Environmental behaviors of microplastics in aquatic systems: A systematic review on degradation, adsorption, toxicity and biofilm under aging conditions

Microplastics (MPs, < 5 mm) in the environment have attracted worldwide attention due to their wide distribution and difficulty in handling. Aging processes such as UV irradiation, biodegradation, physical abrasion and chemical oxidation can affect the environmental behavior of MPs. This review article summarizes different aging processes of MPs and subsequent effects on the adsorption of pollutants, the leaching of additives, and the toxicity of MPs. In addition, the formation process of biofilm on the surface of MPs and the interactions between biofilm and aged MPs are revealed. MPs can accumulate different environmental pollutants (organic pollutants, heavy metals, microorganisms, etc.) through surface adsorption, pore filling and distribution. Moreover, the aging of MPs affects their adsorption performance toward these pollutants due to a series of changes in their specific surface area and oxygen-containing functional groups. The release of some toxic additives such as phthalates after aging can enhance the toxic effects of MPs. Aging also changes the shape and size of MPs, which can affect the eating habits of the organisms and further increase the potential toxicity of MPs. This article conducts a systematical analysis and summary of the environmental behavior and physicochemical properties of MPs as well as the changes due to MPs aging, which helps to better understand the impact of aging on MPs in the environment. Future research on MPs aging should reduce the knowledge gap between laboratory simulation and actual conditions and increase the environmental relevance.

Photo-aging of polyvinyl chloride microplastic in the presence of natural organic acids

In this study, a new photo-aging pathway in the aquatic environments and the underlying transformation mechanism were described for polyvinyl chloride microplastic (PVC-MP). Our results indicated that the photo-aging of PVC-MP was strongly dependent on particle size and the aging reaction could be facilitated in the presence of low-molecular-weight organic acid (LMWOA) and LMWOA-Fe(III) complex under simulated and natural sunlight irradiation and ambient conditions. The hydroxyl radical (OH•) generated from the photolysis of LMWOA or its ferric complexes played a dominant role in enhancing PVC-MP degradation. In situ Fourier transform infrared and Raman spectroscopic techniques and theoretical calculations further confirmed that C-Cl bond cleavage and formation of polyene and carbonyl underwent on the PVC-MP surface, especially in the presence of LMWOA and LMWOA-Fe(III). Moreover, PVC-MP surface oxidation also led to the increase of the specific surface area and affinity towards water as indicated by the results of scanning electron microscopy, Brunauer-Emmett-Teller tests and contact angles for water, which would further enhance the adsorption of polar contaminants on PVC-MP and thus increase the health risk of PVC-MP on aquatic organisms.

Microplastics act as vectors for antibiotic resistance genes in landfill leachate: The enhanced roles of the long-term aging process

Microplastics (MPs) are found to be ubiquitous and serve as vectors for other contaminants, and the inevitable aging process changes MP properties and fates. However, whether the MPs in aging process affects the fates of antibiotic resistance gene (ARGs) in aquatic environments is poorly understood. Herein, the physicochemical property alteration of MPs being aged in landfill leachate, an important reservoir of MPs and ARGs, was investigated, and microbial community evolution and ARGs occurrence of MP surface during the aging process were analyzed. Aging process remarkably altered surface properties, including increasing specific surface areas, causing the formation of oxygen-containing groups, and changing surface morphology, which further increased the probability of microbial colonization. The bacterial assemblage on MPs showed higher biofilm-forming and pathogenic potential compared to leachate. ARGs quantification results suggested that MPs exhibited selective enrichment for ARGs in a ratio of 5.7-10³ folds, and the aging process enhanced the enrichment potential. Further co-occurrence networks suggested that the existence of non-random, closer and more stable ARGs-bacterial taxa relations on MP surface affected the ARG transmission. The study of ARG partitioning on MPs indicated that extracellular DNA was a nonnegligible reservoir of ARGs attached on MP surface, and that biofilm bacterial community influenced ARGs partitioning pattern during the aging process. This study confirmed that the aging process could enhance the potential of MPs as vectors for ARGs, which would promote the holistic understanding of MP behavior and risk in natural environments.

Adsorption and desorption behaviors of antibiotics by tire wear particles and polyethylene microplastics with or without aging processes

Tire wear particles (TWP), as the significant proportion of microplastics (MPs), has adsorbed much attention due to its widespread presence in aquatic ecosystem. However, compared with traditional MPs, few studies have investigated the interaction between TWP and coexisting contaminants. The adsorption-desorption behavior of chlortetracycline (CTC) and amoxicillin (AMX) by original and aged TWP was studied, and polyethylene (PE) was studied for comparison. After aging, small holes and cracks were produced on the surfaces of the TWP and PE. Meanwhile, the specific surface areas (S_BET) of TWP and PE increased, but the aged TWP had a larger S_BET than the aged PE, which indicated that TWP was more likely to degrade than PE. The adsorption kinetics results showed that the adsorption of CTC and AMX by TWP and PE conformed to the pseudo-second-order model. The adsorption isotherm results showed that the Freundlich model could describe the adsorption isotherm data of TWP and PE. The adsorption capacity of antibiotics by TWP increased by 1.13-23.40 times, and by 1.08-14.24 times on PE, after aging. Desorption experiments showed that the desorption amount of antibiotics on TWP and PE in simulated gastric fluid was greater than that in ultrapure water. The desorption amount and rate of CTC and AMX from TWP were higher than those of PE, indicating that TWP might be more harmful to the aquatic environment and organisms. These findings indicated that, compared with PE, TWP might have stronger carrier effects on antibiotics, which might pose more serious potential risks to the aquatic environment and organisms, especially considering the effects of the aging process. This study would expand the research on environmental risk of MPs and contribute to providing new insights into the evaluation of tire material particles.

Abundance of active ingredients in sea-buckthorn oil

Vegetable oils are obtained by mechanical extraction or cold pressing of various parts of plants, most often: seeds, fruits, and drupels. Chemically, these oils are compounds of the ester-linked glycerol and higher fatty acids with long aliphatic chain hydrocarbons (min. C14:0). Vegetable oils have a variety of properties, depending on their percentage of saturation. This article describes sea-buckthorn oil, which is extracted from the well characterized fruit and seeds of sea buckthorn. The plant has a large number of active ingredients the properties of which are successfully used in the cosmetic industry and in medicine. Valuable substances contained in sea-buckthorn oil play an important role in the proper functioning of the human body and give skin a beautiful and healthy appearance. A balanced composition of fatty acids give the number of vitamins or their range in this oil and explains its frequent use in cosmetic products for the care of dry, flaky or rapidly aging skin. Moreover, its unique unsaturated fatty acids, such as palmitooleic acid (omega-7) and gamma-linolenic acid (omega-6), give sea-buckthorn oil skin regeneration and repair properties. Sea-buckthorn oil also improves blood circulation, facilitates oxygenation of the skin, removes excess toxins from the body and easily penetrates through the epidermis. Because inside the skin the gamma-linolenic acid is converted to prostaglandins, sea-buckthorn oil protects against infections, prevents allergies, eliminates inflammation and inhibits the aging process. With close to 200 properties, sea-buckthorn oil is a valuable addition to health and beauty products.

Effect of aging on the bioavailability and fractionation of arsenic in soils derived from five parent materials in a red soil region of Southern China

The effects of aging time and soil parent materials on the bioavailability and fractionations of arsenic (As) in five red soils were studied. The results indicated that As bioavailability in all soils decreased during aging, especially with a sharp decline occurring in the first 30 days. After aging for 360 days, the highest available As concentration, which accounted for 12.3% of the total, was observed in soils derived from purple sandy shale. While 2.67% was the lowest proportion of the available As in soils derived from quaternary red clay. Furthermore, the best fit of the available As changing with aging time was obtained using the pseudo-second-order model (R(2) = 0.939-0.998, P < 0.05). Notably, Al oxides played a more crucial role (R(2) = 0.89, P＜0.05) than did Fe oxides in controlling the rate of As aging. The non-specially and specially absorbed As constituted the primary forms of available As.

Transport and transformation of Cd between biochar and soil under combined dry-wet and freeze-thaw aging

We quantified the transport and transformation of Cd in historically contaminated soil (OS) and artificially contaminated soil (NS), treated with 3% (w/w) rice straw biochar prepared at 400 °C (BC400) and 700 °C (BC700) under combined dry-wet and freeze-thaw cycles for 72 days simulating the natural aging process of 8 years. An improved three-layer mesh experiment was developed to simulate the natural situation in field. The result showed that the total Cd concentration increased in the biochar but decreased in the soil, suggesting that Cd was transported from the soil into the biochar during the aging process. The total Cd concentration in BC400 treated with both soils was higher than that in BC700 treated with both soils, however, BC700 displayed stronger ability on immobilizing Cd than BC400 because the Tessier exchangeable Cd fraction in BC700 treated both soils was lower than that in BC400 treated with both soils. The average Tessier exchangeable Cd fraction in the soil and biochar decreased in all treatments during the aging process, indicating that Cd tended to be more stable in the soil for a long term. The result also showed that biochar could immobilizate Cd by decreasing the Tessier exchangeable Cd fraction of soil and biochar, and the quantitative contributions of biochar and soil to Cd immobilization were different in OS and NS treated with BC400 and BC700. The biochar contribution to the reduction in Tessier exchangeable Cd fraction accounted for 40-85% in NS treated with BC400 and 54-82% in NS treated with BC700. However, in OS treated with biochar, the biochar contribution accounted for nearly 100%, and soil had almost no contribution. In summary, OS did not contribute to Cd immobilization, while NS contributed nearly 50% to Cd immobilization, and BC700 was more effective in immobilizing Cd than BC400.

Nanoscale infrared, thermal and mechanical properties of aged microplastics revealed by an atomic force microscopy coupled with infrared spectroscopy (AFM-IR) technique

Microplastics (MPs) often undergo different degrees of aging, and the aged MPs exhibit different surface properties from pristine MPs. This study explored the nanoscale infrared, thermal and mechanical properties of TiO₂-pigmented MPs before and after aging by using an AFM-IR technique. Results showed that the surface of MPs was relatively smooth before aging, and was rough with more granular domains after aging. The stronger band at 1706 cm^-1 (assigned to CO) and the weaker band at 1470 cm^-1 (assigned to -CH₂) were observed in aged MPs due to oxidation of CH bond in low-density polyethylene (LDPE). The softening temperature of MPs was about 209.50 ± 11.48 °C before aging, but after aging it dropped to 94.91 ± 4.40 °C. Aging process mainly reduced the glass transition temperature of the continuous phase (LDPE) rather than the discrete phase (TiO₂) in MPs. Resonance deviations of the two characteristic peaks (i.e., 299/645 kHz and 311/670 kHz) between unaged and aged MPs were observed, and these characteristic peaks obviously appeared at higher frequencies in aged MPs, suggesting that the MPs after aging became stiffer. A stronger signal at a high frequency and the uniform signal distribution at this frequency confirmed that the mechanical properties of MPs changed after aging. These findings help to better understand the effects of aging process on the physicochemical properties of MPs.

Potential toxicity of nanopolystyrene on lifespan and aging process of nematode Caenorhabditis elegans

In the environment, nanoplastic particles, such as nanopolystyrene, potentially cause toxicity on organisms at various aspects. We here employed endpoints of lifespan and aging-related phenotypes to further investigate the possible long-term effects of nanopolystyrene (100 nm) in Caenorhabditis elegans. After exposure from L1-larvae to adult day-3, nanopolystyrene at high concentrations (100 and 1000 μg/L) reduced the lifespan. Although nanopolystyrene (1 or 10 μg/L) did not affect the lifespan, nanopolystyrene (1 or 10 μg/L) could induce the more severe intestinal reactive oxygen species (ROS) production and decrease in locomotion behavior during the aging process compared with control. Moreover, nanopolystyrene exposure could cause the severe decrease in expressions of some immune response genes, hsp-6 gene, and genes encoding manganese-superoxide dismutases (Mn-SODs) during aging process, suggesting the severe suppression in innate immune response, inhibition in antioxidation defense system, and suppression in mitochondrial unfolded protein response (mt UPR) by nanopolystyrene. Our results highlight the potential of long-term nanopolystyrene exposure in reducing longevity and in affecting health state during the aging process in environmental organisms.

Effects of aging process on adsorption-desorption and bioavailability of fomesafen in an agricultural soil amended with rice hull biochar

Biochar has been introduced as an acceptable soil amendment due to its environmental benefits such as sequestering soil contaminants. However, the aging process in biochar amended soil probably decreases the adsorption capacity of biochar through changing its physico-chemical properties. Adsorption, leaching and bioavailability of fomesafen to corn in a Chinese soil amended by rice hull biochar after 0, 30, 90 and 180days were investigated. Results showed that the addition of 0.5%-2% fresh biochar significantly increases the adsorption of fomesafen 4-26 times compare to unamended soil due to higher SSA of biochar. Biochar amendment also decreases fomesafen concentration in soil pore water by 5%-23% resulting lower risk of the herbicide for cultivated plants. However, the aging process decreased the adsorption capacity of biochar since the adsorption coefficient values which was 1.9-12.4 in 0.5%-2% fresh biochar amended soil, declined to 1.36-4.16, 1.13-2.78 and 0.95-2.31 in 1, 3 and 6-month aged treatments, respectively. Consequently, higher desorption, leaching and bioavailable fraction of fomesafen belonged to 6-month aged treatment. Nevertheless, rice hull biochar was effective for sequestering fomesafen as the adsorption capacity of biochar amended soil after 6months of aging was still 2.5-5 times higher compared to that of unamended soil.

Photocatalytic aging process of Nano-TiO2 coated polypropylene microplastics: Combining atomic force microscopy and infrared spectroscopy (AFM-IR) for nanoscale chemical characterization

Microplastics (MPs) are considered to have greater environmental hazards than large plastics. Most MPs undergo different degrees of aging and aged MPs exhibit different physicochemical properties from pristine ones. This study successfully prepared a nano-TiO₂ coated polypropylene MPs, and explored the nanoscale infrared, thermal, and mechanical properties of MPs before and after photo-aging using a combined AFM-IR technique. Surface height range of MPs was ± 25 nm. The signal intensity of the absorption peak at 1654 cm^-1 in terms of vinylidene end groups gradually increased as the irradiation time prolonged. The softening temperature of MPs decreased from 126.7 °C to 108.5 °C as the irradiation time increased from 0 h to 4 h. The MPs after photo-aging became stiffer, especially for the components surrounding the nano-TiO₂ particle, indicating that photocatalytic reaction accelerated the aging process of MPs. The resonance frequency of MPs surrounding the nano-TiO₂ particle was stronger after photo-aging and the stiffer components were uniformly distributed, confirming that the thermal and mechanical properties of MPs changed after photo-aging. These novel findings are essential to better understand the changes in the surface microstructures, physical properties, and chemical compositions of MPs during aging process.

Relationship between the hs-CRP as non-specific biomarker and Alzheimer's disease according to aging process

BACKGROUND

Microglia are involved in immune surveillance in intact brains and become activated in response to inflammation and neurodegeneration. Microglia have different functions, neuroprotective or neurotoxic, according to aging in patients with PD. The clinical effect of microglia in patients with Alzheimer's disease (AD) is poorly defined. This prospective study was conducted to investigate the clinical effects of microglia according to the aging process in newly diagnosed AD.

METHODS

We examined 532 patients with newly diagnosed AD and 119 healthy controls, and the differences in hs-CRP between these groups were investigated. The patients with AD were classified into 3 subgroups according to age of newly diagnosed AD to investigate the relationship between hs-CRP and the aging process in newly diagnosed AD.

RESULTS

There was significantly higher serum high-sensitivity C-reactive protein (hs-CRP), levels in patients with AD compared with healthy controls. A post-hoc analysis of the 3 AD subgroups showed no significant differences in serum hs-CRP level between each group.

CONCLUSION

We assumed that neuroinflammation play a role in the pathogenesis of AD, but found no clinical evidence that microglia senescence underlies the microglia switch from neuroprotective in young brains to neurotoxic in aged brains. To clarify the role of microglia and aging in the pathogenesis of AD, future longitudinal studies involving a large cohort are required.

Adsorption of tetracycline and Cd(II) on polystyrene and polyethylene terephthalate microplastics with ultraviolet and hydrogen peroxide aging treatment

Microplastics (MPs) could serve as vectors of antibiotics and heavy metals through sorption and desorption. However, the combined adsorption process of antibiotics and heavy metals on aged MPs has rarely been studied. In this study, combined adsorption/desorption of tetracycline (TC) and Cd(II) on/from polystyrene (PS) and polyethylene terephthalate (PET) MPs, as well as ultraviolet (UV) and H₂O₂ aged MPs, was investigated. The specific surface areas of the MPs increased after UV and H₂O₂ aging. Adsorption experiments showed that the pseudo-second-order kinetic model and Freundlich model fitted adsorption of TC and Cd(II) on all of the MPs. The adsorption capacities of TC and Cd(II) were higher on aged MPs than on the pristine MPs, especially on H₂O₂ treated MPs. TC adsorption on the MPs was hardly affected by Cd(II), and Cd(II) adsorption was not significantly affected by TC when the solution pH value was below 8.0. Cd(II) slightly enhanced TC adsorption on the MPs at pH 8.0, especially on the aged MPs. The TC adsorption capacities increased with increasing pH, reaching a maximum at pH 5.0 or 6.0, and they then decreased, while the largest level of Cd(II) adsorption was at approximately pH 6.0. Adsorption of TC and Cd(II) on the pristine and aged MPs was thermodynamically favorable and spontaneous. The trend of the desorption rates of TC and Cd(II) from the MPs in different background solutions was ultrapure water < surface water < simulated gastric fluid. The desorption rates of TC and Cd(II) from the aged MPs were lower than those from the pristine MPs. The results revealed the mechanism of the TC and Cd(II) combined adsorption process on aged MPs, which will provide insight for understanding the aging process and its potential effects on sorption and desorption of antibiotics and heavy metals in the real environment.

Enhanced phototransformation of atorvastatin by polystyrene microplastics: Critical role of aging

Reactive oxygen species (ROS) generated from light irradiation of microplastics (MPs) can potentially affect the environmental fate of organic contaminants when they coexist in the same environment. This study investigated the effect of polystyrene (PS) MPs with different aging degrees on the phototransformation of atorvastatin (ATV) under simulated sunlight. Results showed that the presence of PS MPs facilitated the phototransformation of ATV, and the degradation rate was linearly correlated with the aging degree (i.e., carbonyl index) of MPs. The enhanced effects mainly depended on the contents of oxygen-containing functional groups of PS MPs, which increased the absorption of light energy and the generation of ROS (e.g., singlet oxygen (¹O₂) and triplet-excited state PS (³PS*)). Quenching experiments indicated that ¹O₂ generated from photosensitization of PS was the major contributor to the increased phototransformation of ATV. Additionally, the role of ³PS* became more important in the photodegradation mediated by higher degree aged MPs because much more ¹O₂ was generated from the ³PS* . PS MPs also increased the types and yields of degradation products, especially for higher degree aged MPs, despite the low effect on leachate toxicity. The findings provide a novel insight into the critical role of MPs in the fate of organic contaminants in aquatic environments.

Mutagenicity of ZnO nanoparticles in mammalian cells: Role of physicochemical transformations under the aging process

Zinc oxide nanoparticles (ZnO NPs) potentially undergo physicochemical transformation in the environment, which may lead to unexpected environmental and health risks. The "aging" process is essential for better understanding the toxicity and fate of NPs in the environment. However, the mutagenic effects of aged ZnO NPs are still unexplored. The present study focused on investigating the physicochemical transformation during aging process and clarifying the mutagenicity of naturally aged ZnO NPs in human-hamster hybrid (AL) cells. It was found that ZnO NPs underwent sophisticated physicochemical transformations with aging regardless of original morphology or size, such as the microstructural changes, the formation of hydrozincite (Zn5(CO3)2(OH)6) and the release of free zinc ions. Interestingly, the aged ZnO NPs were investigated to be able to result in much lower cytotoxicity while relatively high degree mutation than fresh ZnO NPs. With characterization of the soluble and insoluble fractions of aged ZnO NPs suspension, together with the control measurements using metal chelator (TPEN) and endocytosis inhibitor (Nystatin), it was revealed that the release of zinc ions and nanoparticle uptake made significantly different contributions to the mutagenicity of fresh and aged ZnO NPs. This study clearly demonstrated that the physicochemical transformation of ZnO NPs with aging plays important and comprehensive roles in the ZnO NPs-induced mutagenicity in mammalian cells.

Adsorption of Cu2+ by UV aged polystyrene in aqueous solution

Microplastics are the critical carriers of heavy metals in the environment. Thus, investigating the adsorption mechanisms between the microplastics and heavy metals is helpful to understand the migration and transformation pattern of the heavy metals in the environment. The adsorption of microplastics towards heavy metals can be largely affected by natural aging (e.g., UV-aging), environmental pH, and salinity. In this study, the adsorption of polystyrene (PS) towards Cu²⁺ and the effects of UV-aging, environment pH, and salinity on the adsorption were systematically investigated. The results show that the adsorption capacity of PS towards Cu²⁺ increased with the UV-aging time, as UV-aging increased the microcracks and oxygen-containing functional groups on the surface of the PS. Adsorption kinetics data followed the pseudo-second-order model, indicating that the interaction between PS and Cu²⁺ is chemical adsorption. Adsorption isotherms data could be well-described by both the Langmuir and Freundlich models, indicating that the adsorption was multilayer adsorption. As the solution pH and salinity can influence the surface charge of the PS, they could also affect the performance of the PS on Cu²⁺ adsorption. High pH facilitated the adsorption of PS towards Cu²⁺, while high salinity (above 1‰) inhibited the adsorption.

Aging of poly (lactic acid)/poly (butylene adipate-co-terephthalate) blends under different conditions: Environmental concerns on biodegradable plastic

Biodegradable plastics (BPs) have been used to replace conventional plastics owing to their environmental harmless and ease of degradation. However, the aging processes of BPs in different environments remain unclear. In this study, we used poly (lactic acid)/poly (butylene adipate-co-terephthalate) (PLA/PBAT) films as model BPs and investigated the 30-d aging behavior of PLA/PBAT films under four conditions (i.e., air without ultraviolet (UV) irradiation, water without UV irradiation, air with UV irradiation, and water with UV irradiation). Our results showed that the aging of PLA/PBAT films was insignificant in all groups except the water with UV irradiation group. In the physical characterization, the PLA/PBAT films exhibited layered structures in water with UV irradiation condition, and the submicron- and nano-sized particles adhered to the bigger-sized fragments. In the chemical characterization, the carbonyl index (CI) of PLA/PBAT films in water with UV irradiation condition decreased from 3.84 to 1.36, and the oxygen-to-carbon (O/C) ratio reached a maximum of 1.78 at 20 d and declined to 0.49 at 30 d, indicating that the oxygen-containing functional groups underwent bond breaking and showed a rapid aging process. This is mainly attributed to the combined effect of hydrolysis and photolysis increases the contact area of PLA/PBAT films and accelerates the aging process. Furthermore, based on two-dimensional correlation spectroscopy (2D-COS) analysis, we suggest that free radicals generated in water with UV irradiation conditions also accelerate the aging process of PLA/PBAT films. This study explored the aging processes of PLA/PBAT films under different conditions, which could aid in clarifying the environmental behavior and provide further information to assess the potential risks of BPs.

Effects of environmental aging on the adsorption behavior of antibiotics from aqueous solutions in microplastic-graphene coexisting systems

The extensive use of nanofillers, such as graphene oxide (GO) and reduced graphene oxide (rGO), as plastic additives has led to the coexistence of microplastics (MPs) and nanomaterials in aquatic environments. However, there is a lack of studies on the adsorption behavior of MPs when coexisting with GO. Moreover, MPs and GO are prone to undergoing aging processes in real environments under conditions such as sunlight exposure, which changes their physicochemical properties and affects their adsorption behavior. In this study, the aging processes of MPs and GO in a real environment were simulated by ultraviolet (UV) irradiation and thermal treatments, respectively. The adsorption behavior of ciprofloxacin (CIP) on three types of MPs (polypropylene (PP), polyamide (PA), and polystyrene (PS)) before and after aging was explored. The MPs are ordered in terms of CIP adsorption capacity as aged-PA > aged-PS > aged-PP > PA > PP > PS, and the adsorption capacity of aged MPs was approximately twofold higher than that of pristine MPs. This paper also studied the adsorption performance of antibiotics in a coexisting system of aged MPs and GO/rGO, and the tetracycline (TC) adsorption capacity was increased by ~336% in aged PP-GO and ~100% in an aged PP-rGO coexisting system. GO/rGO with high degree of oxidation and concentration in an aged- PP-GO/rGO coexisting system are more conducive to the TC adsorption, due to the contribution of oxygen-containing functional groups. Surface and partition adsorption co-occurred during the TC adsorption process. The TC adsorption behavior in the MPs-GO/rGO coexisting system was strongly dependent on the solution pH, which was more favorable under acidic (pH = 3) or alkaline (pH = 11) conditions. This study improves the understanding of the environmental behavior of MPs, graphene, and antibiotics and guides research on strategies for preventing the migration of antibiotics in MPs-GO/rGO coexisting systems.

Relationship between specific leisure activities and successful aging among older adults

Background/Objectives

This study was designed to investigate the association between specific leisure activities and successful aging among older adults, using data from the Chinese Longitudinal Healthy Longevity Survey.

Methods

A total of 7689 older adults were involved in this study and categorized as successful aging group (n = 3989; 51.8%) or non-successful aging group (n = 3703; 48.2%). Participants were identified as successful aging if they had a score of more than 3 points, or as non-successful aging. The points were based on the following five items and each item was assigned 1 point: self-rated health, self-rated psychological status or mood, cognitive function, activities of daily life, and physical activity. Six activities including gardening work, reading newspapers or books, raising domestic animals or pets, playing cards or mahjong, watching TV or listening to radio, and participating in social activities were collected to reflect leisure activities. Chi-square tests, independent sample t-test, and logistic regression analyses were employed to explore the association between specific leisure activities and successful aging.

Results

The prevalence of successful aging was 51.8% among Chinese older adults. A significant positive relationship was found between the frequency of participation in specific leisure activities and successful aging (p < 0.05). Older adults who usually participated in leisure activities had greater odds for successful aging compared to those who never participated in leisure activities (adjusted odds ratio (OR): 1.31 (95% CI: 1.15-1.49) to 1.88 (95% CI: 1.62-2.19)). Older adults participating in one or more leisure activities had greater odds for successful aging compared to those who did not participate in leisure activities (adjusted OR: 1.51 (95% CI: 1.30-1.76) to 4.10 (95% CI: 2.44-6.89)).

Conclusions

The findings provide evidence that participating more frequently and in more leisure activities was associated with a greater probability of successful aging among Chinese older adults. Encouraging older people to participate frequently in a larger number of leisure activities may be a key to promote successful aging. Therefore, the frequency and number of participation in leisure activities should be highlighted and targeted for promoting successful aging.

New insights on metal ions accelerating the aging behavior of polystyrene microplastics: Effects of different excess reactive oxygen species

Microplastics (MPs) will coexist with various pollutants in the environment, but it is not clear whether these pollutants will affect the aging process of MPs. The aging process of polystyrene microplastics (PS-MPs) mediated by Cu²⁺ and Pb²⁺ was investigated in this study. The results showed that the aging rate of PS-MPs mediated by Cu²⁺ and Pb²⁺ were significantly higher than that of ultrapure water (After 7 days of light irradiation, the CI values of aging PS-MPs mediated by ultrapure water, Cu²⁺ and Pb²⁺ increased from 0.030 of original PS-MPs to 0.034, 0.048 and 0.086 respectively). This process may be related to the generation of a large amount of reactive oxygen species, because OH were detected in PS-MPs suspension mediated by Cu²⁺, which were significantly higher than those in ultrapure water, while ¹O₂ mediated by Pb²⁺ were more. However, these photo-aging effects were significantly inhibited by reactive oxygen species (ROS) quencher, which indicated that excessive ROS production was the main reason for metal ions to promote the photo-aging of PS-MPs. In addition, this study reported that excessive ROS will accelerate the formation of carbonyl group on the surface of PS-MPs, and lead to the change of physical and chemical properties of PS-MPs. This study provides new insights for the environmental behavior of MPs under the condition of combined pollution.

Roles of aging in the production of light-flavored Daqu

Daqu, a complex starting material used for Baijiu production, contains microorganisms, enzymes, and volatile compounds. An important part of Daqu production is aging, but the physicochemical and microbial changes during aging remain largely unknown. This study characterized aging according to physicochemical parameters, volatile compounds, and microbial communities. Aging was found to aid in the stabilization of the physicochemical parameters. Solid-phase microextraction-gas chromatography-mass spectrometry was used to detect 72 types of volatile compounds, which were predominantly alcohols, esters, aldehydes, alkenes, and alkanes. During aging, these compounds changed considerably, but their structures eventually stabilized. A high-throughput sequencing approach was used to analyze the changing composition of the microbial communities. In general, aging helped to enrich and stabilize the microbial population for making Baijiu. A total of 35 bacteria were detected as prokaryotic; among these, 15 had a diversity abundance ratio of more than 1%. The dominant bacteria were from the genus Pantoea, but these decreased with aging, while bacteria from Lactobacillus and Weissella increased. After aging for 2 months, Pantoea, Lactobacillus and Weissella accounted for 0.4%, 54.0%, and 18.9%, respectively. A total of 12 eukaryotic yeast and fungi were detected, the most abundant of which were Incertae_Sedis_incertae_sedis, Saccharomycopsis, Trichocomaceae_unclassified, Pichia, Tremellales_unclassified, and Galactomyces. During aging, the levels of Trichocomaceae_unclassified, Saccharomycopsis, and Galactomyces initially decreased but then increased. Pichia stayed unchanged as aging progressed. In conclusion, aging led to rebalanced interactions among Daqu microbes and was important in improving Daqu quality and ensuring its stability.

Enhanced aqueous-phase formation of secondary organic aerosols due to the regional biomass burning over North China Plain

This study reveals the impact of biomass burning (BB) on secondary organic aerosols (SOA) formation in the North China Plain (NCP). Filter samples were analyzed for secondary inorganic aerosols (SIA), oxalic acid (C₂) and related aqueous-phase SOA compounds (aqSOA), stable carbon isotope composition of C₂ (δ¹³C(C₂)) and aerosol liquid water content (ALWC). Based on the PM_2.5 loadings, BB tracer concentrations, wildfire spots and air-mass back trajectories, we distinguished two episodes from the whole campaign, Episode I and Episode II, which were characteristic of regional and local BB, respectively. The abundances of PM_2.5 and organic matter in the two events were comparable, but concentrations and fractions of SIA, aqSOA during Episode I were much higher than those during Episode II, along with heavier δ¹³C(C₂), suggesting an enhanced aqSOA formation in the earlier period. We found that the enhancement of aqSOA formation during Episode I was caused by an increased ALWC, which was mainly driven by SIA during the regional BB event. Our work showed that intensive burning of crop residue in East Asia can sharply enhance aqSOA production on a large scale, which may have a significant impact on the regional climate and human health.

Histone deacetylase activity is altered in brain areas from aged rats

It has been described that histone acetylation levels are decreased in several cellular and in vivo neurodegeneration models as well as in normal brain aging, although the impact of the aging process on histone deacetylases (HDAC) activity yet remains poorly understood. Therefore, our aim was to evaluate the effect of the aging process on HDAC activity in hippocampi and frontal cortices from 3 and 18-months-old Wistar rats. The animals were decapitated at different times of day, in the early morning and in afternoon. HDAC activity was increased in hippocampus from the aged group. Besides, the hippocampal HDAC activity was also significantly increased in early morning. A significant interaction between age and time of the day was observed in frontal cortices, given that the HDAC activity was higher in early morning in the aged group. These data support the hypothesis that the aging-related dysfunction may be related, at least in part, to acetylation imbalance through HDAC activity in rat brain.

Circadian Time Structure of Circulating Plasma Lipid Components in Healthy Indians of Different Age Groups

The circadian rhythm of human circulating lipid components was studied under nearnormal tropical conditions in 162 healthy volunteers (103 males and 59 females; 7 to 75 years of age). They followed a diurnal activity from about 06:00 to about 22:00 and nocturnal rest. These volunteers were divided into four groups: Group A (7-20 years), Group B (21-40 years), Group C (41-60 years) and Group D (61-75 years), comprising 42, 60, 35 and 25 participants, respectively. A marked circadian rhythm was demonstrated for each studied variable in each group by population-mean cosinor analysis (almost invariably p < 0.001). Furthermore, circadian rhythm characteristics were compared among the 4 groups by parameter tests and regressed as a function of age, separately for males and females. A second-order polynomial characterized the MESOR of HDL cholesterol, phospholipids and total lipids, as well as the 24-h amplitude of total cholesterol and phospholipids. The 24-h amplitude of total lipids decreased linearly with age. The 24-h acrophase of the oldest age group (Group D) was advanced in the case of total cholesterol, HDL cholesterol, and total lipids, whereas that of phospholipids was delayed. Mapping the circadian rhythm (an important component of the broader time structure or chronome, which includes a. o., trends with age and extra-circadian components) of lipid components is needed to explore their role in the aging process in health.

Changes in bacterial community structures in soil caused by migration and aging of microplastics

Microplastics (MPs) are classified as emerging pollutants and greatly threatens soil ecosystems. To determine the impact of microplastic migration on soil bacterial diversity, we conducted a 90-day indoor soil column simulation test. Soil and microplastic (granular polystyrene, polypropylene MPs) samples were collected from different soil layers on days 30, 60, and 90. The downward migration trend of MPs was obvious, and its surface functional groups, hydrophobic properties, and crystallinity changed. Bacterial diversity was significantly higher in the surrounding soil than on microplastic surfaces. Also, the topsoil has more bacterial diversity than the middle soil. A higher number of OTUs were detected on microplastic surfaces for the middle soil than in the topsoil. Proteobacteria abundance on microplastic surfaces in the topsoil gradually increased over the course of the experiment, while an opposite trend was observed for the middle soil. Nevertheless, Proteobacteria abundances in both layers were higher than in the surrounding soils. MPs alters the bacterial community composition of soils and provides unique substrates for colonization. The impacts of MPs on soil bacterial communities were better understood in this study. Our findings highlighted the relevance of MPs in soil ecosystems as well as the potential threats they pose.