Mining Ponds Research Articles

WATER INHABITING BIRDS OF MAIGANGA POST COAL MINING PONDS AND ARTIFICIAL WETLAND

Wetlands play a significant role in bird conservation and generally support biological diversity. Historically, bird community assessment has been employed in monitoring and identifying areas for conservation actions. In this study, we examined two post mining ponds and one artificial wetland in Maiganga Coal Mine, Gombe State for wetland avifauna. We focused on water birds (i.e. bird species that depend wholly or partially on water and wetland ecosystems for their survival). Survey was conducted during the onset of dry season in October 2021 to September 2022. Point count technique was used for the survey. A total of 626 individuals of 23 species from 19 genera, 10 families and 6 bird Order were recorded. The White-faced whistling duck was the most abundant bird species and was restricted to the active-mine pond (AMP). AMP was the most diverse of the three water bodies surveyed. However, some species were exclusive to either of the three sites. Similarly, AMP was the most abundant site with 426 individuals from 16 bird species, followed closely by the sedimentation pond with 147 individuals drawn from 15 bird species. The results suggest that water depth, age of establishment and surrounding vegetation structure could be a major determinant of bird species composition and abundance in the study area. The study highlights the importance of restorative actions aimed at recovering modified landscapes, through tree planting and creation of wetlands. This is evident in the presence of waterbirds in Maiganga, a location that was previously devoid of perennial water bodies and...

Reconstructing the Spill Propagation of the Aznalcóllar Mine Disaster

AbstractThe mine pond failure of Los Frailes (Aznalcóllar, Spain) was one of the most catastrophic mining-related disasters worldwide. Despite having been analysed from different disciplines, there have been only two attempts to simulate the propagation of the spill. In both cases, the spill was reconstructed using poor or incorrect topographical data, assuming a spilled hydrograph at the breaking point, and considering the fluid as water. In this research, new pre-failure topographical data were obtained combining field data with remote sensing techniques. These data were used to estimate the spilled hydrograph at the breaking point utilising a two-dimensional hydrodynamic numerical tool. Finally, due to the nature of the spilled fluid, two different attempts of reconstructing the spill propagation process of the Aznalcóllar mine disaster were performed. First, the fluid was considered as water with a suspended sediment load (26–660 g/L), i.e. assuming Newtonian fluid flow. Then the fluid was assumed to be mud-like (non-Newtonian fluid flow). These new simulations revealed that using a Newtonian fluid model, such as water with or without sediment, produced the best results in matching observed and simulated data. The non-Newtonian approach (muds) performed poorly. This suggests the spill behaved more like a concentrated sediment-laden flow than a mud-like one, possibly due to changes in fluid behaviour caused by the mine tailings in the pond after the failure.

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.

Highly Sensitive Whole-Cell Mercury Biosensors for Environmental Monitoring.

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

Physicochemical Variation of Water, Diversity, and Bacterial Community Structure in Post-coal Mining Ponds of Different Ages in Samarinda, East Kalimantan, Indonesia

<p>This study aims to determine physicochemical variation of water, diversity, and community structure of bacteria at post-coal mining ponds of various ages located in Samarinda, East Kalimantan, Indonesia. Bacteria species were identified using a metagenomic approach on the Next-Generation Sequencing (NGS) nanopore platform and analyzed using the QIIME2 pipeline. The result showed that ponds aged > 20 years old had better water quality compared to others < 5 years old. In addition, ponds > 20 years old had lower conductivity values (0,21-0,40 mS/cm), water temperature (29,1-30,1oC), and sulfur content (2,35-6,44 mg/L), as well as higher pH (6,57-7,61) and abundance of sulfur-oxidizing bacteria (SOB) (217-364 CFU/mL). Based on the results, ponds < 5 years old had water quality characterized by higher conductivity (0,27-1,29 mS/cm), water temperature (30,1-31,4 oC), and sulfur content (6,56-15,03 mg/L), lower pH (2,93-3,72), and abundance of SOB (0-38 CFU/mL). Diversity and structure of bacteria community showed that the Operational Taxonomic Unit (OTU) in post-coal mining ponds > 20 years old was 3819 compared to 2027 in those < 5 years old. Bacteria community in post-coal mining ponds > 20 years old consisted of 11 phyla and 45 classes, while those < 5 years old had 9 phyla and 38 classes. Moreover, the relative abundance of families, genera, and species at ponds > 20 years old was also higher. The high water quality, diversity, and community structure of bacteria at ponds > 20 years old showed the successful remediation of ponds water by SOB.</p>

Machine Learning Application to Optimize Spent Mushroom Compost (SMC) Biochar as Filter Media for Heavy Metal Adsorption in Abandoned Mine Water

AbstractThe surging global population strains resources, escalating pollution, and exacerbating water scarcity. Sustainable water management necessitates alternative sources such as abandoned mine water. However, these sources often contain hazardous heavy metals, like lead, copper, iron, and manganese, posing grave health and environmental risks. Conventional methods struggle to effectively treat these heavy metals in abandoned mining ponds, urging the search for cost‐efficient and sustainable solutions. Biochar, particularly from spent mushroom compost (SMC), emerges as a potent adsorbent due to its high surface area and binding groups. Yet, the variability in its efficiency remains a challenge. Conventional empirical models fail to capture the dynamic nature of adsorption processes accurately. Adopting machine learning, specifically an adaptive neuro‐fuzzy inference system (ANFIS), shows potential in predicting adsorption efficiency. This study aims to employ ANFIS to forecast SMC biochar's performance in a lab‐scale metal retention pond, providing design charts for diverse initial metal concentrations and pH levels. Validation through real cases aims to enhance accuracy and establish a framework for future heavy metal adsorption capacities. This research offers a sustainable approach to removing heavy metals from abandoned mining ponds whereas the computational modeling in optimizing SMC biochar introduces a novel approach for practical applications.

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

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

Short Communication: Aplocheilus panchax Hamilton, 1822 Found at Acidic Waters of Abandoned Ex-tin Mining Ponds as Insectivorous Fish and Its Role for Water Quality Improvement

Kepala timah fish or blue panchax is one of the species found at acidic waters of abandoned ex-tin mining pond. Kepala timah fish belongs to the extremophile fishes which can survive in extreme aquatic environments caused by pressure from environmental factors. This study aimed to confirm the kepala timah fish as a species of Aplocheilus panchax and to analyze its natural food habits. Molecular analysis through DNA barcoding was carried out by analyzing the COI gene and confirming the sequence of kepala timah fish in the gene bank on the NCBI website and constructing a phylogenetic tree for kepala timah fish to other A. panchax populations. Analysis of food habits was carried out by identifying the contents of the digestive tract of kepala timah fish which were observed microscopically. The results showed that kepala timah fish found at acidic waters of abandoned ex-tin mining pond was confirmed as Aplocheilus panchax Hamilton, 1822. Some morphological characters confirmed the similarity between kepala timah fish and A. panchax such as a silvery white spot on its head, terminal type of the mouth position, body shape was sagittiform, small dorsal fin on posterior body, and the shape of the caudal fin was rounded or rhomboid. Analysis of the contents of digestive tract showed the food habits of A. panchax found at acidic waters of ex-tin mining pond was insects. The food habits explained that A. panchax was classified as larvivorous or insectivorous fishes. The presence of A. panchax and its metabolic activity at abandoned ex-tin mining ponds can contributed to increasing organic matter in the waters so that it can be beneficial for improving water quality.

Screening, Identification, and Optimization of Sulfur-Oxidizing Bacteria from Post-coal Mining Ponds of Different Ages in Samarinda, East Kalimantan, Indonesia

<p>This research was conducted to isolation, screening, identification, and culture conditions optimization (pH, temperature, thiosulfate concentration, and incubation period) of potential sulfur-oxidizing bacterial (SOB) to reduce sulfur concentrations in post-coal mining ponds water of various ages located in Samarinda, East Kalimantan, Indonesia. The ponds used in this study were ponds < 5 years old and > 20 years old. The research obtained seventy-five bacteria isolates, among them nine isolates can increase the pH of thiosulfate broth media. Among the nine bacteria isolates, three isolates KT1.8, KT1.9, and KT1.13 have the highest potency to reduce sulfur concentration of media were 6%, 148%, and 101%. Based on the similarity of the 16S rDNA sequences, the KT1.8, KT1.9, and KT1.13 isolates were identified as Priestia qingshengii HLS-7 (98.9%), Sphingobacterium siyangensis DS48 (97.6%), and Pseudomonas putida CFBP 4966 (98.3%). The three potential SOB isolates grew better at pH 6 at 30° C temperature with the growth of KT1.8 = 146x1014 cell/mL; KT1.9 = 81x107 cell/mL; and KT1.13 = 33x107 cell/mL; decrease in sulfur concentration KT1.8 = 43.57%; KT1.9 = 43.57%; and KT1.13 = 42.48%. On media containing 10 mM and 20 mM thiosulfate on the sixth day of incubation, cell density isolates KT1.8 = 98x1012 cell/mL; KT1.9 = 25x107 cell/mL; and KT1.13 = 85x106 cell/mL; accompanied by a decrease in sulfur concentration of KT1.8 = 46.52%; KT1.9 = 40.40%; and KT1.13 = 43.71% were obtained. Those three bacteria isolate potential can be developed as bioremediation agents of post-coal mining pond water contaminated by sulfur.</p>

Assessing fish diversity in abandoned mining ponds in Madre de Dios, Peru, using environmental DNA

AbstractThe Peruvian region of Madre de Dios is a biodiversity hotspot located in the Andean‐Amazon region. Since the 1970s, it has experienced the harsh effects of artisanal and small‐scale gold mining (ASGM), which has transformed the primary forests into numerous small mining ponds left abandoned after extraction. Preliminary surveys indicate that these ponds are being recolonized by surrounding biodiversity. These assessments are typically carried out using traditional methods that are costly, difficult to deploy at multiple locations, and have raised safety concerns. In this context, environmental DNA (eDNA) becomes a useful tool for biodiversity monitoring due to its simplicity for sample collection and performance to identify taxonomic groups. In this study, we evaluated fish biodiversity in two mining ponds created by ASGM along with two nearby pristine lakes, unimpacted by mining operations but also influenced by seasonal flooding. We compared two alternative eDNA processing methods and contrasted our results with historic data from traditional biodiversity monitoring. Both eDNA‐based methods yielded comparable results, varying only in logistic requirements and costs. In total, we detected 85 fish MOTUs (22 at the species level) from 5 orders, 22 families, and 41 genera. Some of the species identified with eDNA were rarely registered by traditional monitoring, and we could identify 6 genera associated with ASGM mining ponds only. A major restriction of the eDNA approach in this location was the insufficient local taxa registered in genomic databases which limited our taxonomic resolution. Despite this limitation, our results indicate that eDNA could be a powerful tool for biodiversity estimations in the Western Amazon, identifying more taxa, with much less time and money invested than traditional monitoring. Our results also confirm that abandoned mining ponds are being recolonized by surrounding ichthyofauna, reaching richness levels above nearby unmined oxbow lakes used as reference.

Mercury bioaccumulation in bats in Madre de Dios, Peru: implications for Hg bioindicators for tropical ecosystems impacted by artisanal and small-scale gold mining.

Mercury (Hg) endangers human and wildlife health globally, primarily due to its release from artisanal small-scale gold mining (ASGM). During gold extraction, Hg is emitted into the environment and converted to highly toxic methylmercury by microorganisms. In Madre de Dios (MDD), Peru, ASGM dominates the economy and has transformed rainforests into expansive deforested areas punctuated by abandoned mining ponds. The aim of this study was to evaluate the use of bats as bioindicators for mercury pollution intensity in tropical terrestrial ecosystems impacted by ASGM. We collected 290 bat fur samples from three post-ASGM sites and one control site in Madre de Dios. Our results showed a wide Hg distribution in bats (0.001 to 117.71 mg/kg) strongly influenced by feeding habits. Insectivorous and piscivorous bats from ASGM sites presented elevated levels of Hg surpassing the mercury small mammal threshold for small mammals (10 mg/kg). We observed the highest reported fur mercury concentrations for insectivorous Neotropical bats reported to date (Rhynchonycteris naso, 117 mg/kg). Our findings further confirm that Hg emissions from ASGM are entering local food webs and exposing wildlife species at several trophic levels to higher levels of Hg than in areas not impacted by mining. We also found that three bat genera consistently showed increased Hg levels in ASGM sites relative to controls indicating potential usefulness as bioindicators of mercury loading in terrestrial ecosystems impacted by artisanal and small-scale gold mining.

Unlocking Nature's Elixir: Harnessing Kiambang (Salvinia Molesta) for Sustainable Water Quality Improvement in Post-Coal Mine Ponds

Objectives: Kiambang (Salvinia molesta), a natural aquatic plant, is tested for its ability to improve water quality in three post-coal mine ponds in South Kalimantan, Indonesia: Pond A (Satui), Pond B (Jorong), and Pond C (Angsana). Kiambang's ability to remediate dissolved nutrients and contaminants is the main goal. Theoretical Framework: Using kiambang's ability to absorb dissolved elements and contaminants, the study follows phytoremediation principles. Previous research has shown its promise in many settings, but applying it to South Kalimantan post-coal mine ponds is challenging. Method: A completely randomized controlled experiment with five treatments and a control group was conducted. Water quality measures like dissolved nutrients, heavy metals, and pollutants were measured before and after seven days. We used advanced testing equipment to verify accuracy. Results and conclusion: Kiambang-treated ponds have consistently better water quality. The plant greatly reduced dissolved nutrients, heavy metals, and contaminants. ANOVA analysis verified the significance of these differences (p < 0.05). Kiambang shows potential in phytoremediation, a sustainable and eco-friendly solution to post-coal mining pond water quality issues. Nature-based initiatives are crucial in coal-mining regions, according to the study. Implications of the research: Environmental conservation, sustainable resource use, and ecological applications are affected by this research. Kiambang's water quality management potential benefits post-coal mining ponds, aquatic ecosystems, wetlands, and aquaculture systems. This work enables future research and collaboration to use kiambang in varied environments.

Post-Coal Mining Reclamation Land Sustainability Study in Tebo Regency

This research was conducted at one of the coal mines in Tebo Regency, namely PT. Asia Multi Investama. The technique for determining respondents was determined by purposive sampling with a sample size of 54 people. The data analysis techniques used are laboratory analysis (water and land), descriptive analysis (to determine the reclamation model) and sustainability index measurement using multidimensional scaling (MDS) from the three dimensions of sustainability analyzed, namely the social dimension and the economic dimension. and ecological dimensions. The results of soil and water laboratory analysis show a decline in soil and water quality. The results of observations of vegetation in the field also showed a decrease in plant growth. Management of post-mining reclamation land PT. The current Asia Muti Investama is quite sustainable with an Appraisal Post Coal Mining Sustainable (APCMS) score of 55.27 on a scale of 0 -100. The reclamation model that can be applied is the agroforestry reclamation model with the agrosilvofishery system. The leading tree commodities are rubber and palm oil. For fisheries, this is a place for fish breeding in former mining ponds (voids) with types of tilapia, goldfish and catfish. Sensitive factors as levers that influence the sustainability of PT's former coal mining land. Asia Multi Investama.

The Water Chemistry Quality of the Ex-sand Mining Sites in Gantar District, West Java, for Freshwater Fish Cultivation

Sand mining activities in Gantar District, Indramayu Regency, West Java, have changed water morphology and quality. Many ex-sand mining areas have left large ponds that have not been utilized optimally by the community around the mining area. The research aims to analyze the suitability of water quality in the ex-sand mining area for freshwater fish cultivation. Observations in three water ponds in Bantarwaru Village, Gantar District, in August 2022. Water quality measurements in situ and the laboratory. Water quality parameters observed in situ measured temperature, water depth, brightness, dissolved oxygen (DO), and pH. Laboratory measurements included TSS, TDS, BOD, COD, and chemical elements such as total phosphate, nitrate, nitrite, ammonia, sulfate, and iron. The data obtained were analyzed descriptively by making comparisons with the standard water quality based on standards of Government Regulation Number 22 of 2021 concerning Management of Water Quality and Control of Water Pollution. To find out how suitable the suitability for freshwater fish farming is. Suitability analysis using the weighting and scoring method. The scoring results for ex-sand mining ponds for freshwater fish farming are 81–91% and classified as moderately to highly suitable. This score is good for freshwater fish cultivation.

Operation mercury: Impacts of national‐level armed forces intervention and anticorruption strategy on artisanal gold mining and water quality in the Peruvian Amazon

AbstractArtisanal and small‐scale gold mining (ASGM), a wealth‐generating industry in many regions, is nonetheless a global challenge for governance and a threat to biodiversity, public health, and ecosystem integrity. In 2019, the Peruvian government mobilized a targeted, large‐scale armed intervention against illegal ASGM, which has caused deforestation and water resource degradation in this Tropical Biodiversity Hotspot. Before the intervention, the extent of waterbodies created by mining (mining ponds) was increasing by 33%–90%/year; after, they decreased by 4%–5%/year in targeted zones. Mining activity indicators showed 70%–90% abandonment. New mining activity accelerated in nearby areas outside the targeted area (pond area increases: 42%–83%; deforestation increases +3–5 km2/year). Far from intervention zones, mining remained stable during the study period. Our analysis demonstrates that targeted, large‐scale government intervention can have positive effects on conservation by stopping illegal mining activity and shifting it to permitted areas, thereby setting the stage for governance. Continued conservation efforts must further address the impacts of informal mining while (1) limiting environmental degradation by legal mining; (2) remediating former mining areas to reduce erosion and enable reforestation or alternative uses of the landscape; and (3) sustaining such efforts, as some miners began to return to intervention areas when enforcement relaxed in 2022.

Bioaccumulation of chemical elements at post-industrial freshwater sites varies predictably between habitats, elements and taxa: A power law approach

Elevated environmental levels of elements originating from anthropogenic activities threaten natural communities and public health, as these elements can persist and bioaccumulate in the environment. However, their environmental risks and bioaccumulation patterns are often habitat-, species- and element-specific. We studied the bioaccumulation patterns of 11 elements in seven freshwater taxa in post-mining habitats in the Czech Republic, ranging from less polluted mining ponds to highly polluted fly ash lagoons. We found nonlinear, power-law relationships between the environmental and tissue concentrations of the elements, which may explain differences in bioaccumulation factors (BAF) reported in the literature. Tissue concentrations were driven by the environmental concentrations in non-essential elements (Al, As, Co, Cr, Ni, Pb and V), but this dependence was limited in essential elements (Cu, Mn, Se and Zn). Tissue concentrations of most elements were also more closely related to substrate than to water concentrations. Bioaccumulation was habitat specific in eight elements: stronger in mining ponds for Al and Pb, and stronger in fly ash lagoons for As, Cu, Mn, Pb, Se, V and Zn, although the differences were often minor. Bioaccumulation of some elements further increased in mineral-rich localities. Proximity to substrate, rather than trophic level, drove increased bioaccumulation levels across taxa. This highlights the importance of substrate as a pollutant reservoir in standing freshwaters and suggests that benthic taxa, such as molluscs (e.g., Physella) and other macroinvertebrates (e.g., Nepa), constitute good bioindicators. Despite the higher environmental risks in fly ash lagoons than in mining ponds, the observed ability of freshwater biota to sustain pollution supports the conservation potential of post-industrial sites. The power law approach used here to quantify and disentangle the effects of various bioaccumulation drivers may be helpful in additional contexts, increasing our ability to predict the effects of other contaminants and environmental hazards on biota.

The ecology of coastal wetland ponds created by diamond mining in southern Namibia. 3. Fish

Diamond mining in southern Namibia creates seawalls that hold the ocean at bay, yet seawater overwashes or seeps through to fill landward excavated areas, forming numerous coastal ponds that reach 380 000 m2. These ponds span ages of 1–40 years, with the oldest ponds lying in the north, and the younger ponds in the central and southern areas. We investigated occupation of these mining ponds by marine fishes. The ponds offer sheltered, warm, nutrient-enriched environments, but become hypersaline after 10–12 years. The ponds contained predominantly west coast steenbras Lithognathus aureti and southern mullet Chelon richardsonii, with smaller numbers of seven other fish species, and all nine species being marine. The ichthyofauna was thus depauperate, but similar to that of periodically closed estuaries in the region. The size composition and gonadal development of both predominant species suggest they may breed in at least the younger ponds. However, in older, hypersaline, northern ponds, L. aureti transitions into an entirely female population via protandry, precluding breeding there. Body condition was low for both species in the northern ponds, and gut fullness greatest in the southern ponds. Growth of both species was faster in the ponds than in the sea, but after initially fast growth, L. aureti reached a plateau, suggesting stunting thereafter. Chelon richardsonii attained larger sizes in the ponds than in the ocean. For 10–12 years before hypersalinity sets in, the ponds constitute suitable habitat for fish. They are not estuaries as they have minimal freshwater input, but they do create conditions corresponding to closed estuaries that are otherwise scarce along this arid coastline. However, for a nursery function to be realised, the marine fish must return to the sea or else the ponds become an ‘ecological trap’.

Health risk assessment of potentially toxic elements (PTEs) concentrations in soil and fruits of selected perennial economic trees growing naturally in the vicinity of the abandoned mining ponds in Kuba, Bokkos Local Government Area (LGA) Plateau State, Nigeria.

This study was designed to determine the level of potentially toxic elements (PTEs) contamination in soil and selected fruits and assesses the health risk of inhabitants in the abandoned tin mining community in Kuba, Bokkos LGA. Samples of the abandoned mine soil and selected fruits mango (Magnifera indica), guava (Psidium guajava), avocado pear (Persea americana), and banana (Musa spp)) from the vicinity of the abandoned mine were analyzed for the presence of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the levels of all the PTEs analysed in the abandoned mine soil samples were significantly (p < 0.05) higher than their corresponding values in the control soil from the non-mining area. Except for Cd, the mean concentrations of As, Cr, Cu, Mn, Ni, and Pb were significantly higher than the FAO/WHO maximum permissible limit. Except for Zn in guava fruits and Cd in avocado fruits, the mean concentration of PTEs in fruits from abandoned mines was significantly (p < 0.05) higher than their corresponding control values. In contrast, the mean levels of As, Cr, Cu, Mn, Ni, and Pb in the investigated fruits were significantly (p < 0.05) higher than FAO/WHO maximum permissible limits established for fruits. The studied fruits remarkably took up and bioaccumulated PTEs from the abandoned mine soil. Mango fruit significantly bioaccumulated As (5.40), Cd (3.40), and Zn (2.81). Guava fruit bioaccumulated As (1.50) and Cd (4.60), while avocado bioaccumulated As (3.53), Cd (3.80), and Zn (6.48). Banana bioaccumulated As (0.96), Cd (0.80), and Zn (6.78). The hazard quotient values for PTEs investigated in fruits for adults, and children were several folds greater than 1. The hazard index (HI) for the PTEs through consuming fruits for children and adults was greater than 1, indicating that possible health risks exist for both local children and adults. However, the HI values for the children were higher than those for adults, implying that children were exposed to more potential noncarcinogenic health risks from PTEs than adults. The total cancer risk (TCR) values for Cr and Ni for all the fruits studied were within 10-3-10-1, which is several-fold higher than the permissible limits (10-6and < 10-4), indicating high carcinogenic risk. TCR values for Cd and Pb in all the fruits, except for Cd in guava and avocado fruits for children, were within the range of 10-5-10-4, indicating that they are associated with moderate risk. The CR values for all the PTEs in all the fruits for adults and children except for mango fruit adults were within 10-2-10-1, indicating high carcinogenic risk. In conclusion, the results and risk assessment provided by this study indicate that human exposure to fruits from abandoned mines suggests a high vulnerability of the local community to PTE toxicity. Long-term preventive measures to safeguard the health of the residents need to be put in place.

Characterization of Former Coal Mining Ponds (voids) and Water Management System Planning

Characterization of Former Coal Mining Ponds (voids) and Water Management System Planning

Bioaccumulation and Risk Analysis of Selected Heavy Metals in Clarias Gariapinus and Tilapia Zili Fish Species of Abandoned Mining Ponds

Heavy metals (Cd, Co, Cr, Cu, Ni and Pb) were determined in some selected fish species (Clarias gariepenus and Tilapia zili) from Bokkos abandoned mining sites. Sample matrices examined were flesh gills, kidney and liver of each fish species. Twenty (20) sample sites were selected for the sample matrices under investigation. After sample collection and treatment, heavy metals were determined using Atomic Absorption Spectrophotometer (AAS, Bulk Scientific Model 210 VGP). The concentration patterns for each of the elements in the fish species showed significant and relatively similar patterns in cat fish with Ni having the highest concentration, followed by Cr, Co, Pb Cd and Cu in that order with respective. Cumulative bioconcentration in Tilapia zili showed that Cd &lt; Cu &lt; Pb &lt; Co &lt; Cr &lt; Ni respectively. Pearson correlation showed various interactions and relationships existing between and within sample matrices, indicating that these heavy metals have similar source, species or geochemical interaction. Only Co has a weakly positive correlation 0.58 with Pb while in Tilapia zilli, while Cu has correlation with Ni in Clarias gariepenus. Also the interactions and behaviors of the fish species suggests water and sediment for Cu, Ni and Co, Pb respectively. The relative contributions of Cr, Ni and Pb to the aggregated risk were 59.86%, 0.21%, 38.03% and 1.76% respectively. Consumption of these fish species from the study area therefore poses serious health concern upon consumption over time.