Gold Mining Area Research Articles

Spectral characteristics of the correlation between elemental arsenic and vegetation stress in the Yueliangbao gold mining.

Some soils in the Yueliangbao gold mining area have been contaminated by heavy metals, resulting in variations in vegetation. Hyperspectral remote sensing provides a new perspective for heavy metal inversion in vegetation. In this paper, we collected ground truth spectral data of three dominant vegetation species, Miscanthus floridulus, Equisetum ramosissimum and Eremochloa ciliaris, from contaminated and healthy non-mining areas of the Yueliangbao gold mining region, and determined their heavy metal contents. Firstly, we compared the spectral characteristics of vegetation in the mining and non-mining areas by removing the envelope and derivative transformation. Secondly, we extracted their characteristic identification bands using the Mahalanobis distance and PLS-DA method. Finally, we constructed the inverse model by selecting the vegetation index (such as the PRI, DCNI, MTCI, etc.) related to the characteristic band combined with the heavy metal content. Compared to previous studies, we found that the pollution level in the Yueliangbao gold mining area had greatly reduced, but arsenic metal pollution remained a serious issue. Miscanthus floridulus and Eremochloa ciliaris in the mining area exhibited obvious arsenic stress, with a large "red-edge blue shift" (9 and 6nm). The extracted characteristic wavebands were around 550 and 680-740 nm wavelengths, and correlation analysis showed significant correlations between vegetation index and arsenic, allowing us to construct a prediction model for arsenic and realize the calculation of heavy metal content using vegetation spectra. This provides a methodological basis for monitoring vegetation pollution in other gold mining areas.

A Cost-Effective and Straightforward Approach for Conducting Short- and Long-Term Biomonitoring of Gold Mine Waters

Gold mining pollution has long-lasting effects on the environment, particularly through acid mine drainage (AMD) and heavy metal contamination. Monitoring and assessing the impact of this pollution is crucial, as well as evaluating the effectiveness of remediation efforts. In our study, conducted in the gold mining area of Zlatna (GMAZ), western Romania, we utilised on-site measurements of water temperature, pH, electrical conductivity, and dissolved oxygen, along with the quantification of culturable aerobic bacteria and microfungi using ready-to-use media plates. We also examined the taxonomic richness of water invertebrates (TRWI) and the environmental features of the sites. Our study found significant negative impacts on the water biota in mining areas, with microbial abundance proving to be a reliable indicator of AMD pollution. While water invertebrates can also serve as indicators of mining effects, their abundance alone may not always accurately reflect pollution levels at every site. This multiple-factor analysis highlights the influences of water type, geological characteristics, air temperature, and precipitation on the structure of the aquatic biota. We observed a natural attenuation of mining pollution in the GMAZ in the last seven years. This study demonstrates that the quantification of microbiota, along with TRWI and basic physicochemical parameters, can offer a cost-effective alternative to expensive monitoring methods for assessing mining pollution.

Ethnobotanical knowledge of Dayak Ngaju in utilizing plant species to locate gold mining in Sei Riang Village, Central Kalimantan, Indonesia

Abstract. Sunariyati S, Decenly, Purnama AR, Agnestisia R. 2023. Ethnobotanical knowledge of Dayak Ngaju in utilizing plant species to locate gold mining in Sei Riang Village, Central Kalimantan, Indonesia. Biodiversitas 24: 4145-4150. Indonesia is one of the richest countries in flora and cultural diversity. The strong relationship between the culture and plant diversity has developed ethnobotanical knowledge of the indigenous community, including the knowledge of the Dayak Ngaju Tribe in utilizing plant species as gold indicators. Therefore, this study aimed to inventory and identify the plant species used as gold indicators by Dayak Ngaju in Sei Riang Village, Gunung Mas District, Central Kalimantan, Indonesia using ethnobotanical study and then empirically assess the gold content in the identified plants using laboratory analysis. Ethnobotanical information was collected through in-depth interviews with 25 informants and analyzed with the Informant Agreement Ratio (IAR). Plants mentioned as gold indicators were then identified in the field. The samples of the plants were then examined by atomic absorption spectroscopy to determine gold (Aurum; Au) contents in their root, stem, and leave tissues. The data was analyzed using SPSS 25 with the Parametric Pearson Correlation test to determine the correlation and significance level of Au contents found in the plant tissues and soil. Based on the interview results, the gold miners believed that several plant species could be utilized to indicate gold’s presence in the mining area, as indicated by the value of IAR of 0.540, suggesting that 54% of the informants agreed to use the plants as the gold indicator. Two plant species were identified as gold indicators: Kasuhui (Dipterocarpus sp.) and Hara (Ficus racemosa L.). Significant positive correlations were also exhibited between Au contents in the Kasuhui stem and the Hara root and stem and the soils where they grow. This research is expected to promote the ethnobotanical knowledge of the gold miners from the Dayak Ngaju Tribe in selecting scientifically justifiable gold mining areas.

Total Mercury Content in the Tissues of Freshwater Chelonium (Podocnemis expansa) and a Human Health Risk Assessment for the Amazon Population in Brazil.

Researchers recognize the silent, negative and deleterious effects caused by mercury pollution in gold mining areas. Freshwater turtles are culturally part of the diet of riverside populations in the Amazon region and this area presents mercury (Hg) pollution issues mainly due to gold mining activities. Thus, this research aimed to evaluate the total mercury (THg) content in the different organs of Amazonian giant river turtle (Podocnemis expansa) and carry out a human health risk assessment associated with the consumption of these animals. This study was conducted in the Vila Balbina, municipality of Presidente Figueiredo, state of Amazonas, Brazil. Skin (n = 28), muscle (n = 19) and brain (n = 2) samples were analyzed by Atomic Absorption Spectrometry (TDA-AAS) and a DMA-80™ mercury analyzer was used for the total mercury determinations. The average values found for THg in the skin, muscle and brain samples were, respectively, 0.1045 mg·kg-1, 0.1092 mg·kg-1 and 0.0601 mg·kg-1. Thus, THg was observed even though the P. expansa were kept in captivity, possibly due to previous contamination by air, water and food. The Hazard Quotient (HQ) was calculated considering a 9.07 g·day-1 intake dose of P. expansa and the consumption of turtles once a week showed an HQ = 2.45, which may cause long-term injuries to human health. Although the muscle concentrations were below the maximum limit established by the World Health Organization (WHO) and Brazilian regulatory agencies, it is important to evaluate consumption factors such as amount ingested, frequency and animal gender, which may cause a potential risk to regular consumers due to mercury bioaccumulation. The WHO may consider various aspects in order to warn the Amazon population about the severity and silent hazard of this metal, especially due to the importance of this matrix in the region. This region urgently needs government actions to inhibit clandestine mining and to prevent future serious, chronic health problems of the entire population.

Pathfinder elements and indicator minerals of Au from the Kubi Gold ore deposits in Ghana

The Au mineralization in the Kubi Gold Mining Area in the Birimian of Ghana is associated with garnet (about 85 vol.%), magnetite, pyrrhotite, arsenopyrite, and sulfide minerals, as well as quartz with gold and calcite. These minerals and the included elements can act as indicator minerals or pathfinder elements. For the present work, we collected samples from drill holes at different depths, from the alluvial zone (0–45 m) to the ore zone (75–100 m). The distributions of minerals and elements in the rocks that act as indicator minerals and pathfinder elements in the concession area were investigated along the drill hole cross sections. X-ray diffraction shows that the samples contain garnet, pyrite, periclase, and quartz as the main indicator minerals. By energy-dispersive X-ray spectroscopy, Fe, Mg, Al, S, O, Mn, Na, Cu, Si, and K are identified as corresponding pathfinder elements. The results indicate that the Au mineralization in the Kubi Mine area correlates mostly with the occurrence of garnet, pyrite, goethite, and kaolinite in the host rocks, which show towards the surface increasingly hematitic and limonitic alteration in form of Fe(oxy-)hydroxides.

Analysis of Liver Histology Several Fish in the Air Kotok River in the Gold Mining Area, Lebong Regency

Fish have habitats that are easily exposed to contamination from the environment such as heavy metal waste which can cause changes in the structure and function of body tissues. One type of waste that enters the river in the Lebong Regency River is gold mining processing waste that uses mercury and cyanide. Heavy metals can enter organisms and accumulation and biomagnification of mercury can occur in the bodies of aquatic biota such as fish. There has been no research related to fish histology in the Lebong gold mining area, so the aim of this research was to determine the histological condition of the liver organs of several fish in the form of Hemibagrus nemurus, Rasbora sp, Trichogaster trichopterus, and Macrognathus circumcinctus in the Air Kotok river in the gold mining area of Lebong Regency. The research was conducted using the paraffin method with hematoxylin-eosin staining. Data were analyzed descriptively qualitatively based on the histology of the fish liver. The results of the research on the liver histology, it shows damage to the fish liver structure which includes vacuolization, congestion, pyknosis, dilated sinusoids, melanomacrophages and leukocyte infiltration. The damage to the hepatocytes of this fish can be used as a bio-indicator of exposure to toxic substances in the Air Kotok river, one of which is heavy metal activity from gold mining, which can be a threat to the health and survival of the fish.Keywords: Bengkulu, gold mining waste, heavy metal, hepa

Extraction and monitoring of vegetation coverage based on uncrewed aerial vehicle visible image in a post gold mining area

Vegetation coverage reflects the degree of environmental degradation. Timely and effective monitoring of vegetation conditions is the basis for promoting vegetation protection and improving the ecological environment of mining areas. Exploring vegetation coverage extraction methods and selecting the optimal vegetation index in mining areas can provide scientific reference for estimating vegetation coverage based on vegetation index in mining areas. Uncrewed aerial vehicles (UAVs) are widely used because of their fast real-time performance, high spatial resolution, and easy accessibility. In this study, the performances of nine visible vegetation indices and two threshold segmentation methods for extracting vegetation coverage in a post-gold mining area in the Qinling Mountains were comprehensively compared using visible spectrum UAV images. Of the nine indices, the excess green index (EXG) and visible-band difference vegetation index (VDVI) were the most effective in discriminating between vegetation and non-vegetation by visual interpretation. In addition, the accuracy of the bimodal histogram threshold method in extracting vegetation coverage was higher than that of Otsu’s threshold method. The bimodal histogram threshold method combined with EXG yielded optimal extraction results. Based on optimal methods, the total percentages of fractional vegetation coverage in 2019, 2020, and 2021 were 31.47%, 34.08%, and 42.77%, respectively, indicating that the vegetation in the mining area improved. These results provide valuable guidance for extracting vegetation information and evaluating vegetation restoration in mining areas.

Public Exposure to Natural Radiation and the Associated Increased Risk of Lung Cancer in the Betare-Oya Gold Mining Areas, Eastern Cameroon

Background: This study aims to reevaluate natural radiation exposure, following up on our previous study conducted in 2019, and to assess the associated risk of lung cancer to the public residing in the gold mining areas of Betare-Oya, east Cameroon, and its vicinity.Materials and Methods: Gamma-ray spectra collected using a 7.62 cm×7.62 cm in NaI(Tl) scintillation spectrometer during a car-borne survey, <i>in situ</i> measurements and laboratory measurements performed in previous studies were used to determine the outdoor absorbed dose rate in air to evaluate the annual external dose inhaled by the public. For determining internal exposure, radon gas concentrations were measured and used to estimate the inhalation dose while considering the inhalation of radon and its decay products.Results and Discussion: The mean value of the laboratory-measured outdoor gamma dose rate was 47 nGy/hr, which agrees with our previous results (44 nGy/hr) recorded through direct measurements (in situ and car-borne survey). The resulting annual external dose (0.29±0.09 mSv/yr) obtained is similar to that of the previous study (0.33±0.03 mSv/yr). The total inhalation dose resulting from radon isotopes and their decay products ranged between 1.96 and 9.63 mSv/yr with an arithmetic mean of 3.95±1.65 mSv/yr. The resulting excess lung cancer risk was estimated; it ranged from 62 to 216 excess deaths per million persons per year (MPY), 81 to 243 excess deaths per MPY, or 135 excess deaths per MPY, based on whether risk factors reported by the U.S. Environmental Protection Agency, United Nations Scientific Committee on the effects of Atomic Radiation, or International Commission on Radiological Protection were used, respectively. These values are more than double the world average values reported by the same agencies.Conclusion: There is an elevated level of risk of lung cancer from indoor radon in locations close to the Betare-Oya gold mining region in east Cameroon. Therefore, educating the public on the harmful effects of radon exposure and considering some remedial actions for protection against radon and its progenies is necessary.

Influence of Distance from Forest Edges on Spontaneous Vegetation Succession Following Small-Scale Gold Mining in the Southeast Peruvian Amazon

Few studies describe the factors that influence the natural regeneration in abandoned gold mining areas in the Amazon. Here we focus on the influence of the distance to the forest edge and abandonment time in a spontaneous succession of degraded areas by gold mining in the southeastern Peruvian Amazon. We assessed woody species composition (DBH ≥ 1 cm) and forest stand structure across a chronosequence (2–23 years). A total of 79 species belonging to 30 families were identified. The natural regeneration was dominated by Fabaceae, Malvaceae, and Urticaceae. Together, they represented 60% of the importance index. Cecropia membranacea and Ochroma pyramidale were the dominant pioneer species at the initial successional stage. The basal area and species diversity were directly related to time after abandonment and inversely related to the distance to forest edges. The distance-based redundancy analysis showed that more of the variation in species composition was explained by distance to the forest edge than the abandonment time. Our study revealed that regeneration was relatively slow and provided evidence that the distance to the forest edge is important for natural regeneration in areas degraded by gold mining.

Fractal dimension used as a proxy to understand the spatial distribution for carlin-type gold deposits

The spatial distribution of ore-forming element grades typically exhibits strong nonlinear characteristics as a result of continuous geological processes. The trend of change in ore grade sequences is a crucial indicator of the degree of enrichment of an ore deposit. Therefore, quantitative evaluation of the spatial distribution of ore-forming elements holds great significance for understanding ore-forming processes as well as for ore exploration. In this work, based on the principles of fractal theory, a MATLAB-based program to calculate fractal dimensions was developed, and fractal analysis was conducted on the gold concentration values (g/t) of 25 drill holes in the Lannigou Gold Mining Area, Guizhou, China. Rescaled range analysis and the fractal correlation integral were utilized to obtain the spatial distribution of gold concentrations in the drill holes. Rescaled range analysis revealed that the Hurst exponent (HR/S) values vary in the range of 0.58–0.97, which reflected the persistent behavior of vertical variation in gold tonnage at the studied wells. Furthermore, the relationship between gold grade distribution and associated fluctuations in the fractal dimension derived from the correlation dimension (DC) was discussed. The DC value was found to vary between 1.01 and 1.59, indicating that high-grade gold deposits were distributed along steep fractal gradients and that fractal dimension values could be used as a reliable proxy to efficiently understand the migration pathways of auriferous fluid. Studies have shown that the Hurst exponent of the Au grade sequence exhibited a strong dependence on the grade of mineralization, with gold mineralized veins persisting throughout the studied drill holes. Thus, fractal dimension gradients can serve as an important proxy for identifying the locations of potential economic gold deposits in unexplored areas. Moreover, this approach can be employed to map the distribution patterns of other types of ore deposits.

The natural magnesite efficacy on arsenic extraction from water and alkaline influence on metal release in water

Arsenic (As) removal studies were carried out through batch experiments to investigate the performance of the locally available calcined magnesite mineral rocks from Tanzania. Natural water from a stream source in Tanzania and the prepared synthetic water at the laboratory were used for the studies. Parameters such as initial As concentration, calcined magnesite dosage, contact time and pH were evaluated for As removal using an overhead rea×2 shaker. Arsenic concentration was reduced from 5.3 to 1.1 mg/L As(V) at 180 min when 0.5 g/L calcined magnesite was applied to a synthetic water sample, whereas the concentration of 117 μg/L As(V) and 5.2 μg/L As(III) was reduced to below 0.1 μg/L in natural water. An increase in calcined magnesite dosage resulted in increased As removal up to below 0.01 mg/L. The calcined magnesite raised the pH of the water sample from 6.8 to 10 when the applied dosage increased between 0.002 g/L and 0.05 g/L. The pH was constant at around 10 even when the amount of 0.05 g/L was added 2000 times. Despite the high pH, the amount of magnesium released in water was low. The calcination of magnesite at 500 °C increased surface area by 4 times as compared to the natural magnesite and X-ray diffraction showed presence of MgCO3 phase as the dominant phase at this temperature. The reaction kinetics of As removal on 0.5 g/L calcined magnesite fitted with the pseudo-second-order (R2 = 0.96). Reaction isotherm was strongly fitted with Freundlich isotherm (R2 = 0.98). Linear regression and artificial intelligence neural network showed the As removal was influenced by both contact time and pH. Arsenic can be removed from As water using calcined magnesite and will be suitable for water treatment around gold mining areas.

Mercury content in mining waste and its effect on the surrounding environment (Case study: Small-scale gold mining locations-West Sumbawa)

This study was conducted to determine the content of mercury in the flowing river around small-scale gold mines. Mining wastes from the run of mining are dumped into the watersheds and potentially contaminate the water and sediment in the watershed near the gold mining area. We analyzed the characteristics of the waste and the result was compared with the water quality standards (Environment Minister Decision No.202 of 2004 and Government Regulation No.82 of 2001) and sediment quality standard (the Canadian sediment quality guidelines for the threshold effect level (TEL) and probable effect level (PEL)). We found that wastewater from the gold mining areas was categorized in class IV. The mercury content in the sediment samples did not meet the standards of Canadian sediment quality guidelines for TEL. The content of mercury in the sediment samples from the gold mine site was very high. The sediment mercury samples had been settled for a long time around the watershed. The content of mercury in the mining location indicated that mercury had been contaminating the area around the small-scale gold mining.

Local intensity of artisanal gold mining drives mercury accumulation in neotropical oxbow lake fishes

Driven by surges in global gold prices and additional socio-economic factors, artisanal small-scale gold mining (ASGM) in the Global South is increasing and driving emissions of significant quantities of mercury (Hg) into the air and freshwater. Hg can be toxic to animal and human populations and exacerbate the degradation of neotropical freshwater ecosystems. We examined drivers of Hg accumulation in fish that inhabit oxbow lakes of Peru's Madre de Dios, a region with high biodiversity value and increasing human populations that depend on ASGM. We hypothesized that fish Hg levels would be driven by local ASGM activities, by environmental Hg exposure, by water quality, and by fish trophic level. We sampled fish in 20 oxbow lakes spanning protected areas and areas subject to ASGM during the dry season. Consistent with previous findings, Hg levels were positively associated with ASGM activities, and were higher in larger, carnivorous fish and where water had lower dissolved oxygen levels. In addition, we found a negative relationship between fish mercury levels associated with ASGM and the occurrence of the piscivorous giant otter. The link between fine-scale quantification of spatial ASGM activity and Hg accumulation, as indicated by the result that in the lotic environment, localized effects of gold mining activities are stronger drivers (77 % model support) of Hg accumulation than environmental exposure (23 %) constitutes a novel contribution to a growing body of literature on Hg contamination. Our findings provide additional evidence of high Hg exposure risks to neotropical human and top carnivore populations subject to the impacts of ASGM, which depend on freshwater ecosystems undergoing gradual degradation. The documented spatial variation in Hg accumulation and increased Hg levels in carnivorous fish should serve as a warning to human communities in Madre de Dios to avoid the proximity of high-intensity gold mining areas and minimize local carnivorous fish consumption.

Utilizing the k0-IAEA program to determine rare earth elements in soil samples from gold-mining areas in Sudan

Utilizing the k0-IAEA program to determine rare earth elements in soil samples from gold-mining areas in Sudan

Effect of Arbuscular Mycorrhizal Fungi Inoculation on content and nutrient uptake of four-month-old Angsana (Pterocarpus indicus Willd.) plants in post-gold mining land in Bombana, Southeast Sulawesi

Mining activities are the main cause of nutrient-poor land and damage to soil physical properties. This condition also occurs in the post-Bombana gold mining area. thus negatively impacting plant growth response. Therefore, post-mining land remediation is carried out using environmentally friendly approaches such as Arbuscular Mycorrhizal Fungi and the use of adaptive local plant species such as Angsana (Pterocarpus indicus Willd.). This study aims to determine the levels and uptake of nutrients in the mycorrhizal P. indicus plant in post-gold mining field scale. Sampling was carried out in the laboratory of the Faculty of Forestry and Environmental Sciences, Halu Oleo University and observations of nutrient levels were carried out in the soil and plant laboratory of SEAMEO BIOTROP Bogor, this research was carried out for 3 months (May 2021). This research method used a Randomized Block Design (RAK) with 4 treatments, namely control, Glomus coronatum, G. claroideum and mixed AMF. The results showed that mixed AMF was effective in increasing N, Mn and Fe nutrient levels and G. claroideum increased P and K levels. Mixed AMF increased N, Mn and Fe nutrient levels and nutrient uptake in P. indicus plants four months old on the Bombana Gold Post Mining Land, Southeast Sulawesi.

Mercury Accumulation in Food Crops and Phytoremediation Potential of Wild Plants Thriving in Artisanal and Small-Scale Gold Mining Areas in Uganda

Mercury (Hg) has been used for millennia in artisanal and small-scale gold mining (ASGM) to extract gold from ore as an amalgam that is heated to recover gold. Since there is hardly any sustainable technology that can be used to recover it, the vast percentage of released Hg finds its way into the environment. Currently, ASGM is the largest source of mercury pollution on Earth. Mercury (Hg) is listed among the top 10 most harmful metals by the World Health Organization (WHO), and it is known to cause several neurological disorders in humans. Thus, Hg levels in environmental systems surrounding pollution hotspots such as ASGM mines need to be monitored to ensure their proper management and protect vulnerable ecosystems and human health. This work was aimed to study the level of Hg pollution in soils and plants thriving around ASGM mines in Eastern Uganda and to evaluate the Hg phytoremediation potential of the plants. The total Hg contents were determined for soils, food crops and wild plants growing around ASGM mines. The results for the pH, organic carbon (OC) and electric conductivity (EC) of the soils in the study area were comparable to those of the control soils. The soils in the studied ASGM areas exhibited high Hg concentrations ranging between 723 and 2067 folds more than those of the control soils. All soils were moderately to heavily contaminated according to geoaccumulation (Igeo) index values that ranged between 1.16 and 3.31. The results of this study also showed that the food crops and wild plants accumulated Hg levels that were above the 20 ng/g (0.02 ppm) permissible limit. This study revealed relatively higher levels of Hg in the aerial parts of the plants compared with the underground organs, which can be attributed to Hg deposition, entry through stomata and foliar adsorption. Mercury levels in 47% of the food crop samples were above the FAO/WHO permissible mercury limit of 0.5 µg/g. Similarly, medicinal plants accumulated Hg to levels that were several folds higher than the 0.2 ppm permissible limit of mercury in herbal materials of Canada. Interestingly, this study showed that some wild plant species, especially sedges, exhibited relatively higher levels of mercury accumulation than others thriving in the same environment, an indication that such plants could be utilized in the phytoremediation of Hg-contaminated sites.

Trace mercury migration and human exposure in typical mercury-emission areas by compound-specific stable isotope analysis

Anthropogenic mercury (Hg) emissions have increased significantly since the Industrial Revolution, resulting in severe health impacts to humans. The consumptions of fish and rice were primary human methylmercury (MeHg) exposure pathways in Asia. However, the lifecycle from anthropogenic Hg emissions to human MeHg exposure is not fully understood. In this study, a recently developed approach, termed MeHg Compound-Specific Isotope Analysis (CSIA), was employed to track lifecycle of Hg in four typical Hg-emission areas. Distinct Δ199Hg of MeHg and inorganic Hg (IHg) were observed among rice, fish and hair. The Δ199Hg of MeHg averaged at 0.07 ± 0.15 ‰, 0.80 ± 0.55 ‰ and 0.43 ± 0.29 ‰ in rice, fish and hair, respectively, while those of IHg averaged at − 0.08 ± 0.24 ‰, 0.85 ± 0.43 ‰ and − 0.28 ± 0.68 ‰. In paddy ecosystem, Δ199Hg of MeHg in rice showed slightly positive shifts (∼0.2 ‰) from those of IHg, and comparable Δ199Hg of IHg between rice grain and raw/processed materials (coal, Hg ore, gold ore and sphalerite) were observed. Simultaneously, it was proved that IHg in fish muscle was partially derived from in vivo demethylation of MeHg. By a binary model, we estimated the relative contributions of rice consumption to human MeHg exposure to be 84 ± 14 %, 58 ± 26 %, 52 ± 20 % and 34 ± 15 % on average in Hg mining area, gold mining area, zinc smelting area and coal-fired power plant area, respectively, and positive shifts of δ202HgMeHg from fish/rice to human hair occurred during human metabolic processes. Therefore, the CSIA approach can be an effective tool for tracking Hg biogeochemical cycle and human exposure, from which new scientific knowledge can be generated to support Hg pollution control policies and to protect human health.

Atmospheric mercury in forests: accumulation analysis in a gold mining area in the southern Amazon, Brazil.

The spatial distribution and dispersion of mercury (Hg) is associated with the structural conditions of the environment, primarily land use and vegetation cover. Man-made emissions of the metal from activities such as artisanal and small-scale gold mining (ASGM) can influence this distribution. Forest ecosystems are of particular importance as they constitute one of the most active environments in the biogeochemical cycle of Hg, and understanding these dynamics is essential to better understand its global cycle. In this study, we determined the content of Hg present in different forest strata (soil, leaf litter, herbaceous, underwood/bush, and arboreal), as well as the relationship between the presence of Hg and the landscape heterogeneity, percentage of gold mines, and ground slope. This study was carried out in tropical forest areas of the southern Brazilian Amazon. Accumulation and transport of Hg between forest strata was assessed in order to understand the influence of these forest environments on Hg accumulation in areas where ASGM occurs. We verified that there is a difference in Hg content between forest strata, indicating that atmospheric Hg is accumulated onto the arboreal stratum and transported vertically to strata below the canopy, i.e., underwood/bush and herbaceous, and subsequently accumulated in the leaf litter and transferred to the soil. Leaf litter was the stratum with the highest Hg content, characterized as a receptor for most of the Hg load from the upper strata in the forest. Therefore, it was confirmed that Hg accumulation dynamics are at play between the areas analyzed due to the proximity of ASGMs in the region. This indicates that the conservation of forest areas plays an important role in the process of atmospheric Hg deposition and accumulation, acting as a mercury sink in areas close to man-made emissions.

The Growth of Bacillus cereus (IHB B 379) Isolates at Different Temperature and Concentration of Mercury Chloride (HgCl2)


 
 
 Bacillus cereus (IHB B 379) has been isolated from the sediments of the illegal gold mining area located in Danau Biru Singkawang, these bacteria have resistant properties by being able to grow on media containing HgCl2 with a concentration of 500 ppm. This study aimed to determine the effect of temperature and concentration of mercuric chloride (HgCl2) on the growth of Bacillus cereus (IHB B 379) and to determine the temperature and concentration of mercuric chloride (HgCl2) on the optimum growth of Bacillus cereus (IHB B 379). The study used a Completely Randomized Factorial Design (CRD) consisting of two treatment factors. The first factor was a different temperature treatment with three levels, namely 320C, 370C, and 420C. The second factor was the treatment of the mercuric chloride (HgCl2) concentration with three levels, namely 0 ppm, 250 ppm, and 500 ppm. The Bacillus cereus (IHB B 379) growth test used the delusional method and the number of colonies was calculated using the Total Plate Count (TPC) method. The results showed that the growth of Bacillus cereus (IHB B 379) was seriously affected by the temperature and concentration of HgCl2 . The best growth pattern of Bacillus cereus (IHB B 379) was occurred at 320C and concentration HgCl2 250 ppm. 
 
 
 
 
 
 
 
 
 
 

Trace elements in farmland soils and crops, and probabilistic health risk assessment in areas influenced by mining activity in Ecuador

Consumption of food grown in contaminated soils may be a significant human exposure pathway to pollutants, including toxic elements. This study aimed to investigate the pollution level of trace elements in farmland soil and crops collected in orchards from Ponce Enriquez, one of the Ecuador’s most important gold mining areas. The concentration of arsenic (As), cadmium (Cd), chrome (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) was analyzed in soil and crop samples (celery, chives, corn, herbs, lettuce, turnips, green beans, cassava, and carrots). In addition, a probabilistic human health risk assessment, in terms of hazard quotients (HQ) and cancer risk (CR), was conducted to assess the potential risk related to local crop ingestion. The contents of As, Cr, Cu, and Ni in soils exceeded the Ecuadorian quality guidelines for agricultural soils. The trace elements concentration in local crops was higher than the maximum permissible levels set by the Food and Agriculture Organization of the United Nations (FAO). The HQ and CR of local crop ingestion were several orders higher than the safe exposure threshold, mainly for lettuce, chives, and turnips. Our results revealed that inhabitants of the study area are exposed to developing carcinogenic and non-carcinogenic effects due to long-term food consumption with high trace elements. This study sheds light on the need to assess further the quality of agricultural soils and crops grown in mining areas with signs of contamination to guarantee consumer food safety.