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1.
Water Sci Technol ; 80(2): 300-307, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537766

RESUMO

The aim of this work is to study the performances of isomeric α-, ß-, and γ-FeOOH (goethite, akaganéite and lepidocrocite, including five samples named as Gth1 and Gth2, Aka1 and Aka2, and Lep, respectively) for removing hexavalent chromium (Cr(VI)) from aqueous solutions. The adsorption mechanisms were explored by kinetic and isothermal experiments. Adsorption efficiencies under the different pH values, anions, and the levels of adsorbate and adsorbent were also measured. Results showed that the Cr(VI) adsorption by isomeric FeOOH could be best described by pseudo-second-order kinetic model. The processes of Cr(VI) isothermal adsorption could be greatly fitted by the Langmuir and Freundlich equations with the high correlation coefficients of R2 (>0.92). Also, there were the optimum pH values of 3.0-8.0 for FeOOH to adsorb Cr(VI), and their adsorption capacities were tightly related with the active sites of adsorbents. Cr(VI) adsorptions by these adsorbents were easily influenced by H2PO4-, and then SO42-, while there were little effects by Cl-, CO32- and NO3-. These obtained results could provide a potentially theoretical evidence for isomeric FeOOH materials applied in the engineering treatment of the polluted chromate-rich waters.


Assuntos
Cromo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Cromo/análise , Concentração de Íons de Hidrogênio , Cinética , Poluentes Químicos da Água/análise
2.
Water Sci Technol ; 80(2): 308-316, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537767

RESUMO

In this study, a novel composite of modified diatomite supported nanoscale zero-valent iron (mD-NZVI) was synthesized and characterized. The effects of four factors (mD-NZVI dose, temperature, contact time and initial pH) on the removal of Cr(VI) by mD-NZVI were studied by experimental work and analyzed by response surface methodology (RSM). A second-order polynomial equation fitted by Box-Behnken design was used as a statistical model and proved to be precise in describing the significance of four factors. The analysis results show that the effects of four factors on the removal efficiency of Cr(VI) were significant (F value is 19.83), initial pH was found to be the key factor. In addition, the effect of initial pH was further studied and the maximum removal efficiency of 89.34% was obtained at pH of 3, the decrease in removal efficiency with the increase in pH is a synergistic effect of Cr(VI) species, surface charge of mD-NZVI and OH- amount at different pH.


Assuntos
Cromo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Cromo/análise , Terra de Diatomáceas , Concentração de Íons de Hidrogênio , Poluentes Químicos da Água/análise
3.
Environ Monit Assess ; 191(9): 530, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31372746

RESUMO

Activities in the Bangladeshi leather industries have the potential to cause chemical pollutions thereby deteriorating the working environments, the surrounding residential areas, or even foodstuffs. Therefore, it is important to determine the chemical exposures among the industry workers and residents of the surrounding areas who may be directly or indirectly impacted by the contaminated environment. This study focused on evaluating the hazard arising from exposure to metals due to industrial contamination. Tissue samples of hair and nails were collected from both the leather industry workers and residents in the vicinity of the industries. Using chromium as an indicator of contamination/exposure from the leather industry, it was the most significant metal contaminant for industry workers ranging from 21.85 to 483 mg/kg and for industry-neighboring residents at 6.01 to 296.16 mg/kg. Both the workers and neighboring residents were found to be excessively exposed (P < 0.05) to chromium compared with the investigated control group of people living in a distant village area which had no industrial establishments.


Assuntos
Monitoramento Ambiental , Poluição Ambiental , Intoxicação por Metais Pesados , Metais Pesados/toxicidade , Exposição Ocupacional , Bangladesh , Cromo/análise , Cabelo/química , Humanos , Indústrias , Metais Pesados/análise , Unhas/química
4.
World J Microbiol Biotechnol ; 35(8): 129, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31376017

RESUMO

Metal whole-cell biosensors (WCBs) have been reported as very useful tools to detect and quantify the presence of bioavailable fractions of certain metals in water and soil samples. In the current work, two bacterial WCBs able to report Cr(VI) presence and plants growing on Cr(VI)-enriched soil/medium were used to assess the potential transfer of this metal to organisms of higher trophic levels, and the risk of transfer to the food chain. To do it, the functionality of the WCBs within tissues of inoculated plants in contact with Cr(VI)-contaminated soil and water was studied in vitro and in a controlled greenhouse environment. One WCB was the previously described Ochrobactrum tritici pCHRGFP2 and the second, Nitrospirillum amazonense pCHRGFP2, is a newly engineered naturally-occurring endophytic microorganism. Three rice varieties (IAC 4440, BRS 6 CHUÍ, IRGA 425) and one maize variety (1060) were tested as hosts and subjected to Cr(VI) treatments (25 µM), with different results obtained. Inoculation of each WCB into plants exposed to Cr(VI) showed GFP expression within plant tissues. WCBs penetrated the root tissues and later colonized the shoots and leaves. In general, a higher fluorescence signal was detected in roots, together with a higher Cr content and denser WCB colonization. Best fluorescence intensities per plant biomass of shoots were obtained for plant host IRGA 425. Therefore, by analyzing colonized tissues, both WCBs allowed the detection of Cr(VI) contamination in soils and its transfer to plants commonly used in crops for human diet.


Assuntos
Técnicas Biossensoriais/métodos , Cromo/análise , Ochrobactrum/crescimento & desenvolvimento , Oryza/química , Rhodospirillaceae/crescimento & desenvolvimento , Zea mays/química , Disponibilidade Biológica , Engenharia Metabólica , Microscopia de Fluorescência , Ochrobactrum/genética , Ochrobactrum/metabolismo , Oryza/crescimento & desenvolvimento , Oryza/microbiologia , Rhodospirillaceae/genética , Rhodospirillaceae/metabolismo , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologia
5.
Environ Monit Assess ; 191(9): 578, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31432272

RESUMO

A possible impact of sample preparation on the chemical fractionation results is generally underestimated in studies of forms of occurrence of heavy metals in river sediments. Our analysis of the recently published results of sequential extraction of chromium has revealed the effect of sample grinding on the result of determination of mobile chromium fractions in river sediments. This observation has been experimentally verified along with the analysation of potential effect of river sediment drying conditions on chromium distribution pattern. The studies were carried out on river sediments polluted with tannery effluents (Cr, 29.2-233 mg/kg). The determined content of chromium bound to carbonates in powdered samples was 2 to 7 times higher than those in raw river sediment samples. It was shown that the main reason was the different kinetic characteristics of chromium leaching in these sediments. Using the shrinking core model, it was found that diffusion through the "ash layer" was the rate-controlling step during the extraction of the carbonate fraction of chromium. It has been additionally confirmed that common air drying of sediment samples does not affect the results of chemical fractionation of chromium.The results of our studies are also vital for the assessment of environmental risk posed by river sediments polluted with heavy metals. In the case of sediment samples used in this study, powdering changed the risk category (RAC) from low risk to high risk. Hence, in order to achieve a realistic assessment of chromium mobility and environmental risk, it is advisable to use raw samples, despite their poorer homogeneity, and thus, lower precision of chemical fractionation results.


Assuntos
Cromo/análise , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Rios/química , Poluentes Químicos da Água/análise , Fracionamento Químico , Resíduos Industriais/análise , Polônia , Curtume
6.
Sci Total Environ ; 695: 133886, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31422325

RESUMO

A facile one-pot solvothermal method was applied to synthesize a magnetic biochar composite (MB) using phoenix tree leaves-derived biochar as the carbon matrix. The structure of MB was optimized by varying the load ratio and particle size of Fe3O4 nanoparticles on biochar. Time-dependent structure and composition evolution of solid and liquid phases during heterogeneous solvothermal process were investigated to understand the formation mechanism of MB. Firstly, Fe2+/Fe3+ ions were coordinated by oxygen-containing groups on biochar and part of them were hydrolyzed to form iron hydroxides. Then, those iron-containing precursors were thermally decomposed and reduced to iron oxides; and finally Fe3O4 nanoparticles were generated. The MB had an adsorption capacity for Cr(VI) of 55.0 mg/g in an aqueous solution, which exceeds those of biochar (39.8 mg/g) and Fe3O4 nanoparticles (26.5 mg/g). The adsorption mechanism study reveals that biochar as a carbon skeleton mainly provided binding sites for Cr(VI) and electron-donor groups for reduction of Cr(VI), while Fe3O4 nanoparticles mainly involved in the immobilization of newly formed Cr(III) through formation of Fe(III)-Cr(III) hydroxide. MB exhibited a stable structure with a lower Fe leakage at pH 2.0 than that of a comparable magnetic biochar sample prepared by conventional co-precipitation method. Recycling experiments suggested that MB could keep 84% of its initial removal capability for Cr(VI) even after seven cycles. The results indicate that solvothermal method is a promising alternative to prepare magnetic biochar for adsorption of heavy metal-containing wastewater.


Assuntos
Cromo/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Carvão Vegetal/química , Cromo/análise , Compostos Férricos , Magnetismo , Poluentes Químicos da Água/análise
7.
Environ Monit Assess ; 191(9): 585, 2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31440913

RESUMO

Remediation of heavy metals, other than microbial bioleaching method, is expensive and unsuitable for large contaminated areas. The current study was aimed to isolate, identify, and test the potential of indigenous fungal strains for heavy metal removal from contaminated soil. A total of three metallotolerant fungal strains, i.e., Aspergillus niger (M1DGR), Aspergillus fumigatus (M3Ai), and Penicillium rubens (M2Aii), were isolated and identified by phenotyping and genotyping from heavy metal-contaminated soil of  Hattar Industrial Estate, Pakistan. A. niger was found to be the most successful strain for the removal of heavy metals from the contaminated soil with maximum bioaccumulation efficiency of 98% (Cd) and 43% (Cr). In contrast, A. fumigatus showed comparatively low but still considerable bioleaching potential, i.e., 79% and 69% for Cd and Cr removal, respectively. Maximum metal uptake efficiency, i.e., 0.580 mg g-1 and 0.152 mg g-1 by A. niger strain was noticed for Cd and Cr with Czapek yeast extract (CYE) and Sabouraud dextrose broth (SDB) media, respectively. A. fumigatus (M3Ai) exhibited the maximum bioleaching capacity (0.40 mg g-1) for Cr with CYE medium. The results reveal that A. niger M1DGR and A. fumigatus M3Ai could be used to develop new strategies to remediate soil contaminated with heavy metals (Cd and Cr) through either in situ or ex situ mycoremediation.


Assuntos
Aspergillus flavus/metabolismo , Aspergillus fumigatus/metabolismo , Cádmio/análise , Cromo/análise , Penicillium/metabolismo , Poluentes do Solo/análise , Biodegradação Ambiental , Monitoramento Ambiental , Poluição Ambiental/análise , Paquistão , Solo/química
8.
Food Chem ; 299: 125123, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31299514

RESUMO

Beehive products are considered sentinels for environmental pollutants. The presence of trace elements and pesticides in honey and beeswax may pose a health hazard to consumers. The study's aim was to determine the profile of pesticides and trace elements in Israeli honey and beeswax samples in relation to human risk assessment. At least two pesticides contaminated the honey and beeswax samples simultaneously, in which, amitraz metabolites and coumaphos were frequently detected. The neonicotinoid insecticides and 2,4-dichlorophenoxyacetic acid, were found only in honey samples, whereas the more lipophilic pesticides were predominantly found in beeswax. In honey, chromium displayed the highest mean concentration, followed by zinc, whereas lead and molybdene occurred only in beeswax. Our findings indicate that the daily consumption of honey and beeswax together may compromise children's health. Sucrose-syrup fed honey could not be distinguished from floral honey based on sugar profile, rather by its trace elements levels.


Assuntos
Poluentes Ambientais/análise , Mel/análise , Resíduos de Praguicidas/análise , Oligoelementos/análise , Ceras/análise , Ácido 2,4-Diclorofenoxiacético/análise , Animais , Abelhas , Cromo/análise , Cromo/toxicidade , Contaminação de Alimentos/análise , Herbicidas/análise , Mel/normas , Humanos , Inseticidas/análise , Israel , Resíduos de Praguicidas/toxicidade , Praguicidas/análise , Medição de Risco , Açúcares/análise , Toluidinas/análise , Oligoelementos/toxicidade , Ceras/normas
9.
Environ Pollut ; 252(Pt B): 1550-1560, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31277024

RESUMO

This study aimed to assess the association between exposure to chromium and neuropsychological development among children. A cross-sectional study was conducted with 393 children aged 6-11 years old randomly selected from State-funded schools in two provinces in Southern Spain (Almeria and Huelva), in 2010 and 2012. Chromium levels in urine and hair samples were analyzed by inductively coupled plasma mass spectrometry with an octopole reaction system. Neuropsychological development was evaluated using the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) and three computerized tests from the Behavioural Assessment and Research System (BARS): Reaction Time Test (RTT), Continuous Performance Test (CPT) and Selective Attention Test (SAT). Multivariable linear regression models adjusted for potential confounders, including heavy metals, were applied to examine the association between chromium levels and neuropsychological outcomes. A 10-fold increase in urine chromium levels was associated with a decrease of 5.99 points on the WISC-IV Full-Scale IQ (95% CI: 11.98 to -0.02). Likewise, a 10-fold increase in urine chromium levels in boys was associated with a decrease of 0.03 points in the percentage of omissions (95% CI: 0.0 to 0.05) in the SAT, with an increase of 68.35 points in latency (95% CI: 6.60 to 130.12) in the RTT, and with an increase in the number of trials with latencies > 1000 ms (ß = 37.92; 95% CI: 2.73 to 73.12) in the RTT. An inverse significant association was detected between chromium levels in hair and latency in the SAT in boys (ß = -50.53; 95% CI: 86.86 to -14.22) and girls (ß = -55.95; 95% CI: 78.93 to -32.97). Excluding trials with latencies >1000 ms in the RTT increased latency scores by 29.36 points in boys (95% CI: 0.17 to 58.57), and 39.91 points in girls (95% CI: 21.25 to 58.59). This study is the first to show the detrimental effects of postnatal chromium exposure on neuropsychological development in school-aged children.


Assuntos
Atenção/efeitos dos fármacos , Desenvolvimento Infantil/efeitos dos fármacos , Cromo/análise , Exposição Ambiental/efeitos adversos , Poluentes Ambientais/análise , Inteligência/efeitos dos fármacos , Criança , Cromo/urina , Estudos Transversais , Exposição Ambiental/análise , Poluentes Ambientais/urina , Feminino , Cabelo/química , Humanos , Masculino , Testes Neuropsicológicos , Distribuição Aleatória , Espanha
10.
Water Sci Technol ; 79(11): 2106-2115, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31318348

RESUMO

A magnetic cotton stalk biochar (MCSBC) was synthesized through chemical co-precipitation, based on cotton stalk biochar (CSBC). The MCSBC and CSBC were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and vibrating sample magnetometry. The characterization analyses showed that the magnetization process endowed the CSBC with excellent magnetic properties with a superparamagnetic magnetization of 27.59 emu/g. Batch adsorption experiment results indicated that the Cr(VI) maximum adsorption capacity of MCSBC was 20.05 mg/g, which was higher than that of CSBC (18.77 mg/g). The adsorption kinetic data were well fitted by the pseudo-second-order model and the adsorption isotherms were well represented by the Sips isotherm model. The thermodynamic studies indicated that the adsorption process was spontaneous and endothermic, and the entropy increased. The potential adsorption mechanism was the electrostatic adsorption of anionic Cr(VI) to the positively charged MCSBC surface, the reduction of Cr(VI) into Cr(III) and the complexation of Cr(III) by oxygen-containing functional groups of MCSBC. The regeneration studies showed that MCSBC kept 80% of its initial Cr(VI) adsorption capacity in the cycle. All the findings suggest that this novel magnetic biochar could be used in the field of Cr(VI)-containing wastewater treatment.


Assuntos
Carvão Vegetal/química , Cromo/química , Poluentes Químicos da Água/química , Adsorção , Cromo/análise , Cinética , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise
11.
Environ Monit Assess ; 191(7): 476, 2019 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-31256265

RESUMO

Concentrations of arsenic, nickel and chromium in sediments of the nearshore Pilbara Region of Western Australia's mid -north coast have caused concerns to regulators issuing ocean disposal permits for many years. A meta-analysis of data from a large number of surveys, conducted in support of permit applications over many years and across hundreds of kilometres of coastline, shows that, when assessed as total metal concentrations, chromium and nickel occur routinely at concentrations above those recommended as screening triggers by national guidelines and arsenic more rarely. Arsenic was concentrated in surface sediments, consistent with an organic origin. Concentrations of nickel and chromium were higher in deeper sediment layers, consistent with a natural geological origin. However, sediment particle sizing was a major determinant of total metal concentrations of all three metals, and bioavailability was always much lower and within recommended guidelines. Past dredging activity for channels and berths in the large ports of the Pilbara has most likely led to an elevation of fine fractions of surface sediments within operating port areas, when compared to the undisturbed surrounding areas, and may also have increased the proportion of sediment from deeper substrates at the surface. Whilst total concentrations of chromium and nickel commonly exceed screening guidelines throughout the nearshore Pilbara Region, their bioavailability was low and these metals present a little threat to biota.


Assuntos
Sedimentos Geológicos/análise , Metais/análise , Poluentes Químicos da Água/análise , Arsênico/análise , Disponibilidade Biológica , Cromo/análise , Monitoramento Ambiental , Níquel/análise , Oceanos e Mares , Austrália Ocidental
12.
Environ Pollut ; 252(Pt B): 1399-1405, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31260939

RESUMO

Remediation of hexavalent chromium [Cr(VI)] has been widely studied for its high mobility and toxicity. As Cr(VI) migrates in natural environment, both soils and groundwater are contaminated simultaneously. In the present study, a novel reactor combining adsorption and microbial fuel cell (A-MFC) using Platanus acerifolia leaves was developed for removing Cr(VI) from groundwater and soils. When initial Cr(VI) concentration was 50 mg/L, the adsorption efficiency of A-MFC achieved 98% after 16 h. Afterwards, the leaves were used for fabricating an MFC-integrated leaching reactor. The A-MFC significantly improved the overall Cr(VI) removal efficiency through leaching and 40% of Cr(VI) in the soil column was removed. The electrical voltage and current of A-MFC reactor achieved averagely 343 mV and 141 µA to maintain the system operation without extra energy supply. This novel A-MFC reactor is an environmentally friendly technology which achieved efficient Cr(VI) removal from groundwater and soils using natural materials, proving the concept that integrated self-remediation of Cr(VI) in contaminated soil and groundwater with natural material and energy.


Assuntos
Biodegradação Ambiental , Fontes de Energia Bioelétrica/microbiologia , Cromo/análise , Água Subterrânea/química , Folhas de Planta/metabolismo , Solo/química , Adsorção/fisiologia , Eletricidade , Proteaceae/metabolismo
13.
Food Chem ; 298: 125032, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31260968

RESUMO

A dietary fibre prepared from sugarcane stalk was compared with psyllium husk and wheat dextrin. In contrast to the other dietary fibres, sugarcane fibre was found to contain significant amounts of insoluble dietary fibre (73-86%), lignin (18.66-20.23%), and rare minerals such as chromium (0.67-2.54 mg/100 g) and manganese (1.07-2.34 mg/100 g). Analysis of the ethanol extract also detected compounds with antioxidant activity. Characterisation of five sugarcane fibres prepared from selected strains, harvest periods (growth or storage phase), and processing conditions showed these factors influenced the final composition. Furthermore, using in vitro digestion, we found that potassium, magnesium, chromium, and zinc in were bioaccessible in sugarcane samples. Also, sodium was shown to bind to the sugarcane fibre potentially indicating bile salt binding activity. Results from this study support the use of sugarcane as a source of dietary fibre in functional foods.


Assuntos
Dextrinas/química , Fibras na Dieta/análise , Plantago/química , Saccharum/química , Triticum/química , Antioxidantes/análise , Cromo/análise , Cromo/farmacocinética , Dextrinas/análise , Fibras na Dieta/metabolismo , Indústria de Processamento de Alimentos/métodos , Lignina/análise , Metais/análise , Metais/farmacocinética
14.
Chemosphere ; 235: 440-446, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31272004

RESUMO

Hexavalent chromium Cr(VI) is a common inorganic contaminant in industrial areas and represents a serious threat to human health due its toxicity. Here we report experimental results from a field-scale investigation of Cr(VI) bio-immobilization at Hanford 100H reservation, a U.S Department of Energy facility (Washington State, USA). Microbial Cr(VI) reduction was stimulated via injection of a13C-labeled sodium lactate solution into the high-permeability aquifer consisting of gravel and coarse sand sediments. Concentrations and carbon isotope ratios of metabolites, including dissolved inorganic carbon and total organic carbon, and compound-specific analysis of acetate and propionate, together with phospholipid fatty acids (biomass) have been analyzed to help provide an understanding of the predominant redox processes accompanying Cr(VI) reduction. Results of our study indicate that the injection of an electron donor caused a sharp decrease of Cr(VI) concentration from ∼32 to ∼10 nM. Cr(VI) reduction was associated with a decrease in the concentration of carboxylic acids, such as lactate (∼6 mM to undetectable), propionate (∼9 mM to undetectable), and acetate (∼6 mM to undetectable), as well as dissolved inorganic carbon (30-10 mM C). Carbon isotope data indicate carbon transfers from the original substrate to organic byproducts and mineralized carbon. Concentrations of metabolites and stable isotope data as well as carbon isotope mass balance calculations were used to monitor biologically mediated reduction of Cr(VI).


Assuntos
Cromo/análise , Monitoramento Ambiental/métodos , Água Subterrânea/química , Poluentes Químicos da Água/análise , Animais , Biomassa , Carbono/análise , Isótopos de Carbono/análise , Elétrons , Água Subterrânea/análise , Oxirredução , Suínos , Washington
15.
Environ Monit Assess ; 191(8): 504, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31338610

RESUMO

Leaching of chromium ions causes a serious threat to groundwater around chromite ore processing residue (COPR) dump sites in many countries. As a result, detailed subsurface characterization of the affected region is crucial for assessing the associated risks as well as initiating remedial measures. Though the conventional approaches (e.g., drilling and water sampling) provide important information but are expensive and unable to decipher detailed subsurface scenario. Thus, in the present study, electrical resistivity tomography (ERT) (a cost-effective and faster approach) method has been employed to assess the effect of unplanned COPR waste dump beside agricultural land at Umaran, Kanpur, India, in conjunction with the available geochemical information. Inverted 2-D ERT sections depicted resistivity variation in the subsurface, and its correlation with previous geochemical results reveals the resistivity boundary between contaminated and clean zones as ~ 15 Ω·m. The study also depicts that the contamination plume is slowly migrating towards NE direction below the agriculture land but rate of migration is faster along southern direction. Therefore, the agriculture land and corresponding groundwater at ~ 50 m away from the dump site in NE direction are not affected by COPR leachate. Vertically, the COPR leachate has affected mostly up to ~ 20 m depth in the region inside the dump boundary; however, at some places, it is migrating further downward. Thus, the study demonstrates the efficacy of ERT method in characterizing COPR dump site and provides crucial information in managing safe agriculture practices over the region as well as for initiating scientific remedial measures.


Assuntos
Cromo/análise , Monitoramento Ambiental/métodos , Resíduos Industriais/análise , Instalações de Eliminação de Resíduos , Eletricidade , Água Subterrânea/química , Índia , Tomografia
16.
Environ Monit Assess ; 191(8): 509, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31342188

RESUMO

The aim of this paper is to provide a methodology including statistical tools and spatial techniques, in order to identify the various potential sources of chromium (Crtot) in the Sarigkiol basin, Western Macedonia, Greece, where elevated concentrations of Crtot in groundwater have been recorded since 1996. Integrated hydrochemical approach and statistical analyses including Pearson's correlation coefficient, multivariate statistical analyses (factor analysis and hierarchical cluster analysis), and spatial techniques (Moran's I spatial autocorrelation index and bivariate local indicator spatial association cluster map) were applied to evaluate the chemical analyses of 73 water samples, from irrigation wells, natural springs, and surface water. Both natural and anthropogenic sources of Crtot were recorded; the first (ultramafic-dominated environment) is strongly depicted on the natural spring water, in which Crtot concentrations as high as ~ 130 µg/L were recorded, whereas the second (agricultural activities) acts synergistically in the irrigation wells of the Sarigkiol basin, in which strong correlations of Crtot, P, and NO3- were defined. The paper highlights its findings by outlining the potential sources of elevated concentrations of Cr6+ in the Sarigkiol basin, stressing the need for a closer attention on the role of agricultural activities as an important, though commonly neglected, anthropogenic source of Crtot in groundwater.


Assuntos
Cromo/análise , Monitoramento Ambiental/métodos , Água Subterrânea/química , Rios/química , Poluentes Químicos da Água/análise , Poços de Água , Agricultura , Monitoramento Ambiental/estatística & dados numéricos , Grécia , Análise Multivariada , Análise Espacial
17.
Chemosphere ; 235: 565-574, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31276869

RESUMO

Very few studies have investigated the leaching characteristics of cement activated fly ash and slag treated soils, although the inclusion of cement significantly enhances the material pH and may alter the leachability of elements. In this study the leaching behavior and mechanisms of chromium (Cr), copper (Cu), iron (Fe) and sulfur (S) from cement activated fly ash and slag stabilized soils were evaluated. An array of synthetic precipitation leaching procedure (SPLP), batch water leach test (WLT), toxicity characteristic leaching procedure (TCLP) and pH-Static leach tests were conducted. A geochemical equilibrium model Visual MINTEQ was implemented to identify the leaching controlling mechanisms of the metals. Results indicated that, the leached concentrations of Cr, Cu, Fe and S in SPLP, WLT and TCLP effluents were in the range of 0.016-0.74 mg/L, 0.013-0.17 mg/L, 0.019-0.27 mg/L and 1.78-234 mg/L, respectively. Quantitative comparisons between the standard test procedures suggested the necessity of multiple test methods for a comprehensive leaching assessment. Cr and Cu showed amphoteric leaching behaviors, whereas Fe and S followed cationic leaching patterns. According to the geochemical analyses, amorphous Cr(OH)3; tenorite and Cu(OH)2; ferrihydrite and goethite; gypsum and anhydrite; could control the leaching of Cr, Cu, Fe and S, respectively. The effluent Cr concentrations frequently exceeding the U.S. EPA specified maximum contaminant level of 0.1 mg/L. Yet, the use of cement activated fly ash and slag mixed soils could be beneficial, since less toxic trivalent Cr (III) was identified through geochemical modeling.


Assuntos
Monitoramento Ambiental , Poluentes do Solo/análise , Solo/química , Oligoelementos/análise , Cromo/análise , Cinza de Carvão/análise , Cobre/análise , Ferro/análise , Metais/análise , Metais Pesados/análise
18.
Environ Sci Pollut Res Int ; 26(23): 23625-23637, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31203545

RESUMO

This study reveals the efficient bio-sorption of Cr(VI) species from simulated wastewater using raw (RSV), acid-activated (PSV) and chelated-activated (PSV-C) Sterculia villosa Roxb. shells. Batch optimization experiments were carried out for determining the optimal pH, dosage of bio-sorbent, initial Cr(VI) concentration and incubation temperature. Physico-chemical alterations in the bio-sorbents prior and following bio-sorption of Cr(VI) species were characterized. Equilibrated experimental data at different temperatures was evaluated as a function of time for understanding the isotherm, kinetics and thermodynamics of the bio-sorption process. Sorption rates for all the bio-sorbents (RSV, PSV and PSV-C) alternately fitted to the Langmuir isotherm model and Langmuir maximum adsorption capacity for RSV, PSV and PSV-C were found to be 57.78, 163.51 and 188.68 mg/g, respectively. Cr(VI) sorption by these bio-sorbents followed pseudo-second-order kinetics. Thermodynamic studies suggest endothermic interaction and increased degree of randomness between the bio-sorbents and Cr(VI) species. Regeneration of the bio-sorbents following sorption-desorption revealed that it can be reused and recycled for several times for Cr(VI) removal from wastewater. Graphical abstract.


Assuntos
Quelantes/química , Cromo/química , Poluentes Químicos da Água/química , Adsorção , Biomassa , Cromo/análise , Concentração de Íons de Hidrogênio , Cinética , Sterculia/química , Temperatura Ambiente , Termodinâmica , Águas Residuárias , Água , Poluentes Químicos da Água/análise , Purificação da Água/métodos
19.
Environ Monit Assess ; 191(7): 419, 2019 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-31177337

RESUMO

Certain five heavy metals viz. arsenic (As), cadmium (Cd), chromium (Cr)(VI), mercury (Hg), and lead (Pb) are non-threshold toxins and can exert toxic effects at very low concentrations. These heavy metals are known as most problematic heavy metals and as toxic heavy metals (THMs). Several industrial activities and some natural processes are responsible for their high contamination in the environment. In recent years, high concentrations of heavy metals in different natural systems including atmosphere, pedosphere, hydrosphere, and biosphere have become a global issue. These THMs have severe deteriorating effects on various microorganisms, plants, and animals. Human exposure to the THMs may evoke serious health injuries and impairments in the body, and even certain extremities can cause death. In all these perspectives, this review provides a comprehensive account of the relative impact of the THMs As, Cd, Cr(VI), Hg, and Pb on our total environment.


Assuntos
Arsênico/análise , Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Metais Pesados/análise , Animais , Cádmio/análise , Cromo/análise , Intoxicação por Metais Pesados , Humanos , Chumbo/análise , Mercúrio/análise
20.
Environ Monit Assess ; 191(7): 455, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31227917

RESUMO

In many sub-Saharan states, despite governments' awareness campaigns highlighting potential impacts of aquatic pollution, there is a very limited action to protect the riverine systems. Managing the quality of water and sediments needs knowledge of pollutants, agreed standards, and relevant policy framework supporting monitoring and regulation. This study reports metal concentrations in rivers in industrializing Ethiopia. The study also highlights policy and capacity gaps in monitoring of river and sediments. For two sampling periods in 2013 and 2014, chromium (Cr), copper (Cu), zinc (Zn), and lead (Pb) were monitored in water and sediments of the Leyole and Worka rivers in the Kombolcha city, Ethiopia. The sampling results were compared with international guidelines and evaluated against the Ethiopian water protection policies. Chromium was high in the Leyole river water (median 2660 µg/L) and sediments (maximum 740 mg/kg), Cu concentrations in the river water was highest at the midstream part of the Leyole river (median 63 µg/L), but maximum sediment content of 417 mg/kg was found further upstream. Zinc was the highest in the upstream part of the Leyole river water (median 521 µg/L) and sediments (maximum 36,600 mg/kg). Pb concentrations were low in both rivers. For the sediments, relatively higher Pb concentrations (maximum 3640 mg/kg) were found in the upstream of the Leyole river. Except for Pb, the concentrations of all metals surpassed the guidelines for aquatic life, human, livestock, and irrigation water supplies. The median concentrations of all metals exceeded guidelines for sediment quality for aquatic organisms. In Ethiopia, poor technical and financial capabilities restrict monitoring of rivers and sediments and understanding on the effects of pollutants. The guidelines used to protect water quality is based on the World Health Organization standards for drinking water quality, but this is not designed for monitoring ecological health. Further development of water quality standards and locally relevant monitoring framework are needed. Development of monitoring protocols and institutional capacities are important to overcome the policy gaps and support the government's ambition in increasing industrialization and agricultural intensification. Failure to do so presents high risks for the public and the river ecosystem.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Metais Pesados/análise , Rios/química , Poluentes Químicos da Água/análise , África do Norte , Cromo/análise , Cobre/análise , Ecologia , Ecossistema , Etiópia , Humanos , Chumbo/análise , Desenvolvimento Sustentável , Qualidade da Água , Zinco/análise
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