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1.
Appl Environ Microbiol ; 90(7): e0093324, 2024 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-38953372

RESUMO

Starch utilization system (Sus)D-homologs are well known for their carbohydrate-binding capabilities and are part of the sus operon in microorganisms affiliated with the phylum Bacteroidota. Until now, SusD-like proteins have been characterized regarding their affinity toward natural polymers. In this study, three metagenomic SusD homologs (designated SusD1, SusD38489, and SusD70111) were identified and tested with respect to binding to natural and non-natural polymers. SusD1 and SusD38489 are cellulose-binding modules, while SusD70111 preferentially binds chitin. Employing translational fusion proteins with superfolder GFP (sfGFP), pull-down assays, and surface plasmon resonance (SPR) has provided evidence for binding to polyethylene terephthalate (PET) and other synthetic polymers. Structural analysis suggested that a Trp triad might be involved in protein adsorption. Mutation of these residues to Ala resulted in an impaired adsorption to microcrystalline cellulose (MC), but not so to PET and other synthetic polymers. We believe that the characterized SusDs, alongside the methods and considerations presented in this work, will aid further research regarding bioremediation of plastics. IMPORTANCE: SusD1 and SusD38489 can be considered for further applications regarding their putative adsorption toward fossil-fuel based polymers. This is the first time that SusD homologs from the polysaccharide utilization loci (PUL), largely described for the phylum Bacteroidota, are characterized as synthetic polymer-binding proteins.


Assuntos
Proteínas de Bactérias , Bacteroidetes , Metagenoma , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Bacteroidetes/genética , Bacteroidetes/metabolismo , Celulose/metabolismo , Polímeros/metabolismo , Quitina/metabolismo , Polietilenotereftalatos/metabolismo
2.
Ecotoxicol Environ Saf ; 278: 116445, 2024 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-38733804

RESUMO

Low-density polyethylene (LDPE) conduces massive environmental accumulation due to its high production and recalcitrance to environment. In this study, We successfully enriched and isolated two strains, Nitratireductor sp. Z-1 and Gordonia sp. Z-2, from coastal plastic debris capable of degrading LDPE film. After a 30-day incubation at 30 ℃, strains Z-1 and Z-2 decreased the weight of branched-LDPE (BLDPE) film by 2.59 % and 10.27 % respectively. Furthermore, high temperature gel permeation chromatography (HT-GPC) analysis revealed molecular weight reductions of 7.69 % (Z-1) and 23.22 % (Z-2) in the BLDPE film. Scanning electron microscope (SEM) image showed the presence of microbial colonization and perforations on the film's surface. Fourier transform infrared spectroscopy (FTIR) analysis indicated novel functional groups, such as carbonyl and carbon-carbon double bonds in LDPE films. During LDPE degradation, both strains produced extracellular reactive oxygen species (ROS). GC-MS analysis revealed the degradation products included short-chain alkanes, alkanols, fatty acids, and esters. Genomic analysis identified numerous extracellular enzymes potentially involved in LDPE chain scission. A model was proposed suggesting a coordinated role between ROS and extracellular enzymes in the biodegradation of LDPE. This indicates strains Z-1 and Z-2 can degrade LDPE, providing a basis for deeper exploration of biodegradation mechanisms.


Assuntos
Biodegradação Ambiental , Plásticos , Polietileno , Praias , Espectroscopia de Infravermelho com Transformada de Fourier , Espécies Reativas de Oxigênio/metabolismo , Microscopia Eletrônica de Varredura
3.
Ecotoxicol Environ Saf ; 282: 116695, 2024 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-38981390

RESUMO

Microplastics (MPs) are recognized as a major environmental problem due to their ubiquitous presence in ecosystems and bioaccumulation in food chains. Not only humans are continuously exposed to these pollutants through ingestion and inhalation, but recent findings suggest they may trigger vascular inflammation and potentially worsen the clinical conditions of cardiovascular patients. Here we combine headspace analysis by needle trap microextraction-gas chromatography-mass spectrometry (HS-NTME-GC-MS) and biological assays to evaluate the effects of polystyrene, high- and low-density polyethylene MPs on phenotype, metabolic activity, and pro-inflammatory status of Vascular Smooth Muscle Cells (VSMCs) the most prominent cells in vascular walls. Virgin and artificially aged MPs (4 weeks at 40 °C and 750 W/m2 simulated solar irradiation) were comparatively tested at 1 mg/mL to simulate a realistic exposure scenario. Our results clearly show the activation of oxidative stress and inflammatory processes when VSMCs were cultured with aged polymers, with significant overexpression of IL-6 and TNF-α. In addition, volatile organic compounds (VOCs), including pentane, acrolein, propanal, and hexanal as the main components, were released by VSMCs into the headspace. Type-specific VOC response profiles were induced on vascular cells from different MPs.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas , Inflamação , Interleucina-6 , Microplásticos , Estresse Oxidativo , Microplásticos/toxicidade , Inflamação/induzido quimicamente , Estresse Oxidativo/efeitos dos fármacos , Interleucina-6/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Compostos Orgânicos Voláteis/toxicidade , Poliestirenos/toxicidade , Músculo Liso Vascular/efeitos dos fármacos , Músculo Liso Vascular/citologia , Humanos , Polietileno/toxicidade , Células Cultivadas , Miócitos de Músculo Liso/efeitos dos fármacos
4.
Ecotoxicol Environ Saf ; 283: 116847, 2024 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-39128451

RESUMO

Plastics are widely used worldwide due to their convenience. However, microplastics (MPs) accumulation poses a serious threat to ecosystem health. Therefore, understanding the effects of MPs on living organisms within their native ecosystem is crucial. Previous studies have primarily focused on the impacts of MPs in aquatic environments, whereas the effects of MPs on terrestrial ecosystems have remained largely understudied. Therefore, our study assessed the impacts of MPs on soil ecosystems by characterizing their toxic effects on earthworms (Eisenia fetida). Here, we exposed earthworms to two representative plastics within soil environments: polyvinyl chloride (PVC) and low-density polyethylene (LDPE). Given the known link between MPs and oxidative stress, we next quantified oxidative stress markers and mitochondrial function to assess the effects of MPs on the redox metabolism of earthworms. Mitochondria are crucial metabolic organelles that generate reactive oxygen species via uncontrolled ATP production. Our findings demonstrated that MPs exert different effects depending on their type. Neither the PVC-exposed groups nor the LDPE-exposed groups exhibited changes in oxidative stress, as worked by the action of superoxide dismutase (SOD) and glutathione (GSH). While treatment of the two types of MP did not significantly affect the amount of reactive oxygen species/reactive nitrogen species (ROS/RNS) generated, PVC exhibited a more pronounced effect on antioxidant system compared to LDPE. However, mitochondrial function was markedly decreased in the group exposed to high LDPE concentrations, suggesting that the examined LDPE concentrations were too low to activate compensatory mechanisms. Collectively, our findings demonstrated that exposure of MPs not only influences the antioxidant defense mechanisms of earthworms but also alters their mitochondrial function depending on their types.


Assuntos
Glutationa , Microplásticos , Mitocôndrias , Oligoquetos , Estresse Oxidativo , Polietileno , Cloreto de Polivinila , Espécies Reativas de Oxigênio , Poluentes do Solo , Animais , Oligoquetos/efeitos dos fármacos , Oligoquetos/fisiologia , Estresse Oxidativo/efeitos dos fármacos , Cloreto de Polivinila/toxicidade , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Polietileno/toxicidade , Microplásticos/toxicidade , Poluentes do Solo/toxicidade , Espécies Reativas de Oxigênio/metabolismo , Glutationa/metabolismo , Superóxido Dismutase/metabolismo
5.
Int J Mol Sci ; 25(11)2024 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-38892267

RESUMO

Food safety and quality are major concerns in the food industry. Despite numerous studies, polyethylene remains one of the most used materials for packaging due to industry reluctance to invest in new technologies and equipment. Therefore, modifications to the current materials are easier to implement than adopting whole new solutions. Antibacterial activity can be induced in low-density polyethylene films only by adding antimicrobial agents. ZnO nanoparticles are well known for their strong antimicrobial activity, coupled with low toxicity and UV shielding capability. These characteristics recommend ZnO for the food industry. By incorporating such safe and dependable antimicrobial agents in the polyethylene matrix, we have obtained composite films able to inhibit microorganisms' growth that can be used as packaging materials. Here we report the obtaining of highly homogenous composite films with up to 5% ZnO by a melt mixing process at 150 °C for 10 min. The composite films present good transparency in the visible domain, permitting consumers to visualize the food, but have good UV barrier properties. The composite films exhibit good antimicrobial and antibiofilm activity from the lowest ZnO composition (1%), against both Gram-positive and Gram-negative bacterial strains. The homogenous dispersion of ZnO nanoparticles into the polyethylene matrix was assessed by Fourier transform infrared microscopy and scanning electron microscopy. The optimal mechanical barrier properties were obtained for composition with 3% ZnO. The thermal analysis indicates that the addition of ZnO nanoparticles has increased thermal stability by more than 100 °C. The UV-Vis spectra indicate a low transmittance in the UV domain, lower than 5%, making the films suitable for blocking photo-oxidation processes. The obtained films proved to be efficient packaging films, successfully preserving plum (Rome) tomatoes for up to 14 days.


Assuntos
Embalagem de Alimentos , Polietileno , Solanum lycopersicum , Óxido de Zinco , Óxido de Zinco/química , Óxido de Zinco/farmacologia , Embalagem de Alimentos/métodos , Polietileno/química , Solanum lycopersicum/microbiologia , Antibacterianos/farmacologia , Antibacterianos/química , Testes de Sensibilidade Microbiana , Anti-Infecciosos/farmacologia , Anti-Infecciosos/química , Biofilmes/efeitos dos fármacos
6.
Int J Mol Sci ; 25(10)2024 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-38791107

RESUMO

The present study employs X-ray photoelectron spectroscopy (XPS) to analyze plastic samples subjected to degradation processes with the aim to gain insight on the relevant chemical processes and disclose fragmentation mechanisms. Two model plastics, namely polystyrene (PS) and polyethylene (PE), are selected and analyzed before and after artificial UV radiation-triggered weathering, under simulated environmental hydrodynamic conditions, in fresh and marine water for different time intervals. The object of the study is to identify and quantify chemical groups possibly evidencing the occurrence of hydrolysis and oxidation reactions, which are the basis of degradation processes in the environment, determining macroplastic fragmentation. Artificially weathered plastic samples are analyzed also by Raman and FT-IR spectroscopy. Changes in surface chemistry with weathering are revealed by XPS, involving the increase in chemical moieties (hydroxyl, carbonyl, and carboxyl functionalities) which can be correlated with the degradation processes responsible for macroplastic fragmentation. On the other hand, the absence of significant modifications upon plastics weathering evidenced by Raman and FT-IR spectroscopy confirms the importance of investigating plastics surface, which represents the very first part of the materials exposed to degradation agents, thus revealing the power of XPS studies for this purpose. The XPS data on experimentally weathered particles are compared with ones obtained on microplastics collected from real marine environment for investigating the occurring degradation processes.


Assuntos
Espectroscopia Fotoeletrônica , Plásticos , Polietileno , Espectroscopia Fotoeletrônica/métodos , Plásticos/química , Polietileno/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Análise Espectral Raman/métodos , Poliestirenos/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/análise , Água do Mar/química , Microplásticos/química , Oxirredução
7.
Molecules ; 29(20)2024 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-39459318

RESUMO

This work focused on determining the factors that are of key importance in the oxygen barrier properties of low-density polyethylene (LDPE). It has been shown that, depending on the type and amount of the low-molecular-weight compound (tetracosane, paraffin wax, paraffin oil) introduced into the LDPE matrix, it can contribute to the improvement or deterioration of barrier properties. Tetracosane and paraffin wax incorporated into the LDPE matrix caused a reduction in oxygen permeability parameters compared to neat polyethylene. As their content increased, the barrier properties of the samples towards oxygen also increased. A completely opposite effect was achieved with paraffin oil. The results of comprehensive studies provide evidence that in the case of LDPE blends, two mechanisms are responsible for changing/controlling their transport properties. The first mechanism is associated with changes in the molecular packing in the interlamellar amorphous regions, while the second is related to the crystallinity of the samples. In cases where there are no changes in crystallinity, the density of the amorphous phase becomes the decisive factor in barrier properties, as clearly shown by results assessing chain dynamics.

8.
Environ Geochem Health ; 46(5): 159, 2024 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-38592645

RESUMO

In recent years, low-density polyethylene (LDPE) has emerged as an essential component of the routine tasks that people engage in on a daily basis. However, over use of it resulted in environmental buildup that contaminated aquatic habitats and human health. Biodegradation is the most effective way for controlling pollution caused by synthetic plastic waste in a sustainable manner. In the present study, the LDPE degrading bacterial strain was screened from gut of Earthworms collected from plastic waste dumped area Mettur dam, Salem district, Tamil Nadu, India. The LDPE degrading bacterial strain was screened and identified genotypically. The LDPE degrading Bacillus gaemokensis strain SSR01 was submitted in NCBI. The B. gaemokensis strain SSR01 bacterial isolate degraded LDPE film after 14 days of incubation and demonstrated maximum weight loss of up to 4.98%. The study of deteriorated film using attenuated total reflection-Fourier transform infrared revealed the presence of a degraded product. The degradation of LDPE film by B. gaemokensis strain SSR01 was characterized by field-emission scanning electron microscopy analysis for surface alterations. The energy dispersive X-ray spectroscopy test confirmed that the broken-down LDPE film had basic carbon reduction. The present study of LDPE flim biodegradation by B. gaemokensis strain SSR01 has acted as a suitable candidate and will help in decreasing plastic waste.


Assuntos
Bacillus , Oligoquetos , Humanos , Animais , Polietileno , Índia , Biodegradação Ambiental
9.
Bull Environ Contam Toxicol ; 112(3): 41, 2024 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-38386139

RESUMO

Plastic is an important part of today's human daily lifestyle, and it is classified as a "global pollutant" due to its durability. The natural degradation of plastic is extremely slow and will take a hundred years or more. The ultimate destinations of plastics as well as their effects on the ecosystem vary with the type of plastic and the rate of their degradation. In this study, an attempt was made to explain the degradation of low-density polyethylene (LDPE) plastic beads with the help of selected bacterial isolates in both laboratory and field conditions. 16 S rRNA gene sequencing further identified the bacterial isolates as Micrococcus luteus and Bacillus pumilus, obtained from the municipal waste disposal site near Anand, Gujarat, India. The beads were subjected to photolysis and hydrolysis for a predetermined amount of time in addition to biodegradation. After 60 days of treatment with Pseudomonas aeruginosa, Micrococcus luteus, and Bacillus pumilus in both laboratory and field conditions, a significant percentage decrease in the weight of LDPE beads was observed. Pseudomonas aeruginosa was taken as a positive control. Further, the rate of degradation was found to be accelerated in the presence of 10% starch.


Assuntos
Ecossistema , Polietileno , Humanos , Hidrólise , Fotólise , Biodegradação Ambiental
10.
Angew Chem Int Ed Engl ; 63(8): e202317594, 2024 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-38183405

RESUMO

Hydrocracking catalysis is a key route to plastic waste upgrading, but the acid site-driven C-C cleavage step is relatively sluggish in conventional bifunctional catalysts, dramatically effecting the overall efficiency. We demonstrate here a facile and efficient way to boost the reactivity of acid sites by introducing Ce promoters into Pt/HY catalysts, thus achieving a better metal-acid balance. Remarkably, 100 % of low-density polyethylene (LDPE) can be converted with 80.9 % selectivity of liquid fuels over the obtained Pt/5Ce-HY catalysts at 300 °C in 2 h. For comparison, Pt/HY only gives 38.8 % of LDPE conversion with 21.3 % selectivity of liquid fuels. Through multiple experimental studies on the structure-performance relationship, the Ce species occupied in the supercage are identified as the actual active sites, which possess remarkably-improved adsorption capability towards short-chain intermediates.

11.
Biodegradation ; 34(4): 383-403, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37055700

RESUMO

Plastic accumulation has become a serious environmental threat. Mitigation of plastic is important to save the ecosystem of our planet. With current research being focused on microbial degradation of plastics, microbes with the potential to degrade polyethylene were isolated in this study. In vitro studies were performed to define the correlation between the degrading capability of the isolates and laccase, a common oxidase enzyme. Instrumental analyses were used to evaluate morphological and chemical modifications in polyethylene, which demonstrated a steady onset of the degradation process in case of both isolates, Pseudomonas aeruginosa O1-P and Bacillus cereus O2-B. To understand the efficiency of laccase in degrading other common polymers, in silico approach was employed, for which 3D structures of laccase in both the isolates were constructed via homology modeling and molecular docking was performed, revealing that the enzyme laccase can be exploited to degrade a wide range of polymers.


Assuntos
Polímeros , Pseudomonas aeruginosa , Pseudomonas aeruginosa/metabolismo , Pseudomonas/metabolismo , Bacillus cereus/metabolismo , Lacase/metabolismo , Ecossistema , Simulação de Acoplamento Molecular , Plásticos/análise , Plásticos/metabolismo , Polietileno/química , Polietileno/metabolismo , Biodegradação Ambiental
12.
Biodegradation ; 2023 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-37926750

RESUMO

The present study was proposed with the idea to screen and isolate efficient low-density polyethylene (LDPE) degrading novel bacterial strains from the plastic-contaminated dumping site. The identification of the bacterial isolate was performed with the help of microbiological and molecular characterization approaches. The screening of the best isolate was performed based on its growth in Bushnell-Hass broth supplemented with LDPE sheets as the sole carbon source. The molecular characterization revealed that the isolate WD4 showed a similarity with the Pseudomonas aeruginosa species. A comparative analysis of Pseudomonas aeruginosa WD4 identified in the current study with Pseudomonas putida MTCC 2445 strain was performed. The present study demonstrated that the bacterial isolate showed 9.2% degradation of LDPE films while Pseudomonas putida revealed a 6.5% weight reduction after 100 days of incubation at 37 °C. The end products of the LDPE degradation were analysed using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS). The LDPE degradation products eluted include fatty acids such as octadecanoic, hexadecanoic acid, dodecanal, and octyl palmitoleate, alkanes, and some of the unknown compounds after 100 days of microbial treatment with the isolated strain. The detailed analysis of the by-products generated in the current study indicates their contribution to the biochemical pathway of LDPE degradation. The profound scope lies in the scalability of these bacterial strains at the industrial level to combat the LDPE waste and similar plastic garbage problems, globally.

13.
Ecotoxicol Environ Saf ; 264: 115399, 2023 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-37639827

RESUMO

Physical thickness of low-density polyethylene (LDPE) films might determine the release rate of phthalic acid esters (PAEs) & structural integrity and affect production efficiency. However, this critical issue is still unclear and little reported. Aging effects were evaluated in LDPE films with the thickness of 0.006, 0.008, 0.010 and 0.015 mm in a maize field of irrigation region. The Scanning electron microscope (SEM) results showed that the proportion of damaged area (Dam) to total area of LDPE films was massively lowered with increasing thickness after aging. The highest and lowest Dam was 32.2% and 3.5% in 0.006 and 0.015 mm films respectively. Also, the variations in peak intensity of asymmetric & symmetrical stretching vibrations (ASVI & SSVI) were detected using Fourier transform infrared spectrum (FTIR), indicating that the declines in peak intensity tended to be slower with thickness. Interestingly, the declines in physical integrity were tightly associated with increasing exhalation rate of PAEs. Average releasing rate of PAEs was 38.2%, 31.4%, 31.5% and 19.7% in LDPE films from 0.006 to 0.015 mm respectively. Critically, thicker film mulching can lead to greater soil water storage at plough layer (SWS-PL) and better thermal status, accordingly harvesting higher economic benefit. Therefore, LDPE film thickening may be a solution to reduce environmental risk but improve production efficiency in arid region.


Assuntos
Luz , Polietileno , Solo , Vibração
14.
Molecules ; 28(3)2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36771048

RESUMO

Microplastics and nanoplastics represent one of the major environmental issues nowadays due to their ubiquitous presence on Earth, and their high potential danger for living systems, ecosystems, and human life. The formation of both microplastics and nanoplastics strongly depends on both the type of pristine materials and the degradation processes related to biological and/or abiotic conditions. The aim of this study is to investigate the effect of two of the most relevant abiotic parameters, namely temperature and light, taken under direct control by using a Solar box, on five types of reference polymers: high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET). A multi-analytical approach was adopted to investigate in detail the first steps of plastics degradation. Samples of plastic materials at different degradation times were analyzed by means of 1H NMR spectroscopy and thermal desorption gas chromatography mass spectrometry (TD-GC-MS) technique. Several minor molecular species released during degradation were consistently identified by both techniques thus providing a comprehensive view of the various degradation products of these five types of microplastics.

15.
Bull Environ Contam Toxicol ; 112(1): 19, 2023 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-38142453

RESUMO

Every year, human activities introduce large amounts of synthetic plastics into the environment. Decomposition of the plastic derivatives is very difficult and time consuming, so it is essential to eliminate these pollutants using different methods. Bioremediation, is suitable option, because of the low cost and environmentally safe. In this research, degradation of low-density polyethylene (LDPE) was investigated by two strains, isolated from Hamadan province (Iran) landfill soil. After identification by 16sr DNA primers, their abilities of polyethylene biodegradation were examined by Fourier transform infrared (FTIR), SEM and Gas Chromatography-Mass Spectrometry (GC-MS). Using media contain polyethylene) after and before addition of bacteria), toxicity test was conducted by measuring the germination index, root and hypocotyl length of Lactuca sativa seed. After three months, 10.15% ± 1.04 weight loss of LDPE achieved through strain Stenotrophomonas sp. degradation. Both strains had high biofilm formation capacity, confirmed by Electron microscope images and FTIR analysis. GC-MS confirmed the presence of the end-product of LDPE degradation (Pentacosane, Hexacosane, and Octadecane). Both, Stenotrophomonas sp. and Alcaligenaceae bacterium had significant detoxification ability. In media contain LDPE (without bacteria), decrease in the germination of lettuce seeds was observed.


Assuntos
Poluentes Ambientais , Polietileno , Humanos , Polietileno/química , Biodegradação Ambiental , Stenotrophomonas/metabolismo , Bactérias/metabolismo , Poluentes Ambientais/metabolismo , Plásticos
16.
J Food Sci Technol ; 60(3): 996-1005, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36908340

RESUMO

The shelf life of dried garlic powder packaged in high-density polyethylene (HDPE), low-density polyethylene (LDPE), and aluminum laminated pouch (ALP) under accelerated storage temperature (5° to 40 °C) and humidity (70-90% RH) conditions, was predicted using GAB mathematical model. The water activity value reduced significantly from 0.83 to 0.31 as the moisture content reduced. The temperature had a negative effect on color change and the lightness value and whiteness index of garlic powder significantly decreased from 62.21 to 56.06 and 50.67 to 44.91 respectively, when temperature increased from 70° to 90° C. The storage life of garlic powder was 24, 78 and 210 days in LDPE, HDPE, and ALP, respectively under domestic storage conditions (40 °C, 90% RH). Therefore, under industrial storage conditions (5 °C, 70% RH), garlic could be preserved for 1.32, 4.30 and 7.28 years in LDPE, HDPE and ALP, respectively.

17.
Environ Res ; 209: 112807, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35093312

RESUMO

The occurrence of microplastics (MPs) in soils can negatively affect soil biodiversity and function. Soil amendments applied to MP-contaminated soil can alter the overall soil properties and enhance its functions and processes. However, little is known about how soil amendments improve the quality of MP-contaminated soils. Thus, the present study used a microcosm experiment to explore the potential effects of four types of biochar on the chemical and microbial properties of low-density polyethylene (LDPE) MP-contaminated soil under both drought and well-watered conditions. The results show that the biochars altered soil pH, electrical conductivity (EC), available phosphorous, and total exchangeable cations (TEC) with some variability depending on the biochar type. Oilseed rape straw (OSR)-derived biochars increased soil pH, EC, and TEC under both water conditions with the highest values of 7.94, 0.54 dS m-1 and 22.0 cmol(+) kg-1, respectively. Soil enzyme activities varied under all treatments; in particular, under drought conditions, the fluorescein diacetate activity increased in soils with high temperature (700 °C) biochar. The application of soft wood pellet biochar (700 °C) to MP-contaminated soil increased urease activity by 146% under well-watered conditions. OSR-derived biochars significantly reduced soil acid phosphatase activity under both water conditions. With biochar supplementation, the diversity indices of the bacterial community increased in well-watered soil but not in soil under drought conditions. The abundance of bacterial phyla, such as Firmicutes, Proteobacteria, Actinobacteria, Dictyoglomi, and Gemmatimonadetes, was relatively high in all treatments. Biochar application resulted in negligible variations in bacterial communities under drought conditions but significant variations under well-watered conditions. The findings of this study imply that biochar can be used as a soil amendment to improve the overall soil quality of MP-contaminated soil, but its impact varies depending on the pyrolysis feedstock and temperature. Thus, selecting a suitable biochar is important for improving the soil quality in MP-contaminated soils.


Assuntos
Plásticos , Poluentes do Solo , Carvão Vegetal , Microplásticos , Solo/química , Poluentes do Solo/análise
18.
Molecules ; 27(12)2022 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35744800

RESUMO

Polyethylene, a thermoplastic resin made by ethylene polymerization, is widely used in electrical insulation. In this study, low-density polyethylene (LDPE) is used as a matrix with micro- and nano-ZnO particles as a filler to produce different proportions of micro- and nano-ZnO composites by melt blending. These samples are characterized by Polarized Light Microscopy (PLM) and FTIR tests, with their conductance measured under different field strengths. The current density vs. electric field strength (J-E) curve of micro- and nano-ZnO composites under different field strengths are measured and analyzed. The J-E curves of different composites at different temperatures are measured to explore conductance with temperature. The results of these tests showed that nano-ZnO composites successfully suppressed conductivity at elevated temperatures and electric field strengths, while micro-ZnO composites increased the conductivity relative to pure LDPE.

19.
Artigo em Inglês | MEDLINE | ID: mdl-35675175

RESUMO

Microplastics act as a potential vector for a wide range of contaminants, which have emerged as a major environmental hazard in the modern world. Considering the seriousness of the problem, a simulated laboratory and field experiment were conducted to study the weathering of pristine microplastics following long-term exposure to natural background radiation and the marine environment after being disposed of in the open environment. For the study, polyethylene-originating (HDPE and LDPE) microplastics were chosen. The study revealed that radiation exposure causes surface roughness and cracks, leading to an increased surface area, which can invite a wide spectrum of pollutants to sorb on their surface. Furthermore, we report that the radiation-induced morphological changes favor microbial colonization on the microplastic surface when exposed to the marine environment. The growth of biofilms on the surface of microplastics reduces their hydrophobicity, which may attract a wide variety of polar contaminants. The study led to an interesting finding: that the HDPE microplastic surface is more conducive for biofilm growth in comparison to the LDPE surface.


Assuntos
Microplásticos , Poluentes Químicos da Água , Microplásticos/toxicidade , Plásticos , Polietileno , Poluentes Químicos da Água/análise , Tempo (Meteorologia)
20.
Bull Environ Contam Toxicol ; 109(6): 949-955, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35230452

RESUMO

Mineral bottled water packed in three polymers viz., virgin polyethylene terephthalate (PET), recycled PET, and low-density polyethylene (LDPE) were investigated for the occurrence, migration, and health risk of phthalic acid esters (PAEs) at 25 °C, 35 °C, and 45 °C. The average concentration of six USEPA priority PAEs in refrigerated water samples was highest in recycled PET> LDPE > virgin PET. The highest leaching was seen at 45 °C after 2 days for LDPE water packets with ∑6PAEs amounting to 64,300 ng/L. Similarly, for recycled PET, the highest migration was seen at 45 °C after seven days (3,800 µg/L). Bis 2-ethyl hexyl phthalate (DEHP) and di-n-butyl phthalate (DnBP) were the predominant plasticizers from PET bottles and LDPE water packets, respectively. Predicted concentration after three weeks based on best fit obtained through the polynomial model for PET bottles was seen higher than the recommended limit suggested by USEPA (6 µg/L) and WHO (8 µg/L).


Assuntos
Água Potável , Plastificantes , Água Potável/análise , Plastificantes/análise , Polietileno , Polietilenotereftalatos
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