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Distribution, health and ecological risk assessments of trace elements in Nigerian oil sands

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Acta Geochimica 2024年第1期43卷 59-71页

作者： Odunayo T.Ore Festus m.Adebiyi Department of Chemistry Obafemi Awolowo UniversityIle-Ife 220005Nigeria Department of Chemical Sciences Achievers UniversityOwoNigeria

The Nigerian oil sands represent the largest oil sand deposit in Africa, yet there is little published information on the distribution and potential health and ecological risks of trace elements in the oil resource. In the present study, we investigated the distribution pattern of 18trace elements(including biophile and chalcophile elements) as well as the estimated risks associated with exposure to these elements. The results of the study indicated that Fe was the most abundant element, with a mean concentration of 22,131 mg/kg while Br had the lowest mean concentration of 48 mg/kg. The high occurrence of Fe and Ti suggested a possible occurrence of ilmenite(Fe TiO_(3)) in the oil sands. Source apportionment using positive matrix factorization showed that the possible sources of detected elements in the oil sands were geogenic, metal production, and crustal. The contamination factor, geo-accumulation index, modified degree of contamination, pollution load index, and Nemerow pollution index indicated that the oil sands are heavily polluted by the elements. Health risk assessment showed that children were relatively more susceptible to the potentially toxic elements in the oil sands principally via ingestion exposure route(HQ > 1E-04). Cancer risks from inhalation are unlikely due to CR mal contact pose severe risks(CR > 1E-04). The high concentrations of the elements pose serious threats due to the potential for atmospheric transport, bioaccessibility, and bioavailability.

关键词： Biophile Chalcophile Oil sand Risk assessment Trace element

Constraints on neutron skin thickness and symmetry energy of 208Pb through Skyrme forces and cluster model

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Chinese Physics C 2020年第5期44卷 92-99页

作者： m.moghaddari Amiri O.N.Ghodsi Department of Physics Faculty of ScienceUniversity of MazandaranP.O.Box 47415-416BabolsarIran

We used the cluster structure properties of the 212Po to estimate the neutron skin thickness of *** this purpose,we considered two important components:(a)alpha decay is a low energy phenomenon;therefore,one can expect that the mean-field,which can explain the ground state properties of 212Po,does not change during the alpha decay process.(b)212Po has a high alpha cluster-like structure,two protons and two neutrons outside its core nucleus with a double magic closed-shell,and the cluster model is a powerful formalism for the estimation of alpha decay preformation factor of such *** slope of the symmetry energy of 208Pb is estimated to be 75±25 meV within the selected same mean-fields and Skyrme forces,which can simultaneously satisfy the ground-state properties of parent and daughter nuclei,as their neutron skin thicknesses are consistent with experimental data.

关键词： α-decay isospin asymmetry neutron-skin thickness Hartree-Fock formalism

Wash Waves Generated by High Speed Displacement Ships

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China Ocean Engineering 2015年第5期29卷 757-770页

作者：周利兰高高 R.H.m.Huijsmans Key Laboratory of High Performance Ship Technology ministry of Education Wuhan University of Technology School of Transportation Wuhan University of Technology Delft University of Technology

It is difficult to compute far-field waves in a relative large area by using one wave generation model when a large calculation domain is needed because of large dimensions of the waterway and long distance of the required computing points. Variation of waterway bathymetry and nonlinearity in the far field cannot be included in a ship fixed process either. A coupled method combining a wave generation model and wave propagation model is then used in this paper to simulate the wash waves generated by the passing ship. A NURBS-based higher order panel method is adopted as the stationary wave generation model; a wave spectrum method and Boussinesq-type equation wave model are used as the wave propagation model for the constant water depth condition and variable water depth condition, respectively. The waves calculated by the NURBS-based higher order panel method in the near field are used as the input for the wave spectrum method and the Boussinesq-type equation wave model to obtain the far-field waves. With this approach it is possible to simulate the ship wash waves including the effects of water depth and waterway bathymetry. Parts of the calculated results are validated experimentally, and the agreement is demonstrated. The effects of ship wash waves on the moored ship are discussed by using a diffraction theory method. The results indicate that the prediction of the ship induced waves by coupling models is feasible.

关键词： wash waves wave generation model wave spectrum method Boussinesq type equation wave model motions of moored ship

Bifunctional luminescent and magnetic core/shell type nanostructures Fe_3O_4@CeF_3:Tb^(3+)/SiO_2

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Journal of Rare Earths 2011年第12期29卷 1117-1122页

作者： m.Runowski T.Grzyb S.Lis Department of Rare Earths Faculty of ChemistryAdam Mickiewicz University

A facile co-precipitation and microemulsion methods were applied to obtain core/shell type nanoparticles. Cerium fluoride doped with terbittrn（Ⅲ） ions supplied intensive green luminescence of the system. Due to the presence of magnetite nanoparticles as cores, the prod- uct was highly sensitive to external magnetic field. Both sorts of nanostructures were encapsulated by silica shell. Such external layer of inert oxide can potentially increase the resistance of prepared nanostructttres to thermal oxidation, aggressive agents, changing ofpH or destructive radiation. morphology of the product was examined using transmission electron microscopy （TEm）. Formations of the core/shell type nanostructures were clearly seen in the TEm pictures. Powder X-ray diffraction （XRD） confirmed the structure of the products, their nanocrystallinity and amorphous nature of silica shell. Optical properties were investigated by measuring excitation and emission spectra. Such multifunctional luminescent and magnetic nanoparticles coated with easily functionalized silica shell could be applied in many field of science.

关键词： bifunctional nanoparticles magnetic nanoparticles luminescence core/shell rare earths

Influence of organic and inorganic properties of coal-shale on spontaneous combustion liability

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International Journal of mining Science and Technology 2019年第6期29卷 851-857页

作者： m.Onifade B.Genc N.Wagner The School of mining Engineering University of the WitwatersrandJohannesburg 2050South Africa Department of Geology University of JohannesburgJohannesburg 2092South Africa

Coal and coal-shale undergo low-temperature oxidation when exposed to air,potentially leading to spontaneous ***-shale found in association with coal seams vary considerably in their intrinsic properties and spontaneous combustion liability *** coal-shale samples collected from four different coal mines in Witbank Coalfield,South Africa,were experimentally *** influence of coal-shale intrinsic properties and spontaneous combustion liability indices(determined by the WitsEhac Index and the Wits-CT Index)were *** liability indices indicate relationships with the intrinsic factors and thus,identifying the major intrinsic factors affecting liability toward spontaneous combustion in these coal-shale *** XRF analysis indicated that the coal-shale samples are rich in Si O2,Al2O3 and Fe2O3,while the XRD showed that same coal-shale samples are generally dominated with kaolinite and *** coal-shale occurred in association with medium Rank C bituminous coal and contained varying proportion of *** Wits-Ehac Index was unable to reliably determine liability indices of some coal-shale samples,and hence the Wits-CT Index was *** results obtained from the characterisation tests may be used as a tool to predict the spontaneous combustion liability in carbonaceous material and may serve as a reference when comparing coal-shale from different coal mines.

关键词： Wits-Ehac Index Wits-CT Inde Witbank Coalfield and self-heating

Larger floods reduce soil CO_(2)efflux during the post-flooding phase in seasonally flooded forests of Western Amazonia

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Pedosphere 2021年第2期31卷 342-352页

作者： Emma m.DOCHERTY Andrew D.THOmAS Department of Geography and Earth Sciences Aberystwyth UniversityAberystwyth SY233DB(UK) School of Geography University of LeedsLeeds LS29JT(UK)

Seasonally flooded várzea forests of Western Amazonia are one of the most productive and biodiverse wetland forests in the ***,data on their soil CO_(2)emissions,soil organic matter decomposition rates,and soil C stocks are *** is a concern because hydrological changes are predicted to lead to increases in the height,extent,and duration of seasonal floods,which are likely to have a significant effect on soil C stocks and ***,with no empirical data,the impact of altered flood regimes on várzea soil C cycles remains *** study quantified the effects of maximum annual flood height and soil moisture on soil CO_(2)efflux rate(R_(s))and soil organic matter decomposition rate(k)in the várzea forests of Pacaya Samiria National Reserve,*** study was conducted between may and August *** results showed that R_(s)(10.6–182.7 mg C m^(-2)h^(-1))and k(0.016–0.078)varied between and within sites,and were considerably lower than the values reported for other tropical *** addition,R_(s)was negatively affected by flood height(Pmoisture(Pmentioned *** moisture was the dominant factor influencing R_(s),and it was significantly affected by maximum flood height,even after the floods had subsided(Pmain unchanged but with decomposition processes becoming more anaerobic.

关键词： C cycle climate change greenhouse gas soil CO_(2)emissions soil moisture soil organic matter decomposition rate tropical forest

Geochemistry of metasedimentary rocks of the Sonakhan and mahakoshal greenstone belts,Central India:Implications for paleoweathering,paleogeography and mechanisms of greenstone belt development

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Acta Geochimica 2022年第1期41卷 64-83页

作者： Hamidullah Wani m.E.A.mondal Iftikhar Ahmad Department of Geology Government Degree College for Women PulwamaJammu and Kashmir 192301India Department of Geology Aligarh Muslim UniversityAligarhUttar Pradesh 202002India

A comparative study of the Precambrian Sonakhan(SGB)and mahakoshal(mGB)greenstones belts of Central India has been undertaken to decipher their provenance,paleoweathering,paleogeography,and *** compared to the Upper Continental Crust(UCC),the mGB samples are enriched while the SGB samples are depleted in mafic elements indicating the presence of mafic rocks in the source of the *** is complemented by the Ni–Cr *** REE concentrations,LREE fractionated patterns and negative Eu anomalies of the mGB and SGB samples indicate derivation of sediments from a highly fractionated granitic *** mGB samples also contain the geochemical signature of mafic rocks,it is,therefore proposed that the mGB clastic load were derived from two sources(mafic+felsic)with arc *** is attested by Cr and Zr relationships,and LILE enrichment,and HFSE *** features suggest that the SGB developed as autochthonous while the mGB developed as an allochthonous *** chemical alteration indices such as chemical index of alteration(CIA),plagioclase index of alteration(PIA),and index of compositional variability for mGB samples indicate that they were dominantly derived as the first cycle(with minor recycled)sediments from bimodal sources(dominantly continental arcs)by intense chemical weathering as compared to the SGB samples,which were derived from felsic sources(dominantly cratonic rocks),and partly by recycling through a low chemical *** CIA and PIA values of the samples reveal a change in the climatic conditions from Late Archean to Late *** change is interpreted in terms of migration of the Indian plate from high latitudes in the Late Archean to lower latitudes during the Late *** is consistent with the paleomagnetic data that placed India in the configuration of 2.45 Ga Ur and 1.78 Ga Columbia supercontinents.

关键词： Central Indian Shield Sonakhan and mahakoshal greenstone belts Paleoweathering and paleogeography Greenstone belt development

Seismic response of deep circular tunnels subjected to S-waves:Axial bending

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Underground Space 2024年第4期17卷 267-279页

作者： Chatuphat Savigamin Antonio Bobet Osvaldo P.m.Vitali HR Engineering Services Inc.MedleyFL 33166United States Lyles School of Civil Engineering Purdue UniversityWest LafayetteIN 47907United States Department of Civil Environmentaland Construction EngineeringUniversity of Hawaii at ManoaHonoluluHI 96822United States

Ovaling deformation of circular tunnels has received great interest from the tunneling community because this mode of seismicinduced deformation is considered the most ***,there is growing evidence that other deformation modes can also be important and thus need to be considered in *** study presents a new analytical solution to estimate axial bending(snaking),a mode of deformation caused by S-waves impinging on a tunnel parallel to the tunnel *** solution is developed using the soilstructure interaction approach with the assumption that the interface between the ground and the tunnel lining is frictionless(fullslip).Full dynamic numerical simulations are conducted to verify the new full-slip solution,together with the existing no-slip *** of dynamic amplification are also explored for both full-slip and no-slip interface conditions by changing the wavelength(or frequency)of the seismic input motions.

关键词： Seismic response of tunnels Analytical solutions Soil-structure interaction Axial bending Snaking S-waves

Linear matrix inequality approach for synchronization control of fuzzy cellular neural networks with mixed time delays

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Chinese Physics B 2012年第4期21卷 586-596页

作者： P.Balasubramaniam m.Kalpana R.Rakkiyappan Department of mathematics Gandhigram Rural Institute-Deemed UniversityGandhigram-624302TamilnaduIndia Department of mathematics Bharathiar UniversityCoimbatore-641046TamilnaduIndia

Fuzzy cellular neural networks （FCNNs） are special kinds of cellular neural networks （CNNs）. Each cell in an FCNN contains fuzzy operating abilities. The entire network is governed by cellular computing laws. The design of FCNNs is based on fuzzy local rules. In this paper, a linear matrix inequality （LmI） approach for synchronization control of FCNNs with mixed delays is investigated. mixed delays include discrete time-varying delays and unbounded distributed delays. A dynamic control scheme is proposed to achieve the synchronization between a drive network and a response network. By constructing the Lyapunov-Krasovskii functional which contains a triple-integral term and the free-weighting matrices method an improved delay-dependent stability criterion is derived in terms of LmIs. The controller can be easily obtained by solving the derived LmIs. A numerical example and its simulations are presented to illustrate the effectiveness of the proposed method.

关键词： asymptotic stability chaos fuzzy cellular neural networks linear matrix inequalities synchronization