Evaluation of surface water contamination and its impacts on health in the mining districts of Kambélé and Bétaré-Oya (Eastern-Cameroon).

This study aimed to assess water contamination and associated health risks for populations residing in the mining areas of Kambélé and Bétaré-Oya. Key parameters, including pH, EC, TDS, TSS, and concentrations of metallic elements (Cd, Cr, Fe, Pb and Mn), were measured using established water analysis techniques. The analysis included multivariate statistical assessments, calculation of metal pollution and water quality indices, and health risk determinations, including daily intake (DI) and hazard quotient (HQ). Findings indicate a diverse pH range (5.26 < pH < 8.72), low mineralization (33.22 < EC (µS/cm) < 179.64), and elevated TSS content (22.53 < TSS (in mg/l) < 271.51). Metallic elements were observed in the descending order of Fe > Mn > Pb > Cr > Cd. Water quality assessments using the Water Quality Index (WQI) categorized sites as displaying doubtful to very poor quality, notably Woupy (WQI = 719.14) in Kambélé and Mali (WQI = 794.24) in Bétaré-Oya, with Heavy metal Pollution Index (HPI) values exceeding 100. These outcomes highlight consistent chemical degradation of surface water, posing potential risks to local populations' health and well-being. The study emphasizes the critical need for proactive environmental protection measures in mining areas, recommending the adoption of healthy mining practices and effective site reclamation strategies. Furthermore, future studies should consider exposure duration's potential impact on residents' health problems in these areas. Overall, this study contributes significantly to understanding and addressing the intricate interplay between mining activities, water quality, and public health in the Cameroon countryside.

Chitosan in the treatment of mine spoil rainwater - An approach to protect the aquatic biota.

The mining industry suppresses vegetation, exposing large soil areas in its ordinary operation. Water pollution and turbidity are caused by the carrying of solids, mainly colloidal particles, to the watercourses due to the effect of rainfall events. Therefore, the discharge of those effluents will lead to failure with watercourse quality parameters. Thus, there is a need to treat drainages (rainwaters) from the mining industry. However, using common coagulants and flocculants can result in acute or chronic ecotoxicity for aquatic biota. In this scenario, this research aimed to evaluate using a natural coagulant, the biopolymer Chitosan, to remove turbidity from mining industry spoiled water through bio-coagulation. The ecotoxicity of the natural coagulant was compared to the commonly used coagulants. For this purpose, we used synthetic rainwater (SRW) from the dispersion of fine (colloidal) particles in natural waters. Materials (water and soil) were collected in the mining area's sumps (sedimentation basins). The turbidity of the produced SRW ranged from between 500 and 4000 NTU. Jar Tests using Chitosan (CTS), polyaluminum chloride (PAC®12), and Superfloc®N100 variable doses were carried out to compare the effects of the coagulating/flocculating agents on the SRW turbidity reduction. The obtained results demonstrated the efficiency of CHS on turbidity reduction. The results were encouraging for low turbidity samples (<1000 NTU), making it possible to meet the limit parameters recommended by the Brazilian legislation. In addition, it was possible to conclude both CHS and the effluents treated with this coagulant have lower toxicity to aquatic biota than the combination of PAC®12 and Superfloc®N100.

Long-term sediment records reveal over three thousand years of heavy metal inputs in the Mar Menor coastal lagoon (SE Spain).

The Mar Menor lagoon combined high biological production and environmental quality, making it an important economic engine. However, the pressure of human activities put its ecological integrity at risk, the oldest environmental impact being mining activity recorded since Roman times, about 3500 years ago, reaching its maximum intensity in the 20th century, contributing heavy metals to the lagoon sediments for almost 30 centuries. This work reviews the spatiotemporal evolution of the main heavy metals in this coastal lagoon using data from 272 surface sediment samples obtained during the last 40 years and two deep cores covering the total history of the lagoon (c. 6500 yrs BP), so as their incidence in the lagoon trophic web. The observed patterns in sedimentation, sediment characteristics and heavy metal content respond to the complex interaction, sometimes synergistic and sometimes opposing, between climatic conditions, biological production and human activities, with mining being mainly responsible for Pb, Zn and Cd inputs and port activities for Cu. High Fe/Al, Ti/Al and Zr/Al ratios identify periods of mining activity, while periods of arid climatic conditions and deforestation that increase erosion processes in the drainage basin and silt concentration in the lagoon sediments are determined by high Zr/Rb and, to a lesser extent, Zr/Al and Si/Al ratios. After the cessation of direct discharges into the lagoon in the 1950s, the recent evolution of heavy metals concentration and its spatial redistribution would be determined by hydrographic and biogeochemical processes, solubility of different elements, and coastal works in harbours and on beaches. The bioconcentration factor decreases along the trophic levels of the food web, suggesting that the lagoon ecosystem provides an important service by retaining heavy metals in the sediment, largely preventing their bioavailability, but actions involving resuspension or changes in sediment conditions would pose a risk to organisms.

Quantifying the impacts of coal mining activities on topsoil using Hg stable isotope: A case study of Guqiao mining area, Huainan City.

The Hg released from coal mining activities can endanger soil ecosystems and pose a risk to human health. Understanding the accumulation characteristics of mercury (Hg) in coal mining soil is important for effectively controlling Hg emissions and developing measures for the prevention and control of Hg contamination. To identify the potential sources of Hg in soils, the Hg concentration and isotopic composition characteristics of raw coal and different topsoil types from the areas surrounding a coal mine were determined in this study. The results showed that Hg in coal mainly exists mainly in the form of inorganic Hg, and Hg has experienced Hg2+ photoreduction prior to incorporating into coal. In addition, the composition of Hg isotopes differed significantly among different topsoil types, and the δ202Hg value of the farmland soil exhibited large negative excursions compared to the coal mining soil. The ternary mixed model further revealed the presence of substantial differences in potential Hg sources among the two regions, with the coal mining soil being greatly disturbed by anthropogenic activity, and the relative contributions of Hg from raw coal, coal gangue, and background soil to coal mining soil being 33.42%, 34.4%, and 32.19%, respectively. However, Hg from raw coal, coal gangue and background soil contributed 17.04%, 21.46%, and 61.51% of the Hg in the farmland soil, indicating that the accumulation of Hg in farmland soil was derived primarily from the background soil. Our study demonstrated that secondary pollution in soil caused by immense accumulation of solid waste (gangue) by mining activities offers a significant challenge to ecological security. These findings provide new insights into controlling soil Hg in mining areas and further highlight the urgency of strict protective measures for contaminated sites.

Phytoremediation Potential of Native Plant Species in Mine Soils Polluted by Metal(loid)s and Rare Earth Elements.

Mining activity has an adverse impact on the surrounding ecosystem, especially via the release of potentially toxic elements (PTEs); therefore, there is an urgent need to develop efficient technologies to remediate these ecosystems, especially soils. Phytoremediation can be potentially used to remediate contaminated areas by potentially toxic elements. However, in soils affected by polymetallic contamination, including metals, metalloids, and rare earth elements (REEs), it is necessary to evaluate the behavior of these toxic elements in the soil-plant system, which will allow the selection of the most appropriate native plants with phytoremediation potential to be used in phytoremediation programs. This study was conducted to evaluate the level of contamination of 29 metal(loid)s and REEs in two natural soils and four native plant species (Salsola oppositifolia, Stipa tenacissima, Piptatherum miliaceum, and Artemisia herba-alba) growing in the vicinity of a Pb-(Ag)-Zn mine and asses their phytoextraction and phytostabilization potential. The results indicated that very high soil contamination was found for Zn, Fe, Al, Pb, Cd, As, Se, and Th, considerable to moderate contamination for Cu, Sb, Cs, Ge Ni, Cr, and Co, and low contamination for Rb, V, Sr, Zr, Sn, Y, Bi and U in the study area, dependent of sampling place. Available fraction of PTEs and REEs in comparison to total concentration showed a wide range from 0% for Sn to more than 10% for Pb, Cd, and Mn. Soil properties such as pH, electrical conductivity, and clay content affect the total, available, and water-soluble concentrations of different PTEs and REEs. The results obtained from plant analysis showed that the concentration of PTEs in shoots could be at a toxicity level (Zn, Pb, and Cr), lower than toxic but more than sufficient or natural concentration accepted in plants (Cd, Ni, and Cu) or at an acceptable level (e.g., V, As, Co, and Mn). Accumulation of PTEs and REEs in plants and the translocation from root to shoot varied between plant species and sampling soils. A. herba-alba is the least efficient plant in the phytoremediation process; P. miliaceum was a good candidate for phytostabilization of Pb, Cd, Cu, V, and As, and S. oppositifolia for phytoextraction of Zn, Cd, Mn, and Mo. All plant species except A. herba-alba could be potential candidates for phytostabilization of REEs, while none of the plant species has the potential to be used in the phytoextraction of REEs.

Distributions and potential sources of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in the glacimarine sediments of Arctic Svalbard.

Distribution and sources of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in the glacimarine sediments (35 sites) of Svalbard were investigated. PCBs (32 congeners), traditional PAHs (15 homologs), emerging PAHs (11 homologs), and alkylated PAHs (16 homologs) were widely distributed in the Svalbard sediments (ranges: below method detection limit to 20, 21 to 3600, 1.0 to 1400, and 31 to 15,000 ng g-1 dry weight, respectively). Compositional analysis indicated that PCBs mainly originated from combustion sources, with PAHs being strongly influenced by local sources. Positive matrix factorization analysis showed that PAHs were associated with vehicle and petroleum combustion, coal, and coal combustion. Coal-derived PAHs contributed significantly to the sediments of Van Mijenfjorden. Remnants of coal mining activity trapped in the permafrost appear to enter the coastal environments as ground ice melts. Consequently, PAHs are currently emerging as the most significant contributors to potential risks in the Svalbard ecosystems.

Acoustic Monitoring of Black-Tufted Marmosets in a Tropical Forest Disturbed by Mining Noise.

All habitats have noise, but anthropogenic sounds often differ from natural sounds in terms of frequency, duration and intensity, and therefore may disrupt animal vocal communication. This study aimed to investigate whether vocalizations emitted by black-tufted marmosets (Callithrix penicillata) were affected by the noise produced by mining activity. Through passive acoustic monitoring, we compared the noise levels and acoustic parameters of the contact calls of marmosets living in two study areas (with two sampling points within each area)-one near and one far from an opencast mine in Brazil. The near area had higher anthropogenic background noise levels and the marmosets showed greater calling activity compared to the far area. Calls in the near area had significantly lower minimum, maximum and peak frequencies and higher average power density and bandwidth than those in the far area. Our results indicate that the mining noise affected marmoset vocal communication and may be causing the animals to adjust their acoustic communication patterns to increase the efficiency of signal propagation. Given that vocalizations are an important part of social interactions in this species, concerns arise about the potential negative impact of mining noise on marmosets exposed to this human activity.

Levels and determinants of urinary and blood metals in the geothermal area of Mt. Amiata in Tuscany (Italy).

Natural sources and anthropogenic activities are responsible for the widespread presence of heavy metals in the environment in the volcanic and geothermal area of Mt. Amiata (Tuscany, Italy). This study evaluates the extent of the population exposure to metals and describes the major individual and environmental determinants. A human biomonitoring survey was carried out to determine the concentrations of arsenic (As), mercury (Hg), thallium (Tl), antimony (Sb), cadmium (Cd), nickel (Ni), chromium (Cr), cobalt (Co), vanadium (V), and manganese (Mn). The associations between socio-demographics, lifestyle, diet, environmental exposure, and metal concentrations were evaluated using multiple log-linear regression models, adjusted for urinary creatinine. A total of 2034 urine and blood samples were collected. Adjusted geometric averages were higher in women (except for blood Hg) and younger subjects (except for Tl and Cd). Smoking was associated with Cd, As, and V. Some dietary habits (rice, fish, and wine consumption) were associated with As, Hg, Co, and Ni. Amalgam dental fillings and contact lenses were associated with Hg levels, piercing with As, Co, and Ni. Among environmental determinants, urinary As levels were higher in subjects using the aqueduct water for drinking/cooking. The consumption of locally grown fruits and vegetables was associated with Hg, Tl, and Co. Exposure to geothermal plant emissions was associated only with Tl.

Using homing pigeons to monitor atmospheric organic pollutants in a city heavily involving in coal mining industry.

Coal is the most extensively used fossil fuel in China. It is well documented that coal combustion detrimentally affected air quality, yet the contribution of coal mining activity to air pollution is still largely unknown. Homing pigeons have been applied to assess the occurrence of atmospheric pollutants within cities. Herein, we sampled homing pigeons from both urban and mining areas in a typical coal industry city (Datong, China) as biomonitors for assessing local air pollution. Target organic contaminants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) were frequently detected in lung, liver, and fat tissues of the pigeons. The pollutants were predominately accumulated in lung, validating that respiration was the main accumulation route for these compounds in homing pigeons. In addition, pathological damage examination in lung and liver tissues revealed that the exposure to atmospheric pollutants impaired pigeon health. While the concentrations of PCBs and OCPs were similar in pigeons from urban and mining areas, the concentrations of PAHs were higher in pigeons from urban area. In contrast, more elevated levels of PBDEs (particularly BDE-209) were found in the mining area, which was consistent with the greater pathological damages and particulate matter levels. Unlike coal combustion, coal mining activities did not increase atmospheric PAH exposure to homing pigeons, but intensified PBDE contamination along with increasing emission of particulate matters. Overall, homing pigeons are promising biomonitors for assessing the respiratory exposure and risk of atmospheric pollutants within cities.

Biogeochemical transformation of sulfur and its effects on arsenic mobility in paddy fields polluted by acid mine drainage.

This study aimed to study the biogeochemical behaviour of sulfur and its potential impact on arsenic in farmland polluted by acid mine drainage (AMD). Soil samples were collected from paddy fields that were near arsenic-rich coal mines. Different geochemical analysis technologies, combined with the study of microbial populations, were used to analyse the enrichment and transformation characteristics of exogenous sulfur in the soil profile as well as their coupling effect with arsenic transformation. The results showed that sulfur, iron, and arsenic were obviously enriched in the soil, and sulfur easily migrated to deeper layers. The content of arsenic in contaminated soil was about 1.30-3.14 times higher compared to standard Chinese soil quality. Polluted soil had a higher content of bioavailable sulfur and adsorbed sulfur accounted for about 29% of the total sulfur. This promoted an increased microbial population abundance of Desulfosporosinus. The δ34S values of the polluted soil were lower than the background, ranging from -0.69‰ to 11.44‰, but were higher than the theoretical values. There was evidence of dissimilatory sulfur reduction and enrichment in 34S. A significant positive correlation was observed between the contents of adsorbed sulfur and total arsenic. The biogeochemical transformation of sulfur was conducive to the transformation of iron oxide-bound arsenic into sulfide minerals, which enhanced its stability. These results provide theoretical support for understanding the cycling transformation and environmental impact of sulfur in paddy fields polluted by AMD.

Vegetation and Environmental Changes on Contaminated Soil Formed on Waste from an Historic Zn-Pb Ore-Washing Plant.

Post-mining waste from Zn-Pb ore exploitation undergoes processes of spontaneous succession and changes in soil chemical composition. The Zakawie area was industrially transformed by historical mining activity, ore enrichment, and the metallurgical processing of Zn-Pb ore. The subject of the study was to analyse the rate of vegetation succession (from 1999 to 2019), soil chemistry, and the relationships between them in an anthropogenic habitat with high concentrations of potentially toxic metals. Ecological and geochemical studies were carried out in an area contaminated with waste from a disused Zn-Pb ore-washing plant. Between 1999 and 2019, the transformation of grassland and meadow vegetation into scrub and forest-grassland communities was observed. This transformation led to a decrease in the area of Molinietum caeruleae meadow (from 25.8% in 1999 to 10.7% in 2019), whose place was taken by Prunus spinosa and Rhamnus cathartica. The community of xerothermic limestone grasslands completely disappeared, being replaced in favour of the Diantho-Armerietum and Prunus spinosa community. In this period, the share of lifeforms of plants and species composition (46 and 60, respectively) also changed. The Shannon and Simpson biodiversity index reached high values in the second investigation period, and it was 0.893 and 0.86, respectively. The anthrosols had a high content of Zn-85,360 mg kg-1, Pb-28,300 mg kg-1, Cd-340 mg kg-1, and As-1200 mg kg-1. Carbonates, clay minerals, and fe-oxides are predominant in the mineral composition of the rhizosphere; the metal-bearing phases are stable; and hardly soluble minerals include smithsonite, cerussite, monheimite, hemimorphite, and oxides of Fe and Fe-Mn. Mineralisation/crust processes formed on the epidermis, and their influences on root development were found. Scanning electron microscopy and energy-dispersive X-ray spectroscopy studies on rhizosphere soil components provide information on the type of minerals and their susceptibility to heavy metals release. The identification of some biotic and mineral structures in rhizospheres can be an interesting source of information on pedogenic processes identified in back-scattered electron images.

Mapping annual land disturbance and reclamation in rare-earth mining disturbance region using temporal trajectory segmentation.

Rare-earth mining has caused extensive damage to soil, vegetation, and water, significantly threatening ecosystems. Monitoring environmental disturbance caused by rare-earth mining is necessary to protect the ecological environment. A spatiotemporal remote sensing monitoring method for mining to reclamation processes in a rare-earth mining area using multisource time-series satellite images is described. In this study, the normalized difference vegetation index (NDVI) is used to evaluate the mining impact. Regression analysis is conducted to relate the HJ-1B CCD and Landsat 5/8 data to reduce the NDVI error related to sensor differences between different datasets. The analysis method of NDVI trajectory data of ground objects is proposed, and areas of environmental disturbance caused by rare-earth mining are identified. Pixel-based trajectories were used to reconstruct the temporal evolution of vegetation, and a temporal trajectory segmentation method is established based on the vegetation changes in different disturbance stages. The temporal trajectory of the rare-earth disturbance points is segmented to extract features in each stage to obtain the disturbance year, recovery year, and recovery cycle and evaluate the vegetation recovery after rare-earth mining disturbance. We applied the method to a stack of 20 multitemporal images from 2000 to 2019 to analyze vegetation disturbance due to rare-earth mining and vegetation recovery in the upper reaches of the Guangdong-Hong Kong-Macao Greater Bay Area, China. The results show the following. (1) Mining industry in the study area experienced rapid expansion before 2008, but growth slowed since the policies implemented by the government since 2009 to restrict rare-earth mining. (2) The continuous influence to the land caused by rare-earth mining can last for decades; however, the reclamation activities shorten the recovery cycle of mining land from 5 to 3 years.

Pollution Distribution of Potentially Toxic Elements in a Karstic River Affected by Manganese Mining in Changyang, Western Hubei, Central China.

This study investigated the distribution, pollution level and potential ecological risk of potentially toxic elements (PTEs) from manganese mining in a karstic Danshui River, in Changyang, Western Hubei, Central China. River water and sediments were collected for seven PTEs measurement (As, Cd, Cr, Cu, Mn, Pb and Zn), as well as pH and Eh of the river water were measured. Results showed that the major pollutant was Mn, the river water environment was mainly acidic and oxidizing (288 < Eh, pH < 6.3), and the pollution distribution of Mn in the study area was dominated by the combination of natural processes and anthropogenic activities. In the river water, according to the contamination factor (CF) and pollution load index (IPL) results, Mn was considered the main pollutant. There was low As and Pb pollution downstream as well as Cu pollution upstream. Upstream and downstream areas were the main polluted river sections of the river water samples collected. In river sediments, based on the results of the geo-accumulation index (Igeo) and potential ecological risk index (IPER), it was determined that there was only considerable Mn pollution. The IPER of the PTEs from the river sediments was at acceptable levels, only Mn upstream performed at a moderate ecological risk level. According to Pearson correlation and principal component analysis, Mn originated from manganese mining activities, Cd, Cr and Zn were of natural origin, and Cu may have come from both mining and natural origin, whereas Pb and As were mainly related to the daily activities. Consequently, elemental speciation, mining activities and the distribution of water conservancy facilities were the main impacts of PET pollution distribution in this river.

Cadmium and Lead Pollution Characteristics of Soils, Vegetables and Human Hair Around an Open-cast Lead-zinc Mine.

Atmospheric deposition of cadmium (Cd) and lead (Pb) was investigated together with the accumulation, distribution and health risks from potentially toxic metals in soils, vegetables and human hair at a mining area in southwest China. Annual atmospheric deposition of Cd and Pb were 41.1 and 192 g ha- 1, respectively, and consisted mainly of dry deposition. Agricultural soils experienced high levels of metal pollution around the mine, with 66.4% and 57.3 % of vegetable samples grown on these polluted fields exceeding maximum permissible Cd and Pb concentrations, particularly the leafy vegetables. Residents living near the mining area had high Cd (0.75 mg kg- 1) and Pb (6.87 mg kg- 1) concentrations in their hair, and the maximum values occurred in occupationally exposed individuals. Long-term mining activities have resulted in high health risks to the local population due to Cd and Pb deposition and accumulation from the atmosphere, soils and vegetables.

Patterns in utilization of carbon sources in soil microbial communities contaminated with mine solid wastes from San Luis Potosi, Mexico.

In San Luis Potosí, Mexico, the exploitation of minerals has historically been carried out as an activity that has left in its path environmental liabilities, with high concentrations of heavy metals. These metals have undergone weathering by rain and wind and have moved closer to inhabited locations as is the case of Cerro de San Pedro (CSP) and Villa de la Paz (VDP). The objective of this study is to show the biological alteration of soils due to the presence of heavy metals and metalloids like Cadmium (Cd), Copper (Cu), Lead (Pb) and Arsenic (As) and to find the relationship between contamination and risk indexes. Soil samples were obtained from sites with historical records of mining activity and their surroundings. Several analyses were performed, such as pH levels, organic matter, electrical conductivity, clays, heavy metals and As. Moreover, Community Level Physiological profiling (CLPP) were conducted. The obtained evidence showed high levels of contamination by As and heavy metals in both sites (CSP: 6485.1 mg/Kg of Pb and pH of 4.4; VDP: 7188.2 mg/Kg of As and pH of 7.8). According to the Metal Pollution Index (MPI), 607.0 in CSP and 1050.5 in VDP, presented a high environmental risk, apart from, risk to human health (SQGQI) 35.8 in CSP and 131.5 in VDP. At the same time, CLPPs showed that microbiological communities were selective in taking up substrate groups, in the following order: Carbohydrates > Polymers > Carboxylic acids > Amino acids > Amines/Amides. However, a positive correlation in CSP was only found between both indexes and Amines/Amides (r = 0.46, p < 0.05), and in VDP the D-Galactonic acid-γ-Lactone with the MPI (r = 0.49, p < 0.05), and with the SQGQI (r = 0.45, p < 0.05). Although this behavior was not homogeneous, it was possible to find negative correlations between both indexes and the AWCD with other substrates, influenced by the physicochemical characteristics presented in each studied site. Consequently, according to our findings, a combined effect between the physicochemical characteristics, As, and heavy metals took place, on the metabolic activity, causing alterations to soil functions.

Response of bacterial communities to mining activity in the alpine area of the Tianshan Mountain region, China.

Anthropogenic activities, such as mining, influence soil bacterial community composition and microbial distributions. In the current study, the patterns in microbial distribution and the environmental drivers shaping the soil bacterial community composition in the alpine mining area of the Tianshan Mountain region, China, were investigated, and the bacterial communities were analyzed using 16S rDNA pyrosequencing. The environmental factors and their relationships with the microbial community composition, structure, and diversity were also assessed. The soil organic carbon (SOC) concentration increased along the elevation gradient, with the highest concentration in the mining area, which increased microbial abundance and species richness. Some metals, like Ca, Cu, Pb, and Zn, accumulated significantly in the tailing area and were negatively correlated with the microbial community structure. Proteobacteria, Acidobacteria, Actinobacteria, and Verrucomicrobia were the dominant phyla; these dominant phyla were more abundant in the areas without mining than in the areas with mining at the same altitude. The relative abundance of Proteobacteria and Verrucomicrobia significantly increased along the elevation gradient, while that of Actinobacteria in the mining camp area was more than twice those in the other areas due to higher soil pH. Soil biomass was the highest in the valley. Collectively, these results elucidate the influence of anthropogenic mining activities on soil microbial communities in alpine mining soils and provide a basis for the future management of heavy metal-contaminated areas using the indigenous dominant bacterial phyla.

Phytoperiphyton associated with lagoons generated by mining, San Juan river basin, Chocó-Colombia / Fitoperifíton asociado a lagunas generadas por minería, cuenca del río San Juan, Chocó-Colombia

ABSTRACT Mining activity generates transformations in aquatic ecosystems and adjacent areas, as well as the creation of land depressions or "lagoons" that act as water reservoirs where aquatic communities develop, including the phytoperiphyton. Considering the role of this community in these environments, the purpose of this research was to study the phytoperiphytic community present in lagoons generated by mining processes, in the San Juan basin, Chocó (Colombia). Lagoons with different formation times were selected: 1-5 years, 5-10 years and 10-15 years; three lagoons for each time period. Physical and chemical variables were measured, and phytoperiphyton was collected, using an 8cm2 quadrant, obtaining a scraping area of 120cm2. The community was composed of six divisions, nine classes, 16 orders, 24 families and 33 genera, for a total density of 13108 org/cm2. The lagoons of 10-15 years presented the highest density, with Bacillariophytes as the most representative in all the studied lagoons, both in density and richness. There were differences in density between lagoons, but not in specific richness and diversity. Similarity values indicate that the lagoons have little variability in their phytoperiphytic communities. Conductivity and dissolved total solids are the variables with the greatest variation throughout the study; there are significant differences between lagoons for the variables dissolved oxygen, pH and alkalinity (p<0.05). This study constitutes a baseline for understanding the ecological dynamics of lentic environments generated by mining processes and on the development of phytoperiphytic communities in them.

RESUMEN La actividad minera genera transformaciones en los ecosistemas acuáticos y zonas adyacentes y, entre ellas, se crean depresiones en el terreno o "lagunas", que actúan como reservorios de agua, en los que se desarrollan comunidades acuáticas, como el fitoperifíton. Considerando el papel de esta comunidad en estos ambientes, el propósito de esta investigación fue estudiar la comunidad fitoperifítica presente en lagunas generadas por procesos de extracción minera, en la cuenca del San Juan, Chocó (Colombia). Se seleccionaron lagunas con diferente tiempo de formación: 1-5 años, 5-10 años y 10-15 años; tres lagunas por cada periodo de tiempo. Se midieron variables físicas y químicas y se colectó fitoperifíton, utilizando un cuadrante de 8cm2, obteniéndose un área de raspado de 120cm2. La comunidad, se compuso de seis divisiones, nueve clases, 16 órdenes, 24 familias y 33 géneros, para una densidad total de 13108 org/cm2. Las lagunas de 10-15 años presentaron la mayor densidad con las Bacillariophytas, como las más representativas en todas las lagunas estudiadas, tanto en densidad como en riqueza. Existieron diferencias en densidad entre lagunas, pero no en la riqueza específica y diversidad. Los valores de similaridad indican que las lagunas presentan poca variabilidad en sus comunidades fitoperifíticas. La conductividad y los sólidos totales disueltos son las variables de mayor variación, a lo largo de estudio, existiendo diferencias significativas entre lagunas, para las variables oxígeno disuelto, pH y alcalinidad (p<0,05). Las variables pH y conductividad, se relacionaron positivamente con la densidad de algunos grupos fitoperifíticos. Este estudio, se constituye en una línea base para el conocimiento de la dinámica ecológica de los ambientes lénticos generados por los procesos mineros y sobre el desarrollo de las comunidades fitoperifíticas en ellos.

Influence of iron mining activity on heavy metal contamination in the sediments of the Aqyazi River, Iran.

In order to investigate the degree of contamination of heavy metals (As, Cd, Cr, Cu, Fe, Pb, and Ni) in the Aqyazi River in Iran, sediment samples were collected from the river receiving wastewater from an iron-manufacturing plant. For this study, contamination indices, geoaccumulation index (Igeo), contamination factor (CF), and pollution load index (PLI), were used to assess contamination by the heavy metals. The results of the Igeo indicated that the sediments were moderately contaminated by Cu and strongly to extremely contaminated by Cd. Based on spatial distribution of concentrations and the Igeo, mining activity was the source of Cu and Cd in the Aqyazi River. Furthermore, the elevated Igeo of Cd at upmost northern station was not influenced by the mining activity, suggesting that there may be another upstream anthropogenic source of Cd. The CF values indicated the same trend as the Igeo. The PLI was calculated using all the metals analyzed in this study, and displayed that the sediments were not polluted. However, the PLI was re-calculated using only Cu and Cd and indicated that the sediments were polluted. Our results suggest further studies to trace another source of Cd upstream of the Aqyazi River and to investigate influence of the river waters on accumulation of heavy metals in soils and vegetables downstream.

Toxic and essential trace element concentrations in fish species in the Lower Amazon, Brazil.

The Lower Amazon region (Western Pará, northern Brazil) is greatly affected by mining exploitations (particularly artisanal gold mines) and other industrial and intensive agricultural activities with potentially strong impacts on aquatic ecosystems. Although such impacts include contamination with various toxic elements, to date only the effects of Hg have been considered. In this study, toxic and trace element concentrations were determined in the flesh of 351 fish specimens, including detritivores (Acarí, Pterygoplichthys pardalis), omnivores (Piranha, Pygocentrus nattereri; Pirarucu, Arapaima sp.) and carnivores (Caparari, Pseudoplatystoma fasciatum; Tucunaré, Cichla ocellaris), during the dry and wet seasons in 2015 and 2016. The range of concentrations of toxic element residues were 2-238 µg/kg fresh weight for As, 1-77 µg/kg for Cd, 4-1922 µg/kg for Hg and 1-30 µg/kg for Pb. Only the maximum concentrations of Hg established in the Brazilian legislation for fish destined for human consumption (0.5 mg/kg) were exceeded (in 16% of carnivorous species). The large between-species and seasonal differences observed for all these toxic elements are probably related to the seasonal behaviour and dietary habits of the different fish species. By contrast, essential trace element concentrations were low and not related to seasonal or dietary factors, and the observed differences may be at least partly related to the metabolism of each species. The associations between Hg and the essential trace elements Se, Fe, Co and Mn deserve special attention, as these trace elements may play a role in Hg cycling and methylation and merit further evaluation with the aim of reducing Hg toxicity in aquatic environments.

Health risk assessment and levels of toxic metals in fishes (Oreochromis noliticus and Clarias anguillaris) from Ankobrah and Pra basins: Impact of illegal mining activities on food safety.

Arsenic (As), mercury (Hg), Cadmium (Cd) and lead (Pb) are toxic heavy metals that naturally occur in the ecosystem. Their levels are on the rise due to anthropogenic activities posing threat to aquatic wildlife and humans. In Ghana, pollution of some water bodies has led to unsafe consumption of riverine fishes as well as a shortage of treated potable water principally because the cost of treating polluted water has become expensive across the country. This study aimed to assess the As, Hg, Pb and Cd concentrations in water and fishes from rivers Pra and Ankobrah where activities of artisanal gold mining were carried out resulting in gross pollution of the water bodies. An experimental study was performed to ascertain the levels of As, Hg, Pb and Cd in fish species of Nile tilapia (Oreochromis noliticus) and mudfish (Clarias anguillaris) and aquatic media (water) from the Pra and River Ankobrah basins using the Atomic Absorption Spectrophotometer (AAS) (Varian AA240FS). Both river water samples recorded ranges of 0- 0.0040, 0.0060- 0.0387, 0 - 0.0020, 0.006-0.0093 mg/l for Cadmium, Lead, Arsenic and Mercury respectively. For Cadmium and Arsenic, their levels were comparable (p > 0.05). However, detected values for Lead and Mercury were no comparable (p < 0.05). Toxic metals concentrations in the rivers decreased in the order of Hg > Pb > Cd > As. For the fish samples, values ranged 0-0.08, 0.04-0.42, 0-0.04, and 0.40- 0.60 mg/kg for Cadmium, Lead, Arsenic and Mercury respectively. Generally, appreciably high values were obtained for Mercury. Toxic metals concentrations in the rivers decreased in the order of Hg > Pb > Cd > As. Human health risk assessment from heavy metal exposure through fish consumption from the Rivers for both children and adults showed no significant non-carcinogenic adverse health risk to humans since all calculated values for Hazard Quotient (HQ) were <1. Nonetheless, Target Hazard Quotient (THQ) values calculated for children and adult exposure to Cadmium and Mercury were>1 which implied a likely cause of adverse effects during a person's lifetime.