also measured. There have been few reports in which the amount of mercury transferred from ASGM activities is quantitatively estimated, and this study provides important data for evaluating the environmental impact of mercury released by ASGM activities. The concentration of filtered total mercury and the particulate mercury concentration observed in the dry season were 161 ± 167 μg L−1 and 142 ± 93 μg L−1, respectively, and these values were significantly higher than the values of 24.5 ± 23.9 μg L−1 and 53.7 ± 44 μg L−1 for filtered total mercury and particulate mercury, respectively, observed in the rainy season. On the other hand, the river flow in the rainy and dry seasons was 2.6 × 104 ± 5×103 m3 h−1 and 8.2 × 103 ± 8×102 m3 h−1, respectively, and an apparent increase in the amount of water in the rainy season was observed. The transfer amounts in the rainy and dry seasons obtained from these results were 6.2 × 102 ± 6.7 × 102 g h−1 and 1.6 × 103 ± 1.6 × 103 g h−1, respectively, for filtered total mercury and 1.3 × 103 ± 1.3 × 103 g h−1 and 1.1 × 103 ± 7×102 g h−1, respectively, for particulate mercury. The temporal variations in these values exhibited a wide range, indicating the effects of weather conditions and of the mining process.

Population-based dietary exposure to mercury through fish consumption in the Southern Peruvian Amazon

BackgroundMercury exposure related to artisanal and small-scale gold mining (ASGM) has raised environmental and public health concerns globally. Exposure to mercury, a potent neurotoxin that bioaccumulates in fish, is especially of concern to women of childbearing age (WCBA) and children in high-fish consuming populations. In Madre de Dios (MDD), Peru, an Amazon region with naturally occurring mercury and high ASGM activity, there is significant exposure concern among the mainly riverine, fish-consuming communities. The objective of this study was to conduct the first assessment of mercury exposure in a population-based sample of MDD, identify factors associated with elevated levels and compare the relationship between fish consumption and hair total mercury (H-THg) among persons living in ASGM affected and non-ASGM affected watersheds. MethodsHair samples and household demographic surveys, including a module on fish consumption, were collected from 723 participants across 46 communities within 10 km of the Interoceanic Highway in MDD, who were previously enrolled in the first population-based study in MDD spanning areas affected and unaffected by ASGM. H-THg concentration (natural log transformed) was evaluated for association with independent demographic variables through multilevel multivariate regression models accounting for clustering among households and communities. Samples from canned fish available at local stores were also tested for total mercury. ResultsFish consumption (diversity and total consumed) varied spatially along the highway. 269 participants (37.2%) had elevated H-THg (>2.2 μg/g; median 1.60 μg/g; mean 2.24 μg/g), including 42.7% of WCBA and 20.0% of children under 5. Overall, H-THg was higher among people living in ASGM-affected areas. H-THg concentrations were strongly associated with fish consumption; however, in the multivariate models, household consumption of high trophic level fish was associated with elevated H-THg only in communities located in the ASGM-impacted watersheds. Similarly, the relationship between living in a household engaged in economic activities of fishing or Brazil nut harvesting was associated with higher H-THg, but only among households in the ASGM-affected area. In the non-ASGM affected areas, we observed a positive relationship between household daily fruit consumption and H-THg that was not observed in ASGM-affected areas. ConclusionDiet, residential location, and occupation are strong predictors of mercury exposure in Madre de Dios, Peru. Canned fish may represent a previously overlooked source of dietary Hg exposure in the region. In accordance with the Minamata Convention on Mercury, the significant environmental health concern of mercury exposure in ASGM areas demands policy and programmatic attention.

Comparison of Mercury Contamination in Four Indonesian Watersheds Affected by Artisanal and Small-Scale Gold Mining of Varying Scale

Artisanal and small-scale gold mining (ASGM) accounts for almost half of anthropogenic mercury (Hg) emissions worldwide and causes widespread water pollution. In Indonesia, several studies have identified harmful levels of Hg in areas affected by ASGM. While most of these studies focus on mining areas with thousands of miners, water contamination in smaller ASGM areas is less understood. We evaluated Hg contamination in four ASGM areas in Central Java of varying scale (from 30 to 3000 amalgamator barrels at each area), including Jatiroto, Kebonsari, Gumelar, and Kulon Progo. At each location, we collected water samples along river transects upstream and downstream of ASGM areas during the dry season (June–July 2017). Total Hg (THg) concentrations in stream water increased by orders of magnitude from upstream to downstream of ASGM activities at Jatiroto (1.35–4730 ng/L), with smaller observed increases at the other locations. Dissolved THg concentrations exceeded USEPA criteria for aquatic life (12 ng/L) at two of the four ASGM areas. THg concentrations in tailings exceeded 150,000 ng/L. Notably, THg concentrations in stream water were not directly related to the scale of mining, with Jatiroto having the highest concentrations as second smallest mining areas of the four in this study. Downstream of the mining areas, the fraction of dissolved methyl Hg to dissolved THg reached 20%, indicating that active Hg methylation occurs in the watersheds. Further study is needed to investigate Hg transport in the wet season when rainfall and high stream discharge may mobilize contaminated sediment near mining areas.

Transport of mercury species by river from artisanal and small-scale gold mining in West Java, Indonesia.

To estimate the impact of mercury discharged from artisanal and small-scale gold mining (ASGM) activity, variations in the concentrations of elemental mercury (Hg0), mercury ion (Hg2+), particulate mercury (P-Hg), and total mercury in filtered river water (FT-Hg) were investigated from sampling locations extending from 10km upstream to 30km downstream of ASGM operations in West Java, Indonesia. The average of the annual concentrations at the ASGM site from 2013 to 2017 were 0.14-0.85μgL-1, 0.27-12.9μgL-1, 4.3-49.5μgL-1, and 1.2-12.5μgL-1 for Hg0, Hg2+, P-Hg, and FT-Hg, respectively. The concentration of mercury species decreased as the distance from the ASGM site increased, while the ratio of P-Hg increased towards the lower reaches of the river system, with the percentage of P-Hg estimated at 90% of Hg at the sample location furthest downstream. A high mercury concentration of 600mgkg-1 was observed for suspended particulate matter (SPM) at the ASGM site. The SPM maintained a high concentration of mercury, even in the downstream area. In the annual variations of the mercury species from 2013 to 2017, FT-Hg and P-Hg concentrations tended to decrease from 2016, which suggested a decline of ASGM activity in this area. However, SPM and river sediment showed no apparent changes in their mercury concentrations over this period, indicating that the contamination in the river system is persistent and does not recover quickly.

Sedimentation and sediment core profile of heavy metals in the Owabi reservoir in Ghana

AbstractTropical reservoirs are important for numerous socioeconomic and ecological reasons, including water supply, fishing and flood control. These functions are easily compromised, however, when reservoirs undergo accelerated sedimentation with increased inputs of chemical contaminants. The present study applied the concept of sediment core analysis to evaluate the sedimentation rate in Owabi Reservoir, which has served as a source of drinking water supply in Kumasi, Ghana, for nearly a century. The temporal variation of contamination from heavy metals was also assessed over this period. The sedimentation rate for Owabi Reservoir was estimated to be 6.82 mm/year, suggesting a relatively low rate of sedimentation, which is ecologically healthy in preventing a rapid loss of reservoir water volume. Heavy metal concentrations in the sediment cores taken from the reservoir reflected varying degree of contamination from the 1930s to 2010s. The concentration of iron (Fe) (1,560–1,770 mg/kg) was found to be the highest among the metals in the sediment core, while mercury (Hg) concentration (0.01–0.04 mg/kg) was the lowest. Lead (Pb) contamination peaked in the 1980s. Arsenic (As) and mercury (Hg) contamination exhibited more recent peaks in the 2000s, coinciding with recent widespread issues of artisanal and small‐scale gold mining (ASGM) in Ghana. Thus, even though ASGM activities are known to occur in remote districts, releases from such activities might eventually contaminate reservoirs designated as urban drinking water supplies.

Maternal exposure to arsenic and mercury in small-scale gold mining areas of Northern Tanzania

Artisanal and small-scale gold mining (ASGM) in Tanzania results in occupational exposures and environmental contamination to toxic chemical elements such as arsenic and mercury. Populations living in such areas may be exposed by various routes, and prenatal exposure to arsenic and mercury has been associated with adverse birth outcomes and developmental delays. The aim of this study was to determine if levels of arsenic and mercury differed among pregnant women living in areas with and without ASGM activities in Northern Tanzania. This cross-sectional study is part of the ongoing Mining and Health prospective longitudinal study. Spot urine samples and dried blood spots were collected at the antenatal health clinics from pregnant women (n = 1056) at 16–27 weeks gestation. Urine samples were analyzed for total arsenic (T-As) and dried blood spots were analyzed for total mercury (T-Hg). Women in the ASGM cohort had median T-As levels (9.4 μg/L; IQR: 4.9-15.1) and T-Hg levels (1.2 μg/L; IQR: 0.8-1.86) that were significantly higher than the median T-As levels (6.28 μg/L; IQR: 3.7-14.1) and T-Hg levels (0.66 μg/L; IQR: 0.3-1.2) of women in the non-ASGM cohort (Mann-Whitney U test, T-As: z = −9.881, p = 0.0005; T-Hg: z = −3.502, p < 0.0001). Among pregnant women from ASGM areas, 25% had urinary T-As and 75% had blood T-Hg above the established human biomonitoring reference values of 15 and 0.80 μg/L. In the ASGM cohort, lower maternal education and low socioeconomic status increased the odds of higher T-As levels by 20% (p < 0.05) and 10% (p < 0.05), respectively. Women involved in mining activities and those of low socioeconomic status had increased odds of higher T-Hg by 70% (p < 0.001) and 10% (p < 0.05), respectively. Arsenic and mercury concentrations among women in non-ASGM areas suggest exposure sources beyond ASGM activities that need to be identified. Arsenic and mercury levels in women in Tanzania are of public health concern and their association with adverse birth and child developmental outcomes will be examined in future studies on this cohort.