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1.
Environ Pollut ; 293: 118586, 2021 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-34843854

RESUMO

A large amount of plastic waste is generated yearly worldwide, and landfills are commonly used for the disposal of plastic waste. However, burying in landfill does not get rid of the plastic waste but leave the problem to the future. Previous works have showed that microplastics are presented in the landfill refuse and leachate, which might be potential sources of microplastics. In this work, characteristics of microplastic pollution in an informal landfill in South China were studied. Landfill refuse, underlying soil, leachate, and groundwater samples were collected from different sites within and around the landfill. Results show that microplastics in the landfill refuse and underlying soil varied from 590 to 103,080 items/kg and from 570 to 14,200 items/kg, respectively. Most of the microplastics are fibrous, small sized, and transparent. Polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET) are major polymer types. Scanning electron microscope (SEM) images and Fourier Transform Infrared (FTIR) spectra of the microplastic samples indicate varying degree of weathering. Microplastic abundances in the landfill leachate and groundwater ranged from 3 to 25 items/L and from 11 to 17 items/L, respectively. Microplastics detected in the landfill leachate and groundwater are even smaller compared with those in the refuse and underlying soil and their polymer types are more diverse. This work demonstrated that microplastics presented in an informal landfill without sufficient protection can leak out to the surrounding environment. The microplastic pollution originated from informal landfills should receive more attentions.

2.
J Hazard Mater ; 424(Pt C): 127606, 2021 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-34808447

RESUMO

In this study, a novel iron and nitrogen co-doped biochar (Fe/N-biochar) was successfully prepared and employed as an efficient adsorbent for micropollutants. The maximum adsorption capacity of Fe/N-biochar for bisphenol A (BPA) was 54 mg/g, which is significantly better than that of commercial graphene (19 mg/g) and activated carbon (6 mg/g). Additionally, for eight other common micropollutants (e.g., phenol, acetaminophen, and sulfamethoxazole), Fe/N-biochar also exhibited highly enhanced adsorption performance. The results of adsorption kinetics and isotherms studies showed that the adsorption of micropollutants onto Fe/N-biochar is by monolayer coverage. Thermodynamic studies further suggested that the adsorption process is feasible, spontaneous, and chemical in nature. The adsorption mechanism was investigated by correlation analysis between the adsorption capacity and the physiochemical properties of Fe/N-biochar. The results demonstrated that the strengthening of π-π electron donor-acceptor interactions between the organics and the adsorbent caused by the co-doping of iron and nitrogen was the dominant driving force behind the efficient adsorption of micropollutants. Furthermore, graphitic N and Fe-Nx were identified as the major adsorption sites. Simple heat treatment could effectively restore the adsorption capacity of Fe/N-biochar that had reached adsorption equilibrium. In view of its simple preparation method, highly enhanced adsorption capacity, and excellent recyclability, the prepared Fe/N-biochar can be regarded as a promising candidate for wastewater treatment.

3.
Exp Cell Res ; : 112881, 2021 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-34780784

RESUMO

AIMS: Osteoarthritis (OA) is a common degenerative disease that is pathologically characterized by destruction of the joint matrix and reduction of articular chondrocytes, resulting in joint deformity and motor dysfunction. However, the molecular mechanisms governing this pathology have not been elucidated to date. METHODS: In this study, we determined the expression levels of lncRNAs, circRNAs, and mRNAs extracted from synovial exosomes of OA and control patients. A network of circRNA/lncRNA-miRNA-mRNA interactions was established using MiRanda and TargetScan software to explore OA pathogenesis. The exosomal lncRNA, circRNA and mRNA expression profiles of the OA and control groups were analysed using LC human competing endogenous RNA (ceRNA) microarrays. The differentially expressed genes were analysed to determine their potential roles in the pathogenesis of OA by bioinformatic analysis. RESULTS: There were 52 mRNAs, 196 lncRNAs and 98 circRNAs differentially expressed in synovial exosomes between osteoarthritis synovial and the control group. The final ceRNA network of lncRNAs and circRNAs exhibited a complex interaction between ncRNA and mRNA related to OA pathological mechanisms. An intersection analysis of the ceRNA network showed that 22 miRNAs, 45 lncRNAs, and 34 circRNAs enriched in the PI3K/Akt and autophagy pathways correlated with 7 mRNAs and may play important roles in OA pathological mechanisms. CONCLUSION: Our work analysed mRNA/lncRNA/circRNA expression and displayed the ceRNA network of lncRNAs and circRNAs to profile the pathogenesis of OA in synovial exosomes. The results of this study may help to elucidate the pathogenesis of OA and may provide important references for further research attempting to identify more effective targets for the diagnosis and therapy of OA.

4.
Sci Rep ; 11(1): 18073, 2021 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-34508121

RESUMO

Neural coupled oscillators are a useful building block in numerous models and applications. They were analyzed extensively in theoretical studies and more recently in biologically realistic simulations of spiking neural networks. The advent of mixed-signal analog/digital neuromorphic electronic circuits provides new means for implementing neural coupled oscillators on compact, low-power, spiking neural network hardware platforms. However, their implementation on this noisy, low-precision and inhomogeneous computing substrate raises new challenges with regards to stability and controllability. In this work, we present a robust, spiking neural network model of neural coupled oscillators and validate it with an implementation on a mixed-signal neuromorphic processor. We demonstrate its robustness showing how to reliably control and modulate the oscillator's frequency and phase shift, despite the variability of the silicon synapse and neuron properties. We show how this ultra-low power neural processing system can be used to build an adaptive cardiac pacemaker modulating the heart rate with respect to the respiration phases and compare it with surface ECG and respiratory signal recordings from dogs at rest. The implementation of our model in neuromorphic electronic hardware shows its robustness on a highly variable substrate and extends the toolbox for applications requiring rhythmic outputs such as pacemakers.

5.
Cell Death Discov ; 7(1): 202, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34349099

RESUMO

Cancer is one of the most fatal diseases that threaten human health, whereas more than 90% mortality of cancer patients is caused by tumor metastasis, rather than the growth of primary tumors. Thus, how to effectively control or even reverse the migration of tumor cells is of great significance for cancer therapy. CtBP, a transcriptional cofactor displaying high expression in a variety of human cancers, has become one of the main targets for cancer prediction, diagnosis, and treatment. The roles of CtBP in promoting tumorigenesis have been well studied in vitro, mostly based on gain-of-function, while its physiological functions in tumor invasion and the underlying mechanism remain largely elusive. Snail (Sna) is a well-known transcription factor involved in epithelial-to-mesenchymal transition (EMT) and tumor invasion, yet the mechanism that regulates Sna activity has not been fully understood. Using Drosophila as a model organism, we found that depletion of CtBP or snail (sna) suppressed RasV12/lgl-/--triggered tumor growth and invasion, and disrupted cell polarity-induced invasive cell migration. In addition, loss of CtBP inhibits RasV12/Sna-induced tumor invasion and Sna-mediated invasive cell migration. Furthermore, both CtBP and Sna are physiologically required for developmental cell migration during thorax closure. Finally, Sna activates the JNK signaling and promotes JNK-dependent cell invasion. Given that CtBP physically interacts with Sna, our data suggest that CtBP and Sna may form a transcriptional complex that regulates JNK-dependent tumor invasion and cell migration in vivo.

6.
Zhongguo Yi Liao Qi Xie Za Zhi ; 45(4): 398-400, 2021 Jul 30.
Artigo em Chinês | MEDLINE | ID: mdl-34363365

RESUMO

One of critical technologies in a non-invasive positive airway pressure respirator is to output the airflow for meeting the requirement of respiratory patient in breath. In order to develop a safe and reliable blower driving system, a circuit based on the special chips MC33035 and MC33039 was designed. The linear relationship between the input control voltage and the output air flow was achieved. This designed circuit will be embedded in the non-invasive ventilator system as a module. And based on this circuit, the secure and controllable ventilation flow can be performed.


Assuntos
Respiração , Ventiladores Mecânicos , Humanos , Pulmão
8.
Phys Med Biol ; 66(15)2021 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-34198277

RESUMO

Our study aims to improve the signal-to-noise ratio of positron emission tomography (PET) imaging using conditional unsupervised learning. The proposed method does not require low- and high-quality pairs for network training which can be easily applied to existing PET/computed tomography (CT) and PET/magnetic resonance (MR) datasets. This method consists of two steps: populational training and individual fine-tuning. As for populational training, a network was first pre-trained by a group of patients' noisy PET images and the corresponding anatomical prior images from CT or MR. As for individual fine-tuning, a new network with initial parameters inherited from the pre-trained network was fine-tuned by the test patient's noisy PET image and the corresponding anatomical prior image. Only the last few layers were fine-tuned to take advantage of the populational information and the pre-training efforts. Both networks shared the same structure and took the CT or MR images as the network input so that the network output was conditioned on the patient's anatomic prior information. The noisy PET images were used as the training and fine-tuning labels. The proposed method was evaluated on a68Ga-PPRGD2 PET/CT dataset and a18F-FDG PET/MR dataset. For the PET/CT dataset, with the original noisy PET image as the baseline, the proposed method has a significantly higher contrast-to noise ratio (CNR) improvement (71.85% ± 27.05%) than Gaussian (12.66% ± 6.19%,P= 0.002), nonlocal mean method (22.60% ± 13.11%,P= 0.002) and conditional deep image prior method (52.94% ± 21.79%,P= 0.0039). For the PET/MR dataset, compared to Gaussian (18.73% ± 9.98%,P< 0.0001), NLM (26.01% ± 19.40%,P< 0.0001) and CDIP (47.48% ± 25.36%,P< 0.0001), the CNR improvement ratio of the proposed method (58.07% ± 28.45%) is the highest. In addition, the denoised images using both datasets also showed that the proposed method can accurately restore tumor structures while also smoothing out the noise.

9.
Chemosphere ; 282: 131126, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34118620

RESUMO

Aquaculture ponds are exposed to numerous potential microplastic sources, but studies on their microplastic pollution are still limited. Various culture species may influence the occurrence of microplastic in ponds. In the present study, the occurrence of microplastics was studied in aquaculture ponds for fish, crayfish, and crab, as well as in the natural lake near the aquaculture area around the Honghu Lake, which is the principal freshwater aquaculture area of China. The microplastic abundances ranged from 87 items/m3 to 750 items/m3 in the aquaculture ponds, and 117 items/m3 to 533 items/m3 in the lake. The crab ponds contained higher abundances of microplastics than fish ponds and the nearby natural lakes. Microplastics that were between 100 and 500 µm and larger than 1000 µm in size were predominant in the ponds and nearby lakes, whereas the proportion of microplastics that were smaller than 100 µm was higher in crab ponds than those in other ponds. Fragments and fibers were the predominant shapes of microplastics in the ponds. The proportion of smaller microplastics in the ponds had a positive correlation with the proportion of fragment microplastics. The results of this study implied that differences in the use of plastics in various types of aquaculture ponds might affect their microplastic pollution characteristics. Microplastics discharged from ponds to nearby lakes through drainage processes require attention in further studies.


Assuntos
Microplásticos , Poluentes Químicos da Água , Animais , Aquicultura , China , Monitoramento Ambiental , Lagos , Plásticos , Lagoas , Água , Poluentes Químicos da Água/análise
10.
J Hazard Mater ; 419: 126429, 2021 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-34174620

RESUMO

Sunlight-oxidative ageing is a common and critical process for microplastics (MPs) in aquatic environments. O2•-, 1O2, and •OH generation has been widely proven in this process, which can alter metal speciation based on its reduction and oxidation potential. Herein, chemical speciation of Ag mediated by polystyrene (PS) MPs was determined under simulated sunlight irradiation. The O2•- generation on the PS MPs surfaces is the vital factor for Ag+ reduction, regardless of acid or base conditions. The 1O2 and •OH are dominant factors, and 1O2 played a more important role than •OH for its higher formation amount, causing oxidative dissolution of newly formed Ag0 nanoparticles (NPs). The Ag NPs can hetero-aggregate with PS MPs through electrostatic interactions with O-containing groups (C-O, C-OH and CO), and co-precipitate from the water phase. This hetero-aggregation can stabilize Ag NPs by inhibiting Ag NPs surface photooxidation and suppressing Ag+ release. Transformation of Ag species (from Ag+ to Ag0 NPs) mediated by sunlight with PS MPs significantly suppressed acute toxicity of Ag+ to Escherichia coli, Selenastrum capricornutum, Daphnia magna and zebrafish. This study emphasized that PS MPs play an important role in the speciation, migration and toxicity of Ag+ in freshwater environments.


Assuntos
Microplásticos , Poluentes Químicos da Água , Animais , Cinética , Plásticos , Poliestirenos/toxicidade , Prata/toxicidade , Luz Solar , Poluentes Químicos da Água/toxicidade , Peixe-Zebra
11.
Environ Pollut ; 285: 117485, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34087638

RESUMO

The consumption of disposable face masks increases greatly because of the outbreak of the COVID-19 pandemic. Inappropriate disposal of wasted face masks has already caused the pollution of the environment. As made from plastic nonwoven fabrics, disposable face masks could be a potential source of microplastics for the environment. In this study, we evaluated the ability of new and used disposable face masks of different types to release microplastics into the water. The microplastic release capacity of the used masks increased significantly from 183.00 ± 78.42 particles/piece for the new masks to 1246.62 ± 403.50 particles/piece. Most microplastics released from the face masks were medium size transparent polypropylene fibers originated from the nonwoven fabrics. The abrasion and aging during the using of face masks enhanced the releasing of microplastics since the increasing of medium size and blue microplastics. The face masks could also accumulate airborne microplastics during use. Our results indicated that used disposable masks without effective disposal could be a critical source of microplastics in the environment. The efficient allocation of mask resources and the proper disposal of wasted masks are not only beneficial to pandemic control but also to environmental safety.


Assuntos
COVID-19 , Microplásticos , Humanos , Máscaras , Pandemias , Plásticos , SARS-CoV-2
12.
Environ Chem Lett ; : 1-28, 2021 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-34025333

RESUMO

Pollution by microplastics is of increasing concern due to their ubiquitous presence in most biological and environmental media, their potential toxicity and their ability to carry other contaminants. Knowledge on microplastics in freshwaters is still in its infancy. Here we reviewed 150 investigations to identify the common methods and tools for sampling microplastics, waters and sediments in freshwater ecosystems. Manta trawls are the main sampling tool for microplastic separation from surface water, whereas shovel, trowel, spade, scoop and spatula are the most frequently used devices in microplastic studies of sediments. Van Veen grab is common for deep sediment sampling. There is a need to develop optimal methods for reducing identification time and effort and to detect smaller-sized plastic particles.

13.
Sensors (Basel) ; 21(6)2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33808972

RESUMO

Indoor navigation has attracted commercial developers and researchers in the last few decades. The development of localization tools, methods and frameworks enables current communication services and applications to be optimized by incorporating location data. For clinical applications such as workflow analysis, Bluetooth Low Energy (BLE) beacons have been employed to map the positions of individuals in indoor environments. To map locations, certain existing methods use the received signal strength indicator (RSSI). Devices need to be configured to allow for dynamic interference patterns when using the RSSI sensors to monitor indoor positions. In this paper, our objective is to explore an alternative method for monitoring a moving user's indoor position using BLE sensors in complex indoor building environments. We developed a Convolutional Neural Network (CNN) based positioning model based on the 2D image composed of the received number of signals indicator from both x and y-axes. In this way, like a pixel, we interact with each 10 × 10 matrix holding the spatial information of coordinates and suggest the possible shift of a sensor, adding a sensor and removing a sensor. To develop CNN we adopted a neuro-evolution approach to optimize and create several layers in the network dynamically, through enhanced Particle Swarm Optimization (PSO). For the optimization of CNN, the global best solution obtained by PSO is directly given to the weights of each layer of CNN. In addition, we employed dynamic inertia weights in the PSO, instead of a constant inertia weight, to maintain the CNN layers' length corresponding to the RSSI signals from BLE sensors. Experiments were conducted in a building environment where thirteen beacon devices had been installed in different locations to record coordinates. For evaluation comparison, we further adopted machine learning and deep learning algorithms for predicting a user's location in an indoor environment. The experimental results indicate that the proposed optimized CNN-based method shows high accuracy (97.92% with 2.8% error) for tracking a moving user's locations in a complex building without complex calibration as compared to other recent methods.

14.
J Hazard Mater ; 415: 125615, 2021 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-33725550

RESUMO

Constructed wetlands (CWs) are commonly used for the treatment of wastewater. However, the removal of microplastics in CWs are poorly understood. In this work, the fate and behavior of microplastics of different shapes (film, fragment, and fiber) and sizes (0.5-1 mm and 2-4 mm) were studied. Results showed that the microplastic removal rate was 81.63% in surface flow constructed wetlands (SF-CWs) and 100% in horizontal subsurface flow constructed wetlands (HSF-CWs). Fragments and fibers with 2-4 mm sizes flowed out preferentially from SF-CWs. Retained microplastics accumulated dominantly near the inlet area. Biofilm attachment and physical filtration played an important role in the retention of microplastics. The microplastics' morphological features and the apertures of the substrate related to the transport of microplastics in the substrate. We observed the formation of holes, cracks, and weeny fibers on the surface of the microplastics extracted from the microcosms with a scanning electron microscope (SEM), but we detected no oxidation based on the Fourier transform infrared spectra. Our results suggest that CWs, especially HSF-CWs, are efficient for the removal of microplastic pollution. However, microplastics are persistent in CWs. The potential impacts of microplastics on the function of CWs should be further assessed.

15.
Sci Total Environ ; 780: 146546, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-33770602

RESUMO

Microplastic is an emerging contaminant of concern in soil globally due to its widespread and potential risks on the ecological system. Some basic issues such as the occurrence, source, and potential risks of microplastics in the soil are still open questions. These problems arise due to the lack of systematic and comprehensive analysis of microplastic in soils. Therefore, we comprehensively reviewed the current status of knowledge on microplastics in soil on detection, occurrence, characterization, source, and potential risk. Our review suggests that microplastics are ubiquitous in soil matrices globally. However, the research progress of microplastics in the soil is restricted by inherent technological inconsistencies and difficulties in analyzing particles in complex matrices, and studies on the occurrence and distribution of microplastics in soil environments remain very scarce, especially in Africa, South America, and Oceania. The consistency of the characteristics and composition of the microplastics in the aquatic environment and soil demonstrate they may share sources and exchange microplastics. Wide and varied sources of microplastic are constantly filling the soil, which causes the accumulation of microplastics in the soil. Studies on the effects and potential risks of microplastics in soil ecosystems are also reviewed. Limited research has shown that the combination and interaction of microplastics with contaminants they absorbed may affect soil health and function, and even migration along the food chain. The occurrence and impact of microplastic on the soil depend on the morphology, chemical components, and natural factors. We conclude that large research gaps exist in the quantification and estimation of regional emissions of microplastics in soil, factors affecting the concentration of microplastics, and microplastic disguising as soil carbon storage, which need more effort.

16.
Environ Pollut ; 274: 116554, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33529891

RESUMO

Plastic waste are introduced into the environment inevitably and their exposure in the environment causes deterioration in mechanical and physicochemical properties and leads to the formation of plastic fragments, which are considered as microplastics when their size is < 5 mm. In recent years, microplastic pollution has been reported in all kinds of environments worldwide and is considered a potential threat to the health of ecosystems and humans. However, knowledge on the environmental degradation of plastics and the formation of microplastics is still limited. In this review, potential hotspots for the accumulation of plastic waste were identified, major mechanisms and characterization methods of plastic degradation were summarized, and studies on the environmental degradation of plastics were evaluated. Future research works should further identify the key environmental parameters and properties of plastics affecting the degradation in order to predict the fate of plastics in different environments and facilitate the development of technologies for reducing plastic pollution. Formation and degradation of microplastics, including nanoplastics, should receive more research attention to assess their fate and ecological risks in the environment more comprehensively.


Assuntos
Plásticos , Poluentes Químicos da Água , Ecossistema , Monitoramento Ambiental , Poluição Ambiental , Humanos , Microplásticos , Poluentes Químicos da Água/análise
17.
Pest Manag Sci ; 77(2): 795-804, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32909332

RESUMO

BACKGROUND: Precise quantification of the fitness cost of synthetic auxin resistance has been impeded by lack of knowledge about the genetic basis of resistance in weeds. Recent elucidation of a resistance-endowing IAA16 mutation (G73N) in the key weed species kochia (Bassia scoparia), allows detailed characterization of the contribution of resistance alleles to weed fitness, both in the presence and absence of herbicides. Different G73N genotypes from a segregating resistant parental line (9425) were characterized for cross-resistance to dicamba, 2,4-d and fluroxypyr, and changes on stem/leaf morphology and plant architecture. Plant competitiveness and dominance of the fitness effects was quantified through measuring biomass and seed production of three F2 lines in two runs of glasshouse replacement series studies. RESULTS: G73N confers robust resistance to dicamba but only moderate to weak resistance to 2,4-D and fluroxypyr. G73N mutant plants displayed significant vegetative growth defects: (i) they were 30-50% shorter, with a more tumbling style plant architecture, and (ii) they had thicker and more ovate (versus lanceolate and linear) leaf blades with lower photosynthesis efficiency, and 40-60% smaller stems with less-developed vascular bundle systems. F2 mutant plants had impaired plant competitiveness, which can lead to 80-90% less biomass and seed production in the replacement series study. The pleiotropic effects of G73N were mostly semidominant (0.5) and fluctuated with the environments and traits measured. CONCLUSION: G73N is associated with significant vegetative growth defects and reduced competitiveness in synthetic auxin-resistant kochia. Management practices should target resistant kochia's high vulnerability to competition in order to effectively contain the spread of resistance.


Assuntos
Bassia scoparia , Chenopodiaceae , Herbicidas , Dicamba/farmacologia , Resistência a Herbicidas/genética , Herbicidas/farmacologia , Mutação
18.
Pest Manag Sci ; 77(4): 1775-1785, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33236492

RESUMO

BACKGROUND: Lack of fitness costs has been reported for multiple herbicide resistance traits, but the underlying evolutionary mechanisms are not well understood. Compensatory evolution that ameliorates resistance costs, has been documented in bacteria and insects but rarely studied in weeds. Dicamba resistant IAA16 (G73N) mutated kochia was previously found to have high fecundity in the absence of competition, regardless of significant vegetative growth defects. To understand if costs of dicamba resistance can be compensated through traits promoting reproductive success in kochia, we thoroughly characterized the reproductive growth and development of different G73N kochia biotypes. Flowering phenology, seed production and reproductive allocation were quantified through greenhouse studies, floral (stigma-anthers distance) and seed morphology, as well as resulting mating and seed dispersal systems were studied through time-course microcopy images. RESULTS: G73N covaried with multiple phenological, morphological and ecological traits that improve reproductive fitness: (i) 16-60% higher reproductive allocation; (ii) longer reproduction phase through early flowering (2-7 days); (iii) smaller stigma-anthers separation (up to 60% reduction of herkogamy and dichogamy) that can potentially promote selfing and reproductive assurance; (iv) 'winged' seeds with 30-70% longer sepals that facilitate long-distance seed dispersal. CONCLUSION: The current study demonstrates that costs of herbicide resistance can be ameliorated through coevolution of other fitness penalty alleviating traits. As illustrated in a hypothetical model, the evolution of herbicide resistance is an ongoing fitness maximization process, which poses challenges to contain the spread of resistance. © 2020 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.


Assuntos
Bassia scoparia , Chenopodiaceae , Herbicidas , Dicamba , Flores , Resistência a Herbicidas/genética , Herbicidas/farmacologia
19.
Mar Pollut Bull ; 162: 111901, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33310377

RESUMO

This literature review was conducted to collect present data on microplastics pollution in Iran's ecosystems. Most of the studies performed in aquatic environment were conducted in Persian Gulf & Oman Sea (70%). The Persian Gulf, along with the beaches of Bushehr and Hormozgan Provinces, are the most studied areas. Moreover, most of the studies were conducted in aquatic environments and only four studies were conducted in terrestrial environment (4/42). One study has assessed microplastics in commercial salt and another study has reported the microplastics presence in Iranian bottled mineral water brands. The investigation of microplastics associated with biota was highlighted, customarily for fish species. Microplastics were also present in urban wastewater samples in Sari and Bandar Abbas cities. Three studies were performed in freshwater ecosystems until now (Haraz River, Anzali wetland, and Taleqan dam). The need for further studies in this field still exists, especially in terrestrial and freshwater compartments.


Assuntos
Microplásticos , Poluentes Químicos da Água , Animais , Cidades , Ecossistema , Monitoramento Ambiental , Oceano Índico , Irã (Geográfico) , Omã , Plásticos , Poluentes Químicos da Água/análise
20.
Sci Total Environ ; 754: 141948, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32916488

RESUMO

There is a rising concern regarding the accumulation of microplastics in the aquatic ecosystems. However, compared to the marine environment, the occurrence, transport, and diffusion of microplastics in freshwater sediment are still open questions. This paper summarizes and compares the methods used in previous studies and provides suggestions for sampling and analysis of microplastics in freshwater sediment. This paper also reviews the findings on microplastics in freshwater sediment, including abundance, morphological characteristics, polymer types, sources, and factors affecting the abundance of microplastics in freshwater sediment. The results show that microplastics are ubiquitous in the investigated sediment of rivers, lakes, and reservoirs, with an abundance of 2-5 orders of magnitude across different regions. Low microplastics concentration was observed in the Ciwalengke River with an average abundance of 30.3 ± 15.9 items/kg. In particular, an extremely high abundance of microplastics was recorded in the urban recipient in Norway reaching 12,000-200,000 items/kg. Fibers with particle size less than 1 mm are the dominant shape for microplastics in freshwater sediment. In addition, the most frequently recorded colors and types are white/transparent, and PE/PS, respectively. Finally, we conclude that the consistency of morphological characteristics and components of microplastics between the beach or marine sediments and freshwater sediments may be an indicator of these interlinkages and source-pathways. Microplastics in freshwater sediment need further research and exploration to identify its spatial and temporal variations and driving force through further field sampling and implementation of standard and uniform analytical methodologies.

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