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1.
Environ Technol ; : 1-10, 2024 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-39150864

RESUMEN

This article explores the benefits of electrochemical oxidation in pulsed mode, using potential, current, and power pulses. While potential and current pulse electrochemical technology has been previously studied for wastewater treatment, no study has included power pulses until now. The objective of this work is to highlight the advantages of power pulses by applying this pulse type to the electrochemical oxidation of a probe molecule, alachlor. For this aim, the influence of operating parameters and the comparison of the different pulse modes were investigated and compared to the results obtained with the electrochemical oxidation of alachlor in continuous mode. The study shows that the best results were obtained with the power pulse electrochemical oxidation with 100% alachlor degradation after 180 min and a mineralisation yield of 38.3% after 240 min. These results were better than those reported in the literature for treatments with continuous current input using platinum electrodes. This new technique could be an effective and efficient way to treat contaminated water and reduce the pressure on freshwater reserves.

2.
J Hazard Mater ; 471: 134270, 2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38640676

RESUMEN

Alachlor, a widely used chloroacetanilide herbicide for controlling annual grasses in crops, has been reported to rapidly trigger protein denaturation and aggregation in the eukaryotic model organism Saccharomyces cerevisiae. Therefore, this study aimed to uncover cellular mechanisms involved in preventing alachlor-induced proteotoxicity. The findings reveal that the ubiquitin-proteasome system (UPS) plays a crucial role in eliminating alachlor-denatured proteins by tagging them with polyubiquitin for subsequent proteasomal degradation. Exposure to alachlor rapidly induced an inhibition of proteasome activity by 90 % within 30 min. The molecular docking analysis suggests that this inhibition likely results from the binding of alachlor to ß subunits within the catalytic core of the proteasome. Notably, our data suggest that nascent proteins in the endoplasmic reticulum (ER) are the primary targets of alachlor. Consequently, the unfolded protein response (UPR), responsible for coping with aberrant proteins in the ER, becomes activated within 1 h of alachlor treatment, leading to the splicing of HAC1 mRNA into the active transcription activator Hac1p and the upregulation of UPR gene expression. These findings underscore the critical roles of the protein quality control systems UPS and UPR in mitigating alachlor-induced proteotoxicity by degrading alachlor-denatured proteins and enhancing the protein folding capacity of the ER.


Asunto(s)
Acetamidas , Retículo Endoplásmico , Herbicidas , Complejo de la Endopetidasa Proteasomal , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Respuesta de Proteína Desplegada , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/metabolismo , Acetamidas/farmacología , Acetamidas/toxicidad , Herbicidas/toxicidad , Retículo Endoplásmico/efectos de los fármacos , Retículo Endoplásmico/metabolismo , Respuesta de Proteína Desplegada/efectos de los fármacos , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Complejo de la Endopetidasa Proteasomal/metabolismo , Complejo de la Endopetidasa Proteasomal/efectos de los fármacos , Citosol/metabolismo , Citosol/efectos de los fármacos , Simulación del Acoplamiento Molecular , Estrés Proteotóxico
3.
J Xenobiot ; 13(4): 560-571, 2023 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-37873813

RESUMEN

Pesticide compounds can influence denitrification processes in groundwater in many ways. This study observed behavior of three selected pesticides under denitrifying conditions. Alachlor, terbuthylazine, and tebuconazole, in a concentration of 0.1 mL L-1, were examined using two laboratory denitrifications assays: a "short" 7-day and a "long" 28-day test. During these tests, removal of pesticides via adsorption and biotic decomposition, as well as the efficiency of nitrate removal in the presence of the pesticides, were measured. No considerable inhibition of the denitrification process was observed for any of the pesticides. On the contrary, significant stimulation was observed after 21 days for alachlor (49%) and after seven days for terbuthylazine (40%) and tebuconazole (36%). Adsorption was in progress only during the first seven days in the case of all tested pesticides and increased only negligibly afterwards. Immediate adsorption of terbuthylazine was probably influenced by the mercuric chloride inhibitor. A biotic loss of 4% was measured only in the case of alachlor.

4.
Artículo en Inglés | MEDLINE | ID: mdl-36459856

RESUMEN

Alachlor is one of the most widely used herbicides and can also be a carcinogenic compound. It is of great significance to establish a sensitive analytical method for the determination of alachlor in the environment and organisms. In this study, a high-performance liquid chromatography tandem mass spectrometry cubed (LC/MS3) method was developed and validated to quantify alachlor in human breast cancer cells (McF-7 cells). The cell samples were processed by simple protein precipitation with acetonitrile, then the analytes were separated on a Waters AcQuity® UPLC BEH (2.1 × 50 mm I.D, 1.7 µm) column using the gradient elution with solvent A (0.1 % formic acid) and solvent B (acetonitrile) at a flow rate of 0.5 mL/min. MS3 detection in positive ion mode was used to detect the analytes. The MRM3 transitions at m/z 270.1 â†’ 238.0 â†’ 162.1 and 312.2 â†’ 238.1 â†’ 147.2 were used to determine alachlor and butachlor, respectively. The run time for each sample was only 4 min. This method was validated for various parameters including accuracy, precision, selectivity, linearity, lower limit of quantitation (LLOQ), etc. The LC/MS3 assay was linear in the concentration range 0.5-50 ng/mL (R2 ≥ 0.995). For all concentrations, the precision is < 9.49 %, and the intra-day and intra-day accuracy is < 13.05 %. Cytotoxic potential of alachlor against McF-7 cell lines was measured by MTT method after 48 h of incubation. For alachlor, half maximal inhibitory concentration (IC50) on McF-7 cells was 87.95 µg/mL. This method was successfully applied to cellular pharmacokinetic study of alachlor in McF-7 cells after administration with a dose of 20 µg/mL.


Asunto(s)
Espectrometría de Masas en Tándem , Ratas , Animales , Humanos , Cromatografía Liquida , Ratas Sprague-Dawley , Espectrometría de Masas en Tándem/métodos , Células MCF-7 , Reproducibilidad de los Resultados , Cromatografía Líquida de Alta Presión/métodos
5.
Pestic Biochem Physiol ; 184: 105063, 2022 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-35715071

RESUMEN

Alachlor is a widely used herbicide for the cultivation of various grains employed as food for cattle. The mechanisms leading to the toxic effects of alachlor on epithelial cells of the bovine mammary gland are not well known. Thus, this study was conducted to clarify the toxicological effects of alachlor on the immortalized epithelial cell line of the bovine mammary gland (MAC-T) cells. After treatment, many factors related to cell viability, proliferation, and cellular homeostasis were evaluated. Alachlor arrested cell cycle progression by blocking the expression of cyclin and cyclin-dependent kinases, and induced the breakdown of Ca2+ homeostasis. The cytosolic and mitochondrial levels of Ca2+ were also abnormally increased after the treatment of cells with alachlor, ultimately leading to the depolarization of mitochondrial membrane potential in MAC-T cells. The signaling cascade was found to be dysregulated by the abnormal phosphorylation of signaling molecules involved in PI3K/AKT (AKT, p70S6K, and S6) and MAPK/JNK (JNK and c-Jun) pathways. In these mechanisms, exposure to alachlor led to a reduction in the viability and proliferation of MAC-T cells. Altogether, the toxic effects of alachlor can lead to abnormal conditions in epithelial cells of the bovine mammary gland, which might hinder these cells from performing their main role, such as producing milk.


Asunto(s)
Glándulas Mamarias Animales , Fosfatidilinositol 3-Quinasas , Acetamidas , Animales , Calcio/metabolismo , Bovinos , Puntos de Control del Ciclo Celular , Células Epiteliales , Homeostasis , Glándulas Mamarias Animales/metabolismo , Proteínas Proto-Oncogénicas c-akt
6.
J Biosci Bioeng ; 133(4): 340-346, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-35078710

RESUMEN

Omega-3 polyunsaturated fatty acids (PUFAs) such as eicosapentaenoic acid (EPA, C20:5ω-3) are essential for human health and fish growth especially in aquaculture sector. However, with the growing of aquaculture, the demand of PUFA supply also has been increasing. Fistulifera solaris, a marine diatom, is known for its ability to accumulate 65% of lipid content per dry cell weight, and can produce the high content of EPA. Thus, this diatom shows a great potential to be a feedstock of omega-3 PUFAs for fish feeds. In this study, in order to further understand and enhance the metabolism of PUFA biosynthesis in the diatom, the impacts of ketoacyl-ACP synthase (KAS) and ketoacyl-CoA synthase (KCS) inhibition on the PUFA production were analyzed by adding the specific inhibitors. KAS and KCS enzymes both play a role in the fatty acid elongation. As a result, the inhibition of KAS showed an increase in EPA content without arresting the cell growth. On the other hand, inhibition of KCS did not show a significant impact on the PUFA content in F. solaris. Our finding suggests that the specific suppression of KAS function can be a promising way to enhance the omega-3 PUFA production in F. solaris.


Asunto(s)
Diatomeas , Ácidos Grasos Omega-3 , Ácido Eicosapentaenoico/metabolismo , Ácido Graso Sintasas/metabolismo , Ácidos Grasos Omega-3/metabolismo , Ácidos Grasos Insaturados/metabolismo
7.
Environ Toxicol Chem ; 41(1): 122-133, 2022 01.
Artículo en Inglés | MEDLINE | ID: mdl-34967044

RESUMEN

The increasing use of agrochemicals, alone and in combination, has been implicated as a potential causative factor in the decline of amphibians worldwide. Fertilizers and pesticides are frequently combined into single-use tank mixtures for agricultural applications to decrease costs while meeting the food demands of a growing human population. Limited data are available on the effects of increased nitrogen levels in nontarget species, such as amphibians, and therefore investigating alterations in the nitrogen cycle and its impacts on amphibians needs to be considered in best management practices going forward. The objective of the present study was to elucidate the impact of fertilizer (urea) and herbicide (atrazine and/or alachlor) tank mixtures on the hepatic metabolome of juvenile leopard frogs as well as to investigate alterations in oxidative stress by relating these changes to glutathione (GSH) levels. Herbicide exposure only moderately increased this parameter in amphibians, however, urea alone and in combination with either atrazine or alachlor statistically elevated GSH levels. Interestingly, urea also inhibited pesticide uptake: calculated bioconcentration factors were greatly decreased for atrazine and alachlor when urea was present in the exposure mixture. Metabolomic profiling identified fluxes in hepatic metabolites that are involved in GSH and carbohydrate metabolic processes as well as altered intermediates in the urea cycle. Ultimately, understanding the biological impacts of nitrogenous fertilizers alone and in combination with pesticide exposure will inform best management practices to conserve declining amphibian populations worldwide. Environ Toxicol Chem 2022;41:122-133. © 2021 SETAC.


Asunto(s)
Atrazina , Herbicidas , Plaguicidas , Animales , Atrazina/metabolismo , Atrazina/toxicidad , Fertilizantes/toxicidad , Glutatión/metabolismo , Herbicidas/metabolismo , Herbicidas/toxicidad , Plaguicidas/metabolismo , Rana pipiens , Ranidae , Urea
8.
Chemosphere ; 292: 133417, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34954194

RESUMEN

Bio-Fenton reaction supported by glucose oxidase (GOx) for producing H2O2 was applied to degrade persistent chloroacetanilide herbicides in the presence of Fe (Ⅲ)-citrate at pH 5.5. There were pH decrease to 4.3, the production of 8 mM H2O2 and simultaneous consumption to produce •OH radicals which non-specifically degraded the herbicides. The degradation rates followed the order acetochlor ≈ alachlor ≈ metolachlor > propachlor ≈ butachlor with the degradation percent of 72.8%, 73.4%, 74.0%, 47.4%, and 43.8%, respectively. During the Bio-Fenton degradation, alachlor was dechlorinated and filtered into catechol via the production of intermediates formed through a series of hydrogen atom abstraction and hydrogen oxide radical addition reactions. The current Bio-Fenton reaction leading to the production of •OH radicals could be applied for non-specific oxidative degradation to various persistent organic pollutants under in-situ environmental conditions, considering diverse microbial metabolic systems able to continuously supply H2O2 with ubiquitous Fe(II) and Fe(III) and citrate.


Asunto(s)
Glucosa Oxidasa , Herbicidas , Acetamidas , Compuestos Férricos , Peróxido de Hidrógeno
9.
Heliyon ; 7(9): e08010, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34589629

RESUMEN

The purpose of this study was to explore the stability and toxicity of the herbicides and their degradation byproduct after exposure to different environmental factors. Triazines (atrazine, propazine, simazine) and chloroacetanilides (acetochlor, alachlor, metolachlor) which are commonly used herbicides were evaluated for cytotoxicity in different UV (254 nm and 365 nm) and temperature (4 °C, 23 °C, and 40 °C) conditions as well as degradation rates. Atrazine with the highest LD50 (4.23 µg mL-1) was less toxic than the other tested triazine herbicides Chloroacetanilides tested were more toxic than tested triazines, with LD50 0.08-1.42 µg mL-1 vs 1.44-4.23 µg mL-1, respectively. Alachlor with LD50 0.08 µg mL-1 showed the strongest toxic response as compared with other tested herbicides. Temperatures only did not alter cytotoxicity of the tested herbicides, except for acetochlor and alachlor showing about 45 % more cell death after exposure to 40 °C for 2 h. At all 3 tested temperatures, 2 h of UV treatments did not affect cytotoxic effects of the tested herbicides, except for acetochlor and alachlor. At 4 °C, acetochlor toxicity was attenuated about 63 % after UV 365 nm exposure; but alachlor toxicity was enhanced after either UV 254 or 365 nm exposure for about 40 % and 24 %, respectively. At 23 °C, acetochlor toxicity was enhanced about 35 % after UV 254 nm exposure, but attenuated about 48 % after UV 365 nm exposure. Alachlor toxicity was enhanced about 34 % after UV 254 nm and 23 °C exposure. In combination of UV 254 nm and 40 °C, acetochlor toxicity was lowered by 63 % and alachlor toxicity was no change as compared with 4 °C, no UV group. After co-treatment with UV 365 nm and 40 °C both acetochlor and alachlor toxicity was enhanced 55 % and 80 %, respectively. Through degradation analysis by LC-MS/MS, alachlor showed the most dramatic degradation (only 0.58 %-10.58 % remaining) after heat and UV treatments.

10.
J Environ Sci Health B ; 55(7): 620-629, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32364417

RESUMEN

Alachlor is one of the most widely used herbicides and can remain in agricultural soils and wastewater. The toxicity of alachlor to marine life has been rarely studied; therefore, we evaluated the physiological and transcriptional responses in the marine dinoflagellate Prorocentrum minimum. The herbicide led to considerable decreases in P. minimum cell numbers and pigment contents. The EC50 was determined to be 0.373 mg/L. Photosynthesis efficiency and chlorophyll autofluorescence dramatically decreased with increasing alachlor dose and exposure time. Real-time PCR analysis showed that the photosynthesis-related genes PmpsbA, PmatpB, and PmrbcL were induced the most by alachlor; the transcriptional level of each gene varied with time. PmrbcL expression increased after 30 min of alachlor treatment, whereas PmatpB and PmpsbA increased after 24 h. The PmpsbA expression level was highest (5.0 times compared to control) after 6 h of alachlor treatment. There was no significant change in PmpsaA expression with varying treatment time or concentration. Additionally, there was no notable change in the expression of antioxidant genes PmGST and PmKatG, or in ROS accumulation. These suggest that alachlor may affect microalgal photosystem function, with little oxidative stress, causing severe physiological damage to the cells, and even cell death.


Asunto(s)
Acetamidas/toxicidad , Dinoflagelados/efectos de los fármacos , Herbicidas/toxicidad , Fotosíntesis/efectos de los fármacos , Clorofila/metabolismo , Dinoflagelados/fisiología , Ecotoxicología , Expresión Génica/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Fotosíntesis/genética , Especies Reactivas de Oxígeno/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa
11.
Pestic Biochem Physiol ; 163: 216-226, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31973860

RESUMEN

Due to the increasing use of chlorinated organic compounds, environmental pollution is a key issue in agricultural and industrial areas. In this study, biodegradation of chloroacetanilide herbicides, such as alachlor and metolachlor, by eight fungal strains of Trichoderma spp. originating from different microorganism collections was investigated. The tested fungi converted 80-99% of alachlor and 40-79% of metolachlor after 7 days of incubation. Biotransformation of herbicides was performed mainly by dechlorination and hydroxylation reactions. Eight alachlor metabolites and four byproducts of metolachlor conversion were detected in Trichoderma cultures, including two metolachlor intermediates for the first time identified in fungi. Moreover, in the cultures of six Trichoderma strains supplemented with chloroacetanilides, a decrease in toxicity was observed toward tested Artemia franciscana crustaceans. Simultaneously, 7 days after the application of the spores of T. koningii IM 0956, T. citrinoviride IM 6325, T. harzianum KKP 534, T. viride KKP 792 and T. virens DSM 1963 the length of roots and shoots of rapeseed seedlings treated with alachlor or metolachlor significantly increased. All tested strains exhibited plant growth-promoting traits, such as siderophore production, 1-aminocyclopropane-1-carboxylate deaminase (ACCD) activity, and phosphate solubilization, even in the presence of chloroacetanilide herbicides.


Asunto(s)
Herbicidas , Trichoderma , Acetamidas , Biodegradación Ambiental , Biotransformación
12.
Water Res ; 161: 549-559, 2019 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-31233967

RESUMEN

Pesticides are emerging contaminants frequently detected in the aquatic environment. In this work, a novel approach combining activated carbon adsorption, oxygen plasma treatment and ozonation was studied for the removal of the persistent chlorinated pesticide alachlor. A comparison was made between the removal efficiency and energy consumption for two different reactor operation modes: batch-recirculation and single-pass mode. The kinetics study revealed that the insufficient removal of alachlor by adsorption was significantly improved in terms of degradation efficiency and energy consumption when combined with the plasma treatment. The best efficiency (ca. 80% removal with an energy cost of 19.4 kWh m-³) was found for the single-pass operational mode of the reactor. In the batch-recirculating process, a complete elimination of alachlor by plasma treatment was observed after 30 min of treatment. Analysis of the reactive species induced by plasma in aqueous solutions showed that the decomposition of alachlor mainly occurred through a radical oxidation mechanism, with a minor contribution of long-living oxidants (O3, H2O2). Investigation of the alachlor oxidation pathways revealed six different oxidation mechanisms, including the loss of aromaticity which was never before reported for plasma-assisted degradation of aromatic pesticides. It was revealed that the removal rate and energy cost could be further improved with more than 50% by additional O3 gas bubbling in the solution reservoir.


Asunto(s)
Ozono , Contaminantes Químicos del Agua , Purificación del Agua , Acetamidas , Peróxido de Hidrógeno , Oxidación-Reducción , Agua
13.
Environ Sci Pollut Res Int ; 26(12): 11951-11961, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-30825124

RESUMEN

NZVI has long been used for the remediation of different groundwater contaminants but their tendency to get oxidized easily has always been a barrier to their reductive ability. In this work, we have made an attempt to enhance the aerobic stability of the nanoparticles by synthesizing them in a medium consisting of a viscous solvent, glycerol, and water. The XRD analysis of the nanoparticles reveals that the particles prepared in the presence of glycerol have a very thin coating of iron oxides on the outer surface of the nanoparticles in comparison with those prepared in the aqueous medium. These nanoparticles were applied for the simultaneous reduction of two groundwater contaminants, nitrate ions, and alachlor, which is an herbicide. Stock solutions of these two contaminants were prepared and then they were mixed in varying amounts and were treated by different doses of the nanoparticle. The optimized dose of the nanoparticles obtained for almost 97% removal of both the contaminants is 2.05 g/L. The studies showed that increasing the concentration of either of the contaminants while the other one was kept fixed led to a decrease in the removal efficiency. The studies conducted to see the effect of pH variation showed that the best removal can be achieved when the pH is 3 or even less than it, showing that acidic pH leads to higher removal values. Such nanoparticles which can be prepared easily at low-cost and can simultaneously act upon different contaminants are highly desired.


Asunto(s)
Acetamidas/análisis , Glicerol/química , Nitratos/análisis , Contaminantes Químicos del Agua/análisis , Acetamidas/química , Agua Subterránea , Hierro/análisis , Hierro/química , Modelos Químicos , Nanopartículas/química , Nitratos/química , Óxidos de Nitrógeno/análisis , Oxidación-Reducción , Contaminantes Químicos del Agua/química , Purificación del Agua
14.
Ecotoxicol Environ Saf ; 162: 1-9, 2018 Oct 30.
Artículo en Inglés | MEDLINE | ID: mdl-29957402

RESUMEN

The filamentous fungus Trichoderma koningii is capable of fast and effective eliminate alachlor (90% after 72 h when added separately and 80-60% in the presence of 1-5 mM of copper). After 168 h over 99% elimination of alachlor resulted in detoxification and was connected with the mitigation of reactive oxygen species (ROS) production. Using MS/MS techniques, seven dechlorinated and hydroxylated metabolites were identified. Cytochrome P450 and laccase participate in biotransformation of the herbicide by this non-ligninolytic fungus. Laccase activity is stimulated both by copper and the mixture of copper and alachlor, which seems to be important for combined pollutants. T. koningii is characterized by high tolerance to copper (up to 7.5 mM). The metal content in mycelia reached 0.9-7.76 mg in 1 g of dry biomass. Our results suggest that T. koningii strain seems to be a promising tool for bioremediation of agricultural areas co-contaminated with copper-based fungicides and chloroacetanilide herbicides.


Asunto(s)
Acetamidas/metabolismo , Cobre/metabolismo , Herbicidas/metabolismo , Trichoderma/metabolismo , Acetamidas/toxicidad , Biodegradación Ambiental , Biotransformación , Cobre/toxicidad , Sistema Enzimático del Citocromo P-450/metabolismo , Herbicidas/toxicidad , Iones , Lacasa/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Trichoderma/efectos de los fármacos , Trichoderma/enzimología
15.
Aptamers (Oxf) ; 2: 82-87, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-34079924

RESUMEN

Functional nucleic acids, including aptamers and deoxyribozymes, have become important in a variety of applications, particularly sensors. Aptamers are useful for recognition because of their ability to bind to targets with high selectivity and affinity. They can also be paired with deoxyribozymes to form signaling aptazymes. These aptamers and aptazymes have the potential to significantly improve the detection of small molecule pollutants, such as herbicides, in the environment. One challenge when developing aptazymes is that aptamer selection conditions can vary greatly from optimal deoxyribozyme reaction conditions. Aptamer selections commonly mimic physiological conditions, while deoxyribozyme selections are conducted under a wider range of divalent metal ion conditions. Isolating aptamers under conditions that match deoxyribozyme reaction conditions should ease the development of aptazymes and facilitate the activities of both the binding and catalytic components. Therefore, we conducted in vitro selections under different divalent metal ion conditions to identify DNA aptamers for the herbicides atrazine and alachlor. Conditions were chosen based on optimal reaction conditions for commonly-used deoxyribozymes. Each set of conditions yielded aptamers that were unrelated to aptamers identified under other selection conditions. No particular set of conditions stood out as being optimal from initial binding analysis. The best aptamers bound their target with high-micromolar to low-millimolar affinity, similar to the concentrations used during the selection procedures, as well as regulatory guidelines. Our results demonstrate that different metal ion concentrations can achieve the common goal of binding to a particular target, while providing aptamers that function under alternate conditions.

16.
ACS Appl Mater Interfaces ; 9(20): 17115-17124, 2017 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-28467036

RESUMEN

As Fenton systems suffer from the undesirable Fe(III)/Fe(II) cycle, great efforts were made to realize the effective reduction of Fe(III) to Fe(II). The effects of hydrothermal carbon (HTC) on the Fe(III)/H2O2 Fenton-like reaction and the subsequent degradation of alachlor in water was systematically investigated, and the results indicated that HTC could enhance alachlor degradation in Fe(III)/H2O2 by promoting the Fe(III)/Fe(II) cycle via electron transfer from HTC to Fe(III) ions. The apparent alachlor degradation rate constant in the HTC-G/Fe(III)/H2O2 system (7.02 × 10-2 min-1) was about 3 times higher than that in the Fe(III)/H2O2 system (2.25 × 10-2 min-1). The electron spin resonance spectra analysis revealed that HTC consists of abundant carbon-centered persistent free radicals to act as the electron donor. Meanwhile, the hydroxyl groups on the surface of HTC also played an important role in the enhanced alachlor degradation because the decrease in the surface hydroxyl groups on HTC significantly decreased the degradation of alachlor. On the basis of these results, an Fe(III) complex with surface hydroxyl groups on HTC was proposed to favor the electron transfer from the hydroxyl groups to Fe(III), and then, the simultaneously produced Fe(II) could accelerate the catalytic decomposition of H2O2 to facilitate alachlor degradation. These findings shed new light on the possible roles of carbon materials in a natural aquatic environment and provide a new pathway for environmental pollutant control and remediation of organic contaminants by HTC.

17.
ACS Appl Mater Interfaces ; 9(10): 8751-8758, 2017 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-28240850

RESUMEN

This study reports the H2O2 activation with different hematite nanocrystals and ascorbate ions for the herbicide alachlor degradation at pH 5. We found that hematite nanoplates (HNPs) exposed with {001} facets exhibited better catalytic performance than hematite nanocubes (HNCs) exposed with {012} facets, which was attributed to the formation of inner-sphere iron-ascorbate complexes on the hematite facets. The 3-fold undercoordination Fe cations of {001} facet favors the formation of inner-sphere iron-ascorbate complexes, while the 5-fold undercoordination Fe cations of {012} facet has stereo-hindrance effect, disfavoring the complex formation. The surface area normalized alachlor degradation rate constant (23.3 × 10-4 min-1 L m-2) of HNPs-ascorbate Fenton system was about 2.6 times that (9.1 × 10-4 min-1 L m-2) of HNCs-ascorbate counterpart. Meanwhile, the 89.0% of dechlorination and 30.0% of denitrification in the HNPs-ascorbate Fenton system were also significantly higher than those (60.9% and 13.1%) of the HNCs-ascorbate one. More importantly, the reductive dissolution of hematite by ascorbate was strongly coupled with the subsequent H2O2 decomposition by surface bound ferrous ions through surface iron cycle on the hematite facets in the hematite-ascorbate Fenton systems. This coupling could significantly inhibit the conversion of surface bound ferrous ions to dissolved ones, and thus account for the stability of hematite nanocrystals. This work sheds light on the internal relationship between iron geochemical cycling and contaminants degradation, and also inspires us to utilize surface iron cycle of widely existent hematite for environmental remediation.

18.
Ecotoxicol Environ Saf ; 139: 454-462, 2017 May.
Artículo en Inglés | MEDLINE | ID: mdl-28213322

RESUMEN

Lignocellulosic wastes and by-products containing lignin are now available in large amounts from forestry and industrial activities, and could be promising organic materials for the biosorption of pesticides by soils in order to reduce point-source pollution. Adding these materials to soil requires understanding the process of pesticide sorption-desorption by wood-soils, as sorption capacity could increase, with changes in pesticide bioavailability and final fate. The objective of this work was to study the effect that pine and oak wood added to soils had on the sorption/desorption of the pesticides linuron, alachlor, and metalaxyl. Experiments were conducted with two sandy loam and sandy clay soils each amended with two wood doses (5% and 50%) after different incubation times (0, 5 and 12 months). A low wood dose (5%) had no significant impact on the sorption (Kf) of alachlor, but Kf increased for linuron (up to 5.4-1.7 times) and metalaxyl (up to 4.4 and 8.6 times) in all wood-soil systems. The results were not significantly different after different incubation times. The desorption results indicated that wood decreases the sorption irreversibility of alachlor, and increases that of linuron and metalaxyl, with a varying effect of the wood-soil incubation time. The addition of a high wood dose to soil (50%) was more significant for increasing the sorption of all the pesticides, and the sorbed amounts remaining after desorption (>49% for linuron, >33% for alachlor and >6% for metalaxyl), although there was no apparent discrimination between the two types of woods. The role of the nature of the organic carbón (Koc values) for sorption was evidenced for alachlor and metalaxyl, but not for linuron. These outcomes are of interest for extending wood application to soil as a barrier for avoiding environmental risk by point-source pollution due to the use and management of pesticides in farming systems.


Asunto(s)
Plaguicidas/análisis , Contaminantes del Suelo/análisis , Suelo , Madera , Acetamidas/análisis , Adsorción , Alanina/análogos & derivados , Alanina/análisis , Linurona/análisis
19.
J Genomics ; 4: 42-7, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27672405

RESUMEN

We recently isolated Micrococcus sp. strain 2385 from Ochlockonee River, Florida and demonstrated potent biodegradative activity against two commonly used pesticides- alachlor [(2-chloro-2`,6`-diethylphenyl-N (methoxymethyl)acetanilide)] and endosulfan [(6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9methano-2,3,4-benzo(e)di-oxathiepin-3-oxide], respectively. To further identify the repertoire of metabolic functions possessed by strain 2385, a draft genome sequence was obtained, assembled, annotated and analyzed. The genome sequence of Micrococcus sp. strain 2385 consisted of 1,460,461,440 bases which assembled into 175 contigs with an N50 contig length of 50,109 bases and a coverage of 600x. The genome size of this strain was estimated at 2,431,226 base pairs with a G+C content of 72.8 and a total number of 2,268 putative genes. RAST annotated a total of 340 subsystems in the genome of strain 2385 along with the presence of 2,177 coding sequences. A genome wide survey indicated that that strain 2385 harbors a plethora of genes to degrade other pollutants including caprolactam, PAHs (such as naphthalene), styrene, toluene and several chloroaromatic compounds.

20.
Genom Data ; 8: 134-8, 2016 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-27330991

RESUMEN

We recently isolated a Pseudomonas sp. strain W15Feb9B from Ochlockonee River, Florida and demonstrated potent biodegradative activity against two commonly used pesticides - Alachlor [(2-chloro-2',6'-diethylphenyl-N (methoxymethyl)acetanilide)] and Endosulfan [(6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9methano-2,3,4-benzo(e)di-oxathiepin-3-oxide], respectively. To further identify the repertoire of metabolic functions possessed by strain W15Feb9B, a draft genome sequence was obtained, assembled, annotated and analyzed. The genome sequence of strain 2385 has been deposited in GenBank under accession number JTKF00000000; BioSample number SAMN03151543. The sequences obtained from strain 2385 assembled into 192 contigs with a genome size of 6,031,588, G + C content of 60.34, and 5512 total number of putative genes. RAST annotated a total of 542 subsystems in the genome of strain W15Feb9B along with the presence of 5360 coding sequences. A genome wide survey of strain W15Feb9B indicated that it has the potential to degrade several other pollutants including atrazine, caprolactam, dioxin, PAHs (such as naphthalene) and several chloroaromatic compounds.

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