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1.
Nanomaterials (Basel) ; 9(4)2019 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-30986971

RESUMO

This study proves that the new developed zinc-doped hydroxyapatite (ZnHAp) colloids by an adapted sol-gel method can be widely used in the pharmaceutical, medical, and environmental industries. ZnHAp nanoparticles were stabilized in an aqueous solution, and their colloidal dispersions have been characterized by different techniques. Scanning Electron Microscopy (SEM) was used to get information on the morphology and composition of the investigated samples. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the elemental compositions of ZnHAp colloidal dispersions. The homogeneous and uniform distribution of constituent elements (zinc, calcium, phosphorus, oxygen) was highlighted by the obtained elemental mapping results. The X-ray diffraction (XRD) results of the obtained samples showed a single phase corresponding to the hexagonal hydroxyapatite. The characteristic bands of the hydroxyapatite structure were also evidenced by Fourier-transform infrared spectroscopy (FTIR) analysis. For a stability assessment of the colloidal system, ζ-potential for the ZnHAp dispersions was estimated. Dynamic light scattering (DLS) was used to determine particles dispersion and hydrodynamic diameter (DHYD). The goal of this study was to provide for the first time information on the stability of ZnHAp particles in solutions evaluated by non-destructive ultrasound-based technique. In this work, the influence of the ZnHAp colloidal solutions stability on the development of bacteria, such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), was also established for the first time. The antimicrobial activity of ZnHAp solutions was strongly influenced by both the stability of the solutions and the amount of Zn.

2.
Artigo em Inglês | MEDLINE | ID: mdl-30972672

RESUMO

Soil-exchangeable aluminum (Al) has toxic effects on living organisms in acidic soils. Earthworm presence and activity can alter soil pH, which has a significant influence on Al toxicity. However, the effects of earthworms on soil Al toxicity and fractions are still largely unknown. This laboratory study focused on the effects of three earthworm species (endogeics Pontoscolex corethrurus and Amynthas robustus, anecis Amynthas aspergillum) on soil acidification, Al fraction distribution, and base cation release. Three native earthworm species and a soil (latosolic red soil) collected from a botanical garden in South China were incubated under laboratory conditions. After 40 days of incubation, six Al fractions in soil, namely exchangeable (AlEx), weakly organically bound (AlOrw), organically bound (AlOr), amorphous (AlAmo), Al occluded in crystalline iron oxides (AlOxi), and amorphous aluminosilicate and gibbsite (AlAag) fractions, were extracted using a sequential procedure. Soil pH; organic carbon; total nitrogen; total Al (AlTotal); exchangeable K, Na, Ca, Mg contents; and CEC were determined as well. Compared to control soil, pH values increased by 0.79, 0.41, and 0.57 units in casts in the presence of P. corethrurus, A. robustus, and A. aspergillum, and 0.70, 0.32, and 0.50 units in non-ingested soil, respectively. Compared to control soil, the 61.7%, 30.7%, and 36.1% of AlEx contents in casts and 68.5%, 25.9%, and 39.0% of AlEx in non-ingested soil significantly decreased with the addition of P. corethrurus, A. robustus, and A. aspergillum, respectively. Moreover, compared to control soil, the 78.7%, 37.7%, and 40.1% of exchangeable Ca2+ and 12.3%, 24.7%, and 26.8% of exchangeable Mg2+ contents in casts significantly increased with the presence of P. corethrurus, A. robustus, and A. aspergillum, respectively. Soil treated with P. corethrurus had higher soil pH values, exchangeable Ca2+ contents, and lower AlEx than those with A. robustus and A. aspergillum. Results of principal component analyses showed that P. corethrurus, A. robustus, and A. aspergillum casts and non-ingested soil differ for soil pH, Al fractions, and exchangeable base cations release. These results indicate that earthworms, especially P. corethrurus, can reduce soil Al toxicity, increase soil pH, and affect the release of exchangeable base cations.

3.
Artigo em Inglês | MEDLINE | ID: mdl-30838490

RESUMO

This study focused on the study of earthworm survival, growth, reproduction, enzyme activities, and protein contents to evaluate and predict the effects of different soil pH levels and determine the optimal risk assessment indicators for the effects. Survival rate, growth rate, and cocoon number as well as four enzyme (glutathione peroxidase (GSH-PX), superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) activities and two proteins (total protein (TP) and metallothionein (MT)) contents in earthworms were determined to characterize the responses of earthworm activity to five soil pH levels. These biological datasets (survival, growth, and reproduction) were compared with biochemical indexes (GSH-PX, SOD, POD, CAT, TP, and MT), mainly using biphasic dose-response models. The results indicated that the soil pH value had significant inhibitory effects on the survival, growth, and reproduction of earthworms beginning with 3.0, 4.0, and 5.2, respectively. The dose-response models (J-shaped and inverted U-shaped curves) statistics indicated that the critical values (ECZEP) of the GSH-PX, SOD, POD, CAT, TP, and MT inhibited by soil acid stress were 3.46, 3.76, 3.35, 3.54, 3.50, and 3.96 (average 3.60), respectively. In the present study, the fitting curve analysis showed that the responses of the CAT activities and TP and MT contents in earthworm in response to soil pH have the behavior of hormesis.

4.
Environ Sci Pollut Res Int ; 26(6): 5251-5266, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29429112

RESUMO

This study investigates the spatiotemporal variability of major and trace elements, dissolved organic carbon (DOC), total dissolved solids (TDS), and suspended particulate matter (SPM) in surface waters of several hydrosystems of the Loire River watershed in France. In particular, this study aims to delineate the impact of the abovementioned water physicochemical parameters on natural iron and manganese physical speciation (homoaggregation/heteroaggregation) among fine colloidal and dissolved (< 10 nm), colloidal (10-450 nm) and particulate (> 450 nm) phases in Loire River watershed. Results show that the chemistry of the Loire River watershed is controlled by two end members: magmatic and metamorphic petrographic context on the upper part of the watershed; and sedimentary rocks for the middle and low part of the Loire. The percentage of particulate Fe and Mn increased downstream concurrent with the increase in SPM and major cations concentration, whereas the percentage of colloidal Fe and Mn decreased downstream. Transmission electron microscopy analyses of the colloidal and particulate fractions (from the non-filtered water sample) revealed that heteroaggregation of Fe and Mn rich natural nanoparticles and natural organic matter to the particulate phase is the dominant mechanism. The heteroaggregation controls the partitioning of Fe and Mn in the different fractions, potentially due to the increase in the ionic strength, and divalent cations concentration downstream, and SPM concentration. These findings imply that SPM concentration plays an important role in controlling the fate and behavior of Fe and Mn in various sized fractions. Graphical abstract Physical speciation by heteroaggregation of (Fe-Mn) compounds: high [SPM] → [Fe-Mn] particulate faction; low {SPM] → [Fe-Mn] colloid-dissolved fraction.


Assuntos
Metais/análise , Material Particulado/análise , Poluentes Químicos da Água/análise , Coloides/química , Monitoramento Ambiental , França , Ferro/análise , Ferro/química , Manganês/análise , Metais/química , Material Particulado/química , Rios , Poluentes Químicos da Água/química
5.
J Environ Manage ; 232: 117-130, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30471545

RESUMO

Mine soils often contain metal(loid)s that may lead to serious environmental problems. Phytoremediation, consisting in covering the soil with specific plants with the possible addition of amendments, represents an interesting way of enhancing the quality of mine soils by retaining contaminants and reducing soil erosion. In order to study the effect of an assisted phytoremediation (with willow and ryegrass) on the properties of soil pore water (SPW), we investigated the impact of amendment with biochar (BC) combined with the planting of willow and ryegrass on the behavior of several metal(loid)s (Pb, Zn, Ba, As, and Cd) in a mine soil. Data on the physicochemical parameters and concentrations of the different metal(loid)s in both SPW and in plant tissues of willow and ryegrass highlight the importance of BC for SPW properties in terms of reductions in soluble concentrations of Pb and Zn, although there was no effect on the behavior of As and Cd. BC also increased soluble concentrations of Ba, probably related to ion release by the BC. By improving major ions available in mine soil, BC improved the lifetime of plants and enhanced their growth. Plant development did not appear to significantly affect the physicochemical parameters of SPW. Willow and ryegrass growing on soil with BC incorporated Cd and Ba into their tissues. The influence of plants on the behavior of metal(loid)s was noticeable only for ryegrass growing in soil with 2% BC, where it modified the behavior of Pb and Ba.


Assuntos
Lolium , Metais Pesados , Salix , Poluentes do Solo , Cádmio , Carvão Vegetal , Chumbo , Solo , Água , Zinco
6.
Materials (Basel) ; 11(11)2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30405033

RESUMO

Contamination of water with heavy metals such as lead is a major worldwide problem because they affect the physiological functions of living organisms, cause cancer, and damage the immune system. Hydroxyapatite, (Ca5(PO4)3OH) is considered one of the most effective materials for removing heavy metals from contaminated water. The hydroxyapatite nanopowders (N-HAp) obtained by a co-precipitation method were used in this research to determine the effectiveness in removing lead ions from contaminated solutions. In this study, we have investigated the structure and morphology of N-HAp nanopowders using X-ray diffraction (XRD), electronic transmission microscopy (TEM), and scanning electron microscopy (SEM). The structure information was also obtained by spectroscopy measurements. The Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy measurements revealed the presence of peaks corresponding to the phosphate and hydroxyl groups. The ability of N-HAp nanopowders to adsorb lead ions from aqueous solutions were established. The results of the kinetic and equilibrium studies on the removal of Pb (II) from aqueous solution revealed that the adsorption of lead (II) cations is due to the surface reaction with the hydroxyl terminal groups on the adsorbent and the combination of the positive charges of the metal cations with the negative charges on the adsorbent surfaces. These observations could validate the use of these ceramic nanopowders in ecological remediation strategies.

7.
Materials (Basel) ; 11(8)2018 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-30081467

RESUMO

The present study demonstrates the effectiveness of hydroxyapatite nanopowders in the adsorption of zinc in aqueous solutions. The synthesized hydroxyapatites before (HAp) and after the adsorption of zinc (at a concentration of 50 mg/L) in solution (HApD) were characterized using X-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM, respectively). The effectiveness of hydroxyapatite nanopowders in the adsorption of zinc in aqueous solutions was stressed out through ultrasonic measurements. Both Langmuir and Freundlich models properly fitted on a wide range of concentration the equilibrium adsorption isotherms, allowing us to precisely quantify the affinity of zinc to hydroxyapatite nanopowders and to probe the efficacy of hydroxyapatite in removal of zinc ions from aqueous solutions in ultrasonic conditions.

8.
Materials (Basel) ; 11(5)2018 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-29695049

RESUMO

The research conducted in this study presented for the first time results of physico-chemical properties and in vitro antimicrobial activity of hydroxyapatite plant essential oil against Gram-positive bacteria (methicillin-resistant Staphylococcus aureus (MRSA) and S. aureus 0364) and Gram-negative bacteria (Escherichia coli ATCC 25922). The samples were studied by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy to determine the morphology and structure of the nanocomposites of hydroxyapatite coated with basil (HAp-B) and lavender (HAp-L) essential oils (EOs). The values of the BET specific surface area (SBET), total pore volume (VP) and pore size (DP) were determined. The results for the physico-chemical properties of HAp-L and HAp-B revealed that lavender EOs were well adsorbed on the surface of hydroxyapatite, whereas basil EOs showed a poor adsorption on the surface of hydroxyapatite. We found that the lavender EOs hydroxyapatite (HAp-L) exhibited a very good inhibitory growth activity. The value of the minimum inhibitory concentration (MIC) related to growth bacteria was 0.039 mg/mL for MRSA, 0.02 mg/mL for S. aureus and 0.039 mg/mL E. coli ATCC 25922. The basil EO hydroxyapatite (HAp-B) showed poor inhibition of bacterial cell growth. The MIC value was 0.625 mg/mL for the HAp-B sample in the presence of the MRSA bacteria, 0.313 mg/mL in the presence of S. aureus and 0.078 mg/mL for E. coli ATCC 25922.

9.
Environ Sci Pollut Res Int ; 25(26): 25744-25756, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28730365

RESUMO

Biochar is a potential candidate for the remediation of metal(loid)-contaminated soils. However, the mechanisms of contaminant-biochar retention and release depend on the amount of soil contaminants and physicochemical characteristics, as well as the durability of the biochar contaminant complex, which may be related to the pyrolysis process parameters. The objective of the present study was to evaluate, in a former contaminated smelting site, the impact of two doses of wood biochar (2 and 5% w/w) on metal immobilization and/or phytoavailability and their effectiveness in promoting plant growth in mesocosm experiments. Different soil mixtures were investigated. The main physicochemical parameters and the Cd, Pb, and Zn contents were determined in soil and in soil pore water. Additionally, the growth, dry weight, and metal concentrations were analyzed in the different dwarf bean plant (Phaseolus vulgaris L.) organs tested. Results showed that the addition of biochar at two doses (2 and 5%) improved soil conditions by increasing soil pH, electrical conductivity, and water holding capacity. Furthermore, the application of biochar (5%) to metal-contaminated soil reduced Cd, Pb, and Zn mobility and availability, and hence their accumulation in the different P. vulgaris L. organs. In conclusion, the data clearly demonstrated that biochar application can be effectively used for Cd, Pb, and Zn immobilization, thereby reducing their bioavailability and phytotoxicity.


Assuntos
Cádmio/química , Carvão Vegetal , Chumbo/química , Zinco/química , Disponibilidade Biológica , Cádmio/metabolismo , Poluentes Ambientais , Chumbo/metabolismo , Metalurgia , Solo/química , Poluentes do Solo/análise , Madeira/química , Zinco/metabolismo
10.
Environ Sci Pollut Res Int ; 23(9): 8367-78, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26780058

RESUMO

The phytoavailabilities and potential remobilization of potentially toxic elements (PTEs) such as Zn, Pb, Cd, As, and Sb were assessed in contaminated technosols from former mining and smelting sites. The PTE concentrations in soil pore water (SPW) and diffusive gradients in thin films (DGT)-measured concentration (C DGT) methods were used to assess the bioavailabilities of PTE and their remobilization in this study. Together with classical Chelex-100 DGT probes to measure Zn, Cd, and Pb, novel ferrihydrite-backed DGT were used for As and Sb measurements alongside with Rhizon soil moisture sampler method for SPW sampling. To assess the phytoavailabilities of PTE, a germination test with dwarf beans as a plant indicator was used for this purpose. Dwarf bean primary leaves showed high Zn concentrations in contrast to Pb and Cd which showed low phytoavailabilities. Despite As and Sb are present in high concentrations in the mine tailings, their phytoavailabilities indicate very low bioavailabilities. The amounts of Zn, Pb, Cd, As, and Sb extracted with DGT devices correlated well with the total dissolved PTE concentrations in the SPW. The highest R values were observed for Zn, followed by Cd and Pb, indicating the ability of the soil to sustain SPW concentrations, which decreased in that order. Good correlations were also observed between each of dissolved PTE concentrations in SPW, DGT-measured PTE concentrations (C DGT), and the accumulation of PTE in dwarf bean primary leaves. It could be concluded that the use of Rhizon soil moisture samplers and DGT methods may be considered to be a good methods to predict the PTE bioavailabilities in contaminated technosols.


Assuntos
Monitoramento Ambiental/instrumentação , Poluentes do Solo/análise , Solo/química , Monitoramento Ambiental/métodos , Compostos Férricos , Mineração , Plantas , Poluentes do Solo/toxicidade , Água
11.
Chemosphere ; 145: 543-50, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26706463

RESUMO

Copper-contaminated soils were managed with aided phytoextraction in 31 field plots at a former wood preservation site, using a single incorporation of compost (OM) and dolomitic limestone (DL) followed by a crop rotation with tobacco and sunflower. Six amended plots, with increasing total soil Cu, and one unamended plot were selected together with a control uncontaminated plot. The mobility and phytoavailability of Cu, Zn, Cr and As were investigated after 2 and 3 years in soil samples collected in these eight plots. Total Cu, Zn, Cr and As concentrations were determined in the soil pore water (SPW) and available soil Cu and Zn fractions by DGT. The Cu, Zn, Cr and As phytoavailability was characterized by growing dwarf beans on potted soils and determining the biomass of their plant parts and their foliar ionome. Total Cu concentrations in the SPW increased with total soil Cu. Total Cu, Zn, Cr and As concentrations in the SPW decreased in year 3 as compared to year 2, likely due to annual shoot removals by the plants and the lixiviation. Available soil Cu and Zn fractions also declined in year 3. The Cu, Zn, Cr and As phytoavailability, assessed by their concentration and mineral mass in the primary leaves of beans, was reduced in year 3.


Assuntos
Cobre/metabolismo , Helianthus/crescimento & desenvolvimento , Chumbo/metabolismo , Poluentes do Solo/metabolismo , Tabaco/crescimento & desenvolvimento , Zinco/metabolismo , Biodegradação Ambiental , Biomassa , Cobre/análise , França , Helianthus/metabolismo , Chumbo/análise , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/metabolismo , Solo/química , Poluentes do Solo/análise , Tabaco/metabolismo , Zinco/análise
12.
Environ Sci Pollut Res Int ; 22(23): 18759-71, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26199007

RESUMO

This study aimed at assessing the effect of nitrogen addition under two forms, nitrate and ammonium, on the stabilization of Zn, Pb, and Cd by Populus euramericana Dorskamp grown in contaminated soils for 35 days under controlled conditions. Temporal changes in the soil pore water (SPW) were monitored for pH, dissolved organic carbon (DOC), and total dissolved concentrations of metals in the soils rhizosphere. Rhizospheric SPW pH decreased gradually with NH4(+) addition and increased with NO3(-) addition up to one unit, while it slightly decreased initially then increased for the untreated control soil DOC increased with time up to six times, the highest increase occurring with NH4(+) fertilization. An increase in the metal concentrations in the rhizospheric SPW was observed for NH4(+) addition associated with the lowest rhizospheric SPW pH, whereas the opposite was observed for the control soil and NO3(-) fertilization. Fertilization did not affect plant shoots or roots biomass development compared to the untreated control (without N addition). Metals were mostly accumulated in the rhizosphere and N fertilization increased the accumulation for Zn and Pb while Cd accumulation was enhanced for NH4(+) addition. Collectively, our results suggest metal stabilization by P. euramericana Dorskamp rhizosphere with nitrogen fertilization and are potential for phytostabilization of contaminated technosol.


Assuntos
Compostos de Amônio/toxicidade , Fertilizantes/toxicidade , Nitratos/toxicidade , Populus/crescimento & desenvolvimento , Poluentes do Solo/toxicidade , Biodegradação Ambiental , Biomassa , Cádmio/metabolismo , Chumbo/metabolismo , Metais , Óxidos de Nitrogênio , Fotoquímica , Brotos de Planta/química , Populus/metabolismo , Rizosfera , Poluentes do Solo/análise , Zinco/metabolismo
13.
J Environ Manage ; 159: 37-47, 2015 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-26042630

RESUMO

Organic compounds resulting from the decomposition of organic amendments are used in the remediation of trace element (TE) contaminated soils. The mobility, phytoavailability and soil exposure intensity of molybdenum (Mo), chromium (Cr), zinc (Zn), copper (Cu), Cobalt (Co) and Arsenic (As) were evaluated in the phytoremediation of contaminated technosols after the addition of two organic matter types, fresh ramial chipped wood (RCW) and composted sewage sludge (CSS). The experiment consisted of nine main treatment blocks: (A) 3X unamended soil (NE), (B) 3X soil amended with RCW and (C) 3X soil amended with mature CSS. Total dissolved TE concentrations were determined in soil pore water (SPW) sampled by Rhizon samplers. The soil exposure intensity was assessed by standard Chelex 100 DGT (diffusive gradient in thin films) probes. TE phytoavailability was characterized by growing dwarf beans on potted soils and analyzing their foliar TE concentrations. The results of the present study indicate that the addition of fresh RCW and CSS has a positive effect on contaminated technosols. RCW decreased the mobility of all the studied TE in the SPW, whereas CSS reduced the mobility of Mo, Cr and Co, while it increased the mobility of Zn, Cu and As compared with the NE soil. The Zn soil exposure intensity assessed by DGT was not significantly changed by the addition of RCW and CSS, while the Cr soil exposure intensity was significantly decreased after RCW addition compared with the soil treated with CSS and the NE soil. In contrast Cu and Co were non labile in the three soils. Both RCW and CSS decreased the foliar concentration and the mineral mass of Mo, Zn, Cr, As and Co in the bean leaves but increased the foliar Cu concentration.


Assuntos
Metais/análise , Poluentes do Solo/análise , Solo/química , Oligoelementos/análise , Biodegradação Ambiental , Disponibilidade Biológica , Cobalto , França , Metalurgia , Metais/farmacocinética , Plantas , Esgotos , Água , Madeira/química
14.
Environ Sci Pollut Res Int ; 22(8): 5961-74, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25378030

RESUMO

This study reports the chemical bioavailability of several potentially toxic elements (Zn, Pb, Cd, As, and Sb) in contaminated Technosols from two former smelting and mining areas. Though these elements have long been recognized as potentially harmful elements, understanding of their toxicity and environmental behavior in Technosols developed on former mining and smelting sites are more limited, particularly for As and Sb. Surface soils were sampled from metallophyte grassland contaminated with Zn, Pb, and Cd located at Mortagne-du-Nord (North France) and from a former mining settling basin contaminated with As, Pb, and Sb located at la Petite Faye (Limoges, France). Various selective single extraction procedures (CaCl2, NaNO3, NH4NO3, DTPA, and EDTA) were used together with germination tests with dwarf beans whose shoots were analyzed for their potentially toxic element concentrations after 21 days of growth. The extraction capacity of the potentially toxic elements followed the order EDTA > DTPA > NH4NO3 > CaCl2 > NaNO3 for both studied areas. Pearson's correlation coefficient analysis between the concentrations of potentially toxic elements accumulated in bean primary leaves or their mineral mass with their extractable concentrations showed a positive significant correlation with dilute CaCl2 and nitrate solutions extraction procedures. In contrast, for all studied elements, except Pb, the complexing and chelating extractants (EDTA and DTPA) exhibited poor correlation with the dwarf bean leaves concentrations. Moreover, results showed that the 0.01 M CaCl2 extraction procedure was the most suitable and provided the most useful indications of metal phytoavailability for studied elements.


Assuntos
Fabaceae/metabolismo , Poluentes do Solo/análise , Antimônio/análise , Cádmio/análise , Cádmio/metabolismo , Monitoramento Ambiental , Fabaceae/crescimento & desenvolvimento , França , Germinação , Chumbo/análise , Chumbo/metabolismo , Mineração , Solo/química , Poluentes do Solo/metabolismo , Distribuição Tecidual , Zinco/análise , Zinco/metabolismo
15.
J Colloid Interface Sci ; 437: 71-79, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25313469

RESUMO

A Na exchanged montmorillonite (Mt) was used as a starting layered material for the preparation of two organoclays synthesized with benzyl decyltrimethyl ammonium (BDTA) cationic surfactant and the tri-ethylene glycol mono n-decyl ether(C10E3), a nonconventional nonionic surfactant. The adsorption of the surfactants was performed at an amount of 0.7 times the cation exchange capacity (CEC) for BDTA and below the critical micelle concentration (cmc) where C10E3 is in a monomer state, leading to the intercalation of a lateral monolayer surfactant arrangement within the interlayer space and about 5-7% organic carbon content in organoclays. The environmental properties of both nonionic (C10E3Mt) and cationic (BDTAMt) organoclays were compared to those of the starting Mt clay with the sorption of three micro-pollutants: benzene, dimethyl-phthalate and paraquat. The adsorption isotherms and the derivative data determined through the fitting procedure by using Langmuir, Freundlich and Dubinin-Radushkevitch equation models explicitly highlighted the importance of the chemical nature of the micropollutants, which play on the adsorbents efficiency. The adsorption data combined with FTIR and XRD supplementary results suggest that C10E3Mt nonionic organoclay, although being less efficient for the retention of the different micropollutants, turned out to be the most polyvalent adsorbent since such hybrid material could adsorb the entire studied organic compounds.


Assuntos
Silicatos de Alumínio/química , Compostos Orgânicos/química , Adsorção , Argila , Microscopia Eletrônica de Transmissão , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
16.
Environ Sci Pollut Res Int ; 21(17): 10307-19, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24809492

RESUMO

The remediation of copper-contaminated soils by aided phytostabilisation in 16 field plots at a wood preservation site was investigated. The mobility and bioavailability of four potentially toxic trace elements (PTTE), i.e., Cu, Zn, Cr, and As, were investigated in these soils 4 years after the incorporation of compost (OM, 5 % w/w) and dolomite limestone (DL, 0.2 % w/w), singly and in combination (OMDL), and the transplantation of mycorrhizal poplar and willows. Topsoil samples were collected in all field plots and potted in the laboratory. Total PTTE concentrations were determined in soil pore water (SPW) collected by Rhizon soil moisture samplers. Soil exposure intensity was assessed by Chelex100-DGT (diffusive gradient in thin films) probes. The PTTE phytoavailability was characterized by growing dwarf beans on potted soils and analyzing their foliar PTTE concentrations. OM and DL, singly and in combination (OMDL), were effective to decrease foliar Cu, Cr, Zn, and As concentrations of beans, the lowest values being numerically for the OM plants. The soil treatments did not reduce the Cu and Zn mineral masses of the bean primary leaves, but those of Cr and As decreased for the OM and DL plants. The Cu concentration in SPW was increased in the OM soil and remained unchanged in the DL and OMDL soils. The available Cu measured by DGT used to assess the soil exposure intensity correlated with the foliar Cu concentration. The Zn concentrations in SPW were reduced in the DL soil. All amendments increased As in the SPW. Based on DGT data, Cu availability was reduced in both OM and OMDL soils, while DL was the most effective to decrease soil Zn availability.


Assuntos
Arsênico/análise , Compostos de Cálcio , Metais Pesados/análise , Óxidos , Poluentes do Solo/análise , Solo , Biodegradação Ambiental , Disponibilidade Biológica , Biomassa , Cobre/análise , Poluição Ambiental , Plantas , Populus , Oligoelementos/análise , Água/química , Madeira/química
17.
Environ Sci Pollut Res Int ; 21(7): 5054-65, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24371008

RESUMO

This study reports the chemical fractionation of several potentially toxic elements (Zn, Pb, Cd, As, and Sb) in contaminated technosoils of two former smelting and mining areas using two sequential extraction schemes. The extraction schemes used in this study were the Tessier's scheme and a modified BCR scheme. The fractions were rearranged into four equivalent fractions defined as acid soluble, reducible, oxidizable, and residual to compare the results obtained from two sequential extraction schemes. Surface soils were samples from a waste landfill contaminated with Zn, Pb, and Cd located at Mortagne-du-Nord (MDN; North France) and from a settling basin contaminated with PTE such as As, Pb, and Sb located at La Petite Faye (LPF; Limoges, France). The study of the Zn, Pb, Cd, As, and Sb partitioning in the acid soluble, reducible, oxidizable, and residual fractions of the technosoils revealed that Zn, Cd, and Pb were mainly associated with the acid soluble and reducible fractions for MDN site, while As, Sb, and Pb were associated with residual fraction for LPF site. Fractionation results indicate that the percentages of Zn, Pb, Cd, As, and Sb extracted in Fe-Mn oxide bound fraction of Tessier's scheme were always higher than those extracted by modified BCR scheme. This may be attributed to the stronger Tessier's scheme conditions used to extract this fraction. In contrast the percentages of Zn, Pb, Cd, As, and Sb extracted in the organic fraction of the modified BCR scheme were always higher than those of the Tessier's scheme. The order of mobility of PTE was as follows: Cd > Zn > Pb in MDN site and As > Sb > Pb in LPF site. PTE were distributed in all soil fractions, with the most relevant enrichments in extractable and residual fractions. A significant amount of Cd, Pb, and Zn were rather mobile, which suggests that these elements can be readily available to plants and soil organisms.


Assuntos
Fracionamento Químico/métodos , Metais Pesados/química , Poluentes do Solo/química , Solo/química , Monitoramento Ambiental , França , Metais Pesados/análise , Mineração , Poluentes do Solo/análise
18.
J Environ Manage ; 129: 134-42, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-23916835

RESUMO

The statistical variation of soil properties and their stochastic combinations may affect the extent of soil contamination by metals. This paper describes a method for the stochastic analysis of the effects of the variation in some selected soil factors (pH, DOC and EC) on the concentration of copper in dwarf bean leaves (phytoavailability) grown in the laboratory on contaminated soils treated with different amendments. The method is based on a hybrid modeling technique that combines an artificial neural network (ANN) and Monte Carlo Simulations (MCS). Because the repeated analyses required by MCS are time-consuming, the ANN is employed to predict the copper concentration in dwarf bean leaves in response to stochastic (random) combinations of soil inputs. The input data for the ANN are a set of selected soil parameters generated randomly according to a Gaussian distribution to represent the parameter variabilities. The output is the copper concentration in bean leaves. The results obtained by the stochastic (hybrid) ANN-MCS method show that the proposed approach may be applied (i) to perform a sensitivity analysis of soil factors in order to quantify the most important soil parameters including soil properties and amendments on a given metal concentration, (ii) to contribute toward the development of decision-making processes at a large field scale such as the delineation of contaminated sites.


Assuntos
Cobre/análise , Monitoramento Ambiental/métodos , Poluição Ambiental/prevenção & controle , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/análise , Biodegradação Ambiental , França , Modelos Teóricos , Método de Monte Carlo , Processos Estocásticos
19.
Nanoscale Res Lett ; 7(1): 576, 2012 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-23088756

RESUMO

The aim of this study was to obtain saccharide (dextran and sucrose)-coated maghemite nanoparticles with antibacterial activity. The polysaccharide-coated maghemite nanoparticles were synthesized by an adapted coprecipitation method. X-ray diffraction (XRD) studies demonstrate that the obtained polysaccharide-coated maghemite nanoparticles can be indexed into the spinel cubic lattice with a lattice parameter of 8.35 Å. The refinement of XRD spectra indicated that no other phases except the maghemite are detectable. The characterization of the polysaccharide-coated maghemite nanoparticles by various techniques is described. The antibacterial activity of these polysaccharide-coated maghemite nanoparticles (NPs) was tested against Pseudomonas aeruginosa 1397, Enterococcus faecalis ATCC 29212, Candida krusei 963, and Escherichia coli ATCC 25922 and was found to be dependent on the polysaccharide type. The antibacterial activity of dextran-coated maghemite was significantly higher than that of sucrose-coated maghemite. The antibacterial studies showed the potential of dextran-coated iron oxide NPs to be used in a wide range of medical infections.

20.
Environ Sci Pollut Res Int ; 19(3): 847-57, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21948144

RESUMO

PURPOSE: A former wood exploitation revealing high Cu and As concentration of the soils served as a case study for assisted phytoextraction. METHOD: P-spiked Linz-Donawitz (LD) slag was used as a soil additive to improve physico-chemical soil properties and in situ stabilize Cu and other trace metals in a sandy Cu-contaminated soil (630 mg kg⁻¹ soil). The LD slag was incorporated into the contaminated soil to consist four treatments: 0% (T1), 1% (T2), 2% (T3), and 4% (T4). A similar uncontaminated soil was used as a control (CTRL). After a 1-month reaction period, potted soils were used for a 2-week growth experiment with dwarf beans. RESULTS: Soil pH increased with the incorporation rate of LD slag. Similarly the soil electrical conductivity (EC, in millisiemens per centimetre) is ameliorated. Bean plants grown on the untreated soil (T1) showed a high phytotoxicity. All incorporation rates of LD slag increased the root and shoot dry weight yields compared to the T1. The foliar Ca concentration of beans was enhanced for all LD slag-amended soil, while the foliar Mg, K, and P concentrations were not increased. Foliar Cu, Zn, and Cr concentrations of beans decreased with the LD slag incorporation rate. CONCLUSIONS: P-spiked LD slag incorporation into polluted soil allow the bean growth and foliar Ca concentration, but also to reduce foliar Cu concentration below its upper critical value avoiding an excessive soil EC and Zn deficiency. This dual effect can be of interest for soil remediation at larger scale.


Assuntos
Cobre/química , Fertilizantes/análise , Resíduos Industriais/análise , Fosfatos/química , Poluentes do Solo/química , Solo/química , Oligoelementos/química , Cálcio/análise , Fenômenos Químicos , Cromo/análise , Cobre/análise , Condutividade Elétrica , Recuperação e Remediação Ambiental/métodos , Concentração de Íons de Hidrogênio , Metalurgia , Phaseolus/química , Phaseolus/crescimento & desenvolvimento , Fosfatos/análise , Raízes de Plantas/química , Raízes de Plantas/crescimento & desenvolvimento , Brotos de Planta/química , Brotos de Planta/crescimento & desenvolvimento , Poluentes do Solo/análise , Solubilidade , Espectrometria por Raios X , Oligoelementos/análise , Zinco/análise
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