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1.
Sci Total Environ ; 690: 1151-1161, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470478

RESUMO

Shooting activities is an important source of Pb in contaminated soils. Lead accumulates in superficial soil horizons because of its low mobility, favouring its uptake by plants and representing a high transference risk to the trophic chain. A combination of phytoremediation with nanoremediation techniques can be used to recover firing range soils and decrease the mobility, bioavailability and toxicity of Pb. This study examines in depth the changes in Pb behaviour in firing range soils by adding hydroxyapatite nanoparticles (HANPs). These nanoparticles (NPs) may immobilise Pb and improve the quality of these areas. The use of HANPs and the Pb effects were assessed in three different species (Sinapis alba L., Lactuca sativa L. and Festuca ovina L.), focusing on their germination and early growth, through phytotoxicity assays. Single extractions with CaCl2 (0.01 M) in soils treated with HANPs show that these NPs retained Pb and reduced highly its availability and mobility. HR-TEM and TOF-SIMS were used to determine the interactions between HANPs and Pb, as well as with soil components. According to TOF-SIMS and HR-TEM/EDS analysis, Pb was mainly retained by HANPs but also associated lightly to organic matter, Fe compounds and silicates. Phytotoxicity assays exposed that S. alba, L. sativa and F. ovina were able to germinate and develop in the firing range soils despite the high available Pb contents before adding HANPs. After adding HANPs, Pb retention increased, favouring the germination and the growth of roots in the three species. These results suggest that HANPs can be used to decrease the availability and the toxicity of Pb without negative effects in the species growth. Accordingly, the combination of phytoremediation and nanoremediation techniques can be a great tool to stabilise these soils, avoiding the Pb transfer to nearby areas and its entry in the trophic chain.


Assuntos
Durapatita/química , Recuperação e Remediação Ambiental/métodos , Chumbo/toxicidade , Nanopartículas/química , Plantas/efeitos dos fármacos , Poluentes do Solo/toxicidade , Bioensaio , Solo , Armas
2.
Chemosphere ; 235: 1081-1088, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561298

RESUMO

A bench-scale apparatus was used for the low-temperature thermal desorption (LTTD) treatment of oil-based drill cuttings (OBDCs). The effects of treatment temperature, treatment duration, sand/OBDCs mixing ratio, and initial oil content on the LTTD treatment performance were investigated. It was found that the petroleum hydrocarbons (PHCs) were barely left in the high-oil-content drill cuttings after LTTD (at 300 °C for 20 min), and thus the overall soil health was improved. The desorption kinetics models of PHCs under various conditions were established, and it was found that the LTTD of OBDCs followed nonlinear least-squares exponential kinetics (adjusted R2 > 0.9). The energy consumption models of LTTD treatment under different temperatures were also developed. The modeling results are of practical guiding significance and useful for designing effective LTTD treatment systems of OBDCs.


Assuntos
Recuperação e Remediação Ambiental/métodos , Hidrocarbonetos/isolamento & purificação , Modelos Teóricos , Petróleo , Adsorção , Temperatura Baixa , Cinética , Poluentes do Solo/análise , Temperatura Ambiente
3.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2837-2844, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418210

RESUMO

As a conventional technology, the ecological floating bed has been widely used to repair waste water body. However, it can only repair the surface oxygen-enriched water, and has limited ability to repair the lower anoxic water. To meet the needs of the restoration of black and odorous water body, we designed a submersible ecological media box (submerged group) and compared it with traditional ecological floating bed (floating bed group). Water quality of black and odorous water before and after the restoration was examined, with the growth status of aquatic plants and the accumulation ability of N and P being investigated. The results showed that with the prolongation of repairing time, the removal rate of each pollutant increased gradually in both treatments. The removal ability of the submerged group for TN, NH4+-N, TP was better than that of the floating bed group, but its ability to remove CODMn was slightly inferior than that of the floating bed group. Plants (Vallisneria natans) in the submerged group grew better than that in the floating bed group (Acorus cala-mus), with similar patterns of the absorption and accumulation capacity and removal rate of TN and TP. In addition, the plasma membrane permeability and malondialdehyde content of V. natans were lower than that of A. calamus and the chlorophyll content of A. calamus was higher than that of V. natans, indicating that V. natans is more suitable for planting in black and odorous water bodies. Thus, the submersible ecological media box is a new in-situ integrated remediation device, which is more suitable to repair the black and odorous water.


Assuntos
Recuperação e Remediação Ambiental/métodos , Hydrocharitaceae , Poluição da Água , Animais , Biodegradação Ambiental , Ecologia , Camundongos , Nitrogênio , Fósforo , Água
4.
Environ Monit Assess ; 191(9): 566, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31418123

RESUMO

Mercury (Hg) is a pollutant that poses a global threat, and it was listed as one of the ten leading 'chemicals of concern' by the World Health Organization in 2017. The review aims to summarize the sources of Hg, its combined effects on the ecosystem, and its remediation in the environment. The flow of Hg from coal to fly ash (FA), soil, and plants has become a serious concern. Hg chemically binds to sulphur-containing components in coal during coal formation. Coal combustion in thermal power plants is the major anthropogenic source of Hg in the environment. Hg is taken up by plant roots from contaminated soil and transferred to the stem and aerial parts. Through bioaccumulation in the plant system, Hg moves into the food chain, resulting in potential health and ecological risks. The world average Hg concentrations reported in coal and FA are 0.01-1 and 0.62 mg/kg, respectively. The mass of Hg accumulated globally in the soil is estimated to be 250-1000 Gg. Several techniques have been applied to remove or minimize elevated levels of Hg from FA, soil, and water (soil washing, selective catalytic reduction, wet flue gas desulphurization, stabilization, adsorption, thermal treatment, electro-remediation, and phytoremediation). Adsorbents such as activated carbon and carbon nanotubes have been used for Hg removal. The application of phytoremediation techniques has been proven as a promising approach in the removal of Hg from contaminated soil. Plant species such as Brassica juncea are potential candidates for Hg removal from soil.


Assuntos
Poluentes Ambientais/análise , Poluentes Ambientais/toxicidade , Recuperação e Remediação Ambiental/métodos , Mercúrio/análise , Mercúrio/toxicidade , Biodegradação Ambiental , Carvão Mineral/análise , Cinza de Carvão/análise , Monitoramento Ambiental/métodos , Mostardeira/crescimento & desenvolvimento , Nanotubos de Carbono/química , Centrais Elétricas , Solo/química
5.
Environ Monit Assess ; 191(9): 542, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31385044

RESUMO

The river Ganges, the National Heritage, and the lifeline of millions of Indians, unfortunately, ranked the second most polluted rivers of the world in 2017. This review reveals the current trends of the water quality of the Ganges assessed around 36 stretches during 2012-2016, to indicate an improvement around 6 (16.7%), deterioration around 14 (38.9%), and non-significant changes around 16 (44.4%) stretches. An increase in dissolved oxygen and a decrease in biochemical oxygen demand were observed at six stretches (Devprayag [S5], Rishikesh upstream [S7], Varanasi upstream [S19], Mokama upstream [S25], Mokama downstream [S26], and Munger [S27]). The total and fecal coliform contamination decreased at seven stretches (Rudraprayag [S2 and S3], Devprayag [S5 and S6], Rishikesh [S7], Varanasi upstream [S19], and Munger [S27]) due to improved hygienic conditions, but it increased subsequently at eight stretches (Haridwar [S8], Kanpur [S15], Raibareili [S16], Prayagraj [S17 and S18], Patna [S24], Berhampore [S30], and Serampore [S31]) due to improper defecation and mass bathing during 2007-2016. Dissolved oxygen level declined significantly, and biochemical oxygen demand increased (> 3 ppm), alarmingly at places receiving heavy untreated sewage water. The water quality of the Ganges was good up to Rishikesh, because of an undisrupted flow of the uncontaminated water from the higher altitudes (≥ 372 m) with higher forest cover, lower temperatures (< 21 °C), and higher dissolved oxygen (≥ 8.5 ppm) and due to the dissolution of antipathogenic chemical constituents of the medicinal herbs, pollutant degrading alkaline phosphatase, and bacteriophages. The present review is a systematic collection of data on river pollution, its scientific analyses, and its relationship with 6Ps (namely population, poverty, pollution, precipitation, plantation, and periodicity). Not only that, but the river water restoration measures have also suggested through the novel interlinked water working groups for implementing integrated water management strategies.


Assuntos
Monitoramento Ambiental/métodos , Recuperação e Remediação Ambiental/métodos , Rios/química , Esgotos/análise , Poluição da Água/análise , Qualidade da Água , Bactérias Gram-Negativas/isolamento & purificação , Índia , Oxigênio/análise
6.
Sci Total Environ ; 689: 1037-1043, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31466144

RESUMO

Dissolved organic matter (DOM) elucidated from biochars enhances the dissolution of iron oxides and reduction of iron. However, given that reduction mechanism of iron (Fe(III)) in the practical biochar applications for soil amendment and environmental remediation have not been fully elucidated, this study laid great emphasis on the photo-induced Fe(II) liberated from DOM-Fe(III) complexes. Thus, pyrolysis of biomass was carried out at 300 °C to maximize DOM release from biochars. Moreover, three different biomass samples (rice straw (R), granular sludge (G) from an anaerobic digester, and spent coffee grounds (C)) were chosen as carbon substrates for biochars preparation. To demonstrate the transformation of Fe(III), 1 and 5 wt% biochar was applied to the clean (S1) and arsenic-contaminated (S2) soil with/without the light. The results indicate that the light condition produces more Fe(II). The amount of Fe(II) accounts for 25.3, 28.6, and 30.7% of total iron under the light with 5 wt% GB, RB, and CB in S1, and 10.6, 13.1, and 13.8% in S2. This study demonstrates that Fe(II) is generated more under ultraviolet irradiation than visible light and dark condition. In addition, a control experiment without biochar showed that DOM plays an important role in the reduction of Fe(III). The mobility of arsenic increased under the light condition since the intermediates of DOM photo-degradation accelerates the dissolution of iron oxides and arsenic competes with DOM for the adsorption. Therefore, there was no significant correlation between the elution of arsenic and the formation of Fe(II) during the reductive dissolution of iron oxide under the light condition.


Assuntos
Arsênico/análise , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/análise , Adsorção , Arsênico/química , Biomassa , Carbono , Carvão Vegetal/química , Compostos Férricos , Ferro/química , Oryza , Oxirredução , Solo/química , Poluentes do Solo/química
7.
Sci Total Environ ; 691: 1082-1088, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466190

RESUMO

The turmeric industry produces a huge amount of residues annually. After undergoing different extraction process, turmeric residue biomass may be transformed from waste to resource. Turmeric residues exhibit different characteristics suitable for various environmental applications. In this work, the adsorption of Cu(II) onto turmeric residues from microbial (TR-A) and chemical (TR-B) extraction was investigated. The characteristics of the residues were examined via Brunauer-Emmett-Teller analysis, thermogravimetric analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, and elemental analysis. Then, applications to Cu(II) immobilization were identified. Results suggested that although TR-B had better thermal stability, larger surface area, and more pores than TR-A, the adsorption capacity of Cu(II) onto TR-A was higher (13.12 mg/g) than that onto TR-B (7.37 mg/g) because TR-A had more microbial cell debris, metabolites, and S element than TR-B. In practice, TR-A-added soil achieved 40% more Cu immobilization than TR-B-added soil under continuous leaching of simulated acid rain. Consequently, the residues extracted using the microbial method prevented pollution after the traditional extraction process and transformed waste into a material for environmental remediation.


Assuntos
Cobre/química , Curcuma/química , Recuperação e Remediação Ambiental/métodos , Adsorção , Fracionamento Químico , Cinética , Espectroscopia de Infravermelho com Transformada de Fourier
8.
Environ Monit Assess ; 191(9): 590, 2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31444645

RESUMO

Organic sediment contaminants [polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), and polycyclic aromatic hydrocarbons (PAHs)] were assessed using secondary monitoring data from a former tidal estuary (Boat Harbour) impacted by historical industrial effluents. Spatiotemporal characterization of PCDD/Fs and PAHs in sediments was conducted to inform a sediment remediation program designed to return this contaminated aquatic site back to a tidal lagoon. Spatiotemporal variations of sediment PCDD/F and PAH concentrations across Boat Harbour and off-site reference locations were assessed using secondary monitoring data collected between 1992 and 2015. Sediment PCDD/F toxic equivalency (TEQ) and PAH concentrations were compared to sediment quality guidelines. Sediment PCDD/F concentrations exceeded the highest effect thresholds posing severe ecological health risks. High sediment PCDD/F concentrations have persisted in Boat Harbour despite implementation of Pulp and Paper Mill Effluent Chlorinated Dioxins and Furans Regulations in 1992. PAH concentrations varied greatly. Five individual PAH compounds frequently exceeded severe effect thresholds, in contrast to total PAHs, which were below severe effect thresholds. Forensic analysis using PAH diagnostic ratios suggests pyrogenic PAHs derived from wood processes or coal combustion were likely sources. Twenty-five years of monitoring data revealed large data gaps in our understanding of sediment characteristics in Boat Harbour. Gaps included spatial (vertical and horizontal) and temporal variations, presenting challenges for remediation to accurately delineate sediment contaminants. Deeper horizons were poorly characterized compared to shallow sediments (0-15 cm). Historical secondary monitoring data showed that spatial coverage across Boat Harbour was inadequate. Due to severe ecological health risks associated with high sediment PCDD/F concentrations, remediation of the entire sediment inventory is recommended. Detailed vertical and horizontal sampling within Boat Harbour, establishment of local baseline concentrations, and additional sampling in down-gradient-receiving environments for a suite of contaminants are required to better characterize sediments prior to remediation.


Assuntos
Benzofuranos/análise , Dibenzofuranos Policlorados/análise , Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos/química , Dibenzodioxinas Policloradas/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Monitoramento Ambiental
9.
Bull Environ Contam Toxicol ; 103(3): 484-489, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31399772

RESUMO

Burning of wheat and rice straw on field, after crop harvest, is a quick, cheap and an easy way for land clearing. The ashes generated after burning are mixed with soils and due to their alkaline nature, they may affect the degradation of applied herbicides. Therefore, present paper reports degradation of sulfosulfuron in aqueous suspension of the wheat (WSA) and rice (RSA) straw ashes. The results suggested that both ashes significantly enhanced sulfosulfuron dissipation in water and effect was more with the RSA. The solution pH affected sulfosulfuron dissipation and in control buffers (no ash) herbicide degradation followed the order: acidic > alkaline > neutral. Addition of the RSA significantly increased sulfosulfuron degradation in buffers, but effect was more evident at neutral and alkaline pH. The study has relevance in assessing degradation of sulfosulfuron in soils where crop residues are burned for land clearing.


Assuntos
Recuperação e Remediação Ambiental/métodos , Oryza/química , Pirimidinas/química , Poluentes do Solo/química , Sulfonamidas/química , Triticum/química , Herbicidas/química , Concentração de Íons de Hidrogênio , Suspensões
10.
Curr Microbiol ; 76(10): 1199-1206, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31278425

RESUMO

The formation of acid mine drainage (AMD), which results from the oxidation of sulfur minerals by air and water, can be accelerated by acidophilic and chemolithotrophic bacteria such as Acidithiobacillus ferrooxidans. Our previous study revealed that walnut shell powder and its phenolic component inhibit the growth of A. ferrooxidans. However, their inhibitory effect on AMD formation in the environment needs verification. We established a bioleaching system to test whether walnut shell powder and its phenolic component can limit AMD formation. Our results showed that lignin and cellulose isolated from walnut shell decreased metal ion concentrations through absorption, whereas the phenolic component increased pH by downregulating the expression of Fe2+-oxidizing genes and rus operon genes of A. ferrooxidans. Only walnut shell powder showed an excellent ability to curb AMD by binding metal ions and increasing the pH value. On probing deeper into the alteration of the bacterial community structure in the bioleaching system, we found that the bacterial community became more diverse-the amount of A. ferrooxidans decreased and that of some non-acidophilic bacteria increased. The bacterial community in samples treated with walnut shell powder or its phenolic component had low abundance in the pathways of metabolism and energy production, as determined by phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt). In other words, preponderant microbes, mainly A. ferrooxidans, lacked energy to grow well in the treated samples. Our findings provide a practical applicability of walnut shell powder to reduce leaching from a complex environmental community.


Assuntos
Ácidos/química , Poluentes Ambientais/química , Recuperação e Remediação Ambiental/métodos , Juglans/química , Microbiota , Mineração , Acidithiobacillus/genética , Acidithiobacillus/crescimento & desenvolvimento , Bactérias/classificação , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Concentração de Íons de Hidrogênio , Metais/química , Microbiota/genética , Fenóis/química , Enxofre/química
11.
Environ Pollut ; 253: 365-376, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31325881

RESUMO

Enormous research interest is devoted to fabricating three-dimensional graphene-based gels (3D GBGs) toward improved conversion of solar energy by virtue of the intrinsic properties of single graphene and 3D porous structure characteristics. Here, this concise minireview is primarily focused on the recent progress on applications of 3D GBGs, including aerogels and hydrogels, in photocatalytic degradation of pollutants from water and air, such as organic pollutants, heavy metal ions, bacteria and gaseous pollutants. In particular, the preponderances of 3D GBG photocatalysts for environmental pollutants degradation have been elaborated. Furthermore, in addition to discussing opportunities offered by 3D GBG composite photocatalysts, we also describe the existing problems and the future direction of 3D GBG materials in this burgeoning research area. It is hoped that this review could spur multidisciplinary research interest for advancing the rational utilization of 3D GBGs for practical applications in environmental remediation.


Assuntos
Poluentes Ambientais/química , Recuperação e Remediação Ambiental/métodos , Grafite/química , Gases , Géis , Metais Pesados , Energia Solar , Luz Solar , Água/química
12.
Environ Pollut ; 253: 625-635, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31330354

RESUMO

The potential of electrokinetic (EK) remediation to remove from soils one particular group of contaminants - contaminants of emergent concern (CECs), remains largely overlooked. The present study aimed to evaluate the efficiency of the EK process for the remediation of an agricultural clay soil containing CECs. The soil was spiked with four CECs - sulfamethoxazole, ibuprofen, triclosan and caffeine - and their status (i.e. residual amounts and spatial distribution) evaluated at the seventh day of EK treatment at a defined current intensity, directionality and duration of void period. The characterization of the soil physicochemical properties was also undertaken. The results showed similar degradation trends in all applied EK strategies, which were suchlike to that of the natural attenuation (biotic control): sulfamethoxazole > ibuprofen ≥ triclosan ≥ caffeine. The removal of the CECs was higher under a 10 mA constant current application than in the natural attenuation (up to 2.8 times higher; from 13 to 85%). Caffeine was the exception with its best removal efficiency being achieved when the ON/OFF switch mode with a void period duration of 12 h was used (36%). The use of electro-polarization reversal mode did not favour the remediation. The soil pH variations resulting from EK application were determinant for triclosan remediation, which increased with soil pH increase. The only EK condition that promoted the removal of all CECs was the ON/OFF switch mode of 12 h (removals between 36 and 72%), in which only minor physicochemical disturbances of the soil were observed. This is in accordance with a potential application of EK in-situ. The last is reinforced by the low estimated electrical cost of the best EK technology - 2.33 €/m3 for the 7 days. Overall the EK remediation processes are a promising technology to stimulate in situ the removal of CECs from agricultural soils.


Assuntos
Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/química , Solo/química , Argila , Eletricidade , Técnicas Eletroquímicas , Poluentes do Solo/análise
13.
Ecotoxicol Environ Saf ; 182: 109472, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31352210

RESUMO

In present study, reductive graphene oxide and silver nanoparticles co-comodified TiO2 nanotube arrays were prepared, and which was investigated to degrade tetrabromobisphenol A. The arrays co-modified with silver nanoparticles and reductive graphene oxide prepared by electrodeposition method exhibited good photoelectrocatalytic degradative activity for tetrabromobisphenol A, and the degradation efficiency reached 99.6% within 80 min. The synergistic effect of high photoresponse of Ag nanoparticles with their high capture ability for photogenerated electrons and the extended wavelength absorption range of reductive graphene oxide resulted in the highest degradation efficiencies. Degradation is postulated to follow a stepwise reductive debromination mechanism.


Assuntos
Recuperação e Remediação Ambiental/métodos , Grafite/química , Nanotubos/química , Bifenil Polibromatos/análise , Prata/química , Luz Solar , Titânio/química , Catálise , Eletrodos , Oxirredução , Fotólise , Bifenil Polibromatos/efeitos da radiação
14.
Ecotoxicol Environ Saf ; 182: 109470, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31352212

RESUMO

In the past few years, polyhalogenated carbazoles (PHCZs) have been of increasing concern because their structure is similar to that of legacy POPs. In the present study, an analytical method, including intensive cleanup and fractionation procedures in combination with instrumental parameters, was developed to determine ultratrace polyhalogenated carbazoles (PHCZs) in soil and sediment. The eluting sorbents, volume and packing of the column were optimized. Our results showed that 5 g of florisil and 4 g of silica gel under 150 mL of hexane/DCM = 3:1 presented good performance in terms of recovery and repeatability. GC-HRMS, GC-MS/MS (EI-MRM) and GC-MS (EI-SIM) were applied to compare the performance of PHCZ analysis. For sensitivity, EI-MRM presents method detection limits comparable to those of GC-HRMS and much lower than those of EI-SIM. Regarding selectivity, GC-HRMS performed better than the other two techniques since GC-HRMS can reduce interference from perfluorokerosene (PFK) and DDX (DDT, DDE, and DDD) due to its high resolution. GC-HRMS was then further optimized by shortening the run time and modifying the SIM ion. The final method was successfully applied to determine PHCZs in soil and sediment, and the target compounds had almost 100% detection frequency in the samples. The ubiquitous presence of PHCZ in soil and sediment calls for a further investigation of its source, distribution and degradation in the environment.


Assuntos
Carbazóis/análise , Recuperação e Remediação Ambiental/métodos , Sedimentos Geológicos/química , Hidrocarbonetos Halogenados/análise , Poluentes do Solo/análise , Solo/química , Cromatografia Gasosa-Espectrometria de Massas , Hexanos/química , Limite de Detecção , Silicatos de Magnésio/química , Dióxido de Silício/química , Espectrometria de Massas em Tandem
15.
Environ Monit Assess ; 191(8): 519, 2019 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-31359137

RESUMO

One of the most important factors considered in leaching salt-affected soils is reducing the amount of water and leaching time particularly when magnetizing water is used. In this study, soil column experiments were conducted to assess the rate of salt removal and estimate the amount of water required for leaching in order to reduce salinity (EC) to ≤ 4 dS m-1 and sodicity (ESP) to < 10. Soil samples with EC = 216 dS m-1 and ESP = 82 were taken from Basrah City, Iraq, for the conduction of laboratory experiments, and these samples were subjected to magnetized water (MW) with magnetic fields of 1, 3, 5, 7, and 9; different exposure time; and constant flow velocity. Experimental results were compared with the results of control soil columns leached with non-magnetized water (NMW), and the comparison shows that the leaching times for MW with magnetic fields of 9, 7, 5, 3, and 1 were less by 17.3%, 10.8%, 8.9%, 7.6%, and 3.9%, respectively. Also, less amount of MW was required for leaching, but when field magnetic was 9, the amount was increased by 20%. Predicted values of EC and ESP obtained from the proposed equations were found in agreement with experimental results.


Assuntos
Recuperação e Remediação Ambiental/métodos , Campos Magnéticos , Poluentes do Solo/análise , Solo/química , Água/química , Iraque , Modelos Teóricos , Salinidade
16.
Sci Total Environ ; 688: 818-826, 2019 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-31255820

RESUMO

Cd contamination in agricultural soils threatens the safety of agricultural products and poses human health risk via food chain. However, the remediation of Cd polluted alkaline soils has not drawn the public concern, and the corresponding efficient amendments that can reduce Cd accumulation in crop grains are relatively few. In current study, mercapto-modified attapulgite (MA in abbreviation) was selected as the amendment to conduct winter wheat (Triticum aestivum L.) cultivation pot experiment to investigate the effect of MA on Cd accumulation in winter wheat and Cd bioavailability in alkaline soil. MA had no adverse impact on the normal growth of winter wheat but could inhibit Cd accumulation in wheat grain of both cultivars grown in alkaline soil with a maximum reduction of 75%, while pH-regulating amendment sepiolite had no reduction effect. In the term of soil chemistry, MA could decrease the zeta potential of soil particles and enhance the sorption amount of Cd on soil particles, resulted in the increase of Fe-Mn-oxides bounded Cd fraction in alkaline soil. The enhanced sorption effect combined with complexation effect of MA itself, made the exchangeable and bioavailable Cd concentrations in the soil decrease. In the term of plant uptake, MA could inhibit the uptake of Cd via roots from the soil, and hinder Cd transfer from roots to grains. MA had environmental friendliness and capability in the aspect of soil pH, effective cation exchange capacity and available micronutrients in the soil. The high performance of MA in inhabitation of Cd in winter wheat revealed that it was an efficient immobilization agent with great application potential for Cd-polluted alkaline soil.


Assuntos
Cádmio/metabolismo , Recuperação e Remediação Ambiental/métodos , Compostos de Magnésio , Compostos de Silício , Poluentes do Solo/metabolismo , Triticum/metabolismo , Solo/química
17.
Ecotoxicol Environ Saf ; 182: 109432, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31306919

RESUMO

Vegetation cover can be used in the phytomanagement of polluted areas by adding value to abandoned sites and reducing the dispersion of pollutants by erosion. Appropriate amendments, that allow both efficient plant growth and the immobilization of contaminants in the soil must be chosen in order to optimize the efficiency of this process. We used a mining technosol mainly contaminated by arsenic (1068 mg kg-1) and lead (23387 mg kg-1) to study the effect of three amendments (biochar, compost and iron grit) on (i) physico-chemical properties of the soil and soil pore water, (ii) metal(loid) mobility, bioavailability and bioaccessibility (CaCl2 and Simple Bioaccessibility Extraction Test (SBET)), and (iii) the capability of Trifolium repens to germinate and grow. All the amendments used increased the pH and electrical conductivity of the SPW, resulting in a 90% decrease in the concentration of lead in the soil pore water (SPW). We also demonstrated a decrease in Pb phytoavailability. The amendments allowed the establishment of a plant cover, although the addition of iron grit alone did not allow any clover germination. For the Pontgibaud technosol, the combination of the three amendments resulted in a significant decrease in As and Pb concentrations in clover tissues, mainly in the aerial organs. The amendments also made it possible for some of them to halve the phytoavailable fraction of arsenic. However, for compost, both the As concentrations in the SPW, and the bioavailable fraction of As increased. All the amendments used had contrasting effects on the bioaccessible fractions of metal(loid)s. The most efficient amendment combination was the addition of 5% biochar and 5% compost.


Assuntos
Arsênico/química , Carvão Vegetal/química , Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Trifolium/química , Compostagem , Ferro/química , Mineração , Solo/química , Poluentes do Solo/análise
18.
Chemosphere ; 233: 890-895, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340416

RESUMO

The reduction of halocarbons by NADH models and NADH under ambient conditions is reported as a new type of reactivity pointing towards a hitherto unknown disruptive pathway for NADH/NADPH-dependent processes. The reaction was studied with the omnipresent pesticide DDT, the inhalation anesthetic halothane, and several simple halocarbons. The halide-hydride exchange represents a biochemical equivalent for the reduction of halocarbons by traditional synthetic reagents like silanes (R3Si-H) and stannanes (R3Sn-H). High precision thermochemical calculations (CBS-QB3) reveal the carbon-hydrogen bond dissociation energy of NADH (70.8 kcal·mol-1) to be lower than that of stannane (SnH4: 78.1 kcal·mol-1), approaching that of the elusive plumbane (PbH4: 68.9 kcal·mol-1). The ready synthetic accessibility of NADH models, their low carbon-hydrogen bond dissociation energy, and their dehalogenation activity in the presence of air and moisture recommend these compounds as substitutes for the air-sensitive or toxic metal hydrides currently employed in synthesis.


Assuntos
DDT/metabolismo , Poluentes Ambientais/metabolismo , Recuperação e Remediação Ambiental/métodos , Halotano/metabolismo , Hidrocarbonetos Halogenados/análise , Hidrocarbonetos Halogenados/metabolismo , NAD/metabolismo , Carbono/química , Hidrogênio/química , Ligações de Hidrogênio , Indicadores e Reagentes , Silanos/química , Compostos de Estanho/química
19.
Chemosphere ; 233: 913-919, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340419

RESUMO

Thermal desorption has been widely employed to treat soils contaminated with chlorinated organics. The off-gas of thermal desorption must be treated to avoid secondary pollution. In this study, the treatment of DDTs in thermal desorption off-gas by pulsed corona discharge plasma was investigated. The effects of important operation parameters, including energy density, gas temperature, humidity, and O2 content, on DDTs degradation were investigated. The main degradation products were also studied. The DDTs degradation efficiency increased with the increase in energy density, gas temperature, and O2 content. The degradation efficiency of DDTs was achieved to 84.6% when the initial concentration, energy density, and gas flow rate were 2.0 mg/m3, 17.8 J/L, and 3.0 L/min, respectively. Maximum DDTs degradation efficiency was observed when the gas was at 5% relative humidity. The main degradation products identified were DM, phenol, benzene, acetic acid, and formic acid. It was calculated that 87% of chlorine in the degraded DDTs was converted into chloride ion.


Assuntos
DDT/metabolismo , Poluição Ambiental/análise , Recuperação e Remediação Ambiental/métodos , Gases em Plasma/química , Poluentes do Solo/análise , Solo/química , Cloro/química , Umidade , Temperatura Ambiente
20.
Environ Pollut ; 252(Pt B): 1464-1475, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31265957

RESUMO

In this study, a proposed integrated high-gravity technology for air pollution control, CO2 capture, and alkaline waste utilization was comprehensively evaluated from engineering, environmental, and economic perspectives. After high-gravity technology and coal fly ash (CFA) leaching processes were integrated, flue gas air emissions removal (e.g., sulfate dioxide (SO2), nitrogen oxides (NOx), total suspended particulates (TSP)) and CO2 capture were studied. The CFA, which contains calcium oxide and thus, had high alkalinity, was used as an absorbent in removing air pollution residues. To elucidate the availability of technology for pilot-scale high-gravity processes, the engineering performance, environmental impact, and economic cost were simultaneously investigated. The results indicated that the maximal CO2, SO2, NOx, and TSP removal efficiencies of 96.3 ±â€¯2.1%, 99.4 ±â€¯0.3%, 95.9 ±â€¯2.1%, and 83.4 ±â€¯2.6% were respectively achieved. Moreover, a 112 kWh/t-CO2 energy consumption for a high-gravity process was evaluated, with capture capacities of 510 kg CO2 and 0.468 kg NOx per day. In addition, the fresh, water-treated, acid-treated, and carbonated CFA was utilized as supplementary cementitious materials in the blended cement mortar. The workability, durability, and compressive strength of 5% carbonated CFA blended into cement mortar showed superior performance, i.e., 53 MPa ±2.5 MPa at 56 days. Furthermore, a higher engineering performance with a lower environmental impact and lower economic cost could potentially be evaluated to determine the best available operating condition of the high-gravity process for air pollution reduction, CO2 capture, and waste utilization.


Assuntos
Poluentes Atmosféricos/química , Poluição do Ar/prevenção & controle , Compostos de Cálcio/química , Dióxido de Carbono/química , Recuperação e Remediação Ambiental/métodos , Gravitação , Óxidos/química , Carbonatos/química , Carvão Mineral/análise , Cinza de Carvão/química , Óxidos de Nitrogênio
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