Human health risk assessment of PM10-bound heavy metals and PAHs around the Latin America's Largest opencast coal mine.

Air pollution in opencast coal mine areas is a critical issue, resulting in harmful severe effects on human health. Therefore, it is essential to understand the air pollution factors and to assess the risks to humans. This study evaluated the potential risks (carcinogen and non-carcinogen) of inhalation exposure to PM10-bound heavy metals and Polycyclic Aromatic Hydrocarbons (PAHs) in an open pit mine in northern Colombia. During February-May 2022, PM10 samples were collected at eight sites. Heavy metals (i.e., Al, Cr(VI), Mn, Cu, Zn, As, Pb) and PAHs (thirteen priority PAHs, and one non-priority PAH) levels linked to PM10 were analyzed by X-ray fluorescence and gas chromatography-mass spectrometry, respectively. PM10 concentrations were found to range between 4.70 and 59.90 µg m-3. Out of the three different zones of the study area (i.e., North Zone, South Zone, and Populated Zone), the North Zone recorded the highest daily average concentrations of Cr(VI) (104.16 ng m-3), Mn (28.39 ng m-3), Cu (33.75 ng m-3), Zn (57.99 ng m-3), As (44.92 ng m-3), and Pb (27.13 ng m-3). The fraction of the analyzed heavy metals at all monitoring sites was 82%-89% for Al, followed by Cr(VI) with 3%-6%. Cr(VI) was the major contributor to the carcinogenic risk values, while Cu, Cr(VI), and As were the main drivers for the non-carcinogenic risk. The average cancer risk range for heavy metals was 3.30 × 10-04 -5.47 × 10-04. On the other hand, the cancer risk for PAHs exposure was acceptable. The average incremental lifetime cancer risk (ILCR) values varied between 2.87 × 10-07 and 4.21 × 10-07. Benzo[a]pyrene contributed to 54%-56% of the total risk from inhalation of PM10-bound PAHs, while Indeno[1,2,3-cd]pyrene contributed to 16%-19%. Based on the Monte Carlo sensitivity analysis, exposure to Cr(VI) was the main factor affecting cancer risk in the North, South, and Populated Zones. A suitable risk assessment and management plan requires understanding PM10-bound heavy metals and PAHs concentration levels as well as their potential health risks, mainly in open-cast coal mine zones. Our study found that people living near open-pit mines face potential health risks, so it is crucial to establish policies and regulations to control emission sources.

Caracterización de un Consorcio Microbiano Metanogénico de una Mina de Carbón en la Cuenca de Bogotá / Characterization of a Methanogenic Microbial Consortium from a Coal Mine in Bogotá Basin

RESUMEN En el trabajo se estudió un consorcio microbiano metanogénico de una mina de carbón de la cuenca de Bogotá en Colombia. Se establecieron cultivos de enriquecimiento de carbón ex situ para el crecimiento y la producción de gas de novo. El gas biogénico producido por los cultivos se analizó mediante cromatografía de gases con detectores de ionización de llama y conductividad térmica. Los cultivos se utilizaron para aislar estirpes microbianas y para generar bibliotecas del gene 16S rARN empleando de cebadores de bacteria y de arquea. El análisis de cromatografía de gases mostró producción de metano a 37 oC, pero no a 60 oC, donde el CO2 fue el componente principal del gas biogénico. El análisis de la secuencia del gen 16S rARN de estirpes microbianos y de las bibliotecas de clones, estableció que el consorcio microbiano metanogénico estuvo formado por especies de bacterias de los géneros Bacillus y Gracilibacter más la arquea del género Methanothermobacter. El consorcio microbiano metanogénico identificado es potencialmente responsable de la generación de gas biogénico en la mina de carbón La Ciscuda. Los resultados sugirieron que los metanógenos de este consorcio producían metano por vía hidrogenotrófica o de reducción de CO2.

ABSTRACT The work studied the methanogenic microbial consortium in a coal mine from the Bogotá basin in Colombia. Ex situ coal-enrichment cultures were established for in vitro growth and de novo gas production. Biogenic gas produced by cultures was analyzed by gas chromatography using thermal conductivity and flame ionization detectors. Cultures were used to isolate microbial specimens and to generate 16S rRNA gene libraries employing bacterial and archaeal primer sets. The gas chromatographic analysis showed methane production at 37 oC, but not at 60 oC, where CO2 was the major component of the biogenic gas. 16S rRNA gene sequence analysis of microbial isolates and clone libraries established that the methanogenic microbial consortium was formed by bacteria species from Bacillus and Gracilibacter genera plus archaea from the Methanothermobacter genus. This meth-anogenic microbial consortium was potentially responsible for biogenic gas generation in La Ciscuda coal mine. The results suggested that these methanogens produced methane by hydrogenotrophic or CO2 reduction pathways.

A first evaluation of water resource conditions after an environmental reclamation effort at a former degraded coal mining area in Southern Brazil.

In southern South America, Brazil, in the state of Santa Catarina, the neglect and lack of environmental supervision during coal mining caused the contamination of surface and groundwater by acid mine drainage (AMD). By the force of the local law, environmental reclamation actions in these abandoned areas have been carried. A scientific work of monitoring and assessment of the water resources within these areas has never been developed, as the efficacy of the reclamation strategies has never been discussed. This work aims to fill this gap by presenting and analyzing the environmental reclamation strategy of a former degraded coal mining area and its impacts on local water resources. The water monitoring plan in Area IV's was carried out in groundwater, and in lentic (ponds) and lotic (rivers) environments of surface waters, fourteen monitoring campaigns were conducted. The results showed that upstream and downstream river points have different water qualities, with the downstream points having poorer water quality, still affected by past mining activities. From the surface water perspective, the reclaiming method adopted was effective in three of the four ponds, presenting problems only in the downstream one. Two hypotheses were proposed; the first hypothesis is that contamination happens due to leaching of the material that still remains on the ponds' banks into the water. Another hypothesis is that the contamination comes from the upstream groundwater inflow into the pond, which runs through the entire area before reaching the pond. Those results serve to further access the actual monitoring perspectives as well as to better develop future reclaiming strategies.

Environmental and health risk assessment of agricultural areas adjacent to uranium ore fields in Brazil.

To investigate the risks posed by trace and rare earth elements (REEs) in two tropical uranium ore fields, metal concentrations from 50 vegetable samples (corn and soybean) and their corresponding agricultural soils were evaluated in a U mining area and a U-rich coal mining area in Brazil. Samples from both areas had metal concentrations (REE: La to Lu, and trace elements: As, Pb, Cd, Ni, Cu, Cr, Mn, Zn, Ba, U, Sr) that were higher than the guidelines proposed by the Brazilian environmental agency. Soils from the U mining area (Poços de Caldas) generally had higher contents of trace elements than the coal mining area (Figueira), with the exception of Ni and Cr, indicating a higher risk of pollution, which was confirmed by a pollution load index that was greater than unity. For both sites, concentrations of uranium in the soil and plants, its hazard quotients and the soil contamination factor were higher in agricultural fields closer to the mines, indicating that contamination and the consequent risks to human health were distance dependent. REE concentrations averaged 52.8 mg kg-1 in the topsoils and 0.76 mg kg-1 in the grains for Figueira, whereas higher values of 371 mg kg-1 (topsoils) and 0.9 mg kg-1 (grains) were found in Poços de Caldas. Based upon corn and soybean consumption, the estimated intake dose of the REE was lower than the intake dose predicted to be problematic for human health for both sites, indicating limited risk related to the ingestion of REE.

Identification of mercury and nanoparticles in roots with different oxidation states of an abandoned coal mine.

The morphology and composition of roots with different degrees of oxidation as a function of time were evaluated aiming to identify possible hazardous elements and nanoparticles. The roots were obtained from an abandoned coal mine located in the city of Criciúma, Santa Catarina, Brazil. From the roots, analyses were performed to identify nanoparticles (NPs) and ultrafine particles (UFPs), containing possible hazardous elements (PHEs) that cause potential environmental risks and impacts on human health. The identification of nanoscale materials requires greater robustness, so advanced integrated techniques have been used. The characterization of different types of roots was done by using focused ion beam (FIB), to evaluate nano-compound assemblies with high-resolution transmission electron microscopy/energy dispersive spectroscopy (HR-TEM/EDS). The results showed the presence of NPs containing Hg, Co, Cr, Ni, and V. The presence of these elements has increased consistently with the increase of C concentration in the roots, suggesting that the PHEs were gradually released from organic matter and inorganic minerals of coal. However, even with their decrease in roots, it was found that these elements still remained in the soil in significant quantities, even after 15 years of inactivation of the coal mine.

Genotoxicity in Brazilian coal miners and its associated factors.

The present study aims to evaluate the potential genotoxic and associated factors among coal miners, divided by degree of exposure. Blood and buccal smears were collected from 158 workers, who actively participate in different activities in coal mining, and 48 individuals living in the same city but do not have participation in coal mining activities (control group). The workers were divided into three different groups, according to the level of contact with coal extraction. A questionnaire intended to identify factors associated with DNA damage was performed in participants. The results regarding oral mucosa micronucleus test showed a significant difference ( p < 0.001) of the worker groups 1 and 2 in relation to the control group, where the group 1 has a higher degree of exposure to coal than group 2. For the lymphocyte micronucleus test and comet assay, there was no significant difference between the exposed groups and control group. There is an association between the outcome and the fact of living in the municipality of the mining company and the exposure to radiation in the last 12 months. Besides, the multivariate analysis showed an association of the tail moment with radiation exposure in the last 12 months. Thus, the findings of this study reveal genotoxicity in oral mucosa cells of workers exposed to coal and that workers with higher degree of contact with coal have a more pronounced response.

In vitro genotoxic effect of secondary minerals crystallized in rocks from coal mine drainage.

Coal processing generates a large volume of waste that can damage human health and the environment. Often these wastes produce acid drainage in which several minerals are crystallized (evaporites). This study aimed to identify secondary minerals, as well as the genotoxic potential of these materials. The samples were collected at two sites along the Rocinha River in Santa Catarina state (Brazil): (1) directly from the source of the acid drainage (evaporite 1), and (2) on the river bank (evaporite 2). The samples were characterized by X-ray diffraction and by particle-induced X-ray emission techniques. In vitro genotoxicity testing using Comet assay and Micronucleus test in V79 cells was used to evaluate evaporite samples. Our study also used System Biology tools to provide insight regarding the influence of this exposure on DNA damage in cells. The results showed that the samples induced DNA damage for both evaporites that can be explained by high concentrations of chromium, iron, nickel, copper and zinc in these materials. Thus, this study is very important due to the dearth of knowledge regarding the toxicity of evaporites in the environment. The genetic toxicity of this material can be induced by increased oxidative stress and DNA repair inhibition.

Hydrogeochemical features of surface water and groundwater contaminated with acid mine drainage (AMD) in coal mining areas: a case study in southern Brazil.

Effects of acid mine drainage (AMD) were investigated in surface waters (Laranjinha River and Ribeirão das Pedras stream) and groundwaters from a coal mining area sampled in two different seasons at Figueira city, Paraná State, Brazil. The spatial data distribution indicated that the acid effluents favor the chemical elements leaching and transport from the tailings pile into the superficial water bodies or aquifers, modifying their quality. The acid groundwaters in both sampling periods (dry: pH 2.94-6.04; rainy: pH 3.25-6.63) were probably due to the AMD generation and infiltration, after the oxidation of sulfide minerals. Such acid effluents cause an increase of the solubilization rate of metals, mainly iron and aluminum, contributing to both groundwater and surface water contamination. Sulfate in high levels is a result of waters' pollution due to AMD. In some cases, high sulfate and low iron contents, associated with less acidic pH values, could indicate that AMD, previously generated, is nowadays being neutralized. The chemistry of the waters affected by AMD is controlled by the pH, sulfide minerals' oxidation, oxygen, iron content, and microbial activity. It is also influenced by seasonal variations that allow the occurrence of dissolution processes and the concentration of some chemical elements. Under the perspective of the waters' quality evaluation, the parameters such as conductivity, dissolved sodium, and sulfate concentrations acted as AMD indicators of groundwaters and surface waters affected by acid effluents.