Mine Spoil Research Articles

Study on the Development Rule of Mudstone Cracks in Open-Pit Mine Dumps Improved with Xanthan Gum

The stability of open-pit mine slopes is crucial for safety, especially for spoil dump slopes, which are prone to cracks leading to landslides. This study investigates the use of xanthan gum (XG) to enhance the stability of mudstone in spoil dumps. Various concentrations of xanthan gum were mixed with mudstone and subjected to dry–wet cycle tests to assess the impact on crack development. Pore and crack analysis system (PCAS) was utilized for image recognition and crack analysis, comparing the efficiency of crack rate and length modification. The study found that xanthan gum addition significantly improved mudstone’s resistance to crack development post-drying shrinkage. A 2% xanthan gum content reduced the mudstone crack rate by 45% on average, while 1.5% xanthan gum reduced crack length by 46.2% and crack width by 26.3%. Xanthan gum also influenced the fractal dimension and water retention of mudstone cracks. The optimal xanthan gum content for mudstone modification was identified as between 1.5% and 2%. Scanning electron microscopy imaging and X-ray diffraction tests supported the findings, indicating that xanthan gum modifies mudstone by encapsulation and penetration in wet conditions and matrix concentration and connection in dry conditions. These results are expected to aid in the development of crack prevention methods and engineering applications for open-pit mine spoil dump slopes.

Granular characterisation of coal spoil dump using unmanned aerial vehicle data to enhance stability analysis

Open pit mining operations generate significant spoil dumps that need to be characterised for stability to identify potentially unstable slopes. However, the current subjective practice for spoil characterisation often involves tedious and risky field work. To this end, this study demonstrated the use of periodically acquired unmanned aerial vehicle (UAV)-based images over a coal mine spoil dump in New South Wales, Australia. A granular approach that captures the variability of each truck offload pile on a dump was adopted through morphology-based segmentation and ensemble algorithm-based classification which consolidates predictions from multiple classifiers. Overall accuracy of over 90% in the material characterisation based on the classification framework was achieved. The two-dimensional classification outcome was then transformed into three-dimensional (3D) block models using a point-based interpolation approach for stability analysis. The factor of safety derived from the granular approach offered improved assessment of failure risk compared to the conventional approaches, which treat the entire dump as a uniform category. This rapid classification and assessment method proposed in this study will help reduce the uncertainty associated with the variability of spoil dumps in slope stability assessments, thereby enhancing the safety and efficiency of mining operations.

Characterization of mine spoils for the reclamation of degraded lands of the Jos-Bukuru tin field, central Nigeria

Tin mining operations on the Jos Plateau have left a lasting impact on the environment, resulting in derelict land, mine spoils, and over a thousand abandoned mining ponds. These ponds have become potential hazards, endangering unsuspecting members of the public. This study aims to provide a comprehensive geochemical and geotechnical characterization of the mine spoils to assess their suitability for the reclamation and restoration of the degraded mined lands. The geochemical analysis reveals that the mine spoils exhibit a strong to moderate level of acidity, with a pH range of 3.91 to 5.90 (average: 4.85). Furthermore, they display deficiencies in essential nutrients such as phosphorus (average: 0.02%) and potassium (average: 0.31%), as well as trace elements such as copper (average: 19.15 ppm), manganese (average: 165.15 ppm), and zinc (average: 53.24 ppm). Notably, the mine spoils are enriched in iron (average: 6.31%). These findings highlight the inadequate presence of both micronutrient and macronutrient elements necessary for successful revegetation which is a crucial component of reclamation. Results from the geotechnical tests indicate that the mine spoils possess an average fines content of 56.03%, a mean liquid limit of 38.06%, and a mean plasticity index of 15.52%. Additionally, the average linear shrinkage value is measured at 10%. The average values for maximum dry density (MDD) and optimum moisture content (OMC) are 1.65 g/cm³ and 19%, respectively. The unsoaked California bearing ratio (CBR) averages 34.64%, while the coefficient of permeability for the spoil is approximately 1.24x10-3 mm/sec. Furthermore, the spoils average cohesion (C) was measured to be 12.150 while the mean angle of internal friction is 30.77 KN/M2. These results collectively indicate that mechanical and chemical stabilization, involving the use of lime, fly ash, and other soil-stabilizing agents is imperative for the effective reclamation of the degraded lands using the mine spoils. Such measures if adopted and implemented will mitigate the risk of accidents and drowning incidents from mining ponds and other abandoned pits involving unsuspecting members of the public and will contribute to the overall environmental restoration efforts in the Jos-Bukuru Tin Field.

Taxonomic and functional diversity along successional stages on post-coalmine spoil heaps

Coal is the most abundant fossil fuel in Europe, but the excavation of hard coal has covered large areas with disposed rock waste, and turned the natural habitats into disturbed novel ecosystems with harsh conditions differ in time and space. To examine the spontaneous complex successional gradient, we studied a large number of post coalmine heaps in Upper Silesia, which differ in vegetation type and age. Cluster analysis based on plant community composition (367 species in total) separated all surveyed plots on coal mining spoil heaps with herbaceous vegetation from Late Stage (LS) forests aged 14–56 years. Furthermore, the herbaceous vegetation was sub-grouped to three stages: Initial Stage (IS) aged 2–5 years, Early Stage (ES) aged 3–8 years and Mid-Stage (MS) aged 5–12 years. MS vegetation was characterised by the highest species richness and diversity (47 and 2.79) compared to ES (30 and 2.18) and IS (9 and 1.6), but higher species number and a similar diversity index occurred in LS (37 and 2.81). Functional diversity (FD) and community weighted mean (CWM) of nine functional traits showed higher (23.1) functional richness, higher (0.72) functional divergence, higher (4.5) functional dispersion, and higher value (24.4) of Rao’s quadratic entropy in LS compared to those calculated from the first three stages. Species at the initial successional stage (IS) were characterised by lower canopy height, seed mass, higher lateral spread, and specific leaf area (SLA). Additionally, the lowest (0.22 mg CO2 per hour per square metre) soil respiration (Sr) rate was recorded from IS compared to (0.53, 0.82 and 1.00) from ES, LS and MS, respectively. The soil water content (SWC) was the most important factor affecting the soil respiration, while the soil temperature (St) did not follow the well-studied relationship between soil respiration and soil temperature. Our spatial and temporal analyses illustrated changes in plant community assembly processes in the course of spontaneous vegetation succession on post coalmine spoil heaps. The importance of trait mediated abiotic filtration in community assembly in initial-, early-, and mid-stages of succession with an increase in competitive exclusion at the late successional stage was emphasized.

Factors driving plant diversity in the spontaneous vegetation of the novel ecosystem of post-coal mining spoil heaps and their relationship with soil respiration

The subject of the paper is the analysis of the relationship between spontaneous vegetation diversity and soil respiration in novel post-coal mine ecosystem. In the natural and semi-natural ecosystems, soil respiration process (Rs) is a crucial ecosystem function regulating terrestrial ecosystems’ carbon cycle. Soil respiration depends on the quality and quantity of the soil organic matter (SOM), the soil microbes’ activity, and root metabolism. The listed factors are directly related to the composition diversity of vegetation plant species (biochemistry). For many years, soil respiration parameters have been studied in natural and seminatural vegetation communities and ecosystems. However, there still need to be a greater understanding of the relationship between vegetation plant species diversity and soil respiration as a crucial ecosystem function. Plant species diversity has to be analysed through both the taxonomic diversity and the functional diversity. These approaches reflect the composition, structure, and function of plant species communities. We hypothesise that the diversity of the spontaneous vegetation species composition shapes the amount of soil respiration in a post-coal mine novel ecosystem. The soil respiration differs significantly along the vegetational types driven by habitat gradients and is significantly higher in highly functional richness and dispersion vegetation patches. Contrary to our expectation, soil respiration was the highest in the less diverse vegetation types – both taxonomical and functional evenness were non-significant factors. Only functional dispersion is weakly negative correlated with soil respiration level (SRL).

Delving into the diversity of genus Ironus Bastian, 1865 with special reference to Ironus dentifurcatus Argo & Heyns, 1972 (Ironidae: Enoplida), collected from coal mines

Summary In the exploration of nematode diversity within the coal mine spoil of Sonebhadra district, an isolate of Ironus dentifurcatus Argo & Heyns, 1972 was collected from the soil surrounding the roots of Prosopis juliflora. This study aims to unravel taxonomic intricacies of I. dentifurcatus through analysis of morphometric data, morphological characteristics utilising both light and scanning electron microscopy, and genetic scrutiny employing the SSU 18s rDNA gene marker. The study adds valuable information to the evolutionary history of I. dentifurcatus by constructing a comprehensive phylogenetic tree. This analysis is further augmented by an exploration of phylogeography and genetic divergence within the genus Ironus Bastian, 1865. The results reveal the genetic variability within the species of Ironus and the possible adaptative radiations in the group.

Biological Flora of Britain and Ireland: Silene uniflora‡

Abstract This account presents information on all aspects of the biology of Silene uniflora Roth (S. maritima With., S. vulgaris Garcke subsp. maritima (With.) Á. & D. Löve), Sea Campion, that are relevant to understanding its ecological characteristics and behaviour. The main topics are presented within the standard framework of the Biological Flora of Britain and Ireland: distribution, habitat, communities, responses to biotic factors, responses to environment, structure and physiology, phenology, floral and seed characters, herbivores and disease, history and conservation. Silene uniflora is a mat‐like perennial herb that in Britain and Ireland is primarily distributed in coastal habitats, notably on sea cliffs and shingle banks but also at the drift line and rarely on sand; it also has populations on mountains and heavy metal mine waste tips. All of these substrates tend to be oligotrophic, loose‐textured and freely draining, and often with adverse ion concentrations. It is found in suitable habitats around much of the Atlantic and Baltic coasts of Europe. Its breeding system is gynodioecious and gynomonoecious (some individuals bearing female flowers only, some bearing hermaphrodite flowers only and others with both types of flower). The proportions of the three types of individual vary considerably between populations, but hermaphrodite flowers tend to predominate. The showy, white, nectar‐producing flowers are produced continuously over the entire summer and are pollinated mainly by long‐tongued Hymenoptera and night‐flying moths but autogamous selfing is also frequent. Silene uniflora and its close relative S. vulgaris were the subject of a classic, decadal study involving genetical and transplant experiments that was seminal in the development of ‘experimental taxonomy’. More recently, attention has focused on the rapid evolution of Zn‐tolerant populations of S. uniflora growing on mine spoil and contaminated river gravels. It has also become a model organism for the study of sexually transmitted, castrating fungal diseases in plants (notably of the genus Microbotryum).

Probability distributions of geotechnical properties for heterogeneous lignite mine spoils

ABSTRACT During surface coal mining, large amounts of overburden waste materials, known as spoils, are excavated and dumped, creating massive heaps. The sustainable management of these areas is a global priority, but a comprehensive geotechnical characterization has not yet been achieved due to limited research on the spoils’ geotechnical properties. This study conducts an advanced statistical analysis of lignite mine spoil materials from a large heap in Greece to determine suitable probability distributions. Five distributions - normal, lognormal, Weibull (2 and 3 parameters), and Gamma - were evaluated, considering the high variability of spoil material properties. The lognormal and Weibull distributions were found to best fit most geotechnical parameters, except for cohesion, which showed an uncommon distribution. In some cases, the normal distribution can be used for a simplified analysis. The findings can guide the analysis of spoil materials, as advanced numerical and stochastic methods are essential for robust geotechnical design.

Analysis of effects and factors linked to soil microbial populations and nitrogen cycling under long-term biosolids application

Information about impacts of long-term biosolids application on soil microbial populations and functional groups and N cycling is important for evaluating soil health and agroecosystem sustainability under long-term biosolids application. Mine spoil plots received annual biosolids application from 1973 to 2010 at low (16.8 Mg ha−1 yr−1), medium (33.6 Mg ha−1 yr−1), and high rates (67.2 Mg ha−1 yr−1). A no-biosolids control received chemical fertilizer at the agronomic rate. Soil samples were collected in three seasons per year spanning 2003–2005 for measuring soil moisture, pH, soil organic C (SOC), total and extractable heavy metals (Cd, Cu, Ni, Zn), NO3−, N mineralization potential (NMP), microbial biomass C (MBC), and populations of three N-cycling bacteria (NCB) groups: ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and denitrifying bacteria (DNB). Soil samples were collected again in 2008 and 2010 for quantifying total and extractable heavy metals, and in 2018 (eight years after biosolids applications ended) for measuring SOC, MBC, NMP, and microbial respiration. During 2003–2005, mean MBC was 315, 554, 794, and 1001 mg kg−1 in the control, low, medium, and high biosolids treatments, respectively. Populations of NCB did not differ among treatments. Biosolids application increased total and extractable metal concentrations but the effect of biosolids rates were much lower on extractable than total concentrations. Soil extractable Cd and Cu concentrations decreased from medium to high applications, likely due to complexing with biosolids organic matter. Partial least squares regression analysis identified a strong positive effect on MBC of SOC and a weak negative effect of Cu, explaining the strong net positive effect of biosolids on MBC. In 2018, the medium and high biosolids treatments maintained higher SOC, MBC, NMP, and microbial respiration than the control. This study provided further evidence that long-term biosolids application has positive effects on soil microbes that persist for years after ending application.

Exploring the influence of ground-dwelling ant bioturbation activity on physico-chemical, biological properties and heavy metal pollution in coal mine spoil

Coal mining activities increase the soil concentrations of heavy metals manifold thus impacting soil health and biodiversity. The understanding of the impact of bioturbation activities by ant colonies on soil in coal mine spoil site across different restoration ages is not studied. The study aimed to investigate the influence of bioturbation activities by two most common and distinct coal mine site inhabiting ant species (C. compressus and C. longipedem) at six different ages (2, 4, 6, 8, 10 and 12 years old) on the soil heavy metal concentrations of Fe, Zn, Mn, Cu, Ni, Pb, Cd and Cr, pH, OM, TC, TN, soil enzyme activity of DH, ACP, β-glucosidase and proteases properties of soil. Soil samples were collected from opencast coalmine spoils during October and November 2017. Reference (Ref.) soil samples (n=10 per site) were collected (from area adjacent to ant nest colony approximately 2–5 m distance) from a depth of 0–15 cm and ant nest debris soil of each ant species (n=10 per site) were collected from each site. Heavy metal pollution decreased and pH, OM, TC, TN and soil enzyme activity of DH, ACP, β-glucosidase and proteases of soil in both Ref. soil and ant nest debris soil increases with the increase of mine site restoration age. Our study revealed that different age of the mine spoil have more profound effects on the soil quality and heavy metal content. Contrary to our hypothesis, regression analysis did not support our notion that ant bioturbation activity directly accelerate heavy metal breakdown. Instead, our findings suggests that ant colonies prefer to construct their nest for the locations with lower heavy metal concentrations and higher enzyme activity and increase in soil porosity is a key factor behind the low heavy metal concentration in the nest debris soil.

Plant Species and Functional Diversity of Novel Forests Growing on Coal Mine Heaps Compared with Managed Coniferous and Deciduous Mixed Forests

(1): The Upper Silesia region of Poland is one of the most extensively altered regions of Europe due to human activity, especially coal mining. (2): We used cluster analysis to examine the floristic composition of three classified forest communities: forests developed on post-coal mine mineral heaps (HF), mixed deciduous forests (DECI), and managed secondary coniferous forests (CON). Vegetation data were collected from 44 randomly selected plots, and plant traits connected with persistence, dispersal, and regeneration were taken from commonly used plant trait databases. (3): Higher species richness, species diversity, and evenness (36, 2.7, and 0.76, respectively) were calculated for HF plots compared with those plots from DECI (22, 1.9, and 0.62) and CON (18, 2.0, and 0.71) plots. Higher functional richness (0.173, 0.76) and functional divergence were determined for HF compared with those calculated for DECI (FRic 0.090, FDiv 0.71) and CON (FRic 0.026, FDiv 0.69). In contrast, the substrate from HF forests had significantly lower soil respiration (0.76 mg-CO2 h/m2) compared with substrates from both CON and DECI forests (0.90 and 0.96 mg-CO2 h/m2, respectively); (4): A set of complex abiotic stresses which plants suffer from on coal mine spoil heaps shaped different patterns of taxonomic and functional diversity. These findings demonstrate the importance of investigating successional aspects and carbon dynamics of de novo forests which have developed on post-coal mine spoil heaps in urban industrial areas.

Ecological Assessment of Restored Rock Phosphate Mine Spoils in the Maldevta Area of Garhwal Himalayas

This research explores the complex interaction between vegetation restoration and soil recovery, with a particular focus on the ecological restoration of an area in Maldevta, Garhwal Himalayas, that was once mined. The Himalayan ecology, which is abundant in minerals and biodiversity, is under a great deal of stress from mining, building roads, and grazing. The research area experienced open-pit mining, which degraded the soil and eliminated vegetation from what had once been a tropical dry mixed deciduous forest. Analyzing the restored soil's physical and chemical properties reveals a varied profile that affects fertility, structure, and nutrient composition. The loamy sand is made up of different percentages of sand (72.4%), silt (16.96%), and clay (9.89%). The chemical characteristics of the soil include potassium (5.10%), phosphorus (0.33%), nitrogen (0.042%), and electrical conductivity (EC) of 0.21 ohms/cm. The pH of the soil is 7.80. Employing the quadrat method for vegetation analysis, the study underscores the dominance of key plant species like Lantana camara, Mallotus philippensis, and Bombax ceiba in the restored ecosystem. The results demonstrate how restoration initiatives improve soil conditions, vegetation structure, and species diversity. By highlighting the crucial relationship between soil and vegetation dynamics, this study adds insightful information that can improve the effectiveness of ecological restoration projects. The work supports the long-term establishment of self-sustaining ecosystems by offering a thorough grasp of the intricate biological mechanisms leading to the rehabilitation of degraded landscapes in the fragile Himalayan region.

Cadmium, Cu, Hg, Sb, Se and Ti contamination in abandoned and active mining sites in Ghana shows concerns for soil and human health risks

The presence of potentially toxic elements (PTEs) in soils of gold mining sites poses health concerns to residents in mining communities. A study was conducted to assess the potential hazards to human health associated with the presence of PTEs in active, abandoned, and profile gold mine sites. We collected 102 soil samples, determined their total element contents, and calculated their pollution load index (PLI), enrichment factor (EF), and contamination factor (CF). The risks to human health were calculated for adult males, adult females, and children who ingested contaminated soil particles orally using the hazard quotient (HQ) and hazard index (HI). The soils' total Cd concentrations were above the global average of 0.2 mg/kg: abandoned (2.86 mg/kg), active (3.93 mg/kg), and profile (4.04 mg/kg). High Hg levels were found in active mine soil (0.92 mg/kg), profile (0.89 mg/kg), and abandoned mine soils (0.87 mg/kg). The active, abandoned, and profile soils had Ti concentrations of 14.18, 6.74, and 4.82 mg/kg, respectively, above the global average of 0.57 mg/kg. All sites were contaminated with Cd, Cu, Hg, Sb, Se and Ti, according to the PLI values (active = 6.03, abandoned = 4.61, and profile = 6.24). Cd, Hg, and Ti in mine spoils were related to Al, Fe, Mn, pH, TC, clay, and P in multivariate analysis (correlation and PCA). The presence of metals in the environment can be attributed to both natural processes and human activities. The HI values in children exceeded the critical value of 1.0, indicating a significant likelihood of non-carcinogenic hazards. The use of green space technology is crucial for the restoration of ecological integrity and the preservation of public health.

Vegetation establishment in soils polluted by heavy metal(loid)s after assisted natural remediation

Background and aimsThis field-base study evaluates the long-term effectiveness of in-situ remediation measures applied to soils residually polluted by potentially toxic elements (PTEs) in an area affected by a mining spill in SW Spain.MethodsTo evaluate the remediation treatments success, their influence on key soil properties and on the development of spontaneous vegetation in the treated soils was investigated. The treatments were based on human derived by-products valorization, and consisted of: biopiles, marble sludge and gypsum mining spoil addition, and their combination with an organic amendment (vermicompost).ResultsAmendments application improved the soil properties and reduced PTEs availability. As a result, an enhancement in spontaneous development of vegetation cover and diversity of plant species in the treated soils was followed. Spergularia rubra and Lamarckia aurea, two primary plant species growing in the studied area and that exhibit strong association to soils with the highest levels of pollution, showed high Pb and As accumulation in shoots ande in roots. Exceptionally, accumulation of these pollutants occurred in L. aurea roots, which can explain its high presence in soils with more limited vegetation development and in which no additional plant species can thrive.ConclusionsThe occurrence of S. rubra and L. aurea in the amended soils may be indicative of improved soil conditions and reduced toxicity induced by the remediation measures implemented. They may also be considered key species in the area since their presence can promote the recolonization of the degraded soils by species less tolerant to their residual pollution.

Legacy coal mining impacts downstream ecosystems for decades in the Canadian Rockies

Mountaintop removal coal mining leaves a legacy of disturbed landscapes and abandoned infrastructure with clear impacts on water resources; however, the intensity and persistence of this water pollution remains poorly characterized. Here we examined the downstream impacts of over a century of coal mining in the Crowsnest Pass (Alberta, Canada). Water samples were collected downstream of two historical coal mines: Tent Mountain and Grassy Mountain. Tent Mountain hosts a partially reclaimed surface mine that closed in 1983. Selenium concentrations downstream of Tent Mountain reached 185 μg/L in a lake below the mine spoil pile, and up to 23 μg/L in Crowsnest Creek, which drains the lake and the mine property. Further downstream, a well-dated sediment core from Crowsnest Lake records increases in sediment, selenium, lead, carbon, nitrogen, and polycyclic aromatic compounds that closely tracked the history of mining at Tent Mountain. In contrast, episodic discharge of mine water from abandoned underground adits at Grassy Mountain drive periodic (but short-term) increases in iron, various metals, and suspended sediment. These results underscore the lasting downstream impacts of abandoned and even reclaimed coal mines.

Geotechnical characterisation of coal spoil piles using high-resolution optical and multispectral data: A machine learning approach

Geotechnical characterisation of spoil piles has traditionally relied on the expertise of field specialists, which can be both hazardous and time-consuming. Although unmanned aerial vehicles (UAV) show promise as a remote sensing tool in various applications; accurately segmenting and classifying very high-resolution remote sensing images of heterogeneous terrains, such as mining spoil piles with irregular morphologies, presents significant challenges. The proposed method adopts a robust approach that combines morphology-based segmentation, as well as spectral, textural, structural, and statistical feature extraction techniques to overcome the difficulties associated with spoil pile characterisation. Additionally, it incorporates minimum redundancy maximum relevance (mRMR) based feature selection and machine learning-based classification. This automated characterisation will serve as a proactive tool for dump stability assessment, providing crucial data for improved stability models and contributing to a greener and more responsible mining industry .

Assessment of factors determining the rate and direction of plant communities development on coal mining spoils (the case study of the Gorlovskoye anthracite deposit)

The aim of the study. Identification and assessment of specific succession processes on self-revegetating coal mining spoils of the Gorlovskoye anthracite deposit, as related to the abiotic factors. Location and time of the study. The coal mining spoils of the Gorlovskoye anthracite deposit (54.568880 NL, 83.588956 EL), Novosibirsk region, Iskitimsky district, June 2023. Methods. The properties of soil substrates in technogenic landscapes were determined by officially attested and widely used methods of soil analyses. In field conditions, soil hardness was measured with a penetrometer, then soil density was calculated from its values using the dependence function. Total carbon and nitrogen contents were determined using a Perkin Elmer 2400 Series II CHNS/O analyzer. Statistical processing of the data was carried out using cluster, principal components and Spearman's correlation analyses. Results. In the anthracite coal mining spoils in the forest-steppe conditions of West Siberia, the high content of physical clay and clay-producing rocks in the developing soils promotes predominantly herbaceous plant groups, whereas slope areas with a high content of stones benefits the growth of woody vegetation.

Experience in the development of regulations based on the results of experimental studies for the conservation and restoration of biodiversity

One primary cause of biodiversity loss is the absence of standardized guidelines and regulations that provide clear instructions for implementing conservation measures. The development of technological frameworks, solidified in regulatory acts, enables the creation of a methodological foundation for biodiversity conservation and restoration for industrial companies as part of their corporate ESG policies. Between 2013 and 2023, the Kuzbass region gained significant experience in developing regulatory legal acts (RLAs) based on restoration technologies for various ecosystems on mine spoil heaps, as well as conducting environmental assessments and compensatory measures. A crucial part of this work involves publishing methodological recommendations for coal companies and integrating innovative technologies into the content of state standards in the field of “Environmental Protection” and Best Available Technologies (BAT). A total of 6 methodological recommendations were developed, of which 3 technologies were included in the BAT list for biodiversity restoration, and another 3 technologies are undergoing the stage of drafting a state standard. The preparation of new GOST-R standards helps industrial companies perceive biodiversity as an opportunity to demonstrate their environmental responsibility and minimize financial and reputational risks.

Soil and environment quality in artisanal small-scale mining areas in western Côte d’Ivoire

Artisanal small-scale gold mining activities grow in different regions of Côte d’Ivoire, causing enormous soil and environmental damages. This study was conducted in the vicinity of illegal artisanal small-scale gold mining zones to investigate soil quality using environmental assessment tools, mainly pollution and geochemical accumulation indexes. The mining spoil from artisanal pits was sampled directly between 0 and 20 cm, collecting 500 g of soil per sampling point. Sub-samples of soil were analyzed for multi-element using X-ray fluorescence technique. The results of the XRF analysis revealed higher trace element levels at some sampling points than the recommended levels. High arsenic concentrations were identified at three sampling sites: cavally sites with 7.09 and 16.08 mg kg-1 and Zérégbo with 9.57 mg kg-1. Moreover, significant concentrations of Cu and Pb were found at the Cavally site whilst Singouiné and Zérégbo showed high concentrations of Co and Cr. The study, globally, revealed the environmental hazards caused by the organized artisanal mining.

Spatio-temporal trends of mercury levels in alluvial gold mining spoils areas monitored between rainy and dry seasons in the Peruvian Amazon

Artisanal and small-scale gold mining (ASGM) in the Amazon has degraded tropical forests and escalated mercury (Hg) pollution, affecting biodiversity, ecological processes and rural livelihoods. In the Peruvian Amazon, ASGM annually releases some 181 tons of Hg into the environment. Despite some recent advances in understanding the spatial distribution of Hg within gold mine spoils and the surrounding landscape, temporal dynamics in Hg movement are not well understood. We aimed to reveal spatio-temporal trends of soil Hg in areas degraded by ASGM.,. We analyzed soil and sediment samples during the dry and rainy seasons across 14 ha of potentially contaminated sites and natural forests, in the vicinities of the Native community of San Jacinto in Madre de Dios, Peru. Soil Hg levels of areas impacted by ASGM (0.02 ± 0.02 mg kg−1) were generally below soil environmental quality standards (6.60 mg kg−1). However, they showed high variability, mainly explained by the type of natural cover vegetation, soil organic matter (SOM), clay and sand particles. Temporal trends in Hg levels in soils between seasons differed between landscape units distinguished in the mine spoils. During the rainy season, Hg levels decreased up to 45.5% in uncovered soils, while in artificial pond sediments Hg increased by up to 961%. During the dry season, uncovered degraded soils were more prone to lose Hg than sites covered by vegetation, mainly due to higher soil temperatures and concomitantly increasing volatilization. Soils from natural forests and degraded soil covered by regenerating vegetation showed a high capacity to retain Hg mainly due to the higher plant biomass, higher SOM, and increasing concentrations of clay particles. Disturbingly, our findings suggest high Hg mobility from gold mine spoil to close by sedimentary materials, mainly in artificial ponds through alluvial deposition and pluvial lixiviation. Thus, further research is needed on monitoring, and remediation of sediments in artificial to design sustainable land use strategies.