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1.
Inorg Chem ; 58(17): 11294-11299, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31411862

RESUMO

The first two examples of polyoxopalladates(II) (POPs) containing tetravalent metal ion guests, [MO8Pd12(PO4)8]12- (M = SnIV, PbIV), have been prepared and structurally characterized in the solid state, solution, and gas phase. The interactions of the metal ion guests and the palladium-oxo shell were studied by theoretical calculations. The POPs were shown to possess anticancer activity by causing oxidative stress inducing caspase activation and consecutive apoptosis of leukemic cells.


Assuntos
Antineoplásicos/farmacologia , Metais Pesados/química , Compostos Organometálicos/farmacologia , Polímeros/química , Antineoplásicos/síntese química , Antineoplásicos/química , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Células HL-60 , Humanos , Íons/química , Modelos Moleculares , Compostos Organometálicos/síntese química , Compostos Organometálicos/química
2.
Inorg Chem ; 58(17): 11351-11363, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31433627

RESUMO

Iron storage in biology is carried out by cage-shaped proteins of the ferritin superfamily, one of which is the dodecameric protein Dps. In Dps, four distinct steps lead to the formation of metal nanoparticles: attraction of ion-aquo complexes to the protein matrix, passage of these complexes through translocation pores, oxidation of these complexes at ferroxidase centers, and, ultimately, nanoparticle formation. In this study, we investigated Dps from Listeria innocua to structurally characterize these steps for Co2+, Zn2+, and La3+ ions. The structures reveal that differences in their ion coordination chemistry determine alternative metal ion-binding sites on the areas of the surface surrounding the translocation pore that captures nine La3+, three Co2+, or three Zn2+ ions as aquo clusters and passes them on for translocation. Inside these pores, ion-selective conformational changes at key residues occur before a gating residue to actively move ions through the constriction zone. Ions upstream of the Asp130 gate residue are typically hydrated, while ions downstream directly interact with the protein matrix. Inside the cavity, ions move along negatively charged residues to the ferroxidase center, where seven main residues adapt to the three different ions by dynamically changing their conformations. In total, we observed more than 20 metal-binding sites per Dps monomer, which clearly highlights the metal-binding capacity of this protein family. Collectively, our results provide a detailed structural description of the preparative steps for amino acid-assisted biomineralization in Dps proteins, demonstrating unexpected protein matrix plasticity.


Assuntos
Proteínas de Bactérias/química , Proteínas de Ligação a DNA/química , Listeria/química , Metais Pesados/química , Proteínas de Bactérias/biossíntese , Proteínas de Ligação a DNA/biossíntese , Modelos Moleculares , Eletricidade Estática
3.
Ecotoxicol Environ Saf ; 182: 109443, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31398782

RESUMO

The continuous presence of toxic elements in the aquatic environments around mine tailings occurs due to bioleaching or chemical extraction promoted by the mining operations. Biogenic passivation treatment of tailings dams can be a new environment-friendly technique to inhibit the solubility of heavy metals. In spite of current bioleaching researches, we tried to minimize the mobility of the trace elements in the laboratory scale through the formation of a passivation layer in the presence of a mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The X-ray diffraction (XRD) and scanning electron microscope (SEM) represented the jarosite generation as an inhibitory layer on the mineral surfaces of the tested materials. More detailed observations on electron probe micro-analyzer (EPMA) showed the co-precipitation of metals with the passivation layer. Thereby, the passivation layer demonstrates potential in elements immobilization which, in turn, can be optimized in the natural systems. Our working hypothesis was to exploit and optimize the formation of the passivation layer to maximize the immobilization of heavy metals (e.g., Cu, Cr). The optimization process of bioleaching experiments using indigenous bacteria caused a reduced solubility for Cu (from around 20% to 4.5%) and Cr (from around 30% to 10.6%) and the formation of 6.5 gr passivation layer. The analyses finally represented the high efficiency of the passivation technique to minimize metals bioleaching in comparison to earlier studies.


Assuntos
Metais Pesados/química , Mineração , Sulfetos/química , Poluentes Químicos da Água/química , Acidithiobacillus , Acidithiobacillus thiooxidans , Bactérias , Biodegradação Ambiental , Compostos Férricos , Metais Pesados/análise , Minerais , Solubilidade , Sulfatos , Sulfetos/análise , Poluentes Químicos da Água/análise
4.
Environ Monit Assess ; 191(8): 527, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31367793

RESUMO

Nowadays, anthropogenic inflow of heavy metals (HM) into the environment far exceeds their natural quantities in Ukraine. The main sources of HM inflow are enterprises that use high-temperature processes in the production cycle-combustion of fuel and thermal processing of raw materials. Examples of such enterprises are Avdiivka Coke and Chemical Plant (the largest in Europe) and the Zmiiv Thermal Power Plant (the largest in Ukraine), which use high-temperature processes associated with the use of black coal that are considered as important sources of heavy metals in the soil. On the basis of analytical data of 3000 samples of surface layer of Ukrainian soils, which form the basis of the nationwide GIS "Microelements in soils of Ukraine," it was established that the spatial distribution of the content of accessible forms of copper in the upper soil layer in Ukraine varies greatly and practically does not depend on the type of soil formation and is determined mainly by geochemical factors such as saturation of parent rocks with copper, as well as anthropogenic influence. The emissions from the Avdiivka Coke and Chemical Plant resulted in the formation of a clearly defined contamination range of soil and vegetation by HM in the adjoining territories exceeding the threshold levels of copper. In the zone of influence of the Zmiiv Thermal Power Plant, the technogenic load on agricultural lands is much less and does not exceed the medical and sanitary indicators of the content of heavy metals in the soils, but due to the high pipe height (180-250 m), the toxic emissions of the enterprise dissipate to a large area and form a regional technogenic background of available copper in soils.


Assuntos
Cobre/análise , Produtos Agrícolas/química , Metais Pesados/análise , Poluentes do Solo/análise , Solo/química , Agricultura , Cobre/química , Monitoramento Ambiental/métodos , Metais Pesados/química , Centrais Elétricas , Ucrânia
5.
Environ Monit Assess ; 191(9): 575, 2019 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-31422469

RESUMO

Industrial effluents are one of the foremost concerns relating to the anthropogenic environmental pollution. The effluents from the tanning and textile industries in Dhaka, Bangladesh, were characterized chemically and physicochemically with multivariate statistical techniques. The concentrations of heavy metals viz., Pb, Cd, Cr, Mn, Fe, Ni, Cu, and Zn were determined by atomic absorption spectrometer while concentrations of anions viz., F-, Cl-, NO2-, NO3-, and SO42- were measured by ion chromatograph. The physicochemical parameters viz., temperature, pH, electrical conductivity (EC), salinity, turbidity, dissolved oxygen (DO), and biological oxygen demand (BOD) were measured by a multiparameter meter while total suspended solids (TSS) and total dissolved solids (TDS) were measured gravimetrically. This study showed that effluents from both industries demonstrated high levels of TSS, TDS, EC, and heavy metals. Tannery effluents have lower pH and DO, and higher BOD, Cl-, SO42-, and Cr concentrations while textile dyeing effluents have higher pH, NO2-, and NO3- concentrations, compared to the standard limits promulgated by the Bangladesh government. Multivariate statistical techniques such as cluster analysis and principal component analysis along with the correlation matrices showed significant association among the measured parameters and identified pollution sources as well as effluent types in the study area which could be linked to the processes used in textile dying and tanning industries. This study will be useful for identifying pollutants emanating from the two industries and will guide future industrial aquatic studies where multiple industrial runoffs are concerned.


Assuntos
Monitoramento Ambiental/métodos , Resíduos Industriais/análise , Curtume , Indústria Têxtil , Poluentes Químicos da Água/análise , Ânions/análise , Ânions/química , Bangladesh , Metais Pesados/análise , Metais Pesados/química , Análise Multivariada , Poluentes Químicos da Água/química
6.
An Acad Bras Cienc ; 91(3): e20180334, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31411254

RESUMO

The aim of this study is to discuss the concentration distribution, composition and possible sources of trace metals and 13 PAHs in topsoils of the University campus, in the city of São Paulo, the largest city of South America. Mineralogy and granulometry of topsoils (0-10 cm) samples, were determined and As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, V, Zn, Hg, Pt, Pd and PAHs concentrations were quantified in the bulk fraction. The average clay content of soils was 221±61.8 g kg-1 and total carbon was low (mean of 25 g kg-1). Concentrations of metals were generally lower than the reference value established by the São Paulo State Environmental Agency and other studies in the São Paulo urban area, except for Cd, Ni, Pb, Cr and Zn. The mean concentration of the sum of 13 PAHs was 0.33 mg kg-1 and fluorene, indeno(1,2,3-cd)pyrene, anthracene, pyrene and benzo(ghi)perylene were the most abundant compounds. PAHs and trace metals variability were constrained in PMF analysis and showed an association with exhaust and non-exhaust vehicular emissions. The results also pointed out a spatial pattern in the campus area related to traffic conditions and intensity and terrain slope.


Assuntos
Metais Pesados/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Solo/química , Oligoelementos/análise , Universidades , Brasil , Cidades , Monitoramento Ambiental , Humanos , Metais Pesados/química , Hidrocarbonetos Policíclicos Aromáticos/química , Medição de Risco , Análise Espacial , Oligoelementos/química , Poluição Relacionada com o Tráfego/análise , Emissões de Veículos/análise
7.
Photochem Photobiol Sci ; 18(8): 2061-2070, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31339127

RESUMO

Firefly luciferases have been widely used for bioanalytical purposes during the last 5 decades. They usually emit yellow-green bioluminescence and are pH-sensitive, displaying a color change to red at acidic pH and higher temperature and in the presence of heavy metals. Besides the usual applications as bioanalytical reagents and as reporter genes, firefly luciferases' pH- and metal-sensitivities have been recently harnessed for intracellular metal and pH biosensing. Previously we cloned the luciferase of the Brazilian Amydetes vivianii firefly which displays the most blue-shifted color among known firefly luciferases. Here we purified it, characterized and investigated the kinetic properties and the pH, metal and thermal sensitivities of this firefly luciferase. This luciferase displays the lowest reported KM for ATP, the highest catalytic efficiencies, and the highest thermostability among the studied recombinant beetle luciferases, making this enzyme and its cDNA an ideal reagent for sensitive ATP assays and reporter gene. The blue-shifted spectrum, higher thermostability, lower pH- and thermal-sensitivities and protein fluorescence studies indicate a more rigid active site during light emission. This enzyme displays an unmatched selective spectral sensitivity for cadmium and mercury, making it a promising ratiometric indicator of such toxic metals. Finally, the weaker thermal-sensitivity compared to other firefly luciferases makes this enzyme a better ratiometric pH indicator at temperatures above 30 °C, suitable for mammalian cell assays.


Assuntos
Trifosfato de Adenosina/análise , Técnicas Biossensoriais , Cádmio/metabolismo , Vaga-Lumes/enzimologia , Luciferases de Vaga-Lume/metabolismo , Metais Pesados/metabolismo , Temperatura Ambiente , Animais , Cádmio/química , Fluorescência , Concentração de Íons de Hidrogênio , Cinética , Luciferases de Vaga-Lume/química , Metais Pesados/química
8.
Ecotoxicol Environ Saf ; 182: 109399, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31279281

RESUMO

Soil washing with chelators, a viable method for treating soils contaminated with potentially toxic metals, has drawn increasing attentions. The objective of this study was to determine a new generation of mixed degradable chelating agents from N, N-bis (carboxymethyl) glutamic acid (GLDA), [S, S]-stereoisomer of ethyleneiaminedisucc--inic acid (EDDS), nitrilotriacetic acid (NTA), and citric acid (CA), and to evaluate its effectiveness and feasibility to reduce toxic metals contamination in two different agricultural soils. A comparative leaching test conducted on the four individual degradable chelating agents showed that the capacity of single chelator in mobilizing copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) varied significantly. Using a combination of GLDA and NTA was more advantageous than using a single chelating agent in extracting potentially toxic metals. The removal efficiencies of Cu, Zn, Cd, and Pb reached 38.2, 9.8, 71.4, and 19.5% for soil 1, and 25.0, 5.2, 59.7, and 18.5% for soil 2, respectively, at mixed chelator (MC) concentrations of 3 mmol/L (GLDA) and 2 mmol/L (NTA), pH of 6.0, and a contact time of 4.0 h. The effects of washing conditions, chelator concentration, pH values, and contact time on the removal efficiencies of target toxic metals were investigated. The results showed that the combined chelating agent has a lower pH dependence, making it feasible for a wider range of applications. The effects of the chelating agents on the morphological distribution of potentially toxic metals and the soil enzyme activity before and after the treatments were also studied. After washing, the content of the water-soluble, acid-soluble, reducible, and oxidizable target metals showed a certain degree of decrease. Although the activities of catalase, urease, and invertase appeared to be inhibited during a short period of time, their activities were stimulated and later promoted with the degradation of the chelating agent. In general, the chelating agent combination has a great potential for toxic metals leaching.


Assuntos
Metais Pesados/química , Poluentes do Solo/química , Cádmio , Quelantes/química , Ácido Cítrico/química , Metais Pesados/análise , Metais Pesados/toxicidade , Solo/química , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Zinco
9.
Environ Sci Pollut Res Int ; 26(25): 25762-25774, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31267404

RESUMO

Among air pollutants, particulate matter (PM) has been identified as a major cause of environmental pollutants due to the advancement of industrial development and the generation of smaller particles. Particulate matter, in particular, is defined only by the size of particles and thus is not enough to study its composition yet. However, edible crops grown in contaminated atmospheres can be contaminated with heavy metals contained in particulate matter in the atmosphere, which can seriously damage food safety. In this study, we investigated the influence of the accumulation of particulate matter on leafy vegetables cultivated at areas with different levels of PM in atmosphere. Four districts of Gyeongsangnam-do were chosen to conduct this experiment: outdoor spaces of three respectively located in industrial, near-highway, and rural areas were considered, and research plant growth chambers at Gyeongsang National University were used as the control. After 3 weeks of cultivation in those conditions, the results showed that Pb in milligrams per kilogram of fresh weight (FW) was 0.383 in Chrysanthemum coronarium and 0.427 in Spinacia oleracea that were grown near the highway, which exceeded the 0.3 mg kg-1 FW standard set by the Republic of Korea, EU, and CODEX. However, when those vegetables were sufficiently washed with tap water, it was confirmed that the heavy metal content fell into the safety standard range.


Assuntos
Poluentes Atmosféricos/análise , Metais Pesados/análise , Material Particulado/análise , Folhas de Planta/química , Atmosfera , Produtos Agrícolas , Poluentes Ambientais , Poluição Ambiental , Metais Pesados/química , República da Coreia , Spinacia oleracea , Verduras
10.
Environ Pollut ; 253: 171-180, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31306824

RESUMO

In order to exhaustively investigate the physical and chemical mechanisms of heavy metal immobilization in sludge incineration residue (SIR)-based magnesium potassium phosphate cement (MKPC), this work investigated the influence of Pb2+ and Zn2+ on the compressive strength and microstructure of SIR-based MKPC, and the efficiency of Pb and Zn immobilization. Taking the difference of Ksp (solubility product) of different heavy metal compounds as the entry point, the physical and chemical mechanisms of Pb and Zn immobilization, and the competitive mechanism between coexisting ions, were comprehensively analyzed. It was discovered that Pb2+ is in the form Pb3(PO4)2, and Zn2+ is immobilized in the form Zn2(OH)PO4 [Zn3(PO4)2 is preferentially formed, when the pH > 7, Zn3(PO4)2 is converted to Zn2(OH)PO4]. The low solubility of heavy metal phosphates is the main reason that Pb2+ and Zn2+ are well immobilized. The preferential formation of Pb3(PO4)2 (Ksp = 8 × 10-43) and Zn3(PO4)2 (Ksp = 9.0 × 10-33) reduced the amount of MgKPO4·6H2O (Ksp = 2.4 × 10-11), resulting in a decrease in compressive strength. Besides, coexisting Pb2+ and Zn2+ has a competitive effect: Pb2+ will weaken the immobilization efficiency of Zn2+. The new exploration of these mechanisms provide a theoretical basis for rationally adjusting the Magnesia/Phosphate ratio to enhance the compressive strength and improve the efficiency of heavy metals immobilization.


Assuntos
Incineração/métodos , Chumbo/química , Zinco/química , Materiais de Construção , Íons , Magnésio , Compostos de Magnésio , Metais Pesados/química , Minerais/química , Fosfatos/química , Potássio , Compostos de Potássio , Esgotos/química
11.
Sci Total Environ ; 686: 476-483, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31185396

RESUMO

Nowadays, the problem of heavy metal pollution in vegetables is received wide attention. In this work, attapulgite clay (ATTP), as a cheap and readily available inorganic mineral material, was modified with nano zero-valent iron (nFe0@ATTP) for heavy metal immobilization in soil. Batch experiments were employed to evaluate the optimal remediation performance by ATTP before and after modified with nFe0 through planting Pakchoi (Brassica chinesis L.) in Cd, Cr, and Pb contaminated soil from Changsha. The results showed that amendments can all increase the pH value of soils, and notably decrease the concentration of extractable Cd, Cr, and Pb in soil. The germination rate and root length of Pakchoi were promoted, and the activities of peroxidase (POD), catalase (CAT), and malondialdehyde (MDA) contents were notably reduced besides superoxide dismutase (SOD) activity after treatments with ATTP and nFe0@ATTP. Vicia faba-micronucleus test indicated that the application of amendments reduced the toxicity of heavy metals on the genetic material of Vicia faba root tip cells. The nFe0@ATTP were found to well convert Cd, Cr, and Pb into less bioavailable state in soil, thus blocking heavy metal uptake by plants. This material could be a promising amendment for heavy metals contaminated soil.


Assuntos
Argila/química , Metais Pesados/química , Poluentes do Solo/química , Verduras/crescimento & desenvolvimento , Recuperação e Remediação Ambiental , Compostos de Magnésio/química , Compostos de Silício/química , Solo/química , Poluentes do Solo/análise
12.
Chemosphere ; 232: 96-112, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31152909

RESUMO

Heavy metal contamination in aqueous system has attracted global attention due to the toxicity and carcinogenicity effects towards living bodies. Among available removal techniques, adsorptive removal by nanosized materials such as metal oxide, metal organic frameworks, zeolite and carbon-based materials has attracted much attention due to the large active surface area, large number of functional groups, high chemical and thermal stability which led to outstanding adsorption performance. However, the usage of nanosized materials is restricted by the difficulty in separating the spent adsorbent from aqueous solution. The shift towards the use of adsorptive composite membrane for heavy metal ions removal has attracted much attention due to the synergistic properties of adsorption and filtration approaches in a same chamber. Thus, this review critically discusses the development of nanoadsorbents and adsorptive nanocomposite membranes for heavy metal removal over the last decade. The adsorption mechanism of heavy metal ions by the advanced nanoadsorbents is also discussed using kinetic and isotherm models. The challenges and future prospect of adsorptive membrane technology for heavy metal removal is presented at the end of this review.


Assuntos
Recuperação e Remediação Ambiental , Metais Pesados/química , Adsorção , Carbono , Filtração , Íons , Cinética , Estruturas Metalorgânicas , Metais Pesados/análise , Nanocompostos/química , Óxidos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Zeolitas/química
13.
Environ Sci Pollut Res Int ; 26(21): 22082-22096, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31147996

RESUMO

In this study, TiO2 nanotubes (TNTs) and AgCl-modified TNTs nanocomposites with multiple crystal phases were synthesized through a hydrothermal method without calcination. The resultant samples had a large Brunauer-Emmett-Teller surface area. Additionally, the Ag modification process reduced the recombination rate of electron-hole pairs in the synthesized sample and possessed more oxygen vacancy sites. The surface area of the AgCl-modified TNTs was smaller than that of non-modified TNTs sample; however, the nanocomposites exhibited outstanding photocatalytic performance and adsorption properties. AgCl compounds present on the TNTs surface effectively interacted with Hg0, improving the dye photodegradation efficiency. The Hg0 removal efficiencies of the TNTs and AgCl-modified TNTs samples were about 63% and 86%, respectively. The crystal violet (CV) and malachite green (MG) removal efficiencies of the AgCl-modified TNTs sample were around 57% and 72%, respectively. Both dyes photodecomposition efficiencies for AgCl-modified TNTs sample are higher than those of TNTs sample. The oxygen vacancy on the AgCl-modified TNTs surface was determined to be advantageous for OH- and arsenate adsorption through ligand exchange. The maximum adsorption quantity of As5+ calculated by Langmuir equation was 15.38 mg g-1 (TNTs) and 21.10 mg g-1 (AgCl-modified TNTs).


Assuntos
Metais Pesados/química , Nanocompostos/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Arseniatos , Corantes/química , Nanotubos/química , Fotólise , Trinitrotolueno
14.
Environ Sci Pollut Res Int ; 26(22): 23119-23128, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31183760

RESUMO

With the widespread use of metal oxide nanoparticles (MNPs), agricultural soil is gradually becoming a primary sink for MNPs. The effect of these nanoparticles on the fate and the toxicity of co-existing heavy metals is largely unknown. In this paper, pot experiments were conducted to evaluate the impact of ZnO nanoparticles (ZnO-NPs) on Cd toxicity and bioaccumulation in a soil-rice system. Different amounts of ZnO-NPs were added to three different levels of Cd-contaminated paddy soil (L-Cd, 1.0 mg kg-1; M-Cd, 2.5 mg kg-1; H-Cd, 5.0 mg kg-1). The results showed that the addition of ZnO-NPs significantly increased the soil pH value, and the soil pH value increased with the increase in ZnO-NP concentration. Reductions in plant height and biomass under Cd stress were recovered and increased after the addition of ZnO-NPs; the addition of ZnO-NP promoted rice biomass increased by 13~22% and 25~43% in the M-Cd and H-Cd groups, respectively, compared with that of the respective control treatment. A high concentration of ZnO-NPs could increase the concentration of bioavailable Cd in rhizosphere soil. In the L-Cd group, the Cd concentration of the rice in the L-Z500 treatment increased to 0.51 mg kg-1, exceeding the limit for acceptable Cd concentrations in rice of China (0.2 mg kg-1). This work revealed that ZnO-NPs could improve plant growth, especially in the early-growth stage, and alleviate the toxic effects of Cd. However, the addition of high-concentration (500 mg kg-1) ZnO-NPs in the lower Cd pollution soil could significantly facilitate the accumulation of Cd by Oryza sativa L.


Assuntos
Cádmio/análise , Nanopartículas Metálicas/análise , Metais Pesados/análise , Oryza/crescimento & desenvolvimento , Poluentes do Solo/análise , Agricultura , Biomassa , China , Nanopartículas Metálicas/química , Metais Pesados/química , Óxido de Zinco/química
15.
Environ Sci Pollut Res Int ; 26(22): 23173-23191, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31190302

RESUMO

It is evident from the past studies that dust fallout is a severe concern due to its impact to urban air quality and public health. This study mainly examines the spatial and seasonal variation of dustfall at ambient levels and chemical characterization of its insoluble fraction for Kharagpur Town, India. Dustfall samples were collected monthly for 1 year (July 2014 to June 2015) from four sampling sites. The results showed that the maximum dustfall deposition is found during summer (March to June) and in the range of 2.01 ± 0.36 to 15.74 ± 3.83 ton km-2 month-1, and minimum deposition is during monsoon season (July to October) in the range of 0.42 ± 0.72 to 7.38 ± 5.8 ton km-2 month-1. Selected metals like Sc, V, Cr, Co, Ni, Zn, Y, Zr, Ce, Hf, and Pb were analyzed using the high-resolution inductively coupled mass spectrometer (HR-ICP-MS) technique, and the contamination level of heavy metals was assessed using the geoaccumulation index (Igeo) and enrichment factor (EF). To estimate the sources for the metallic contaminants, principal component analysis (PCA) was conducted. The US EPA health risk assessment model was applied to determine the hazard index and hazard quotient values. The results show the significant level of enrichment for Pb (EF = 41.79) and Cr (EF = 4.39). The Igeo values point out moderate contamination by Pb (Igeo = 2.01) and Cr (Igeo = 1.6) in Kharagpur Town. This study suggests that in the context of noncancer risk of heavy metals as determined by the hazard index (HI) and hazard quotient (HQ) values, ingestion is the main source of exposure to dust in adults and children followed by dermal contact. Considering the inhalation route, carcinogenic risk level of Cr, Co, and Ni for adults and children is lower than the EPA's safe limit (10-6 to 10-4), indicating that cancer risk of these metals due to exposure to dustfall in Kharagpur is negligible.


Assuntos
Poeira/análise , Metais Pesados/análise , Adulto , Poluição do Ar/análise , Criança , Cidades , Humanos , Índia , Metais Pesados/química , Medição de Risco , Estações do Ano , Estados Unidos , United States Environmental Protection Agency/legislação & jurisprudência
16.
Ecotoxicol Environ Saf ; 182: 109370, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31254859

RESUMO

Heavy metals, especially gaseous heavy metals, have high toxicity and do harm to human. Heavy metal volatilization characteristics of co-combusted municipal solid wastes (MSW) and sewage sludge (SS) from different mass fraction of MSW and SS, different temperature and different O2 concentration atmosphere was investigated. Performance of calcium-based sorbents was also studied. Volatilization efficiency of As, Cr, Cu, Ni, Pb and Zn in MSW was 100%, 45.89%-66.58%, 75.62%-92.45%, 42.33%-65.70%, 39.25%-68.76% and 53.57%-84.62%, and that in SS was 28.37%-40.75%, 33.78%-43.42%, 46.08%-56.69%, 35.04%-51.52%, 18.54%-44.99% and 14.72%-48.88%. Volatilization efficiency of heavy metals increased as mass fraction of SS in a blend decreased and as temperature increased. Volatilization efficiency of all heavy metals examined decreased as O2 concentration increased at high temperature and that of Cu, Pb and Zn increased as O2 concentration increased at low temperature. CaO, Ca(OH)2 and CaCO3 declined the volatilization of As, Cr, Cu, Ni, and Zn, while enhanced that of Pb. With calcium-based sorbents, volatilization efficiency of As, Cr, Cu, Ni, and Zn decreased from 70.06%, 39.91%, 75.52%, 44.08% and 40.10% to 54.24%, 33.73%, 39.98%, 20.56% and 32.06%, while that of Pb increased from 47.23% to 100%. Fitting formula was set to predict the heavy metals volatilization, and risk evaluation of gaseous heavy metals was exhibited.


Assuntos
Cálcio/química , Poluentes Ambientais/química , Incineração , Metais Pesados/química , Eliminação de Resíduos Líquidos , Adsorção , Poluentes Ambientais/análise , Gases , Humanos , Metais Pesados/análise , Esgotos , Resíduos Sólidos , Volatilização
17.
Environ Sci Pollut Res Int ; 26(22): 22945-22957, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31177420

RESUMO

Groundwater is a major source of drinking water for many Canadians, and contamination by heavy metals poses a significant risk to people and the environment. In this study, three water quality indices are studied in the vicinity of an unlined landfill in a semiarid climate. The study investigates indices using geostatistical analysis and ordinary kriging. This study employs a novel coupling technique in order to compare the index-based maps to a groundwater quality map from overlapping heavy metal kriged maps. A total of 11 heavy metals were evaluated in preliminary analysis, but only four (Mn, As, Fe, and U) had higher concentrations than allowable limits in some or all of the monitoring wells at the site. Results from mean-based classification of indices suggest the aquifer in proximity to the landfill has been impacted by metal contaminants. Kriged maps show that the spatial variations of Mn and U are similar, while results of Fe and As are also similar. However, the two sets of maps have distinctly different patterns. Maps for indices show an elevated plateau extending from the unlined landfill to the southeast corner, implying that the landfill may have negatively impacted groundwater quality. A groundwater quality map is developed by overlaying the heavy metal maps. The resulting map shows that the north and west parts of the study have lower groundwater pollution with respect to metal contaminants. The groundwater quality map may be more applicable for practitioners who need comprehensive water quality measurement.


Assuntos
Água Potável/análise , Água Subterrânea/análise , Metais Pesados/análise , Canadá , Água Potável/química , Metais Pesados/química , Análise Espacial , Instalações de Eliminação de Resíduos , Qualidade da Água
18.
Environ Sci Pollut Res Int ; 26(22): 23002-23009, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31183751

RESUMO

The aim of this study was to find the concentration of lead (Pb), cadmium (Cd), nickel (Ni), manganese (Mn), and zinc (Zn) in feed, drinking water, and their residues in meat and internal organs in broilers at three different locations in Charsadda. For this purpose, a total of 48 representative water and feed samples and 240 meat and internal organs of broilers were collected. Significantly (P < 0.05) higher concentrations of Zn and Mn were found in feed samples. In water samples assessed for heavy metals, a significantly (P < 0.05) higher concentration of Pb was observed at Umerabad and Kula Dher as compared with Nisatta whereas a significantly (P < 0.05) higher concentration of Ni was recorded at Umerabad as compared with Nisatta and Kula Dher. Similarly, a significantly (P < 0.05) higher concentration of Mn in water was recorded at Kula Dher as compared with Nisatta and Umerabad. The concentration of Pb in water at all locations and the concentration of Ni at Umerabad were above the maximum permissible limits. A significantly (P < 0.05) higher concentration of Pb in the liver, breast, and thigh muscles and a significantly (P < 0.05) higher concentration of Mn in the liver, gizzard, breast, and thigh muscles of broilers were recorded at Kula Dher. A significantly (P < 0.05) higher mean concentration of Pb, Cd, Ni, Mn, and Zn was recorded in the liver as compared with the gizzard, breast, and thigh muscles. It was concluded from the present study that broiler farms near the roadside/canal and waste disposal site/wastewater drains cause accomulaiton of high concentrations of some heavy metals in meat and internal organs of broiler birds.


Assuntos
Metais Pesados/análise , Animais , Cádmio/análise , Galinhas/metabolismo , Monitoramento Ambiental , Humanos , Manganês/análise , Carne , Metais Pesados/química , Níquel/análise , Paquistão , Saúde Pública , Águas Residuárias , Zinco/análise
19.
Environ Pollut ; 246: 999-1007, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31159149

RESUMO

The binding of metal ions with humic acid (HA) plays an important role in the aggregation of HA and the migration of metal ions in the environments. The effects of common cations (Na+, Mg2+, Ca2+ and Al3+) and heavy metal ions (Ag+, Cd2+, Cu2+, Cr3+ and Eu3+) on the aggregation of HA were investigated systematically by aggregation kinetics, spectroscopic techniques and molecular dynamic (MD) simulations. The critical coagulation concentration (CCC) of mono-, di- and trivalent cations could be predicted by the Schulze-Hardy rule. The aggregation of HA in the presence of Na+ and Ag+ was mainly due to the reduction of repulsive force and the hydrogen bonds between HA molecules. While the complexation of di- and trivalent cations with carboxylic/phenolic groups, or the cation-π interactions enhanced the intra- or inter-molecular bridges in HA and then contributed greatly to the aggregation of HA. Heavy metal ions could easily pass through the electric double-layer of HA compared with common cations. MD simulations further signified the strong aggregation ability of HA molecules in solutions containing high valence metal ions. These findings are important for understanding not only how the influence of metal ions on the aggregation of HA, but also the conditions which ions more efficient for aggregation.


Assuntos
Cátions/química , Substâncias Húmicas , Simulação de Dinâmica Molecular , Ácidos Carboxílicos/química , Ligações de Hidrogênio , Cinética , Metais Pesados/química , Fenóis/química , Análise Espectral , Poluentes Químicos da Água/química
20.
Environ Pollut ; 252(Pt B): 1142-1153, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252112

RESUMO

Proper management of waste crop residues has been an environmental concern for years. Yellow mealworms (larvae of Tenebrio molitor Linnaeus, 1758) are major insect protein source. In comparison with normal feed wheat bran (WB), we tested five common lignocellulose-rich crop residues as feedstock to rear mealworms, including wheat straw (WS), rice straw (RS), rice bran (RB), rice husk (RH), and corn straw (CS). We then used egested frass for the production of biochar in order to achieve clean production. Except for WS and RH, the crop residues supported mealworms' life activity and growth with consumption of the residues by 90% or higher and degraded lignin, hemicellulose and cellulose over 32 day period. The sequence of degradability of the feedstocks is RS > RB > CS > WS > RH. Egested frass was converted to biochar which was tested for metal removal including Pb(II), Cd(II), Cu(II), Zn(II), and Cr(VI). Biochar via pyrolysis at 600 °C from RS fed frass (FRSBC) showed the best adsorption performance. The adsorption isotherm fits the Langmuir model, and kinetic analysis fits the Pseudo-Second Order Reaction. The heavy metal adsorption process was well-described using the Intra-Particle Diffusion model. Complexation, cation exchange, precipitation, reduction, deposition, and chelation dominated the adsorption of the metals onto FRSBC. The results indicated that crop residues (WS, RS, RB, and CS) can be utilized as supplementary feedstock along with biochar generated from egested frass to rear mealworms and achieve clean production while generating high-quality bioadsorbent for environment remediation and soil conditioning.


Assuntos
Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Metais Pesados/química , Tenebrio/fisiologia , Adsorção , Animais , Biomassa , Dieta , Cinética , Lignina , Metais Pesados/análise , Oryza/metabolismo , Solo/química , Poluentes do Solo/análise , Triticum/metabolismo , Zea mays/metabolismo
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