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1.
J Environ Manage ; 267: 110665, 2020 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-32421682

RESUMEN

The electro-kinetic remediation of soils using different powering strategies has been studied, in order to clarify which is the best strategy to couple solar powering with this remediation technology, in a context of developing more sustainable electrochemical remediation technologies. Direct powering from photovoltaic panels (Case a), application of constant electric fields with the same average value of Case a (Case b) and application of constant specific power with the same average value of Case a (Case c) have been compared. Results show an outstanding influence of the powering strategy on the removal efficiency of clopyralid (model of herbicide used in this work). The direct use of solar power profiles obtained the lowest removal efficiencies, which contrasts with the higher expected sustainability of this powering strategy. Reversion of pollutant transport overnight and extreme electric field values at noon help to explain the lower efficiency of this strategy. Evaporation mechanisms are promoted by operating at extreme large electric fields. In addition, harsher conditions lead to a higher negative soil affectation in terms of regions affected by extreme pHs, water contents and/or conductivities and to lower specific pollutant removals. Therefore, maximum efficiencies were found for Case b (constant electric potential gradient) with a total removal over 110 g kWh-1 and only a slight affectation into the final soil properties.


Asunto(s)
Restauración y Remediación Ambiental , Herbicidas , Contaminantes del Suelo , Energía Solar , Suelo
2.
Chemosphere ; 250: 126268, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32234619

RESUMEN

The effectiveness of rice waste biochars on heavy metal and metalloid abatement and detoxification was investigated using comprehensive studies based on As and Cd immobilization, bioaccumulation in tubifex, and microbial community changes in contaminated sediment. The remediation effects of biochars produced at different pyrolytic temperatures (400-700 °C) were evaluated. Bioaccumulation of heavy metal and metalloid in the tubifex tissue and change of indigenous microbial community under treatment of different biochars were assessed. Biochars produced at 700 °C exhibited greater effect on decreasing the concentrations of As and Cd in aqueous phase, and TCLP extractable and bioavailable metal(loid) in solid phase of sediment. The concentration of As and Cd in water phase decreased by 26%-89% and 22%-71% under the treatment of straw biochar, and decreased by 13%-92% and 5%-64% under the treatment of rice husk biochar, respectively. As and Cd contents in the tubifex tissue were positively correlated with their concentrations in aqueous phase. High-temperature biochars significantly reduced metal(loid) bioaccumulation in tubifex. The richness and biodiversity of microbial community were both greater in all biochars remediated sediment compared to non-treated sediment. These results indicated that rice waste biochars could effectively inhibit the bio-availability and toxicity of heavy metal and metalloid in sediment, and the higher-temperature biochar exhibited better performance.


Asunto(s)
Arsénico/química , Cadmio/química , Carbón Orgánico/química , Restauración y Remediación Ambiental , Disponibilidad Biológica , Inactivación Metabólica , Metales Pesados , Oryza , Pirólisis , Temperatura , Agua
3.
J Environ Manage ; 261: 110150, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32148256

RESUMEN

Brownfields redevelopment creates opportunities for enhanced environmental conditions, improved physical and mental health, community cohesion, and economic prosperity. However, brownfields cleanup and recycling projects sometimes fail due to a lack of community engagement. Recent research suggests that such failures can stem from a lack of equitability in the planning process, especially when it comes to decision making. This paper examines issues of equitability in a recent brownfields redevelopment project in Tampa, Florida funded by the U.S. Environmental Protection Agency. The project focused on an underserved and under-resourced community with long-term environmental burdens and health disparities. Our ethnographic research shows that, while the project engaged in multiple and intersecting efforts to include a diversity of community voices in the decision-making process, ultimately structural and organizational power imbalances in sustainability transitions influenced participation in redevelopment initiatives. This study suggests that attending to issues of power articulated through expressions of local and authoritative knowledge about environmental cleanup and redevelopment can lead to deeper levels of community engagement.


Asunto(s)
Restauración y Remediación Ambiental , Toma de Decisiones , Florida , Estados Unidos , United States Environmental Protection Agency
4.
Bull Environ Contam Toxicol ; 104(4): 477-483, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-32193572

RESUMEN

The application of nano-level passivating agents in the remediation of soil heavy metal pollution has received widespread attention, but its harm to soil animals should also be addressed. This study explored the effect of three nanomaterials-nanohydroxyapatite apatite (n-HAP), nano zeolite (n-zeolite), and nanometer iron oxide (n-Fe3O4), on catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) activity and malondialdehyde (MDA) content through filter paper contact test. The effects of nanomaterials spiked at 1.5%wt of soils on earthworm avoidance behavior were also be studied, and the crystallinity and surface charge of three nanomaterials were characterized. The results showed that the activities of CAT, SOD and POD and the content of MDA have been changed at different level. And earthworms have obvious avoidance behavior to the three kinds of nanomaterials. Therefore, nanomaterials do have adverse effects on earthworms, and their biological toxicity should be considered when selecting passivating agents for soil heavy metal pollution remediation.


Asunto(s)
Reacción de Prevención/efectos de los fármacos , Restauración y Remediación Ambiental/métodos , Reacción de Fuga/efectos de los fármacos , Nanoestructuras/toxicidad , Oligoquetos/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Suelo/química , Animales , Catalasa/metabolismo , Malondialdehído/metabolismo , Nanoestructuras/química , Oligoquetos/metabolismo , Peroxidasa/metabolismo , Contaminantes del Suelo/química , Superóxido Dismutasa/metabolismo
5.
Chemosphere ; 250: 126209, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32113096

RESUMEN

To address the challenge of trichloroethene (TCE) remediation in low permeability zone, an inexpensive Cu-Ni bimetallic cathode was proposed in electrokinetic (EK) remediation system to couple electrokinetic migration with in situ electrochemical hydrodechlorination. Aqueous phase TCE was originally added into the anolyte so that breakthrough curves through the low permeability porous soil compartment could be obtained to better understand TCE migration driven by electroosmosis flow using different cathodes. The Cu-Ni cathode resulted in more TCE migration of 7.64 mg compared to that of 5.99 mg with Ni and 4.22 mg with mixed metal oxide (MMO) cathode, suggesting that the Cu-Ni cathode was capable of driving more TCE flux out of the contaminated soil. With the Cu-Ni cathode, 98.4% of TCE flux that reached the cathode was electrochemically reduced on the cathode, which was much higher than that with MMO cathode (77.9%) or Ni cathode (59.6%). TCE mass that was transported by electroosmosis flow increased from 2.04 to 6.68 mg when the voltage gradient increased from 1 to 4 V cm-1, with the normalized energy consumption increasing from 0.06 to 0.16 kWh kg-1 per unit water movement, and from 0.54 to 2.55 kWh g-1 per unit TCE transport. For TCE that did reach the cathode compartment, > 98% degradation maintained at the Cu-Ni cathode with various voltage gradients. The coupled electrokinetic and electrochemical hydrodechlorination technology appears to be a promising strategy for the remediation of low permeability porous media.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Contaminantes del Suelo/análisis , Tricloroetileno/química , Electrodos , Contaminación Ambiental , Óxidos , Permeabilidad , Porosidad , Suelo , Tricloroetileno/análisis , Movimientos del Agua
6.
Chemosphere ; 250: 126317, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32120154

RESUMEN

In the present work, in-situ two pot trials were conducted to explore the direct and residual influences of zeolite (ZL) on plant height, dry biomass and bioavailability of Pb, Cd, Cu, and Zn by growing cabbage followed by corn in goldmine-contaminated (GM-C), smelter factory-contaminated (SF-C), and farmland-contaminated (FL-C) soils. Initially, a single treatment of ZL was applied at 20 t/ha, and cabbage was grown under greenhouse pot conditions. After cabbage harvesting, corn was grown in the same pots without additional application of ZL. The results indicated that ZL as an amendment evidently promoted the cabbage and corn yields, whereas the residual influence of ZL did not promote corn dry matter yield in SF-C and FL-C soils compared to CK. Incorporation of ZL potentially decreased the mobility of Pb, Cd, Cu and Zn in contaminated soils after harvesting cabbage and corn compared with CK. In both crops, the Pb, Cd, Cu and Zn contents in plants root and shoot biomasses were dramatically reduced by the direct and residual impacts of ZL rather than CK. This study highlights that the direct and residual influences of ZL at a 20 t/ha application rate have the possibility to support the reclamation of soils polluted with harmful elements and that, by itself, ZL can promote plant growth and increase the value of field crops. The detailed studied regarding residual influence of ZL for restoration of multi-metal polluted soils would be confirmed at the ex-situ condition.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Zeolitas/química , Agricultura/métodos , Disponibilidad Biológica , Biomasa , Brassica/crecimiento & desarrollo , Productos Agrícolas/metabolismo , Contaminación Ambiental , Metales , Metales Pesados/análisis , Raíces de Plantas/metabolismo , Rotación , Suelo , Contaminantes del Suelo/análisis , Zea mays/crecimiento & desarrollo , Zea mays/metabolismo
7.
Chemosphere ; 250: 126251, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32113100

RESUMEN

Sorption onto clays (montmorillonite and kaolinite), oxidation and sorption by manganese oxides (synthesized MnO and natural MnO), and coupled sorption-oxidation experiments were conducted for the removal of antibiotics sulfadiazine (SDZ) and ciprofloxacin (CIP) at pH 5 and 8. Individual sorption and oxidation modelling were carried out using the first-order kinetic model. A coupled sorption-oxidation kinetic model was developed to predict the simultaneous sorption and oxidation process. The coupled sorption-oxidation enhanced the antibiotic sorption, with the first-order sorption rate constants in the simultaneous presence of clays and manganese oxides (ksorp) being higher than those with clays only (ksorp0). In contrast, a depression was observed; the first-order oxidation and sorption combination rate constants in the simultaneous presence of manganese oxides and clays (kMnO) were lower than those with manganese oxides only (kMnO0). In the coupled sorption-oxidation reaction, 13.5-62.5% of SDZ and CIP removal was attributed to the sorption. The SDZ and CIP species distributions at pH 5 affected the coupled sorption and oxidation systems more than those at pH 8. The best removal efficiency was achieved by the montmorillonite-synthesized MnO combination, mainly due to the higher surface area (ABET) and pore size of montmorillonite and synthesized MnO combination compared to other clays and manganese oxides combinations.


Asunto(s)
Ciprofloxacino/química , Compuestos de Manganeso/química , Modelos Químicos , Óxidos/química , Sulfadiazina/química , Adsorción , Antibacterianos/química , Bentonita , Arcilla/química , Restauración y Remediación Ambiental/métodos , Caolín , Cinética , Manganeso , Oxidación-Reducción
8.
J Environ Manage ; 264: 110417, 2020 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-32217312

RESUMEN

Stream restoration efforts have increased, but the success rate is still rather low. The underlying reasons for these unsuccessful restoration efforts remain inconclusive and need urgent clarification. Therefore, the aim of the present study was to evaluate over 40 years of stream restoration to fuel future perspectives. To this purpose we evaluated the influence of policy goals on stream restoration efforts, biophysical restoration objectives, restoration measures applied including the scale of application and monitoring efforts. Information was obtained from five stream restoration surveys that were held among the regional water authorities in the Netherlands over the last 40 years and from an analysis of the international scientific publications on stream restoration spanning the same time period. Our study showed that there was a considerable increase in stream restoration efforts, especially motivated by environmental legislation. However, proper monitoring of the effectiveness of the measures was often lacking. Furthermore, a mismatch between restoration goals and restoration measures was observed. Measures are still mainly focused on hydromorphological techniques, while biological goals remain underexposed and therefore need to be better targeted. Moreover, restoration practices occur mainly on small scales, despite the widely recognized relevance of tackling multiple stressors acting over large scales for stream ecosystem recovery. In order to increase the success rate of restoration projects, it is recommended to improve the design of the accompanying monitoring programmes, allowing to evaluate, over longer time periods, if the measures taken led to the desired results. Secondly, we advise to diagnose the dominant stressors and plan restoration measures at the appropriate scale of these stressors, generally the catchment scale.


Asunto(s)
Restauración y Remediación Ambiental , Ríos , Ecosistema , Monitoreo del Ambiente , Países Bajos
9.
Ecotoxicol Environ Saf ; 192: 110294, 2020 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-32044601

RESUMEN

Cadmium (Cd) and nickel (Ni) in soil have caused serious environmental problems and increased healthy risks to humans and biota, it is vital important and necessary to develop effective methods to resolve the combined contaminated problems. In this study, strains L5 and L6 with good heavy metal resistant and immobilizing capacities were isolated from Cd and Ni contaminated soil. Bacterial characteristic experiment illustrated that many functional groups (-OH, -NH2 and -COO et al.) were distributed on the surface of L5 and L6. Under the stress of heavy metals, bacterial appearances were distorted. The pot experiment indicated that the concentrations of HOAc-extractable Cd and Ni in soil reduced 6.26-15.33% and 13.31-19.53% with the inoculation of L5 and L6. In addition, the immobilization rates on Cd and Ni improved 61.27-128.50% and 23.69-39.66% with re-inoculation of strains L5 and L6 at 30 days, respectively. After inoculation of strains L5 and L6 for 60 days, the activities of FDA hydrolysis, acid phosphatase, urease, invertase and dehydrogenase in soil increased obviously. Furthermore, bacterial diversity indexes and community structure of soil were also improved. Thus, given the beneficial remediation effects of the isolated strains, L5 and L6 have great potentials for heavy metals contaminated soil remediation.


Asunto(s)
Bacterias/metabolismo , Cadmio/metabolismo , Níquel/metabolismo , Contaminantes del Suelo/metabolismo , Bacterias/enzimología , Bacterias/aislamiento & purificación , Cadmio/análisis , Restauración y Remediación Ambiental , Níquel/análisis , Suelo/química , Microbiología del Suelo , Contaminantes del Suelo/análisis
10.
Chemosphere ; 248: 126054, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32023510

RESUMEN

The aim of this study was to compare the immobilisation of metal(loid)s in two differently contaminated soils using micro zerovalent iron (ZVI) and nano zerovalent iron (nZVI) particles. Chromated copper arsenate-contaminated soil contained high amounts of As, Cu, Cr, and Zn, whereas mining-contaminated soil contained high amounts of As, Cu, and Pb. Contaminated soils were amended using 2% ZVI and nZVI. As determined by the leaching procedures, nZVI was more efficient in immobilising all the studied metal(loid)s in the soils compared to ZVI. The greatest immobilisation was achieved for As in both soils. The long-term stability of immobilised metal(loid)s was studied in mining-contaminated soil by performing thermal oxidation (ageing). In the ZVI and nZVI-treated soils, high retention results were achieved for As and Cu, whereas in the ZVI and nZVI-treated soils, significant desorption of Pb was observed. The results also showed that retention of metal(loid)s over a long period of time could be more effective in soils treated with ZVI, as the crystallisation of Fe in ZVI-treated soil was to a lesser extent compared to the crystallisation of Fe in nZVI-treated soil.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Hierro/química , Nanopartículas del Metal/química , Contaminantes del Suelo/química , Arseniatos , Contaminación Ambiental , Metales , Minería , Suelo , Contaminantes del Suelo/análisis
11.
Chemosphere ; 249: 126056, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32062218

RESUMEN

The Grand Calumet River (GCR), located in northern Indiana, is contaminated due to a wide range of historical industrial activities. This study was conducted to determine the influence of sediment remediation within the GCR on concentrations of chemical contaminants and toxicity to sediment-dwelling organisms. Between 2005 and 2016, sediments with high concentrations of metals and toxic organic compounds were remediated through a combination of removal, addition of activated carbon and organoclay amendments, and capping with sand or relatively uncontaminated sediment. Short-term and long-term sediment toxicity tests with the amphipod Hyalella azteca, the midge Chironomus dilutus, and the mussel Lampsilis siliquoidea were conducted with samples collected in 2013, 2015, and 2017, from 29 sites, including both remediated and non-remediated sites. Sediment chemistry and toxicity data for three groups of remediated sites (US Steel, West Branch, and East Branch) were compared to samples from contaminated but unremediated sites and to relatively uncontaminated reference sites. In general, remediated sediments had lower levels of PAHs, PCBs and metals, although sediments from the US Steel area still had elevated levels of PAH, PCB and chromium. Sediments from the three remediated sites and from reference sites showed significantly reduced toxic effects in short-term sediment bioassays, compared to unremediated sites. Variation in the long-term success of remediation may reflect site-specific factors such as the type of remediation and the potential for recontamination from uncontrolled sources.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Sedimentos Geológicos/química , Contaminantes Químicos del Agua/toxicidad , Anfípodos/efectos de los fármacos , Animales , Bivalvos/efectos de los fármacos , Chironomidae/efectos de los fármacos , Indiana , Metales/toxicidad , Bifenilos Policlorados/farmacología , Hidrocarburos Policíclicos Aromáticos/farmacología , Ríos/química , Pruebas de Toxicidad , Unionidae , Contaminantes Químicos del Agua/análisis
12.
PLoS One ; 15(2): e0228644, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32027709

RESUMEN

Pyrocatalysis uses thermally excited pyroelectric materials for the generation of reactive oxygen species in water. This unique feature allows it to harvest energy in the form of natural temperature gradients or waste heat from industrial processes in order to degrade organic pollutants at low costs. Its further development into an advanced oxidation process for water remediation is dependent on the availability of pH-robust and nonspecific redox assays for the determination of its oxidation capability. Nevertheless, previous studies neglected the influence of pH changes and they were focused mainly on the degradation of one organic compound or specific chemical dosimetries. In this study, a pH-robust and nonspecific reaction protocol of the dichlorofluorescein assay was established for the investigation of the oxidation capability of the pyrocatalytic process. This reaction protocol was tested on three pyroelectric powders (LiNbO3, LiTaO3, BaTiO3) in different amounts and it overcomes major constraints of a previously used dichlorodihydrofluorescein diacetate-based reaction protocol. Instead of its diacetate, dichlorodihydrofluorescein was used as fluorogenic probe and its concentration was drastically reduced to 1 µM. For the first time, these changes enable the determination and comparison of the oxidation capability independently of pH-rising processes, which are present for all investigated pyroelectric powders up to a pH of 11. Additionally, the precision of the dichlorofluorescein assay was drastically increased and the determination and consideration of autoxidation processes was enabled. Of all three pyroelectric powders, BaTiO3 exhibited the highest oxidation capability with a linear increase with respect to the powder amount.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Purificación del Agua/métodos , Fluoresceínas/química , Calor , Concentración de Iones de Hidrógeno , Oxidación-Reducción , Polvos , Especies Reactivas de Oxígeno/química , Contaminantes Químicos del Agua/química
13.
Chemosphere ; 247: 125963, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32069729

RESUMEN

Lead (Pb) pollution in the soil is becoming more and more serious, and lead poisoning incidents also constantly occur. Therefore, the remediation of lead pollution in the soil has attracted widespread attention. In this study, heavy metal lead in soil was remediated by mechanochemical methods. The effects of different ball milling conditions on the toxic leaching concentration and morphological distribution (BCR sequential extraction procedure) of lead in contaminated soil were analyzed, including the addition of calcium dihydrogen phosphate (Ca(H2PO4)2), ball milling time, and ball milling speed. The reaction mechanism was analyzed by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and a laser particle size analyzer. The results show that the optimal conditions for mechanochemical immobilization were 10% additive (Ca(H2PO4)2), milling speed of 550 rpm, and ball milling time for 2 h. Under this condition, the toxic leaching concentration of lead from contaminated soil was 4.36 mg L-1, and in the BCR sequential extraction procedure, Pb was mainly present in the residual fraction (54.96%). The mechanism of mechanochemical solidification of heavy metal lead in soil is that, during the ball milling process, the lead precipitates with Ca(H2PO4)2 to produce dense agglomerates (Pb3(PO4)2 and PbxCa10-x(PO4)6(OH)2), which fixes the lead in the soil and hampers its leaching.


Asunto(s)
Fosfatos de Calcio/química , Restauración y Remediación Ambiental/métodos , Plomo/aislamiento & purificación , Contaminantes del Suelo/química , Pirofosfato de Calcio/química , Precipitación Química , Plomo/química , Metales Pesados/química , Metales Pesados/aislamiento & purificación , Microscopía Electrónica de Rastreo , Contaminantes del Suelo/análisis , Contaminantes del Suelo/aislamiento & purificación
14.
Chemosphere ; 247: 125965, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32069730

RESUMEN

Phosphorous (P) fertilization is an important agronomic practice, but its role in enhancing phytoremediation efficacy and mediating detoxification has rarely been reported in environmental remediation studies. In this study, a pot experiment was undertaken to assess: firstly, the effect of P on phytoextraction of Cu by Ricinus communis L.; secondly, the potential mechanisms by differentiating the effects of the plant from that of P fertilizer (Ca(H2PO4)2); and thirdly, the role of P in physiological detoxification. Results showed that the application of P fertilizer significantly (p ≤ 0.05) increased the plant biomass as well as the Cu concentrations in plant tissues. This enhanced the phytoremediation efficiency represented by the total Cu extraction (up to 121.3 µg Cu plant-1). Phosphorous (P) fertilizer led to a negligible decline in soil pH (0.2 units) but significantly (p ≤ 0.05) reduced the concentrations of soil available in Cu and Fe, due to the formation of insoluble Cu/Fe-phosphate precipitates. Nevertheless, P fertilizer still improved the accumulation and extraction of Cu by R. communis, most likely attributable to the Fe-deficiency induced by applied P fertilizer. Moreover, the application of P fertilizer revealed a significant reduction in MDA, and a profound (p ≤ 0.05) elevation in the amount of photosynthetic pigments, GSH and AsA, along with the enhanced activities of antioxidative enzymes (SOD, POD, and CAT). In this way, Cu toxicity was alleviated. P fertilizers not only enhance the phytoremediation efficiency of Cu-contaminated soils by R. communis, but they also facilitate detoxification, which improves our understanding of the role of P in phytoremediation technologies.


Asunto(s)
Biodegradación Ambiental , Cobre/metabolismo , Fertilizantes , Fósforo/farmacología , Ricinus/efectos de los fármacos , Antioxidantes/análisis , Antioxidantes/farmacología , Biomasa , Cobre/farmacocinética , Restauración y Remediación Ambiental/métodos , Inactivación Metabólica , Fotosíntesis , Ricinus/metabolismo , Suelo/química , Contaminantes del Suelo/análisis , Contaminantes del Suelo/farmacocinética
15.
Chemosphere ; 247: 125968, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32069733

RESUMEN

It was revealed that Anammox process promotes the anaerobic degradation of benzene under denitrification. This study investigates the effect of dissimilatory nitrate reduction to ammonium (DNRA) and exogenous ammonium on anaerobic ammonium oxidation bacteria (AnAOB) during the anaerobic degradation of benzene under denitrification. The results indicate that anammox occurs synergistically with organisms using the DNRA pathway, such as Draconibacterium and Ignavibacterium. Phylogenetic analysis showed 64% (16/25) and 36% (5/25) hzsB gene sequences, a specific biomarker of AnAOB, belonged to Candidatus 'Brocadia fuldiga' and Candidatus 'Kuenenia', respectively. Exogenous ammonium addition enhanced the anammox process and accelerated benzene degradation at a 1.89-fold higher average rate compared to that in the absence of exogenous ammonium and AnAOB belonged to Ca. 'Kuenenia' (84%) and Ca. 'Brocadia fuldiga' (16%). These results indicate that Ca. 'Brocadia fuldiga' could also play a role in DNRA. However, the diversity of abcA and bamA, the key anaerobic benzene metabolism biomarkers, remained unchanged. These findings suggest that anammox occurrence may be coupled with DNRA or exogenous ammonium and that anammox promotes anaerobic benzene degradation under denitrifying conditions. The results of this study contribute to understanding the co-occurrence of DNRA and Anammox and help explore their involvement in degradation of benzene, which will be crucial for directing remediation strategies of benzene-contaminated anoxic environment.


Asunto(s)
Compuestos de Amonio/química , Anaerobiosis , Bacterias/metabolismo , Benceno/metabolismo , Desnitrificación , Restauración y Remediación Ambiental/métodos , Compuestos de Amonio/metabolismo , Bacterias/genética , Reactores Biológicos/microbiología , Nitratos , Nitrógeno/metabolismo , Oxidación-Reducción , Filogenia
16.
Chemosphere ; 250: 126206, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32092571

RESUMEN

In this study, total petroleum hydrocarbon (TPH) removal from fuel-contaminated field soil was investigated. The influence of the washing method (washing before/after sieving), washing time, soil-to-water ratio, and soil particle size on TPH removal efficiency was evaluated under constant stirring speed. Washing the whole contaminated soil is more efficient than separating the soils into particle size fractions and separately washing the fractions. Particles with differing diameters would be more in contact with each other resulting in detachment of contaminants from the soil particle surface. Effects of soil washing time and soil-to-water ratio on TPH removal were not significant in coarse soil particles (greater than 0.15 mm diameter) but significantly affected TPH removal in fine particles (less than 0.15 mm diameter). This study suggests a threshold washing time of 1 h and a threshold soil-to-water ratio of 1:6 for the whole soil in soil washing. However, soil particles less than 0.075 mm (<75 µm) should be separated after washing to meet the Korean soil TPH limit of less than 500 mg/kg. This study demonstrates the importance of finer soils as debrading media and particle size fraction composition of fuel-contaminated soil in soil washing.


Asunto(s)
Restauración y Remediación Ambiental/métodos , Petróleo , Contaminantes del Suelo/análisis , Biodegradación Ambiental , Contaminación Ambiental , Hidrocarburos/química , Tamaño de la Partícula , Suelo , Agua
17.
Chemosphere ; 250: 126249, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32105859

RESUMEN

In this study, we investigated the mechanism of decrease in arsenic (As) bioavailability after addition of biochar (BC) supplemented with iron (Fe)- manganese (Mn)- cerium (Ce) oxide (FMCBC) to As-contaminated paddy soil. We explored the effects of these composites on the oxidation, reduction, microbial community, and soil enzyme activity of As-contaminated paddy soil. Results showed that FMCBCs improve soil pH, significantly improve the redox capacity of soil, and reduce bioavailable forms of As. FMCBCs can convert As from a specifically or non-specifically bound form into amorphous hydrous oxide bound- and crystalline hydrous oxide bound form. The application of FMCBCs increased soil enzyme activity (urease, catalase, alkaline phosphatase, and peroxidase), and greatly influenced the relative abundance of certain microorganisms (Proteobacteria, Acidobacteria, and Gemmatimonadetes), which improved soil enzyme heavy metal tolerance and prevented their denaturation. Thus, FMCBCs can not only change the form and distribution of As in soil but also create an environment suitable for microbial growth, consequently affecting the geochemical cycling of As in soil.


Asunto(s)
Arsénico/análisis , Carbón Orgánico/química , Microbiología del Suelo , Contaminantes del Suelo/análisis , Biodiversidad , Cerio , Contaminación Ambiental/análisis , Restauración y Remediación Ambiental/métodos , Hierro/química , Manganeso/química , Compuestos de Manganeso , Compuestos Orgánicos , Oxidación-Reducción , Óxidos , Suelo/química
18.
Chemosphere ; 250: 126291, 2020 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-32109695

RESUMEN

In the present study, industrial wood flour waste was selected for the first time as the precursor to produce biochar (WFB). The WFB was then used to prepare WFB/BiOBr visible-light photocatalysts, in which WFB acted as the carbon support to enhance the photocatalytic performance of BiOBr. Specifically, the impact of WFB pyrolysis temperature on the visible-light photo-removal performance of WFB/BiOBr was studied through degrading rhodamine B and reducing Cr(VI). The results indicated that when the pyrolysis temperature was 600 °C, the prepared WFB (600-WFB) had the highest graphitization degree, which afterwards significantly enhanced the visible-light photocatalysis performance of the BiOBr. Having higher graphitization degree, 600-WFB/BiOBr exhibited the highest photocatalytic capability. With a dosage of 0.5 g/L, the 600-WFB/BiOBr could completely remove to 20 mg/L of RhB and 5 mg/L of Cr(VI) within 90 min. Since wood flour is an abundantly existed industrial bioresource waste and easily pyrolyzed to prepare biochar, WFB is a promising alternative to replace traditional carbonaceous materials for the design of green and high-efficient visible-light photocatalysts for environmental remediation.


Asunto(s)
Bismuto/química , Restauración y Remediación Ambiental , Catálisis , Carbón Orgánico/química , Harina , Luz , Pirólisis , Rodaminas , Madera/química
19.
Chemosphere ; 247: 126098, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32088008

RESUMEN

The release of concentrated acid solutions by chemical accidents is disastrous to our environmental integrity. Alkaline agents applied to remedy the acid spill catastrophe may lead to secondary damages such as vaporization or spread out of the fumes unless substantial amount of neutralization heat is properly controlled. Using a rigorous thermodynamic formalism proposed by Pitzer to account short-range ion interactions and various subsidiary reactions, we develop a systematic computational model enabling quantitative prediction of reaction heat and the temperature change over neutralization of strongly concentrated acid solutions. We apply this model to four acid solutions (HCl, HNO3, H2SO4, and HF) of each 3 M-equivalent concentration with two neutralizing agents of calcium hydroxide (Ca(OH)2) and sodium bicarbonate (NaHCO3). Predicted reaction heat and temperature are remarkably consistent with the outcomes measured by our own experiments, showing a linear correlation factor R2 greater than 0.98. We apply the model to extremely concentrated acid solutions as high as 50 wt% where an experimental approach is practically restricted. In contrast to the extremely exothermic Ca(OH)2 agent, NaHCO3 even lowers solution temperatures after neutralization reactions. Our model enables us to identify a promising neutralizer NaHCO3 for effectively controlling concentrated acid spills and may be useful for establishment of proper strategy for other chemical accidents.


Asunto(s)
Ácidos , Liberación de Peligros Químicos , Simulación por Computador , Restauración y Remediación Ambiental/métodos , Hidróxido de Calcio , Calor , Bicarbonato de Sodio
20.
J Environ Radioact ; 216: 106186, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32056790

RESUMEN

The diffusion length of 222Rn in uraniferous waste rock was determined through a novel experiment. Large PVC columns were filled to different depths in the range from 0.5 m to 3.0 m with waste rock material from the Ranger uranium mine and the build-up of 222Rn activity concentration in the column headspace above the material was measured after closing the columns with a lid. Measurements were made approximately one month after filling the columns and again after approximately one and two years. The average 222Rn diffusion length derived from the measurements was 1.9 ± 0.2 m in the dry material. The corresponding diffusion coefficient was (7.3 ± 0.7) × 10-6 m2 s-1. For an infinitely thick layer of the dry material, the average value of the 222Rn exhalation flux density relative to the 226Ra activity concentration was estimated as (5.3 ± 0.3) × 10-4 Bq m-2 s-1 per Bq kg-1. From the diffusion length, the waste rock material was characterised as both a source and attenuator of 222Rn for its proposed use as the surface cover on the final landform of the remediated Ranger uranium mine.


Asunto(s)
Restauración y Remediación Ambiental , Monitoreo de Radiación , Australia , Espiración , Radón , Uranio
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