Figure 5a shows that the mining operations by Alufer, CBG, and COBAD exceeded the prescribed noise restrictions, contingent upon the extent of mining operations and the distance between the noise source and the receiver. During the preproduction phase, the transportation of mining equipment and trucks to the site is facilitated by the public road network, and they remain stationed. The impact of noise on the surrounding area during mine installation and decommissioning is limited and temporary (online resources Fig. 1). As a result, further examination was not required for this assessment. The transmission of sound was also influenced by air and ground absorption, which was estimated using the ISO 9613 noise model (Lilic et al. 2018). Assuming constant noise levels from the project throughout the year, the predicted acoustic impact at sensitive receivers would be less than the modeled impact during operation (Fig. 5b). Noise levels at various locations were monitored using an environmentally sensitive receiver (ESR). The background of the initial state levels indicates that the noise at ESR3 (sample station) is 7 dB above the initial state levels during the day and 3 dB above the initial state levels at night, indicating an exceedance of the guideline levels.
4.5 Effects on vegetation and wildlife communities
Figure 7 shows the environmental consequences of the Kerouane Iron Project, which involves the removal of plant life within the physical right-of-way and other project infrastructure, such as access roads, living quarters, and processing facilities. This resulted in the direct loss of 2,929 ha of natural habitat and 466 ha of modified habitats, including a 50–100-meter disturbance buffer around surface mines and infrastructure to accommodate minor design changes, additional unplanned clearing on terrain, and edge effects. The growth of mining activities can have detrimental effects on the vegetation and wildlife communities in numerous villages. Prior research conducted in the Boke bauxite mining region (Sidiki 2019; Camara et al. 2021) found that the extraction of bauxite was the primary cause of landscape devastation, leading to the loss of 5,099 ha of trees and 3,218 ha of forest. This has disrupted weather patterns, leading to a 20% reduction in rainfall over the past 30 years (Dibattista et al. 2023; Sidiki 2019). Forest stripping of hillsides, displacement of plants and animals, and extinction of some species can pose significant environmental risks. These risks can escalate if tree loss is not adequately managed.
As shown in Fig. 8, the Kerouane Iron Project's production schedule forecasts the removal of approximately 1.291 billion tons of ore over an estimated 22-year mine lifespan. Annually, the extraction of approximately 56 million tons of waste rock, primarily phyllite and itabirite, is anticipated. Moreover, the project entails the removal of lateritic soil from the ridge at high elevations, covering a combined area of approximately 235 ha of forest and 45 ha of freshwater.
Figure 9 shows the current status of fauna and flora in the mining project regions. The construction of mines can result in harm to local flora and fauna due to the removal of vegetation, leading to the loss of shelter and food sources. This project has had a substantial impact on birds, fish, plants, and mammals. The iron project regions in Kerouane are home to several non-native plant species, including Laos grass (Chromolaena odorata), Praxelis grass (Praxelis clematidea), Bidens asperata, and Ageratum conyzoides. These plants commonly thrive in disturbed areas and can quickly colonize fallow land. It is worth noting that Praxelis grass is considered an invasive species in Guinea.
4.6 Discussion and Emerging Lessons
The mining industry's environmental footprint is a critical concern as it encompasses the direct and indirect impacts of mineral resource extraction on ecosystems. The concept of environmental footprint, a measure of human demand on Earth's ecosystems, is a useful tool for assessing these impacts. By nature, the mining industry is resource-intensive and has significant environmental implications (Hu et al. 2024). Studies have highlighted the environmental damage and pollution associated with mining activities, emphasizing the need for a comprehensive assessment framework that integrates biophysical variables, technical indicators, and human activity data (Jegede 2016). Such a framework can provide a granular understanding of the environmental damage at the mine level, which is essential for promoting cleaner production and sustainable processes within the industry. Moreover, the ecological footprint method has been applied to various sectors, including the mining industry, to evaluate the environmental impacts of human activities (Cabello et al. 2021). Interestingly, while ecological footprint is a valuable metric, research indicates that individuals and organizations may not be fully aware of the environmental impact of their actions, as evidenced by the weak correlation between actual ecological footprints and self-assessed environmental sustainability (Salazar & Tavares 2018). This suggests a perception gap that could hinder effective environmental management in the mining sector.
The environmental consequences of the mining industry, with a particular focus on bauxite and iron mining projects in Boke, Kerouane, and Guinea, are complex issues that consider ecological, economic, and social factors. Thorough comprehension of the consequences and steps to effectively manage them is necessary for a complete assessment. The mining industry is a significant contributor to Guinea's economy, with substantial resource exports (Sidiki 2019). However, the environmental and socioeconomic effects of mining operations have raised concerns.
Guinea's 2011 mining code, which emphasizes transparency and environmental protection, demonstrates a commitment to sustainable development. However, the Boke region has experienced conflicts exacerbated by mining activities such as youth unemployment and inadequate public service management. Furthermore, it highlights the necessity of considering the entire spectrum of costs, including environmental and social responsibility costs, which can be revealed by an extended cost-benefit analysis of bauxite mining complexes, revealing the true societal impact of mining activities. However, the effectiveness of measures to address environmental concerns in the mining industry is debatable. Although sophisticated codes and regulations are in place, their practical application may be lacking, as evidenced by the environmental degradation and social unrest in mining communities. Malaysia also illustrates the potential for severe environmental consequences when regulations are not rigorously enforced, resulting in significant government intervention and costly remediation.
The importance of effective governance and innovative public-private partnerships to ensure that local communities derive benefits from mining operations is evident, given the conflicts discussed. Moreover, the environmental consequences of mining such as pollution and ecosystem damage are crucial factors that should not be overlooked. For instance, uncontrolled bauxite mining in Malaysia has led to severe environmental degradation, prompting the government to impose a temporary ban on mining activities (Rahmat et al. 2022). This underscores the significance of comprehensive Environmental Impact Assessments (EIAs) and decision-support frameworks, such as the Analytic Network Process (ANP), to guide sustainable mining practices (Rahmat et al. 2022). The concept of sustainability in mining is multifaceted and often lacks a universally accepted definition, leading to specific approaches for assessing sustainability (Phillips 2012). The application of mathematical models to EIAs can help determine the sustainability of mining projects, as demonstrated by a study in Andhra Pradesh, India, which found the proposed bauxite mining project to be unsustainable in its current form (Phillips 2012).
The evaluation of the environmental footprint of mining projects in Boke and Kerouane, Guinea, highlights the importance of comprehensive environmental regulations and their effective enforcement. Mining is crucial for the sustainable development and utilization of resources in Guinea; however, it also has negative environmental impacts, such as deforestation, biodiversity loss, and water pollution. To promote sustainable mining practices and protect the environment, extensive research and community engagement are essential to address potential risks and develop appropriate mitigation strategies. Mining operations can significantly impact surface water resources by increasing the sediment flow into nearby rivers (Carrying et al. 2021). Preventing adverse consequences requires implementing appropriate mitigation measures (Chadli & Boufala 2021). During the rainy season, significant sediment-water flow can be anticipated from sources such as storage areas, disturbed soils, open-pit mining, and mining fleet activities (Chadli & Boufala 2021). To maintain the sediment flow within acceptable limits, primary facilities must have dedicated water management systems and sedimentation ponds. Secondary drainage ditches and attenuation systems are necessary to prevent sediment accumulation in areas, such as roads, facilities, and residential areas. These may include drainage ditches lined with mortar and rubble. To design civil engineering projects that minimize sediment-water flow-induced scour and erosion, it is crucial to ensure that the receiving bodies of water can handle sediment-water flows smoothly (Askham & Poll 2017). Despite the implementation of extensive mitigation measures, the residual impacts of mines on streams located 3–5 km away from the site are expected to remain significant. Beyond this distance, the water quality is likely to return to normal due to sediment deposition and dilution. To address this issue, the project should explore alternatives such as compensatory mechanisms, operational management, and alternative water supply sources for those affected. Soil serves multiple functions, including agricultural use, water filtration, carbon storage, and cultural heritage protection.
Mining can harm natural soils and compromise their ability to maintain ecosystem services. Sources of contamination include mine spoils, polluted water, automobile fuels, oils, and building supplies. Land suitability for agricultural purposes must be evaluated to assess soil resource vulnerability, as emphasized by Yang et al. (2024). Soil suitability for agriculture increased as its sensitivity decreased, with the extent of the change based on the baseline conditions, as noted by (Chen et al. 2020). Due to the removal of valuable topsoil resources and permanent alteration of land surface features in the context of mining project development, agricultural potential may be limited or nonexistent, except for extensive cattle ranching (Pascaud et al. 2017). However, soil remains crucial for supporting biodiversity, influencing surface water drainage, acting as a repository for organic carbon, and protecting archaeological sites, as highlighted by Gastauer et al. (2018). During the operational phase of a mine, it is crucial to consider the potential risks of soil erosion, particularly in rugged terrains subject to scouring or excessive weight (Online Resource Table 5), soil contamination due to dust settling on adjacent soil, and sediment drainage into the surrounding areas (Andrews 2018). Our data revealed that only ESR3 had elevated noise level estimates when evaluated using the World Bank Group Environment, Health, and Safety guidelines (Roli 2016), necessitating the implementation of mitigation measures, such as relocating the mining plant. Strategies could be devised to diminish the significance and proportionality of the impact of noise on ESR3, which has been categorized as central to moderate in importance and proportionate to the sensitivity of the receptor. Temporary noise and vibrations during the construction and closure phases may affect sensitive areas (Lee et al. 2018), and a receptor's well-being can be influenced by numerous factors. To mitigate these impacts, effective working practices should be incorporated into noise and vibration management plans until the completion of mine rehabilitation and closure activities (Melodi 2017). The closure plan for the project should aim to eliminate residual noise sources. The deployment of conveyors for ore transportation leads to a considerable reduction in the number of vehicles in the road network. The British Standards Institution (BSI) TG18-BSI code of practice for noise and vibration specifies that cosmetic impairments should not exceed 15 mm/s at 4 Hz and 20 mm/s at 15 Hz for residential or small commercial buildings. The use of explosives in surface mining can cause ground-borne vibrations (Lee et al. 2018). The nearest noise-sensitive receiver, ESR6, was positioned approximately 900 m away from our location. Given the background noise level of the receiver, it is highly unlikely that any pulse emitted from the mine exceeds it. Moreover, the receiver's intermediate sensitivity and distance from the mine indicated that the resulting vibrations were insignificant.
This study examined three primary categories of air emissions: fugitive dust, combustion emissions, and odor nuisances. Fugitive dust originates from activities such as mining, transportation, and material handling, while combustion emissions are produced by internal combustion engines in vehicles and power plants. Odor nuisance is caused by gas emissions that can affect well-being but do not pose significant health risks. Wind speeds below 1 m/s did not transport substantial amounts of dust particles, although different thresholds have been proposed. Most dust particles settle within 500 m of their source, and mitigation measures are unlikely to be effective for operations that are more than 250 m away. For instance, the Kerouane Iron Project is planned to emit 6,546,158 tons of CO2 emissions over 22 years.
The consequences for ecosystems and wildlife in the vicinity have been substantial, with the degree of impact varying depending on the distance from the ridge. The effects were more pronounced in areas close to the ridge. Although measures to alleviate some of these adverse effects have been implemented, others continue to pose significant challenges. Sharma and Chaudhry (2018) emphasized the need to discourage the introduction of non-native tree species and promote the growth of indigenous species. Replacing early succession species with native forest trees is likely to be a lengthy endeavor, potentially taking many decades for vegetation in mining pits to resemble natural woodlands. Nonetheless, the advantages of native forest trees, such as enhancing soil quality and serving as a habitat for local wildlife, can help mitigate the detrimental consequences of mining operations.
Mining ventures can have substantial ecological consequences, but robust regulatory frameworks are vital for their effective management. Achieving lasting success depends on the proper execution and enforcement of these frameworks. To achieve sustainable mining, it is necessary to conduct long-term environmental impact assessments and cost evaluations. A comprehensive strategy that considers legal, economic, and social aspects can help minimize the environmental footprint. For mining in Boke and Kerouane, a holistic approach that integrates environmental management, socioeconomic factors, and governance reform is essential. Guinea and other countries have demonstrated that mining can contribute to economic growth, while also presenting environmental and social challenges. To ensure equitable benefit sharing and sustainable development, innovative strategies, efficient regulatory implementation, and community engagement are indispensable.