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1.
J Hazard Mater ; 423(Pt B): 127235, 2022 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-34844353

RESUMO

In this study, two-compartment membrane electrochemical remediation (MER) based on the anode process and the cathode process strategies were compared for treating a multi metal -contaminated soil. Remediation effect, as well as energy consumption and risk evaluation of the two strategies under different current density conditions of electroplating-contaminated soil suspension were performed, the following conclusions were drawn. MERs based on both the anode and cathode processes exhibited a synergetic effect because the DC electric field and extractants dissolved more metals from the soil phase into the liquid phase of the suspension compared to a usual soil washing treatment. The maximum Cr, Cu, and Ni removal efficiencies of MERs based on the anode process were 79.5%, 86.2%, and 85.0%, respectively, compared to 27.5%, 72.5%, and 65.9% based on the cathode process. Risk assessment results showed lower soil environmental risk after MER based on the cathode process than after MER based on the anode process. In this study, MER based on the cathode process as an evolving soil remediation strategy was found to present high simultaneous remediation ability for soil heavy metals and leaching materials, showing its advantages of environmental friendliness and economic effectiveness.


Assuntos
Recuperação e Remediação Ambiental , Metais Pesados , Poluentes do Solo , Eletrodos , Galvanoplastia , Metais Pesados/análise , Solo , Poluentes do Solo/análise
2.
Materials (Basel) ; 14(17)2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34501089

RESUMO

In order to solve the shortcomings of the traditional curing agent in the treatment of composite heavy-metal-contaminated soil with the solidification and stabilization method, a new type of cementing material A was used as a curing agent, and the Pb, Cd, Cu composite heavy-metal-contaminated soil was artificially prepared to carry out an experimental study on solidification and stabilization (SS) restoration by the mechanical properties test, leaching performance test, and microscopic test. The results show that in the range of test dosage, with the increase in the curing agent content, the unconfined compressive strength of the solidified body increased, and the resistance to deformation was enhanced. From the perspective of leaching characteristics, the new curing agent A had an excellent curing effect on the composite heavy-metal-contaminated soil. To achieve safe disposal, a curing agent content of 10% applies only for the soil heavily contaminated by heavy metals. The curing agent A could significantly reduce the content of acid-extractable heavy metals after solidifying the heavy metal Pb, Cd, and Cu composite contaminated soil and effectively converted it into a residue state. The solidified phase contained hydrated products such as calcium silicate hydrate (CSH) and ettringite (AFt). These hydrated products can inhibit the leaching performance of heavy metal ions through adsorption, encapsulation, and ion exchange. The study provides a feasible method and reference for the solidification, restoration, and resource utilization of heavy-metal-contaminated soil in the subgrade.

3.
Artigo em Inglês | MEDLINE | ID: mdl-34299808

RESUMO

The pollution of heavy metals in soil is a problem of great concern to international scholars today. This research investigates the current research activities in the field of soil heavy metal pollution remediation and discusses the current areas of research focus and development trends. We conducted a bibliometric analysis of the literature on soil heavy metal pollution remediation from 1999 to 2020. CiteSpace and Vosviewer were used to conduct document co-citation and cluster analyses on the collected data. The research was mainly carried out based on the following factors: chronological distribution, country and institution distribution, source journal analysis, keyword co-occurrence analysis, and reference co-citation analysis. China (2173, 28.64%) and the United States (946, 12.47%) are the top two countries in terms of the number of articles published, and Environmental Science and Pollution Research (384, 5.06%) and Science of the Total Environment (345, 4.55%) published the most articles. The Chinese Academy of Science (485) is the organization that has contributed the most to the total number of publications. Furthermore, based on a keyword co-word analysis with Vosviewer and CitesSpace, it was concluded that the applications of phytoremediation and biochar in the remediation of heavy metals in soil are current research hotspots. Additionally, future research should focus on repair mechanisms, the development of new repair technology and joint repair systems.


Assuntos
Recuperação e Remediação Ambiental , Metais Pesados , Poluentes do Solo , Bibliometria , Biodegradação Ambiental , Metais Pesados/análise , Solo , Poluentes do Solo/análise
4.
Chemosphere ; 275: 129984, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33984900

RESUMO

Soil contamination by heavy metals constitutes a serious global environmental problem, and numerous remediation technologies have been developed. In this study, a novel soil remediation agent, namely composite hydrogel (leftover rice-g-poly(acrylic acid)/montmorillonite/Urea, LR-g-PAA/MMT/urea), was prepared based on free radical polymerization cross-linking technology. Experimental results indicated that the LR-g-PAA/MMT/urea dosage increased from 0% to 10%, the oxidizable state proportions of Cd, Cu, Pb and Zn in contaminated soil increased from 8.3%, 23.7%, 54.0% and 11.4%-71.3%, 61.0%, 76.5%, and 27.9%, respectively. Compared with control experiment, the residue state growth rate were 56.6%, 23.4% and 39.8% for Cu, Pb and Zn respectively with 10% dosage of composite hydrogel. Simultaneously, the LR-g-PAA/MMT/urea was also seen to enhance soil fertility, including organic matter content, cation exchange capacity, and N and P contents. Pot experiments for biological toxicity suggested that the addition of hydrogel weakened the toxic effect of heavy metals on cotton seeds, and the action effect was increasingly visible with the increase of hydrogel dosage. The analysis of the mechanism involved suggested that the organic matter and its possessed characteristic functional groups could weaken the biological toxicity via complexation, adsorption, and ion exchange. Overall, the synthesized composite hydrogel exhibits great potential for the simultaneous remediation and fertility improvement of heavy metal contaminated soil.


Assuntos
Recuperação e Remediação Ambiental , Metais Pesados , Eliminação de Resíduos , Poluentes do Solo , Alimentos , Hidrogéis , Metais Pesados/análise , Solo , Poluentes do Solo/análise
5.
Braz. J. Biol. ; 81(2): 398-405, Mar.-May 2021. tab, graf, ilus
Artigo em Inglês | VETINDEX, VETINDEX | ID: vti-762746

RESUMO

Continuous occurrence of heavy metals is a major cause of environmental pollution due to its toxic effects. At minimum concentrations, these metals are highly reactive and can gather in the food chains and food web, causing major dangers to public health concerns. Soil samples were collected from Paharang drain, Faisalabad. Cadmium tolerant bacteria were isolated and evaluated for their MIC against Cd. The isolated bacterial strain GCFSD01 showed MIC value upto 30 mM/L. The bacterial strain with the highest resistance against Cd was selected for further study. Molecular characterization of bacterial isolate GCFSD01 was performed by 16S rRNA which confirmed it as Bacillus cereus. Optimum growth conditions of bacterial strain were also evaluated. Strain GCFSD01 showed optimum growth at pH 7 and 37 °C temperature. Our result revealed that B. cereus strain GCFSD01 reduced 61.3% Cd after 48 hrs. Multiple metal tolerance and Cd reduction by B. cereus indicate its potential for further use for decontamination of polluted soil.(AU)


A ocorrência contínua de metais pesados é uma das principais causas de poluição ambiental devido aos seus efeitos tóxicos. A contaminação por metais pesados representa um grande risco para todas as formas de vida encontradas no meio ambiente. Em concentrações mínimas, esses metais são altamente reativos e podem se acumular nas cadeias alimentares e na cadeia alimentar, causando grandes perigos às preocupações com a saúde pública. Amostras de solo foram coletadas no esgoto de Paharang, Faisalabad. Bactérias tolerantes ao cádmio foram isoladas da amostra coletada pelo método da placa de ágar. As colônias separadas individuais selecionadas foram avaliadas quanto às suas concentrações inibitórias mínimas contra Cd. A cepa bacteriana isolada GCFSD01 apresentou valores de CIM de 30 mM/L. A colônia bacteriana que apresentou maior resistência contra o Cd foi selecionada para identificação. Após seleção da maior colônia bacteriana resistente ao Cd, coloração de Gram e diferentes testes bioquímicos foram realizados para a caracterização da bactéria isolada. A caracterização molecular do isolado bacteriano GCFSD01 foi realizada por PCR 16S rRNA confirmando a presença de Bacillus cereus. Após a identificação molecular, as condições ótimas de crescimento da cepa bacteriana também foram verificadas. A cepa GCFSD01 apresentou crescimento ótimo em pH 7 e temperatura de 37 °C. Nosso resultado revelou que a cepa de B. cereus GCFSD01 reduziu 61,3% de Cd após 48 horas. A tolerância a múltiplos metais e a redução de Cd por B. cereus indicam seu potencial para uso posterior na descontaminação do solo poluído.(AU)


Assuntos
Bacillus cereus/efeitos dos fármacos , Bacillus cereus/isolamento & purificação , Intoxicação por Cádmio , Análise do Solo
6.
Ecotoxicol Environ Saf ; 215: 112159, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33799133

RESUMO

Biochar (BC) combined with humic acid (HA) and wood vinegar (WV) was designed and prepared as an inexpensive, effective, and environmentally friendly immobilization material (BHW) for metal-polluted soil. The influences of the wood vinegar and humic acid on the immobilization properties and adsorption mechanism of this new material were also investigated. The remediation performance was evaluated using a laboratory-made, nickel-contaminated soil with a Ni2+ concentration of 200 mg per kg surface soil (top 20 cm from agricultural land). The results indicated that the immobilization ratio sequence of nickel (II) in the soil was BC< BH< BHW. The maximum adsorption capacity increased in the same order: BC< BH< BHW. All three adsorption isotherms were better fitted by the Freundlich model, which were consistent with the surface heterogeneity of the remediation materials. The cause of this surface heterogeneous migration may be due to the increase in oxygen-containing groups in the BC introduced by the HA and WV. The WV can increase the number of the oxygen-containing groups in the BC combined with HA, which enhanced the adsorption and immobilization of Ni2+ ions. The results suggested that BHW is recommended for the remediation of metal-contaminated soils, because of its high efficacy, economic feasibility, environmental and food safety.


Assuntos
Carvão Vegetal/química , Níquel/química , Poluentes do Solo/química , Ácido Acético , Adsorção , Agricultura , Poluição Ambiental , Substâncias Húmicas , Metanol , Solo , Poluentes do Solo/análise
7.
J Hazard Mater ; 409: 125022, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33421873

RESUMO

Biochar added to the soil is generally difficult to separate. In order to solve the problem of separating biochar from soil, this paper applies a hydraulic silicate gel material to the preparation of biochar. Non-magnetic silicate bonded biochar (SBC) and magnetic silicate bonded biochar (MSBC) with hydraulic properties were prepared. The new silicate bonded biochar has good adsorption performance, separation and recovery characteristics. The findings are as follows: (1) after three times of soil remediation, the silicate bonded biochar still had good mechanical properties, and the compressive strength was not attenuated, remaining between 210 and 270 N. (2) After three times of SBC and MSBC remediation, total Cd in soil decreased by 29.33% and 31.82% respectively, and available Cd decreased by 60.82% and 62.74% respectively. (3) After three cycles, the recovery rates of SBC and MSBC both exceeded 94.88%, and the highest adsorption regeneration rates of SBC and MSBC reached 83.09% and 92.06%, respectively. (4) The Cd content of wheat after SBC and MSBC repair was reduced by 29.67-37.36% and 47.25-63.74%, respectively.

8.
Braz. j. biol ; 81(2): 398-405, 2021. tab, graf, ilus
Artigo em Inglês | MEDLINE, LILACS, VETINDEX | ID: biblio-1153348

RESUMO

Continuous occurrence of heavy metals is a major cause of environmental pollution due to its toxic effects. At minimum concentrations, these metals are highly reactive and can gather in the food chains and food web, causing major dangers to public health concerns. Soil samples were collected from Paharang drain, Faisalabad. Cadmium tolerant bacteria were isolated and evaluated for their MIC against Cd. The isolated bacterial strain GCFSD01 showed MIC value upto 30 mM/L. The bacterial strain with the highest resistance against Cd was selected for further study. Molecular characterization of bacterial isolate GCFSD01 was performed by 16S rRNA which confirmed it as Bacillus cereus. Optimum growth conditions of bacterial strain were also evaluated. Strain GCFSD01 showed optimum growth at pH 7 and 37 °C temperature. Our result revealed that B. cereus strain GCFSD01 reduced 61.3% Cd after 48 hrs. Multiple metal tolerance and Cd reduction by B. cereus indicate its potential for further use for decontamination of polluted soil.


A ocorrência contínua de metais pesados é uma das principais causas de poluição ambiental devido aos seus efeitos tóxicos. A contaminação por metais pesados representa um grande risco para todas as formas de vida encontradas no meio ambiente. Em concentrações mínimas, esses metais são altamente reativos e podem se acumular nas cadeias alimentares e na cadeia alimentar, causando grandes perigos às preocupações com a saúde pública. Amostras de solo foram coletadas no esgoto de Paharang, Faisalabad. Bactérias tolerantes ao cádmio foram isoladas da amostra coletada pelo método da placa de ágar. As colônias separadas individuais selecionadas foram avaliadas quanto às suas concentrações inibitórias mínimas contra Cd. A cepa bacteriana isolada GCFSD01 apresentou valores de CIM de 30 mM/L. A colônia bacteriana que apresentou maior resistência contra o Cd foi selecionada para identificação. Após seleção da maior colônia bacteriana resistente ao Cd, coloração de Gram e diferentes testes bioquímicos foram realizados para a caracterização da bactéria isolada. A caracterização molecular do isolado bacteriano GCFSD01 foi realizada por PCR 16S rRNA confirmando a presença de Bacillus cereus. Após a identificação molecular, as condições ótimas de crescimento da cepa bacteriana também foram verificadas. A cepa GCFSD01 apresentou crescimento ótimo em pH 7 e temperatura de 37 °C. Nosso resultado revelou que a cepa de B. cereus GCFSD01 reduziu 61,3% de Cd após 48 horas. A tolerância a múltiplos metais e a redução de Cd por B. cereus indicam seu potencial para uso posterior na descontaminação do solo poluído.


Assuntos
Poluentes do Solo/toxicidade , Bacillus cereus/genética , Cádmio/toxicidade , Efluentes Industriais/efeitos adversos , Metais Pesados/análise , Solo , Microbiologia do Solo , Biodegradação Ambiental , RNA Ribossômico 16S/genética
9.
Biology (Basel) ; 9(9)2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32972004

RESUMO

Use of plant growth-promoting bacteria (PGPB) for cultivation of the biofuel crop Miscanthus × giganteus (Mxg) in post-military and post-mining sites is a promising approach for the bioremediation of soils contaminated by metals. In the present study, PGPB were isolated from contaminated soil and screened for tolerance against abiotic stresses caused by salinity, pH, temperature, and lead (Pb). Selected strains were further assessed and screened for plant growth-promoting attributes. The isolate showing the most potential, Bacillus altitudinis KP-14, was tested for enhancement of Mxg growth in contaminated soil under greenhouse conditions. It was found to be highly tolerant to diverse abiotic stresses, exhibiting tolerance to salinity (0-15%), pH (4-8), temperature (4-50 °C), and Pb (up to 1200 ppm). The association of B. altitudinis KP-14 with Mxg resulted in a significant (p ≤ 0.001) impact on biomass enhancement: the total shoot and dry root weights were significantly enhanced by 77.7% and 55.5%, respectively. The significant enhancement of Mxg biomass parameters by application of B. altitudinis KP-14 strongly supports the use of this strain as a biofertilizer for the improvement of plant growth in metal-contaminated soils.

10.
Ecotoxicol Environ Saf ; 206: 111189, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32858328

RESUMO

In this study, a highly effective combined biochar and metal-immobilizing bacteria (Bacillus megaterium H3 and Serratia liquefaciens CL-1) (BHC) was characterized for its effects on solution Pb and Cd immobilization and edible tissue biomass and Pb and Cd accumulation in Chinese cabbages and radishes and the mechanisms involved in metal-polluted soils. In the metal-containing solution treated with BHC, the Pb and Cd concentrations decreased, while the pH and cell numbers of strains H3 and CL-1 increased over time. BHC significantly increased the edible tissue dry weight by 17-34% and reduced the edible tissue Pb (0.32-0.46 mg kg-1) and Cd (0.16 mg kg-1) contents of the vegetables by 24-45%. In the vegetable rhizosphere soils, BHC significantly decreased the acid-soluble Pb (1.81-2.21 mg kg-1) and Cd (0.40-0.48 mg kg-1) contents by 26-47% and increased the reducible Pb (18.2-18.8 mg kg-1) and Cd (0.38-0.39 mg kg-1) contents by 10-111%; while BHC also significantly increased the pH, urease activity by 115-169%, amorphous Fe oxides content by 12-19%, and relative abundance of gene copy numbers of Fe- and Mn-oxidising Leptothrix species by 28-73% compared with the controls. These results suggested that BHC decreased edible tissue metal uptake of the vegetables by increasing pH, urease activity, amorphous Fe oxides, and Leptothrix species abundance in polluted soil. These results may provide an effective and eco-friendly way for metal remediation and reducing metal uptake in vegetables by using combined biochar and metal-immobilizing bacteria in polluted soils.


Assuntos
Carvão Vegetal/química , Compostos Férricos/análise , Leptothrix/crescimento & desenvolvimento , Metais Pesados/análise , Serratia liquefaciens/crescimento & desenvolvimento , Poluentes do Solo/análise , Verduras/química , Cádmio/análise , Chumbo/análise , Leptothrix/genética , Leptothrix/metabolismo , Metais Pesados/metabolismo , Rizosfera , Solo/química , Microbiologia do Solo , Poluentes do Solo/metabolismo , Verduras/metabolismo
11.
Environ Geochem Health ; 42(6): 1589-1600, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31776888

RESUMO

Biochar prepared from waste biomass was evaluated as a soil amendment to immobilize metals in two contaminated soils. A 60-day incubation experiment was set up on a French technosol which was heavily contaminated with Pb due to former mining activities. Grass biochar, cow manure biochar (CMB) and two lightwood biochars differing in particle size distribution (LWB1 and LWB2) were amended to the soil at a rate of 2% (by mass). Rhizon soil moisture samplers were employed to assess the Pb concentrations in the soil solution at regular times. After 30 days of incubation, soil solution concentrations in the CMB-amended soil decreased by more than 99% compared to the control. CMB was also applied to a moderately contaminated Flemish soil and resulted in lowered soil solution Cd and Zn concentrations. While the application of 4% CMB resulted in 90% and 80% reductions in soil solution concentrations of Cd and Zn, respectively, the solid fraction of digestate (as a reference) reduced the soil pore water concentrations by only 63% for Cd and 73% for Zn, compared to the concentrations in the control. These results emphasize the potential of biochar to immobilize metals in soil and water systems, thus reducing their phytotoxicity.


Assuntos
Cádmio/química , Carvão Vegetal/química , Chumbo/química , Poluentes do Solo/química , Zinco/química , Animais , Bélgica , Biomassa , Bovinos , Recuperação e Remediação Ambiental/métodos , França , Esterco , Mineração , Areia , Solo
12.
Environ Geochem Health ; 42(8): 2399-2411, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31587160

RESUMO

Soil contamination by heavy metals and metalloids is a serious problem which needs to be addressed. There are several methods for removal of contaminants, but they are costly, while the method of phytoremediation is eco-friendly and cost-effective. Pteridophytes have been found to remediate heavy metal-contaminated soil. Pteridophytes are non-flowering plant that reproduces by spores. Pteris vittata has been reported as the first fern plant to hyperaccumulate arsenic. The Pteris species belongs to the order Pteridales. Other ferns that are known phytoremediators are, for example, Nephrolepis cordifolia and Hypolepis muelleri (identified as phytostabilisers of Cu, Pb, Zn and Ni); similarly Pteris umbrosa and Pteris cretica accumulate arsenic in leaves. So, pteridophytes have a number of species that accumulate contaminants. Many of them have been identified, while various other are being explored. The present review article describes the phytoremediation potential of pteridophytes plants and suggests as a potential asset for phytoremediation programs.


Assuntos
Recuperação e Remediação Ambiental/métodos , Gleiquênias/fisiologia , Poluentes do Solo/farmacocinética , Arsênio/farmacocinética , Biodegradação Ambiental , Transporte Biológico/efeitos dos fármacos , Gleiquênias/efeitos dos fármacos , Herbivoria , Metais Pesados/farmacocinética , Pteris/efeitos dos fármacos , Pteris/fisiologia , Poluentes do Solo/análise
13.
Artigo em Inglês | VETINDEXEXPRESS, VETINDEX | ID: vti-746049

RESUMO

Abstract Continuous occurrence of heavy metals is a major cause of environmental pollution due to its toxic effects. At minimum concentrations, these metals are highly reactive and can gather in the food chains and food web, causing major dangers to public health concerns. Soil samples were collected from Paharang drain, Faisalabad. Cadmium tolerant bacteria were isolated and evaluated for their MIC against Cd. The isolated bacterial strain GCFSD01 showed MIC value upto 30 mM/L. The bacterial strain with the highest resistance against Cd was selected for further study. Molecular characterization of bacterial isolate GCFSD01 was performed by 16S rRNA which confirmed it as Bacillus cereus. Optimum growth conditions of bacterial strain were also evaluated. Strain GCFSD01 showed optimum growth at pH 7 and 37 °C temperature. Our result revealed that B. cereus strain GCFSD01 reduced 61.3% Cd after 48 hrs. Multiple metal tolerance and Cd reduction by B. cereus indicate its potential for further use for decontamination of polluted soil.


Resumo A ocorrência contínua de metais pesados é uma das principais causas de poluição ambiental devido aos seus efeitos tóxicos. A contaminação por metais pesados representa um grande risco para todas as formas de vida encontradas no meio ambiente. Em concentrações mínimas, esses metais são altamente reativos e podem se acumular nas cadeias alimentares e na cadeia alimentar, causando grandes perigos às preocupações com a saúde pública. Amostras de solo foram coletadas no esgoto de Paharang, Faisalabad. Bactérias tolerantes ao cádmio foram isoladas da amostra coletada pelo método da placa de ágar. As colônias separadas individuais selecionadas foram avaliadas quanto às suas concentrações inibitórias mínimas contra Cd. A cepa bacteriana isolada GCFSD01 apresentou valores de CIM de 30 mM/L. A colônia bacteriana que apresentou maior resistência contra o Cd foi selecionada para identificação. Após seleção da maior colônia bacteriana resistente ao Cd, coloração de Gram e diferentes testes bioquímicos foram realizados para a caracterização da bactéria isolada. A caracterização molecular do isolado bacteriano GCFSD01 foi realizada por PCR 16S rRNA confirmando a presença de Bacillus cereus. Após a identificação molecular, as condições ótimas de crescimento da cepa bacteriana também foram verificadas. A cepa GCFSD01 apresentou crescimento ótimo em pH 7 e temperatura de 37 °C. Nosso resultado revelou que a cepa de B. cereus GCFSD01 reduziu 61,3% de Cd após 48 horas. A tolerância a múltiplos metais e a redução de Cd por B. cereus indicam seu potencial para uso posterior na descontaminação do solo poluído.

14.
Environ Sci Pollut Res Int ; 26(29): 30206-30219, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31422534

RESUMO

Solidification/stabilization technique has been widely adopted to remediate the heavy metal-contaminated sites. In the present work, the strength and leaching characteristics of the contaminated soils solidified/stabilized by cement/fly ash were systemically investigated. Electrical resistivity was also measured to establish empirical relationships for assessment of remediation efficacy. Tests results showed that the unconfined compressive strength increased and the leached ion concentration decreased with increasing curing time. In contrast, the unconfined compressive strength decreased and the leached ion concentration increased with increasing initial heavy metal ion concentration in the specimen. For the strength characteristic, the most notable detrimental effect was induced by Cr3+ and the least was induced by Pb2+. For the leaching characteristic, the trend was reversed. The electrical resistivity of the tested specimen increased significantly with increasing curing time and with decreasing initial ion concentration. The electrical resistivity of the Pb-contaminated specimen was higher than that of the Zn-contaminated specimen, which in turn was higher than that of the Cr-contaminated specimen. Empirical relationships between the strength, leaching characteristic, and electrical resistivity were established, which could be adopted to assess the remediation efficacy of heavy metal-contaminated soil solidified/stabilized by cement/fly ash.


Assuntos
Cinza de Carvão/química , Materiais de Construção , Recuperação e Remediação Ambiental/métodos , Metais Pesados/análise , Poluentes do Solo/análise , Solo/química , Força Compressiva
15.
Sci Total Environ ; 687: 790-799, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31412482

RESUMO

Understanding the mechanisms on how water management can minimize the concentrations of heavy metals in rice grains is important. Two water managements were concerned in our studies, including continuously flooding and alternate wetting and drying (AWD). Compared to AWD, a continuously flooded culture reduces the concentration of cadmium and other metals in the rice grains by reducing the root-to-shoot translocation and the availability of metals in rhizosphere. In a flooded environment, the rice rhizosphere was characterized by an increased soil pH, reduced fluorescein diacetate (FDA) activity, and lower metal bioavailability. In addition, flooding significantly decreased the iron plaque on the root surface and reduced the affinity for metals in rhizosphere. Water managements significantly changed soil microbial diversity, especially the proportion of anaerobic bacteria, including the iron-reducing bacteria Latescibacteria, Desulfuromonadales, and Geobacteraceae. Interestingly, these bacteria exhibited a significant correlation with cadmium that was adsorbed on the root. This study revealed that continuously flooded culture is a valuable strategy for minimizing heavy metal accumulation in rice grains. By increasing the abundance of unique bacterial community, iron plaque formation and the affinity of metals in rhizosphere were reduced, and the uptake and accumulation of heavy metals in rice plants was finally mitigated.


Assuntos
Conservação dos Recursos Hídricos/métodos , Metais Pesados/metabolismo , Oryza/metabolismo , Poluentes do Solo/metabolismo , Microbiologia do Solo
16.
Ecotoxicol Environ Saf ; 182: 109459, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31344591

RESUMO

The utilization of forages grown on metal-contaminated soil can increase the risk of heavy metals entering the food chain and affecting human health because of elevated toxic metal concentrations. Meanwhile, hydrogen sulfide (H2S) and nitric oxide (NO) as signaling molecules are known to promote plant growth in metal-contaminated soils. However, the regulatory mechanisms of such molecules in plant physiology and soil biochemistry have not been well-documented. Hence, we investigate the role of the exogenous application of H2S and NO on alfalfa growth in lead/cadmium (Pb/Cd)-contaminated soil. Our results indicate that the signaling molecules increase the alfalfa chlorophyll and biomass content and improve alfalfa growth. Further, H2S and NO reduce the translocation and bioconcentration factors of Pb and Cd, potentially reducing the risk of heavy metals entering the food chain. These signaling molecules reduce metal-induced oxidative damage to alfalfa by mitigating reactive oxygen species accumulation and increasing antioxidant enzyme activities. Their exogenous application increases soil enzymatic activities, particularly of catalase and polyphenol oxidase, without significantly changing the composition and structure of rhizosphere bacterial communities. Interestingly, H2S addition enriches the abundance of plant-growth-promoting rhizobacteria in soil, including Nocardioides, Rhizobium, and Glycomyces. H2S is more effective than NO in improving alfalfa growth and reducing heavy-metal contamination of the food chain. These results provide new insights into the exogenous application of signaling molecules in alleviating metal-induced phytotoxicity, including an efficient strategy for the safe use of forages.


Assuntos
Cádmio/análise , Sulfeto de Hidrogênio/farmacologia , Chumbo/análise , Medicago sativa/efeitos dos fármacos , Óxido Nítrico/farmacologia , Poluentes do Solo/análise , Irrigação Agrícola , Biomassa , Cádmio/toxicidade , Fumigação , Sulfeto de Hidrogênio/administração & dosagem , Chumbo/toxicidade , Medicago sativa/química , Medicago sativa/crescimento & desenvolvimento , Microbiota/efeitos dos fármacos , Óxido Nítrico/administração & dosagem , Poluentes do Solo/toxicidade
17.
Sci Total Environ ; 688: 299-311, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31229826

RESUMO

Aquatic ecosystem contaminated with hazardous pollutants has become a high priority global concern leading to serious economic and environmental damage. Among various treatment approaches, carbon nanostructured materials have received particular interest as a novel platform for emerging pollutants removal owing to their unique chemical and electrical properties, biocompatibility, high scalability, and infinite functionalization possibility with an array of inorganic nanomaterials and bio-molecules. Within this framework, carbon nanotubes (CNTs) are widely used due to their hollow and layered structure and availability of large specific surface area for the incoming contaminants. Carbon nanotubes can be used either as single-walled, multi-walled, or functionalized nanoconstructs. TiO2/SiO2-functionalized CNTs are among the most promising heterogeneous photocatalytic candidates for the degradation of a range of organic compounds, heavy metals reduction, and selective oxidative reactions. Herein, we reviewed recent development in the application of TiO2 and SiO2 functionalized nanostructured carbon materials as potential environmental candidates. After a brief overview of synthesis and properties of CNTs, we explicitly discussed the potential applications of TiO2/SiO2 functionalized CNTs for the remediation of a variety of environmentally-related pollutants of high concern, including synthetic dyes or dye-based hazardous waste effluents, as polycyclic aromatic hydrocarbons (PAHs), pharmaceutically active compounds, pesticides, toxic heavy elements, remediation of metal-contaminated soil, and miscellaneous organic contaminants. The work is wrapped up by giving information on current challenges and recommended guidelines about future research in the field bearing in mind the conclusions of the current review.

18.
Front Microbiol ; 10: 2694, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31920998

RESUMO

Biochar shapes the soil environment and plant growth. Nevertheless, the mechanisms associated with an improved plant biomass and soil microbiome in low metal-contaminated soils are still unclear. In this study, the influence of biochar on soil physico-chemical properties, plant performance, and rhizosphere microbiota in durum wheat was investigated at the above- and belowground levels. Two kinds of biochar from different feedstocks (wood chips and wheat straw pellets) and two Italian durum wheat varieties, Duilio and Marco Aurelio, were analyzed in a greenhouse using a low-nutrient gleyic fluvisol containing a very small amount of Pb and Zn. Four different treatments were performed: soil-only control (C), soil amended with woody biochar equilibrated with nutrient solution (B1+) and non-activated (B1-), and soil amended with non-activated (B2-) wheat straw biochar. Seven weeks after seed germination, (1) the physico-chemical properties of soil, biochars, and mixtures were assessed; (2) the fresh and dry weight of aboveground plant tissues and roots and other morphometric traits were measured; and (3) metabarcoding of the 16S rRNA bacterial gene was performed on rhizosphere soil samples. The results showed that the biochar from wheat straw had stronger impact on both durum varieties, with higher electrical conductivity, higher levels of available K and Na, and a substantial increase of dissolved Na+, K+, and Cl- ions in pore water. Generally, biochar amendment decreased Zn availability for the plants. In addition, biochar improved plant growth in the early growth stage, and the more positive effect was achieved by combining wheat straw biochar with Marco Aurelio. Rhizosphere bacterial microbiota showed variation in alpha diversity only due to treatment; on the other hand, the differential analysis showed consistent variation among samples with significant effects on amplicon sequence variant (ASV) abundance due to the specific biochar treatment as well as the genotype. The pure B1-, due to its scarce nutrient content with respect to the richer types (B1+ and B2-), had a negative impact on microbiota richness. Our study highlights that an appropriate combination of biochar feedstock and crop species may lead to superior yield.

19.
Environ Pollut ; 244: 431-439, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30359925

RESUMO

Farmland soil heavy metal contamination could pose potential risks to ecosystems, food safety and human health ultimately. Regional researches on the long-term monitoring of heavy metals in a soil-rice grain system, changed with environmental policy adjustment, have been hindered by limited detailed data. In this study, we collected 169 paired paddy rice grain and corresponding soil samples from a former intensive electronic-waste dismantling region to survey the current status of heavy metal contamination, and to reveal the temporal trends over the past decade based on the previous data obtained in 2006 and 2011. Moderate contaminations of Cd, Cu, Zn and Ni were observed in soil currently. Furthermore, 20.7% of rice grain samples exceeded the Cd threshold value. Cd, Cu, Zn and Pb shared the similar spatial distribution pattern with higher concentrations in northwest, which were contrary to Cr, Ni and As. Risk assessment indicated that much attention is required for the carcinogenic risk of Cr, Cd and As and non-carcinogen risk of Cr. Combining the spatial distribution of heavy metals in soil and rice grains, and the potential ecological risks, with the human health risks, the middle-west rice paddies were identified and proposed as priority areas. Percentage of soil Pb, Cd and Zn decreased in most area and slightly increased in northwest and east. Cu decreased in southwest and increased in central part, while Ni slightly increased in the whole region between 2006 and 2016. With the scrutiny of strict environmental policy, Cd still remained relatively constant levels in soil and rice grains during the last decade, which confirmed that the heavy metals were persisted over the long duration. Target sustainable and ongoing green remediation methods should be adopted urgently in specific area to guarantee food safety and human health for local residents.


Assuntos
Grão Comestível/química , Resíduo Eletrônico/análise , Monitoramento Ambiental , Poluição Ambiental/análise , Inocuidade dos Alimentos , Metais Pesados/análise , Oryza/química , Poluentes do Solo/análise , Cádmio/análise , China , Cobre/análise , Qualidade dos Alimentos , Humanos , Chumbo/análise , Níquel/análise , Medição de Risco , Solo/química , Zinco/análise
20.
Ecotoxicol Environ Saf ; 161: 526-533, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-29929128

RESUMO

In this study, metal-tolerant bacteria Serratia liquefaciens CL-1 and Bacillus thuringiensis X30 were compared for their Cd and Pb immobilization in solution and impacts on biomass and Cd and Pb uptake in a radish in metal-contaminated soils under field conditions. Strains CL-1 and X30 significantly reduced water-soluble Cd and Pb concentrations (45-67%) and increased the pH in solution compared to the controls. These strains significantly increased the biomass (25-99%) and decreased edible tissue Cd and Pb uptake in the radish (37-81%) and DTPA-extractable Cd and Pb contents (18-44%) of the rhizosphere soil compared to the un-inoculated controls. Strain CL-1 had higher potential to reduce edible tissue Cd and Pb uptake in the radish and DTPA-extractable Cd content than strain X30. Also, these strains significantly increased Cd translocation factor and strain CL-1 also significantly increased Pb translocation factor of the radish. Furthermore, strain CL-1 significantly increased the ratio of small soil aggregates (< 0.25 mm and 0.25-0.50 mm) of the rhizosphere soil. The results showed that these strains reduced the edible tissue Cd and Pb uptake through decreasing Cd and Pb availability in the soil and increasing Cd or Pb translocation from the roots to the leaves of the radish. The results also suggested the bacteria-related differences in reduced heavy metal uptake in the radish and the mechanisms involved under field conditions.


Assuntos
Bacillus thuringiensis/metabolismo , Metais Pesados/análise , Raphanus/metabolismo , Serratia liquefaciens/metabolismo , Microbiologia do Solo , Poluentes do Solo/análise , Biomassa , Metais Pesados/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raphanus/crescimento & desenvolvimento , Rizosfera , Solo/química , Poluentes do Solo/metabolismo
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