Microplastics (MPs) that have accumulated in the environment are emerging as contaminating pollutants due to their interactions with metal ions. MPs change the migration and transformation of metal ...ions in the environment and afterward impact their environmental presence. Therefore, it is necessary to evaluate the interaction characteristics and mechanisms between Cd2+and MPs for assessing the ecological impacts of MPs. The traditional sequencing batch equilibrium test demonstrated that the sorption of Cd2+ onto MPs was related to the type of MPs present, the pH value of the solution, the ionic strength of the participants and the presence of humic acid. The sorption dynamics and isotherm experiment illustrated that the interactions were controlled by surface sorption and distribution effects. The specific surface area and surface charge were the main factors in managing the sorption process. FTIR spectra and a 2D-COS analysis showed that different functional groups played an important role in the sorption of Cd2+onto MPs. The results from this work afford new insights on how MPs may play an important role in the fate and transport of heavy metals and present a new analysis method for evaluating the environmental behavior of MPs and their role in transporting other contaminants.
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•The Cd-MPs interaction process was highly dependent on solution pH, ionic strength and humic acid.•The sorption was controled by surface sorption and distributional effects.•The 2D-COS analysis stated functional groups played an important role for sorption of Cd2+ on MPs.
As a new type of pollutant, microplastics have attracted increased attention because of their widespread and persistent existence in the water environment. In this study, we investigated one of the ...eight largest lakes in China—Wuliangsuhai Lake in Inner Mongolia. The microplastic concentration in Wuliangsuhai Lake ranges from 3.12 to 11.25 n/L. The different functional areas in Wuliangsuhai can be divided into four categories, namely effluent, fishing, intake and wetland areas. The highest microplastic concentration occurs in the intake area. The collected microplastics are divided into four types, i.e., fibers, pellets, fragments and films, of which fibers are the most abundant. Among the four functional areas of Wuliangsuhai Lake, the highest fiber concentration is observed in the fishing area. The microplastics in Wuliangsuhai Lake are mainly small size, and the microplastics smaller than 2 mm account for 98.2% of the total microplastics, while the microplastic size in the intake area is relatively large. Polystyrene and polyethylene are the main polymer types. Agricultural wastewater, domestic sewage and fishery discharge have the greatest impact on the microplastic distribution. This study reveals that the inland lakes in northern China are polluted by microplastics, which may cause potential harm to the surrounding environment.
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•Microplastics occurrence in Wuliangsuhai Lake were investigated.•The dominant microplastics were polystyrene fiber with 0–2 mm in size.•The discharge of human sewage and industrial wastewater were the main source of microplastics.•The spatial distribution of microplastics varies between different functional areas.
Microplastic pollution is an increasingly important environment problem. Many studies show the occurrence of microplastics in our environmental system. However, the freshwater system is less ...understood, especially in northwest China. We investigated the occurrence and characteristics of microplastics in the Wei River Basin, which is located in northwestern China. The Wei River is the largest tributary of the Yellow River and runs through three major provinces. In the Wei River, the concentration of microplastics in the surface waters varied from 3.67 to 10.7 items /L and in the sediments, the abundance of microplastics varied from 360 to 1320 items/kg. Fiber (50.1%)was the dominant types in water samples and sediments. The small size (<0.5 mm)(68.1%)were the main size of microplastics in Wei River. The types of microplastics were polyethylene, Polyvinyl chloride and polystyrene, as identified using a Fourier transform infrared spectrometer. This study could be a valuable reference for better understanding the microplastics pollution in inland northwestern China.
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•Microplastics were investigated in Wei River in the northwest of China.•The microplastics in the water samples of the Wei River are lower than the microplastics in the sediments.•Fiber and small size (<0.5 mm) were the dominant types and size in water samples and sediments of Wei River.
Microplastics may experience photoaging and breakdown into nanoplastics in aquatic environment as a result of long-term light irradiation. However, the underlying mechanisms responsible for the ...photodegradation of microplastics are largely overlooked. In this study, the photodegradation of microplastics, utilizing polystyrene microplastic (PS-MP) as a model, was investigated under irradiation with simulated solar light for as long as 150 d. A large amount of reactive oxygen species (ROS), including O2•−, 1O2, H2O2 and •OH, were detected in the PS-MP suspension due to light irradiation, which displayed significant relationships with the generated environmentally persistent free radicals (EPFRs). Distinct photoaging of PS-MP was observed with increased surface roughness and decreased particle size. However, these photoaging effects were significantly inhibited by ROS quenchers, suggesting that the generation ROS played a vital role in the PS-MP phototransformation. In addition, ROS induced formation of more oxidative functional groups on the PS-MP, thus enhancing the negative surface potential and the stability of PS-MP in water. This study elucidated the mechanism of formation of ROS by simulated solar light irradiated MPs and their subsequent roles in the phototransformation of MP, thus expanding current knowledge on the fate of MPs in aquatic environments.
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•ROS formed in PS-MP suspension under 150 d simulated sunlight irradiation.•ROS played a vital role in PS-MP phototransformation.•ROS induced formation of more oxidative functional groups on PS-MP surfaces.•Photoaging enhanced the stability of PS-MP in water.
•Photodegradation behaviors of MPs in the presence of clays were firstly explored.•Clay minerals, particularly kaolinite, significantly enhanced the MP photoaging.•The aging of PET was more prominent ...than PVC.•Clay facilitated the production of •OH, greatly contributing to MP degradation.•Photodegradation mechanism of MPs mediated by clay minerals was disclosed.
It is well known that microplastics (MPs) may experience weathering and aging under ultraviolet light (UV) irradiation, but it remains unclear if these processes are impacted by natural components, such as clay minerals. In this study, we systematically investigated the photodegradation behaviors of polyvinyl chloride (PVC) and poly (ethylene terephthalate) (PET), two utmost used plastics, in the presence of clay minerals (kaolinite and montmorillonite). The results demonstrated that the clay minerals, particularly kaolinite, significantly promoted the MPs photodegradation, and the aging of PET was more prominent. The photodegradation was the most distinct at pH 7.0, regardless of the presence or absence of the clay minerals. The results of electron paramagnetic resonance and inhibition experiments of reactive oxygen species indicated that the minerals, particularly kaolinite, remarkably facilitated production of •OH, which was the key species contributing to the photodegradation of MPs. Specifically, UV irradiation facilitated the photo-ionization of MPs, producing hydrated electrons and MP radical cations (MP+). The Lewis base sites prevalent on the clay siloxane surfaces could stabilize the MP radical cations and prevent their recombination with hydrated electrons, which promoted the generation of •OH under aerobic conditions, and facilitated the degradation of MP. Two-dimensional (2D) Fourier transformation infrared (FTIR) correlation spectroscopy (COS) analysis and ultra-high-performance liquid chromatography coupled to a Q Exactive Orbitrap HF mass spectrometer were used to identify the sequential changes of functional groups, and the degradation products of the MPs. This study improves our understanding on the aging of MPs in the complex natural environment.
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Plastics pollution in global soil systems is becoming a severely global issue and potential threat to terrestrial ecosystem serves and human health. Herein, in order to determine the degradability ...and ecological effects of polyethylene (PE) films, we measured the weight loss and characterization of PE films and analyzed variation in microbial community. The results of weight loss, SEM and FTIR spectra exhibited that PE films had unique degradation performance under different conditions. Simultaneously, we investigated the effects of PE films on the microbial community, and the microbiota colonizing on plastics. PE films may change the soil microbial community composition in soil, and hold the post of unique matrix for microbial colonization. These results indicate that the degradation of PE films and microbial community composition in soil can be affected by different conditions (soil layer, time and plants). By assessing the alteration of microbial community composition and PE films in soil, this work will contribute to enhance our understanding on the potential risks of plastics on soil ecosystems and provide a scientific basis for understanding the ecological effect of plastics on soil functions.
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•Degradation characteristics of PE films in soil were assessed.•PE films have different effects on microbial community under different conditions.•Compared with soil, PE films surfaces have unique microbial community composition.•The interactions between PE films and soil microbial community were explored.
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•SPC activated by discharge plasma is used to remove plasticizer from wastewater.•Plasticizer removal efficacy under various experimental conditions is evaluated.•Roles of active ...species in plasticizer removal are evaluated.•Mineralization process and byproducts formation are explored.•Enhancement mechanisms on plasticizer removal in such a system are discussed.
Phthalates, as additives in the plastic production process, were able to enter the water environment, causing huge risks to ecological environment and human health. The potential of phthalates elimination in aqueous using sodium percarbonate (SPC) activated by discharge plasma (marked as “SPC + plasma”) was evaluated, with dimethyl phthalate (DMP) as a model pollutant. Experimental results showed that about 92.1% of DMP was eliminated in the “SPC + plasma” system with the treatment time of 30 min, which was 30.7% higher than that in sole plasma system, and the synergetic intensity for DMP elimination reached up to 127.0; and the energy yield was also raised by 131%. H2O2 and OH radicals formation were promoted but ozone concentration decreased in the “SPC + plasma” system. Appropriate SPC dosage benefited DMP elimination, and the synergetic intensity increased from 2.0 to 127.0 as the SPC dosage increased from 0.06 mmol L−1 to 0.12 mmol L−1. OH radicals, O2·−, 1O2, and CO3·− played crucial roles in DMP elimination, and the roles of O2·− and 1O2 were strengthened in the “SPC + plasma” system. Ultraviolet–visible spectroscopy measurement, total content of organic carbon, atomic force microscopy and three-dimensional fluorescence analysis demonstrated that DMP molecular structure was destroyed during treatment, and some smaller molecular fractions were generated. The main intermediates included phthalic acid monomethyl ester, phthalic acid, o-phthalic anhydride, acetic acid, formic acid, and oxalic acid. The possible enhancement mechanisms for DMP elimination in the “SPC + plasma” system were proposed.
Microplastics are widespread in the environment and might transport readily by ocean currents, wind and atmospheric deposition. Simultaneously, antibiotics and heavy metals could often be detected in ...the environment. They are both positively charged, it is necessary to clarify the interactions of these pollutants with microplastics when they were coexist. In this study, the most commonly used polystyrene (PS) was selected as a representative microplastic. This study investigated the effect of Cd(II) on the sorption of TYL by PS in different coexistence systems. The results showed that: in the composite system, when TYL and Cd(II) coexist, the presence of Cd(II) could inhibit the sorption of TYL by PS, and the inhibitory effect increases with the increase of the concentration of Cd(II), indicating that competitive sorption dominates the sorption. When PS adsorbed Cd(II) first and then adsorbed TYL, the presence of Cd(II) was conducive to the sorption of TYL, and the sorption strengthened with the increase of Cd(II) concentration, indicating that the complexation between TYL and Cd(II) enhanced the sorption of TYL. In addition, initial pH values and ionic strength were essential in the sorption process. Therefore, this study could provide an important basis for evaluating the environmental behavior and ecological risk of microplastics in the process of compound pollution.
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•The effect of Cd(II) on the sorption of TYL by PS was first studied.•The Cd(II) addition inhibited the sorption of TYL by PS in coexist systems.•The Cd(II) addition enhanced the sorption of TYL by PS when Cd(II) first sorbed by PS.•Competition and complexation interactions were involved in the sorption process.
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•PS could accelerate the photolysis of TC at different pH.•1O2 and O2·- as major contributors, which enhanced the degradation of TC.•Aged PS accelerated the photolysis of TC due to ...the generation of EPFRs.•The degradation pathway of TC induced by PS was firstly proposed.•Five reaction pathways were presented based on identified products.
Tetracycline (TC) and polystyrene microplastics (PS MPs), co-occurring in environments inevitably, have been frequently detected in a variety of environmental media. The two major types of emerging pollutants are attracting the global concern due to their potential threat to biota. PS can serve as carriers of TC in aquatic environments, thus dramatically altering environmental behavior of individual PS or TC. However, the photolysis of TC induced by PS remains unknown. In this study, kinetic experiments, quenching experiments, electron paramagnetic resonance analysis (EPR), Two-dimensional correlation Fourier transform infrared spectroscopy (2D-FTIR-COS) and products identification, were conducted to investigate effect and underlying mechanism of PS on photolysis of TC under sunlight irradiation. The corresponding results demonstrated that PS could induce photolysis of TC. The hydroxyl radicals (·OH), singlet oxygen (1O2) and superoxide anion (O2·-) enhanced degradation of TC. Quantitative quenching analysis revealed that both 1O2 and O2·- were main contributors, with contributions of 15.25 ± 2.21% and 11.69 ± 1.84%, respectively. Simultaneously, PS was aged during photolysis of TC, and the intension of O/C was enhanced from 2.07% to 17.92% with increasing aging time. Interestingly, we verified that highly aged PS significantly accelerated the photolysis due to generation of environmentally persistent free radicals (EPFRs), and the degradation pathway of TC induced by PS was firstly proposed. Subsequently, the transformation mainly included five reactions: hydrolysis, hydroxylation, deamination, demethylation and decarbonylation. This work provided a promising strategy for better understanding environmental fate of antibiotics and MPs.
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•Photoaging under simulated sunlight irradiation enhanced the OP of PF-MP.•Simulated sunlight led to the increased generation of EPFRs and ROS in PF-MP.•The generated active species ...in PF-MP contributed to the elevated OP of PF-MP.•The PF-MP with an increased OP induced a higher cytotoxicity.
Phenol-formaldehyde resin microplastic (PF-MP) is one of the major inhalable microplastics in environments released from the manufacture, processing and usage of PF materials. The associated toxicities of PF-MP might be affected by photoaging. In this study, the dynamic evolutions of the oxidative potential (OP) and redox-active species, including environmentally persistent free radicals (EPFRs), reactive oxygen species (ROS), peroxides and conjugated carbonyls, as well as the associated cytotoxicity of PF-MP were systematically investigated as a result of the simulated sunlight irradiation. As the photoaging time extended, the OP of PF-MP increased. The contents of the produced conjugated carbonyls, ROS and PF-bound EPFRs due to light irradiation increased as well, and displayed significant correlations with the OP (Spearman r > 0.6, p < 0.05). The photoaged PF-MP distinctly increased the cellular ROS and reduced the cell viability of human lung epithelial adenocarcinoma cells (A549). The cytotoxicity of PF-MP showed a similar trend with the OP level in PF-MP, suggesting that the produced active species induced the in vitro toxicities. The results not only highlight the adverse health effects of photoaged PF-MP, but also provide new perspectives for the environmental risks of airborne MPs.
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