Geochronology,Mineralogy,and Geochemistry of the Tonsteins from the Permo–Carboniferous Benxi Formation,Ordos Basin,North China Craton

Tonstein layers are found worldwide in the Permo-Carboniferous coal-bearing strata.This study investigates the geochronology,mineralogy,and geochemistry of four tonstein samples from the Permo-Carboniferous Benxi Formation,Ordos Basin,North China Craton(NCC).The typical features of the studied tonsteins include thin beds,lateral continuity,angular quartz grains,and euhedral zircons with similar U-Pb ages,indicating a significant pyroclastic origin.In addition,the tonstein samples have low TiO_(2)/Al_(2)O_(3)ratios(<0.02)and rare earth elements and yttrium(REY)concentrations with obvious negative Eu anomalies,indicating that the tonsteins have a felsic magma origin.Moreover,compared with the mean composition of clay shale,the studied tonsteins are characterized by high concentrations of the elements Nb and Ta,which may affect the concentration of the corresponding elements in surrounding coal seams.The zircon U-Pb ages of the tonsteins(293.9-298.8 Ma)provide a precise chronological framework on the Benxi Formation in the Ordos Basin,constraining the Gzhelian-Aselian stages.The tonsteins were probably sourced from arc volcanism along the western margin of the NCC during the early Permian,implying that the Alxa Terrane had not amalgamated with the NCC at that time.

Volcanic emissions and atmospheric pollution:A study of nanoparticles

The influence of emissions of an active volcano on the composition of nanoparticles and ultrafine road dust was identified in an urban area of the Andes.Although many cities are close to active volcanoes,few studies have evaluated their influence in road dust composition.Air quality in urban areas is significantly affected by nonexhaust emissions(e.g.road dust,brake wear,tire wear),however,natural sources such as volcanoes also impact the chemical composition of the particles.In this study,elements from volcanic emissions such as Si>Al>Fe>Ca>K>Mg,and Si-Al with K were identified as complex hydrates.Similarly,As,Hg,Cd,Pb,As,H,Cd,Pb,V,and salammoniac were observed in nanoparticles and ultrafine material.Mineral composition was detected in the order of quartz>mullite>calcite>kaolinite>illite>goethite>magnetite>zircon>monazite,in addition to salammoniac,a tracer of volcanic sources.The foregoing analysis reflects the importance of carrying out more studies relating the influence of volcanic emissions in road dust in order to protect human health.The road dust load(RD_(10))ranged between 0.8 and 26.8 mg m^(−2)in the city.

Metal-enriched nanoparticles and black carbon:A perspective from the Brazil railway system air pollution

Having a better understanding of air pollutants in railway systems is crucial to ensure a clean public transport.This study measured,for the first time in Brazil,nanoparticles(NPs)and black carbon(BC)on two groundlevel platforms and inside trains of the Metropolitan Area of Porto Alegre(MAPA).An intense sampling campaign during thirteen consecutive months was carried out and the chemical composition of NPs was examined by advanced microscopy techniques.The results showed that highest concentrations of the pollutants occur in colder seasons and influenced by variables such as frequency of the trains and passenger densities.Also,internal and external sources of pollution at the stations were identified.The predominance of NPs enriched with metals that increase oxidative stress like Cd,Fe,Pb,Cr,Zn,Ni,V,Hg,Sn,and Ba both on the platforms and inside trains,including Fe-minerals as hematite and magnetite,represents a critical risk to the health of passengers and employees of the system.This interdisciplinary and multi-analytical study aims to provide an improved understanding of reported adverse health effects induced by railway system aerosols.

Deposition of nanoparticles on school eyeglasses in urban and rural areas:A methodology for a more real assessment of the possible impacts

Because incomplete confirmation is available concerning the influential role of atmosphere contamination on conjunctivitis,myopia,asthma,and allergic rhinitis in Brazil,the focus of the present work is to explore the possible relations among atmosphere contamination and eye problems.Rather that a case study on eye diseases,by way of questionnaires supplemented by the investigation of nanoparticles(NPs)on eyeglasses,the study examines the mechanisms in which NPs and ultra-fine particles are deposited on the glasses of children up to 10 years of age in urban and rural area.The important connection between atmosphere contaminants and individual protection equipment justifies improving indoor school properties in order could protect children’s eyes,particularly in high-pollution/high-particulate areas.

Possibilities of using silicate rock powder:An overview

This study evaluates the on use of crushed rocks(remineralizers)to increase soil fertility levels and which contributed to increase agricultural productivity,recovery of degraded areas,decontamination of water,and carbon sequestration.The use of these geological materials is part of the assumptions of rock technology and,indirectly,facilitates the achievement of sustainable development goals related to soil management,climate change,and the preservation of water resources.Research over the past 50 years on silicate rocks focused on soil fertility management and agricultural productivity.More recently,the combined use with microorganisms and organic correctives have shown positive results to mitigate soil degradation;to expand carbon sequestration and storage;and to contribute to the adsorption of contaminants from water and soil.In this article we show results obtained in several countries and we show that this technology can contribute to the sustainability of agriculture,as well as to reverse global warming.Although mineral nutrients are released more slowly from these types of inputs,they remain in the soil for a longer time,stimulating the soil biota.In addition,they are a technology to soluble synthetic fertilizers replace,since the few nutrients derived from such inputs not consumed by plants are lost by leaching,contaminating groundwater and water resources.In addition,conventional methods rely heavily on chemical pesticides which cause damage to soil’s microfauna(responsible for the decomposition of organic matter and nutrient cycling)and the loss of organic carbon(in the form of dioxide),which is quickly dispersed in the atmosphere.Silicate rock powders are applied in natura,have long-lasting residual effects and reduce greenhouse gas emissions.

Artisanal ceramic factories using wood combustion:A nanoparticles and human health study

The ceramics industry,resulting from developments of modern compounds,is a segment of great influence in worldwide sustainability.Artisanal ceramic factories based on wood combustion have significant risks for the creation and discharge of atmosphere nanoparticles(NPs)and ultra-fine particles(UFPs).At present,there is insufficient recognition on the influence of engineered-NPs on the atmosphere and health.Real improvements are indispensable to diminish contact with NPs.The present study demonstrates the main NPs and UFPS present in an area of intense artisanal wood-combustion ceramic manufacturing.Particulate matter was sampled for morphological,chemical,and geochemical studies by sophisticated electron microbeam microscopy,X-Ray Diffraction,and Raman spectroscopy.From NPs configuration(<10 nm)we identify nucleation.Several amorphous NPs(>10 nm)were produced around the studied artisanal ceramic factories.This study presents an indication of the recent information on population and work-related contact to NPs in the artisanal ceramic factories and their influence on health.

Rare Earth-bearing particles in fly ash carbons:Examples from the combustion of eastern Kentucky coals

Graphitic carbons from the combustion of bituminous coals and,perhaps,other coal ranks,tend to capture iron and a number of hazardous elements,including As,Hg,and Se.Rare earth elements in fly ashes occur in minerals,such as monazite,xenotime,and davidite.They also occur in sub-nm particles,probably in a mineral form,within the AleSi glass on the investigated fly ashes.Just as graphitic carbons can capture Fe and hazardous elements,the carbons surrounding the fly ash glass and magnetic particles captures or encapsulates a broad suite of rare earth elements.

Migmatite-like textures in anthracite:Further evidence for low-grade metamorphic melting and resolidification in high-rank coals

Previous studies demonstrated that melting,initiated by supercritical fluids in the 375-400℃range,occurred as part of anthracite metamorphism in the Appalachian Basin.Based on the known behavior of vitrinite at high temperatures and,to a lesser extent,at high pressures,it was determined that the duration of the heating,melting,and resolidification event was about 1 h.In the current study,featureless vitrinite within banded maceral assemblages demonstratesthe intimate association of melted and resolidified vitrinite with anthracite-rank macerals.By analogy with metamorphosed inorganic rocks,such associations represent diadysites and embrechites,i.e.,cross-cutting and layered migmatites,respectively.Even though the temperature of formation of the anthracite structures is several hundred℃lower than that seen in metamorphosed inorganic rocks,anthracites are metamorphic rocks and the nomenclature for metamorphic rocks may be appropriate for coal.

Nanomineralogy of evaporative precipitation of efflorescent compounds from coal mine drainage

Efflorescent nanophases(NPs) are found as a transitory accumulation of potentially hazardous elements(PHEs),particularly in tropical climates. The central objective of this study was to investigate the distribution of PHEs with NPs through the evaporative formation structures(EFS) of enormously PHEs-rich coal-mine drainages(CMD). The EFS were studied in natural coal mine drainage for five months in order to determine their geochemical and ecological structures and to assess their position in the reduction of PHEs in nature. The largest coal-fired power plant in South America, located in south Brazil, is used as an example of such a problem. In this work, a novel methodology for the analysis of PHEs in CMD precipitates is proposed for this affected coal area.The analytical method, combining X-Ray Diffraction(XRD) and advanced electron microscopies, shows the importance of nanomineralogy in understanding different circumstances of coal contamination. Several ultrafinenanoparticles(UNPs) were identified in the sampled soils and river sediments together with the PHEs. A decrease in PHEs was identified in association with UNPs. However, further investigations are required with regard to the mobility of PHEs in water, atmosphere, soils, and sediments. The EPS was thoroughly studied, acquiring suitable understanding with investigational facts for Ca and Fe-sulphates, pickeringite, and several amorphous phases.

Geochemistry,petrology,and palynology of the Princess No.3 coal,Greenup County,Kentucky

The high volatile C bituminous-rank,Bolsovian-age Princess No.3 coal,a correlative of the heavily-mined Hazard No.7 coal and the Peach Orchard and Coalburg Lower Split coals,was investigated three sites at a mine in Greenup County,Kentucky.The coal exhibits a“dulling upwards”trend,with decreasing vitrinite and a greater tendency towards dull clarain and bone lithotypes towards the top of the coal.The relatively vitrinite-rich basal lithotype is marked by a dominance of lycopod tree spores.The palynology transitions upwards to a middle parting co-dominated by tree fern and small lycopod spores and an upper bench dominated by tree ferns with contributions from small ferns,cordaites,and calamites.The lithotypes generally have a moderate-to high-S content with a variable ash yield.Sulfur,Fe2O3,and certain siderophile elements are highest near the top of the coal.As observed in other coals,uranium and Ge are enriched at the top and bottom margins of the coal.The rare earth chemistry at the top of the coal has a significantly lighter distribution(higher LREE/HREE)than at the base of the coal.

Geochemical,mineralogical,and petrological characteristics of the Cretaceous coal from the middle Benue Trough Basin,Nigeria:Implication for coal depositional environments

The Benue Trough Basin (BTB) of Nigeria is geologically and geo-morphologically subdivided into upper,middle, and lower segments. The BTB is the subject of geological research due to its rich coal depositsthat have the potential for oil and gas. The purpose of the present study is to examine the origins,depositional environments, and thermal history of the selected coals and the processes that influencetheir quality. Coal samples from different open cast coal mines in the middle BTB were examined usingproximate and ultimate, x-ray diffraction (XRD), x-ray fluorescence (XRF), laser ablation induced coupledplasma (LA-ICPMS), and petrographical analyses. The coal samples contained mainly quartz, kaolinite,and organic carbon. The XRD spectra peaks revealed the triclinic and monoclinic structure of kaolin. TheSiO2/Al2O3 ratios confirmed the dominance of quartz and kaolinite. The Ni/Co versus V/Cr, Cu/Zn, and V/Mo values in the studied coals suggest oxic depositional environments, whereas the V/(Ni þ V) and V/(V þ Cr) values indicate oxic to suboxic conditions. The Ce/Ce* values are slightly below 1, which indicates a suboxic depositional environment. Maceral texture is indicative of transformations from subbituminous to high volatile C or B bituminous coal. The maceral components and mineral matter(10%) of the studied coals imply deposition in the planar margin mire, and a river system of planarmargin mire environments, respectively. The high gelification index (GI) and tissue preservation index(TPI) values indicate peat accumulation developed within a wet forest swamp. The ternary diagram ofthe maceral component suggests deposition in a wet moor environment with intermittent moderate tohigh flooding episodes. The studied coals are sub-hydrous vitrinite inferring hydrogen-poor and thermally immature characteristics. The low V and Ni contents, low H/C and high O/C, indicate Type IIIterrestrial organic matter with the potential to generate gaseous hydrocarbons. The investigated coalswere deposited by the river within telmatic, limnic, and limno-telmatic zones in the planar margin mire depositional environments. Overall, the integrated petrologic and geochemical data used in this studyprovides a reliable approach for the assessment of coal depositional environments.

Estimating REY content of eastern Kentucky coal samples based on their associated ash elements

Coal and coal combustion byproducts can be considered as an alternative source of rare earth elements and yttrium （REY）. The study of relationships between REY and other main coal properties could have several advantages such as estimating REY content of coal particles and designing beneficial extraction method. In this investigation, inter-correlations between REY content with coal parameters （proximate and ash elements） for a wide range of eastern Kentucky coal samples （708 records） were explored. Results demonstrate that zircon and monazite are the main source of heavy and light rare earth elements （HREE and LREE）, respectively. Zr has the highest correlation with Y and Th has the strength relationship with Ce and La. In general, LREE have higher interaction with coal ash content in comparison with HREE. Results indicated that REY can be estimated quite satisfactorily by using their associated elements in coal ash.