Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 55
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Environ Manage ; 308: 114619, 2022 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-35121459

RESUMO

The risk of arsenic (As) contamination from gold mining is a long-term environmental concern for mines worldwide. Researchers have mainly focused on As contamination induced by tailings, however, less attention has been paid mineralogically to differentiate the fate of As among different As-bearing matrices. This paper presents a detailed study of the mineralogical and morphological features of three typical As-bearing matrices (waste rock, ores, and tailings) using bulk chemical, microscopic and spectroscopic analyses, and reveals the geochemical behavior of As in those matrices. Results from mineral composition identified by RoqSCAN revealed that the matrices were dominated by quartz, k-feldspar, albite, muscovite, and clay minerals, with subordinate ankerite, chlorite, smectite, hematite, arsenopyrite, pyrrhotite, apatite, pyrite, halite, and calcite. The sequential extraction scheme indicated that As in waste rock, ores and tailings was mainly hosted in arsenopyrite. Microscopic analysis observed that waste rock was significantly different from the ores and tailings in terms of mineralogical and morphological characteristics. For waste rock, from arsenopyrite to hematite, As content decreased from 46.12 wt% to 3.54 wt%. However, arsenopyrite presented as unweathered euhedral crystals or slight fragmentation in ores and tailings and a narrower oxidation rims than that of waste rock. The leaching test of SPLP showed that the highest As leaching was found in waste rock (0.246 mg/L) which was significantly higher than those in ores (0.080 mg/L) and tailings (0.148 mg/L). The As in waste rock displayed weaker geochemical stability than in ores and tailings, as supported by mineralogy analysis. Health risk assessment suggested waste rock had a higher health risk for both adults and children compared with ores and tailings. These findings reaffirm that understanding of As fate among different source materials is paramount for securing humans from As hazards. More must be done to decelerate the continuous oxidation of waste rock, thus mitigating As release into nature.


Assuntos
Arsênio , Arsênio/análise , Criança , Monitoramento Ambiental/métodos , Ouro/análise , Humanos , Mineração
2.
J Hazard Mater ; 427: 128117, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-34974405

RESUMO

Conventional adsorbents for decontaminating arsenic exhibit low efficacy for the removal of arsenite (As(III)). This study aims to develop a robust As adsorbent from natural magnetite (M0) via a facile ball milling process, and evaluate their performance for decontaminating As(III) and As(V) in water and soil systems. The ball milling process decreased the particle size and crystallinity of M0, resulting in pronounced As removal by the ball-milled magnetite (Mm). Ball milling under air facilitated the formation of Fe-OH and Fe-COOH functional groups on Mm interface, contributing to effective elimination of As(III) and As(V) via hydrogen bonding and complexation mechanisms. Synergistic oxidation effects of hydroxyl and carboxyl groups, and reactive oxygen species (O2·-, and ·OH) on the transformation of As(III) to As(V) during the adsorption were proposed to explain the enhanced As(III) removal by Mm. A short-term soil incubation experiment indicated that the addition of Mm (10 wt%) induced a decrease in the concentration of exchangeable As by 30.25%, and facilitated the transformation of water-soluble As into residual fraction. Ball milling thus is considered as an eco-friendly (chemical-free) and inexpensive (scalable, one-stage process) method for upgrading the performance of natural magnetite towards remediating As, particularly for tackling the highly mobile As(III).


Assuntos
Arsênio , Poluentes Químicos da Água , Purificação da Água , Adsorção , Descontaminação , Óxido Ferroso-Férrico , Poluentes Químicos da Água/análise
3.
Chemosphere ; 287(Pt 2): 132113, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34826891

RESUMO

With rising concerns in the practical application of biochar for the remediation of environment influenced by various organic contaminants, a critical review to facilitate insights the crucial role that biochar has played in wastewater and polluted soil decontamination is urgently needed. This research therefore aimed to describe different intriguing dimensions of biochar interactions with organic contaminants, which including: (i) an introduction of biochar preparation and the related physicochemical properties, (ii) an overview of mechanisms and factors controlling the adsorption of organic contaminants onto biochar, and (iii) a summary of the challenges and an outlook of the further research needs in this issue. In the light of the survey consequences, the appearance of biochar indicates the potential in substituting the existing costly adsorbents, and it has been proved that biochar is one promising adsorbent for organic pollutants adsorption removal from water and soil. However, some research gaps, such as dynamic adsorption, potential environmental risks, interactions between biochar and soil microbes, novel modification techniques, need to be further investigated to facilitate its practical application. This research will be conductive to better understanding the adsorption removal of organic contaminants by biochar.


Assuntos
Carvão Vegetal , Poluentes do Solo , Adsorção , Solo , Poluentes do Solo/análise
4.
J Hazard Mater ; 424(Pt A): 127368, 2022 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-34879563

RESUMO

Ionic antibiotics and metals generally coexist, and their interaction can affect their sorption behaviors onto soil minerals, therefore determining their environmental hazards. This study investigated the sorption and cosorption of Zn(II) and chlortetracycline (CTC) onto montmorillonite at different solution pH (3-10) using batch experiments and extended X-ray absorption fine structure (EXAFS) analysis. The Langmuir model could reproduce well the sorption isotherms of Zn(II) and CTC. The presence of CTC/Zn(II) could promote the maximum sorption capacity (Qm) of Zn(II)/CTC, based on site energy distribution (SED) theory. Generally, Zn(II) sorption increased with pH increasing. Comparatively, CTC sorption decreased as pH increased till approximately pH 5.0, then increased continuously with pH increasing. Both CTC and Zn(II) co-existence enhanced their individual sorption in both acidic and neutral environments. The processes behind CTC and Zn(II) sorption mainly included cation exchange and surface complexation. The EXAFS data evidenced that the presence of CTC could alter the species of Zn(II) on montmorillonite via surface complexation at pH 4.5 and 7.5, with Zn-CTC complexes being the predominant species on montmorillonite at pH 7.5. At pH 9.5, Zn(II) may exist onto montmorillonite in precipitated form similar to Zn-Al hydrotalcite-like compound (HTlc) regardless of CTC presence.


Assuntos
Bentonita , Clortetraciclina , Adsorção , Concentração de Íons de Hidrogênio , Zinco
5.
J Hazard Mater ; 424(Pt A): 127371, 2022 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-34879565

RESUMO

Heterogeneity in sediment and aquifer is universal, resulting in preferential flows of injected materials in the high permeability regions and forming flow by-passed zones in the low permeability regions during in-situ subsurface remediation. This adverse effect can considerably delay the completion of remedial operations and significantly increase the cost. Column experiments were designed and conducted to study the transport of starch- and starch-xanthan gum modified Fe-Mn binary oxide particles (SFM and SXFM) in saturated heterogeneous porous media and to reveal the particles' arsenic (As) stabilization performance. Fine-in-Coarse (FIC) and Coarse-in-Fine (CIF) patterns of heterogeneous packings were set up in the columns. Testing results demonstrated that starch-xanthan gum dual treatment on Fe-Mn binary oxides successfully improved the particles' migration capability in heterogeneous porous media and their distribution uniformity attributed to the profound shear thinning behavior of xanthan gum solution. The addition of xanthan gum to the system increased the viscosity and shear thinning property of the SXFM suspension, making it a better candidate for delivery. Both SFM and SXFM stabilized As in heterogeneously packed sediment collected from a contaminated site, with SXFM showing better stabilization performance than SFM. The stabilization effects of SXFM were 90.7-97.0%, compared to 82.0-95.2% of SFM.


Assuntos
Arsênio , Água Subterrânea , Óxidos , Porosidade , Viscosidade
6.
J Environ Manage ; 300: 113679, 2021 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-34509816

RESUMO

Extensive mineral exploitation activities in history have aggravated potential toxic elements (PTEs) contamination in agricultural soils in China. Comprehensive ecological risk assessment is of great significance to orientate the restoration of contaminated soils, especially for those with high background values and multiple sources. The study area is located in the major rice producing area of China. Historically, there was a silver mine and a lead-zinc mine in the area, which were successively closed during the investigation. The intensive mining activities caused serious PTEs pollution in the agricultural soils around the mining area. In this study, five PTEs (As, Cd, Cr, Hg and Pb) selected to assessed the potential of geoaccumulation index in assessing agricultural soil potential risk assessment by identifying ecological risk sources. 315 of soil samples collected in 2009, 2014, 2018 were comprehensively analyzed by single pollution index evaluation (single factor index, geoaccumulation index), comprehensive evaluation (Nemerow index, potential ecological risk index) and trend analysis. Single factor index analysis showed that geoaccumulation index considered the impact of natural diagenesis of background values and human activities on the environment, ensuring high evaluation accuracy comparing to other methods used in typical complex agricultural soils. The modified potential ecological risk index revealed that the high background area did not represent high risk area, which was consistent with the implementation effect of governance measures. This study can provide important insights for policymakers and environmental engineers to quantitatively recognize the soil pollution and the effectiveness of governance based on applicable and reasonable evaluation methods.


Assuntos
Metais Pesados , Poluentes do Solo , China , Monitoramento Ambiental , Humanos , Metais Pesados/análise , Metais Pesados/toxicidade , Mineração , Medição de Risco , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
7.
J Hazard Mater ; 416: 125837, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492794

RESUMO

Paddy soils in southern China are heavily co-polluted by arsenic (As) and cadmium (Cd). The accumulation of these contaminants in rice grains may pose a high health risk. We evaluated the impact of adjusted water management practice (i.e., conventional irrigation and aerobic treatment after heading stage) and the application of two immobilization agents (i.e., CaO and Fe2O3) on the accumulation of As and Cd in rice grains of three rice varieties (i.e., Jinyou-463, Jinyou-268, and Mabayouzhan). The different schemes were tested via conducting a field experiment in paddy soil in Shaoguan, Guangdong Province, China. The results showed that the combined scheme (selecting Jinyou-268, aerobic water management after the heading stage, and 0.09% CaO and 0.5% Fe2O3 amendments) exhibited the best performance in the reduction of As and Cd accumulation in rice grains. This combined scheme decreased the grain As concentration by 26.19% and maintained the Cd at a low level (0.056 mg/kg) as compared to the use of local conventional irrigation patterns. Moreover, health risk assessment demonstrated that by applying the optimal scheme, neither As nor Cd content in rice had carcinogenic risk. However, the grain As remains at a high non-carcinogenic risk. We suggest that future field study design should fully incorporate the uncertainty of the natural environment to make the research conclusions more feasible for popularization and utilization. This study demonstrated an approach of utilizing the synergy effects of various measures for safe rice production in fields subjected to As and Cd contaminations.


Assuntos
Arsênio , Oryza , Poluentes do Solo , Arsênio/análise , Cádmio/análise , China , Solo , Poluentes do Solo/análise
8.
J Environ Manage ; 287: 112342, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-33740743

RESUMO

The production of 2,4,6-trinitrotoluene (TNT) produces a great deal of waste water, and dinitrotoluene sulfonates (DNTs) are the main pollutants in its waste. This paper presents a pilot investigation on the geochemical transformation of DNTs affected by historical wastewater spillage from a typical TNT production company in Northwest China. In the horizontal direction, DNTs diffused from the evaporation pond to the surrounding area of the site, and the concentration of DNTs in the evaporation pond surface soil exceeded 1000 mg/kg. The horizontal distribution of DNTs in the site showed a migration trend to the east and south of evaporation, which was consistent with the terrain of high northwest and low southeast of the site. Due to the high water solubility of pollutants, water flow is the main driving force for the horizontal distribution of DNTs. In the vertical direction, the concentration of pollutants gradually increased with the depth of the soil. DNTs are mainly adsorbed in the third layer (6.0-8.0 m). It can be seen that the accumulation of the 2,4-DNTs-3-SO3- is obviously larger than that of the 2,4-DNTs-5-SO3-, which may be related to the steric hindrance effect of sulfonic acid groups in the two isomers. Results showed DNTs distribution strongly linked to soil physicochemical properties and the migration of DNTs in soil exhibited obvious heterogeneity in time and space. The carcinogenic risks in surface soil (0-1.5 m) and lower soil (1.5-6.0 m, 6.0-8.0 m) are all higher than 1✕10-6; non-carcinogenic risk surface soil (0-1.5 m) is 4.011✕10, which is greater than 1, indicating that they may cause certain harm to the human body. Meanwhile, this study presented a pioneering investigation for the contamination and geochemical transfer of DNTs.


Assuntos
Poluentes do Solo , Trinitrotolueno , China , Dinitrobenzenos , Humanos , Medição de Risco , Solo , Poluentes do Solo/análise
9.
Environ Sci Pollut Res Int ; 28(14): 18050-18061, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33410055

RESUMO

Arsenic (As)-contaminated paddy soil could result in elevated levels of As in rice plants and sequentially harm human health. The Fe3O4-modified biochar (NBC-Fe) prepared by the coprecipitation method was applied in a pot experiment to investigate its effect on mobility and bioavailability of As in soil and to reduce As accumulation in rice tissues (brown rice, husks, spikelets, leaves, stems, and roots). Compared with non-application (CK), application of NBC-Fe significantly increased the cation exchange capacity (CEC), decreased As availability, and raised the As concentration of crystalline hydrous oxide-bound fraction in the soil. The addition of 0.05-1.6% (w/w) NBC-Fe significantly reduced the As concentrations in brown rice by 9.4-47.3%, which was lower than the level set by the National Food Safety Standards of China (0.2 mg/kg). The NBC-Fe treatment decreased As concentrations in iron plaque (DCB-As), and the DCB-As had the very significant correlations (P < 0.01) with the As concentrations in different rice tissues (brown rice, husks, spikelets, leaves, stems, and roots). The NBC-Fe immobilized As to decrease As availability in soil and increased the amount and thickness of iron plaque to sequester As on the surfaces of rice root. This study demonstrates that NBC-Fe is a promising soil amendment for the remediation of As-contaminated soil, therefore reducing As accumulation in rice plant and safety risks for rice consumption.


Assuntos
Arsênio , Oryza , Poluentes do Solo , Arsênio/análise , Cádmio/análise , Carvão Vegetal , China , Humanos , Raízes de Plantas/química , Solo , Poluentes do Solo/análise
10.
J Environ Manage ; 276: 111298, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32937235

RESUMO

The gradual increase of cadmium (Cd) in soils has caused environmental and health risk, and it's important to study the accumulation trend to evoke the awareness of farmland safety management. This research during the period of March in 2017-2018 evaluated the input (irrigation, atmospheric deposition, fertilizer and pesticide application) and the output (runoff and seepage, grain and straw uptake) of Cd in contaminated farmland irrigated with sewage water in Hebei Province. The experimental results indicated sewage irrigation (51.03%), and atmospheric deposition (46.35%) were the main input pathways; Grain uptake (42.72%) and straw removal (50.71%) played a major role in output fluxes. The input-output balance (net transport fluxes) of Cd in the farmland were estimated to be +3621.68 ~ +8899.78 mg·(ha·yr)-1 under different conditions (sewage irrigation with straw returning/straw removal, clean water irrigation with straw returning/straw removal), representing there was a Cd inputting in the farmland during the study. Even in the case of the lowest net transport fluxes, the annual increase of Cd concentration in soils reached to 0.0014 mg/kg. Therefore, it's necessary to take action that cutting off those pathway inputs into farmland ecosystems, such as monitoring the water quality of irrigation water sources, applying fertilizer and pesticide properly. Furthermore, attentions need to be paid to the Cd input into the farmland and environmental risks that may arise while returning straw to the field for improving soil fertility and crop production.


Assuntos
Poluentes do Solo , Solo , Agricultura , Cádmio/análise , China , Ecossistema , Monitoramento Ambiental , Esgotos , Poluentes do Solo/análise
11.
Sci Total Environ ; 707: 136064, 2020 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-31865092

RESUMO

Arsenic (As) is an environmentally hazardous contaminant and can be a serious threat to human health. In China, the remediation needs for a large number of As-contaminated sites renders a strong demand for efficient remedial reagents and cost-effective approaches. In this study, a novel starch-modified FeMn binary oxide (SFM), an amorphous colloidal material, has been synthesized as a remedial reagent and its As stabilization performance has been evaluated. A set of laboratory batch experiments were carried out with SFM of different dosages directly added into three contaminated soils to immobilize As. Results demonstrated that SFM could transform As in soil from non-specifically and specifically sorbed fractions to the more stable form bounded to amorphous iron hydrous oxides, thus reducing the As concentration in TCLP leachates by up to 93.2%. Results from adsorption tests and microscopic analysis indicated that the interactions between SFM and As are mainly controlled by adsorption, oxidation, and precipitation processes. SFM has abundant surface hydroxyl groups, with excellent adsorption properties for both As(V) and As(III), with the maximum adsorption capacities of 160.63 and 284.64 mg/g respectively at pH 7.0. The adsorption process closely fitted pseudo second-order kinetics and Freundlich isotherm model. SFM could increase soil Eh and oxidize As(III) to As(V), which facilitated the As stabilization in soil. Colloidal iron-based material directly used for stabilization in As contaminated soils is reported here for the first time. Starch modification improves both the reactivity and mobility of the stabilization agent in soil. Our findings propose an efficient and convenient reagent for As remediation in soil.

12.
Sci Total Environ ; 708: 135118, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31810666

RESUMO

Arsenic (As) is an environmentally hazardous contaminant which have a serious threat to human health. In recent years, sustainability has drawn increasing attention in the environmental remediation field. Application of natural minerals as a class of iron-containing materials for soil As remediation is meaningful and challenging. In this paper the As sorption ability and soil stabilization of mechanical activated limonite has been studied. Mechanical activation can effectively enhance the adsorption performance of natural limonite. The positive effect of mechanical activation on limonite mainly include: (1) particle size reduction and specific surface area increase; (2) reduction of limonite crystallinity and increase of surface active sites; (3) mineral phase transformation to amorphous iron oxides substances. The average grain size of limonite reduces from 16.8 µm to 0.214 µm after activation while the specific surface area increases from 10.26 m2/g to 56.74 m2/g. The maximum adsorption capacities of mechanically activated limonite (Lm) for As (III) and As (V) were 9.14 mg/g and 8.26 mg/g, respectively at pH 7.0, higher than untreated limonite (L0). Mechanically activated limonite can effectively stabilize As in soils. When Lm dosage was 10%, the stabilization effects could reach about 78%. Limonite could transform the soil As from non-specifically and specifically sorbed fraction to amorphous iron hydrous oxides bounded fractions. Mechanically activated limonite (Lm) exhibited good adsorption and stabilization performance advantages for As in soils.

13.
Environ Geochem Health ; 42(1): 241-253, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31177476

RESUMO

Benzene homologues often used as organic raw materials or as detergents in chemical industry are prone to accidental release into the environment which can cause serious long-term soil pollutions. In a large former herbicide factory site, we investigated 43 locations for benzene homologues contaminations in soil, soil gas, and groundwater and studied the hydrogeological conditions. An inverse distance weighted interpolation method was employed to determine the pollutants three-dimensional spatial distribution in the soils. Results showed that benzene homologues residues were mainly originated from the herbicide production workshop and that the pollution had horizontally expanded at the deeper soil layer. Contaminants had already migrated 15 m downward from ground surface. Contaminant phase distribution study showed that NAPL was the primary phase (> 99%) for the pollutants accumulated in the unsaturated zone, while it had not migrated to groundwater. The primary mechanism for contaminant transport and attenuation included dissolution of "occluded" NAPL into pore water and pollutant volatilization into soil pore space. Risk assessment revealed that the pollutants brought unacceptable high carcinogenic and non-carcinogenic risks to public health. In order to convert this former chemical processing factory site into a residential area, a remediation to the polluted production workshop sites is urgently required.


Assuntos
Derivados de Benzeno/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Poluentes Atmosféricos/análise , Derivados de Benzeno/toxicidade , Carcinógenos Ambientais/análise , Carcinógenos Ambientais/toxicidade , Indústria Química , Exposição Ambiental/efeitos adversos , Recuperação e Remediação Ambiental , Água Subterrânea/análise , Água Subterrânea/química , Herbicidas , Solo/química , Poluentes do Solo/toxicidade , Volatilização
14.
Huan Jing Ke Xue ; 40(11): 5090-5097, 2019 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854578

RESUMO

To explore the source and pollution characteristics of soil arsenic, mineralogy and chemical analysis methods were used to analyze the ore, waste rock, sediment, and river and soil samples around the mining area. Under a polarized light microscope, As-bearing mineral-arsenopyrite was found in the soil, ore, and waste rock around the Banbishan gold mine. Moreover, arsenopyrite in the waste rock has already experienced weathering and oxidation, and the oxidized arsenopyrite easily migrates and is released in the soil, which is potentially harmful. Because of the effect of mining transportation activities and indigenous smelting, arsenic was mainly distributed in the topsoil, at a depth of 0-20 cm, in the farmland on both sides of the road and in the places where villagers were gathered. The soil arsenic content in Xiaowulan Village and Gaozhangzi Village ranged from 7.2 to 196.2 mg·kg-1 and exceeded the rate of arsenic by 45.9% and 82.1%. According to the assessment by the RAC method, the farmland soil in Xiaowulan Village and Gaozhangzi Village were mainly at low to medium risk, although some soil points in Xiaowulan Village were at high risk. In general, the effects of the mining activities of the surrounding environment were not optimistic. As-bearing minerals in the oxidation of long-term weathering can cause much arsenic to be activated, which in turn, affects the local crops and long-term residents living around the mining area. It is suggested to carry out risk assessments for arsenic in the soil-crop-atmospheric-human system, and further study the conversion rules and mechanisms of arsenopyrite during weathering, to provide scientific guidance for the environmental protection of cultivated land.

15.
Huan Jing Ke Xue ; 40(8): 3785-3791, 2019 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854788

RESUMO

The mining and smelting of arsenic-containing metal minerals, and the large-scale use of chemicals and pesticides, has resulted in the widespread pollution of soils in southwestern and southern China. In this study, the stabilizing effect of Fe-Ce oxide (FC) on three representative arsenic-contaminated soils was evaluated. The microscopic adsorption characteristics of FC and As(Ⅴ) were explored by scanning electron microscopy and energy disperse spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that FC can significantly reduce arsenic concentrations by 84.1%-98.3% during the Toxicity Characteristic Leaching Procedure (TCLP), and showed strong pH adaptability in alkaline soil. It efficiently transformed (non-)specifically sorbed arsenic (F1+F2) into hydrous oxides phases of Fe and Al (F3+F4). FC also significantly reduced available P by 47.13%-60.32% in different types of soil. FC can not only release As(Ⅴ) adsorption sites occupied by P in soils, but also effectively prevents non-point source pollution of the surrounding water. SEM-EDS and XPS analysis detected Fe, Ce, and As on the surface of As(Ⅴ) adsorption products, and As was mainly adsorbed on the surface of Fe atoms. The results of this study provide a scientific basis for soil arsenic stabilization in China.

16.
Huan Jing Ke Xue ; 40(9): 4072-4080, 2019 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854870

RESUMO

Natural iron-containing minerals present in the geosphere in the form of crystalline minerals can be used as adsorption material for removal of arsenic from wastewater and remediation of arsenic-contaminated soils. In this paper, the adsorption and desorption of arsenic onto different iron-containing materials including hematite, limonite, siderite, ilmenite, magnetite, Fe2O3, Fe3O4, and Fe-Mn binary oxide (FMBO) were studied in laboratory experiments. The mechanism of arsenic adsorption was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). The results showed that arsenic adsorption is fitted by pseudo-second-order kinetics and the Langmuir isotherm model for almost all adsorbents, suggesting monolayer adsorption of arsenic onto the minerals. The sorption efficiency and capacity of arsenic by FMBO are much higher than those of other materials. Furthermore, limonite has high sorption efficiencies for both As(Ⅲ) and As(Ⅴ) among the natural iron-containing minerals, and their adsorption capacities are 3.96 mg·g-1 and 2.99 mg·g-1, respectively. The XRD results showed that natural limonite contains a large number of weak crystalline mineral components such as goethite, which can provide relatively abundant arsenic adsorption sites. Thus, limonite appears to be the most suitable natural mineral for arsenic adsorption.

17.
Sci Total Environ ; 667: 691-700, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30849609

RESUMO

Bioremediation of organic pollutants has been identified as an economically efficient and environmentally friendly method. Here, a pot experiment was conducted to evaluate the bioremediation efficiency of dibutyl phthalate (DBP) by Gordonia phthalatica sp. nov. QH-11 in agricultural soils, along with the effect of this exogenous organism on the native microbial community and ecosystem functions during the bioremediation process. The results showed that inoculation with strain QH-11 accelerated DBP degradation in the soil and decreased DBP accumulation in plants, thereby reducing the health risks associated with vegetables grown in those soils. High-throughput sequencing demonstrated that both DBP contamination and the bioremediation process significantly altered prokaryotic community composition, structure, and network interactions; however, these effects were greatly reduced after 30 d. Dibutyl phthalate affected the prokaryotic community by influencing soil properties rather than directly impacting on microorganisms. In addition, ecosystem functions, like the nitrogen cycle, were significantly altered. Contamination with DBP promoted nitrogen fixation and the denitrification processes while inhibiting nitrification. Bioremediation may mitigate some of the changes to nitrogen cycling, helping to maintain the balance of prokaryotic community function. According to this study, bioremediation through highly efficient degradation bacteria may be a safe and promising method for reducing PAEs contamination in soil-vegetable systems.


Assuntos
Biodegradação Ambiental , Dibutilftalato/metabolismo , Bactéria Gordonia/metabolismo , Microbiologia do Solo , Poluentes do Solo/metabolismo , Agricultura , Ecossistema , Solo
18.
J Hazard Mater ; 369: 353-361, 2019 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-30784965

RESUMO

In this study, in-situ treatment using dry jet mixing construction method and SPC (single superphosphate and calcium oxide) new binder are used to solidify/stabilize a heavy metal contaminated site soil with relatively high content of organic matters. Time-dependent field performance of the soils at 41 and 326 days after treatment is evaluated, which includes electrical conductivity (EC), leachability of heavy metals and chemical oxygen demand (COD), soil penetration resistance, acid neutralization capacity (ANC), and chemical speciation of heavy metals. The results indicate that the stabilized soils exhibit satisfactory performance which is comparable with the laboratory study. In-situ SPC treatment significantly decreases EC values and increases penetration resistance values of the soils. Leachability of lead, zinc, cadmium and COD decreases with increasing SPC content or curing time. Large percentages of heave metals in the soils are transformed from exchangeable fractions to residual fractions after treatment. These, coupled with the improved ANC, result in low heavy metal leachability in stabilized soils.

19.
Huan Jing Ke Xue ; 39(3): 1430-1437, 2018 Mar 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965492

RESUMO

pH is one of the most important factors affecting speciation and stabilization of arsenic and heavy metals in soil. In this study, Fe-Mn binary oxide (FMBO), synthesized by redox and precipitation reactions, was taken as the research object to evaluate its stabilization effects on As, Pb, Cd, Zn, and Cu in three types of soils under different pH conditions and to study the impacts on soil pH and buffering capacity. The results showed that the leaching concentrations of As and Pb were lower in the pH range of 3-9 (neutral and weak acidic) and 5-10 (neutral and weak alkaline); and Cd, Zn, and Cu were stable in the pH range of 7-11 (alkaline). The stability and stabilization effects of FMBO were better under alkaline conditions than acidic. In the optimal pH range, the optimum stabilization efficiency of FMBO could reach 92.7%, 100%, 97.0%, 88.7%, and 82.7% for As, Pb, Cd, Zn, and Cu, respectively. In addition, FMBO addition could increase soil pH and the acid buffering capacity moderately, which improved heavy metal stabilization and made it more suitable for acid soils and areas with more acid rain. From the correlation of contaminants and soil elements in the leachates, Fe played an important role in As stabilization, and pH had a great influence on the stabilization of Pb, Cd, Zn, and Cu.

20.
J Environ Qual ; 47(2): 312-317, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29634792

RESUMO

(Burk.) F.H. Chen, a valuable Chinese medicine, is currently confronted with arsenic (As) contamination in China due to soil pollution. Our previous research demonstrated that Fe(0) and zeolite had a certain inhibitory effect on As accumulation in . In order to further reduce As accumulation in the plant, a synthetic iron material (Fe-Ce oxide [FC]) with high As adsorption capacity was tested for As remediation. In the study, after FC was applied to the As-contaminated soil, was planted in the soil. The As leaching behavior of the treated soil and As accumulation in were evaluated. The results showed that FC immobilized As more effectively than Fe(0) and zeolite in soils with high As concentrations. When the FC dosage was 0.5 % (w/w), As concentration of root (the main medicinal part) decreased by 56%, and root biomass increased by 55%. Results indicated FC could reduce the non-specifically adsorbed As fraction (F1) and specifically adsorbed As fraction (F2) by 22 to 31% and 5 to 17%, respectively, thus reducing the toxicity characteristic leaching procedure leachable As concentration by 41 to 67%. The finding of an iron plaque coating on the plant root and its function as a barrier to As uptake by is reported here for the first time. The occurrence of iron plaque led to a reduction in As concentration in the phellem and xylem-phloem by 66 to 80% and 43 to 70%, respectively. Our findings will help in developing As contamination control in areas where is planted and set a foundation for a FC-based As immobilization technology.


Assuntos
Arsênio/farmacocinética , Panax notoginseng/química , Arsênio/análise , China , Óxidos , Solo , Poluentes do Solo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...