Potential application of bioelectrochemical systems in cold environments.

Globally, more than half of the world's regions and populations inhabit psychrophilic and seasonally cold environments. Lower temperatures can inhibit the metabolic activity of microorganisms, thereby restricting the application of traditional biological treatment technologies. Bioelectrochemical systems (BES), which combine electrochemistry and biocatalysis, can enhance the resistance of microorganisms to unfavorable environments through electrical stimulation, thus showing promising applications in low-temperature environments. In this review, we focus on the potential application of BES in such environments, given the relatively limited research in this area due to temperature limitations. We select microbial fuel cells (MFC), microbial electrolytic cells (MEC), and microbial electrosynthesis cells (MES) as the objects of analysis and compare their operational mechanisms and application fields. MFC mainly utilizes the redox potential of microorganisms during substance metabolism to generate electricity, while MEC and MES promote the degradation of refractory substances by augmenting the electrode potential with an applied voltage. Subsequently, we summarize and discuss the application of these three types of BES in low-temperature environments. MFC can be employed for environmental remediation as well as for biosensors to monitor environmental quality, while MEC and MES are primarily intended for hydrogen and methane production. Additionally, we explore the influencing factors for the application of BES in low-temperature environments, including operational parameters, electrodes and membranes, external voltage, oxygen intervention, and reaction devices. Finally, the technical, economic, and environmental feasibility analyses reveal that the application of BES in low-temperature environments has great potential for development.

Environmental factors influencing the soil-air partitioning of semi-volatile petroleum hydrocarbons: Laboratory measurements and optimization model.

The soil-air partition coefficient (KSA) values are commonly utilized to examine the fate of organic contaminants in soils; however, their measurement has been lacking for semi-volatile petroleum hydrocarbons within soil contaminated by crude oil. This research utilized a solid-phase fugacity meter to determine the KSA values of n-alkanes and polycyclic aromatic hydrocarbons (PAHs) under crucial environmental conditions. The results showed a notable increase in KSA values with the extent of crude oil contamination in soil. Specifically, in the 3 % crude oil treatment, the KSA values for n-alkanes and PAHs increased by 1.16 and 0.66 times, respectively, compared to the 1 % crude oil treatment. However, the KSA values decreased with changes in temperature, water content, and particle size within the specified experimental range. Among these factors, temperature played a significant role. The KSA values for n-alkanes and PAHs decreased by 0.27-0.89 and 0.61-0.83 times, respectively, with a temperature increase from 5 °C to 35 °C. Moreover, the research identified that the molecular weight of n-alkanes and PAHs contributed to variations in KSA values under identical environmental factors. With an increase in temperature from 5 °C to 35 °C, the range of n-alkanes present in the air phase expanded from C11 to C34, and PAHs showed elevated levels of acenaphthene (ACE) and benzo (b) fluoranthene (BbFA). Furthermore, heightened water content and particle size were observed to facilitate the volatilization of low molecular weight petroleum hydrocarbons. The effect of environmental variables on soil-air partitioning was evaluated using the Box-Behnken design (BBD) model, resulting in the attainment of the lowest log KSA values. These results illustrate that soil-air partitioning is a complex process influenced by various factors. In conclusion, this study improves our comprehension and predictive capabilities concerning the behavior and fate of n-alkanes and PAHs within soil-air systems.

Key Role of Vegetation Cover in Alleviating Microplastic-Enhanced Carbon Emissions.

Microplastics (MPs) are considered to influence fundamental biogeochemical processes, but the effects of plant residue-MP interactions on soil carbon turnover in urban greenspaces are virtually unknown. Here, an 84-day incubation experiment was constructed using four types of single-vegetation-covered soils (6 years), showing that polystyrene MP (PSMP) pollution caused an unexpectedly large increase in soil CO2 emissions. The additional CO2 originating from highly bioavailable active dissolved organic matter molecules (<380 °C, predominantly polysaccharides) was converted from persistent carbon (380-650 °C, predominantly aromatic compounds) rather than PSMP derivatives. However, the priming effect of PSMP derivatives was weakened in plant-driven soils (resistivity: shrub > tree > grass). This can be explained from two perspectives: (1) Plant residue-driven humification processes reduced the percentage of bioavailable active dissolved organic matter derived from the priming effects of PSMPs. (2) Plant residues accelerated bacterial community succession (dominated by plant residue types) but slowed fungal community demise (retained carbon turnover-related functional taxa), enabling specific enrichment of glycolysis, the citric acid cycle and the pentose phosphate pathway. These results provide a necessary theoretical basis to understand the role of plant residues in reducing PSMP harm at the ecological level and refresh knowledge about the importance of biodiversity for ecosystem stability.

Evaluation of nocturnal apnea and airflow limitation as indicators for cognitive dysfunction in patients with chronic obstructive pulmonary disease/obstructive sleep apnea hypopnea syndrome overlap syndrome.

OBJECTIVE: The aim of this study is to investigate how much intermittent hypoxemia and airflow limitation contribute to cognitive impairment in overlap syndrome (OS), which is the coexistence of two common diseases, obstructive sleep apnea hypopnea syndrome (OSAHS) and chronic obstructive pulmonary disease (COPD). METHODS: We conducted a cross-sectional study of patients with OSAHS, COPD or OS, compared with normal controls, to determine the association between sleep apnea/pulmonary function-related indicators and cognitive dysfunction in individuals with OSAHS, COPD or OS. RESULTS: A total of 157 participants were recruited. Both OSAHS and OS presented lower adjusted Montreal cognitive assessment (MoCA) scores compared with COPD group. In addition, the MoCA score was significantly lower in COPD group compared with control group. The incidence of cognitive impairment was 57.4% in OSAHS group, and 78% in OS group, which were significantly higher than COPD group (29%) and control group (8.8%). Furthermore, a broader range of cognitive domains were affected in OS group compared with OSAHS group. Elevated levels of oxygen desaturation index (ODI) and/or apnea hypopnea index (AHI) were positively correlated with increased Epworth sleeping scale (ESS) in OSAHS and OS. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF) were positively correlated with cognitive scores in OSAHS but not in OS. Serum level of hypoxia-inducible factor-1α (HIF-1α) was significantly higher in OS. Logistic regression identified ODI as an independent risk factor for cognitive impairment in OS, while severity of snoring and PEF were independent risk factors in OSAHS. DISCUSSION: This study revealed significant cognitive impairment in OS, OSAHS and COPD. Sleep-related indicators are warranted in OS patients for detection, differentiation and grading of cognitive impairment, whereas pulmonary functions are warranted in OSAHS patients for detection and early intervention of cognitive impairment.

N, S, and Cl tri-doped carbon boost the switching of radical to non-radical pathway in Fenton-like reactions: Synergism of N species and defects.

Heteroatom doping represents a promising strategy for enhancing the generation of singlet oxygen (1O2) during the activation of peroxymonosulfate (PMS) using carbon-based catalysts; however, it remains a formidable challenge. In this study, we systematically controlled the structure of metal-free carbon-based materials by introducing different heteroatoms to investigate their efficacy in degrading organic pollutants in water via PMS activation. The results of reactive oxygen species detection showed that the dominant free radical in the four samples was different: CN (•SO4- and •OH), CNS (•O2-), CNCl (1O2), and CNClS (1O2). This led to the transformation of active species from free radicals to non-free radicals. The tri-doped carbons with nitrogen, sulfur, and chlorine (CNClS) exhibited exceptional performance in PMS activation and achieved a remarkable degradation efficiency of 95% within just 6 min for tetracycline. Moreover, a strong linear correlation was observed between the ratio of pyridine-N/graphite-N and ID/IG with the yield of 1O2, indicating that N species and defects play a crucial role in CNClS as they facilitate the transition from radical to non-radical pathways during PMS activation. These findings highlight the possibility that adjustable tri-heteroatom doping will expand the Fenton-like reaction for the treatment of actual wastewater.

Polyethylene microplastic-induced microbial shifts affected greenhouse gas emissions during litter decomposition in coastal wetland sediments.

Microplastic contamination has become increasingly aggravated in coastal environments, further affecting biogeochemical processes involved with microbial community shifts. As a key biogeochemical process mainly driven by microbiota in coastal wetland sediments, litter decomposition contributes greatly to the global greenhouse gas (GHG) budget. However, under microplastic pollution, the relationship between microbial alterations and GHG emissions during litter decomposition in coastal wetlands remains largely unknown. Here, we explored the microbial mechanism by which polyethylene microplastic (PE-MP) influenced greenhouse gas (i.e., CH4, CO2 and N2O) emissions during litter decomposition in coastal sediments through a 75-day microcosm experiment. During litter decomposition, PE-MP exposure significantly decreased cumulative CH4 and CO2 emissions by 41.07% and 25.79%, respectively. However, there was no significant change in cumulative N2O emissions under PE-MP exposure. The bacterial, archaeal, and fungal communities in sediments exhibited varied responses to PE-MP exposure over time, as reflected by the altered structure and changed functional groups of the microbiota. The altered microbial functional groups ascribed to PE-MP exposure and sediment property changes might contribute to suppressing CH4 and CO2 emissions during litter decomposition. This study yielded valuable information regarding the effects of PE-MP on GHG emissions during litter decomposition in coastal wetland sediments.

Toxicity Mechanisms of Nanoplastics on Crop Growth, Interference of Phyllosphere Microbes, and Evidence for Foliar Penetration and Translocation.

Despite the increasing prevalence of atmospheric nanoplastics (NPs), there remains limited research on their phytotoxicity, foliar absorption, and translocation in plants. In this study, we aimed to fill this knowledge gap by investigating the physiological effects of tomato leaves exposed to differently charged NPs and foliar absorption and translocation of NPs. We found that positively charged NPs caused more pronounced physiological effects, including growth inhibition, increased antioxidant enzyme activity, and altered gene expression and metabolite composition and even significantly changed the structure and composition of the phyllosphere microbial community. Also, differently charged NPs exhibited differential foliar absorption and translocation, with the positively charged NPs penetrating more into the leaves and dispersing uniformly within the mesophyll cells. Additionally, NPs absorbed by the leaves were able to translocate to the roots. These findings provide important insights into the interactions between atmospheric NPs and crop plants and demonstrate that NPs' accumulation in crops could negatively impact agricultural production and food safety.

Urbanization influences dissolved organic matter characteristics but microbes affect greenhouse gas concentrations in lakes.

Recognition and prediction of dissolved organic matter (DOM) properties and greenhouse gas (GHG) emissions is critical to understanding climate change and the fate of carbon in aquatic ecosystems, but related data is challenging to interpret due to covariance in multiple natural and anthropogenic variables with high spatial and temporal heterogeneity. Here, machine learning modeling combined with environmental analysis reveals that urbanization (e.g., population density and artificial surfaces) rather than geography determines DOM composition and properties in lakes. The structure of the bacterial community is the dominant factor determining GHG emissions from lakes. Urbanization increases DOM bioavailability and decreases the DOM degradation index (Ideg), increasing the potential for DOM conversion into inorganic carbon in lakes. The traditional fossil fuel-based path (SSP5) scenario increases carbon emission potential. Land conversion from water bodies into artificial surfaces causes organic carbon burial. It is predicted that increased urbanization will accelerate the carbon cycle in lake ecosystems in the future, which deserves attention in climate models and in the management of global warming.

Interactions among microorganisms functionally active for electron transfer and pollutant degradation in natural environments.

Compared to single microbial strains, complex interactions between microbial consortia composed of various microorganisms have been shown to be effective in expanding ecological functions and accomplishing biological processes. Electroactive microorganisms (EMs) and degradable microorganisms (DMs) play vital roles in bioenergy production and the degradation of organic pollutants hazardous to human health. These microorganisms can strongly interact with other microorganisms and promote metabolic cooperation, thus facilitating electricity production and pollutant degradation. In this review, we describe several specific types of EMs and DMs based on their ability to adapt to different environments, and summarize the mechanism of EMs in extracellular electron transfer. The effects of interactions between EMs and DMs are evaluated in terms of electricity production and degradation efficiency. The principle of the enhancement in microbial consortia is also introduced, such as improved biomass, changed degradation pathways, and biocatalytic potentials, which are directly or indirectly conducive to human health.

Dominant factors analyses and challenges of anaerobic digestion under cold environments.

With the development of fermentation technology and the improvement of efficiency, anaerobic digestion (AD) has been playing an increasingly primary role in waste treatment and resource recovery. Temperature is undoubtedly the most important factor because it shapes microbial habitats, changes the composition of the microbial community structure, and even affects the expression of related functional genes. More than half of the biosphere is in a long-term or seasonal low-temperature environment (<20 °C), which makes psychrophilic AD have broad application prospects. Therefore, this review discusses the influencing factors and enhancement strategies of psychrophilic AD, which may provide a corresponding reference for future research on low-temperature fermentation. First, the occurrence of AD has been discussed. Then, the adaptation of microorganisms to the low-temperature environment was analyzed. Moreover, the challenges of psychrophilic AD have been reviewed. Meanwhile, the strategies for improving psychrophilic AD are presented. Further, from technology to application, the current situation of psychrophilic AD in pilot-scale tests is described. Finally, the economic and environmental feasibility of psychrophilic AD has been highlighted. In summary, psychrophilic AD is technically feasible, while economic analysis shows that the output benefits cannot fully cover the input costs, and the large-scale practical application of psychrophilic AD is still in its infancy. More research should focus on how to improve fermentation efficiency and reduce the investment cost of psychrophilic AD.

Elucidating response mechanisms at the metabolic scale of Eisenia fetida in typical oil pollution sites: A native driver in influencing carbon flow.

Previous investigations on the stress response patterns of earthworms (Eisenia fetida) in practical petroleum hydrocarbon (PH) contamination systems were less focused. Therefore, this study investigated the ecotoxicological effect of PH contamination on earthworms based on metabonomics and histological observation, followed by correlation analysis between the earthworm metabolism, PH types and concentrations, soil physicochemical characteristics, and the microbial community structures (i.e., diversity and abundance) and functions. The results showed that due to the abundant PH organics, the cell metabolism of earthworms shifts under PH contamination conditions, leading them to use organic acids as alternative energy sources (i.e., gluconeogenesis pathway). Simultaneously, biomarker metabolites related to cellular uptake, stress response, and membrane disturbance were identified. In addition, when compared to the controls, considerable epicuticle and cuticle layer disruption was observed, along with PH internalization. It was demonstrated that PH pollution preferentially influences the physiological homeostasis of earthworms through indirect (i.e., microbial metabolism regulation) than direct (i.e., direct interaction with earthworms) mechanisms. Moreover, the varied CO2 releasement was verified, which highlights the potential role of earthworms in influencing carbon transformation and corresponds with the considerably enriched energy metabolism-related pathway. This study indicated that PH contamination can induce a strong stress response in earthworms through both direct and indirect mechanisms, which in turn, substantially influences carbon transformation in PH contamination sites.

Photochemical degradation in natural attenuation of characteristics of petroleum hydrocarbons (C10-C40) in crude oil polluted soil by simulated long term solar irradiation.

Photodegradation process plays an important role in the natural attenuation of petroleum hydrocarbons (PHs) in oil contaminated soil. The photodegradation characteristics of PHs (C10-C40) in topsoil of crude oil contaminated soil irradiated by simulated sunlight in 280 d without microbial action were investigated. The results showed that photodegradation rate of PHs was increased with increasing the light intensity and decreased with increasing the initial concentration of PHs. Moreover, the photodegradation capacity of tested PHs was relevant to the length of carbon chain. The photodegradation rates of C10-C20 were higher than that of C21-C40 in photoperiod. C21-C40 showed an obvious trend of photodegradation after 56 d, although their photodegradation rates were less than 20% at the early stage. And, the redundancy analysis indicated that lighting time was the primary factor for photodegradation of PHs under abiotic conditions. The photodegradation rate was well interpreted by a two-stage, first-order kinetic law with a faster initial photolysis rate. The EPR spectrums showed that simulated solar irradiation accelerated the generation of superoxide radicals, which could react with PHs in soil. Also, the function groups in PHs polluted soil were changed after light exposure, which might imply the possible photodegradation pathway of PHs.

Magnetic iron-based nanoparticles biogeochemical behavior in soil-plant system: A critical review.

Increasing attention is being given to magnetic iron-based nanoparticles (MINPs) because of their potential environmental benefits. Owing to the earth abundance and high utilization of MINPs, as well as the significant functions of Fe in sustainable agriculture and environmental remediation, an understanding of the environmental fate of MINPs is indispensable. However, there are still knowledge gaps regarding the largely unknown environmental behaviors and fate of MINPs in soil-plant system. Thus, this review summarizes recent literature on the biogeochemical behavior (uptake, transportation, and transformation) of MINPs in soil and plants. The different possible uptake (e.g., foliar and root adsorption) and translocation (e.g., xylem, phloem, symplastic/apoplastic pathway, and endocytosis) pathways are discussed. Furthermore, drivers of MINPs uptake and transportation (e.g., soil characteristics, fertilizer treatments, copresence of inorganic and organic anions, meteorological conditions, and cell wall pores) in both soil and plant environments are summarized. This review also details the physical, chemical, and biological transformations of MINPs in soil-plant system. More importantly, a metadata analysis from the existing literature was employed to investigate the distinction between MINPs and other engineering nanoparticles biogeochemical behavior. In the future, more attention should be given to understanding the behavior of MINPs in soil-plant system and improving the capabilities of predictive models. This review thus highlights the main knowledge gaps regarding MINPs behavior and fate to provide guidance for their safe application in agrochemicals, crop production, and soil health.

Diatomic catalysts for Fenton and Fenton-like reactions: a promising platform for designing/regulating reaction pathways.

The optimization of the single-atom catalyst (SAC) performance has been the hot spot for years. It is widely acknowledged that the incorporation of adjacent single-atom sites (diatomic catalysts (DACs)) can enable synergistic effects, which can be used in cascade catalysis, dual-function catalysis, and performance regulation of intrinsic active sites. DACs have been widely applied in the CO2 reduction reaction (CO2RR), oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), etc.; however, their application is limited in Fenton or Fenton-like reactions. This perspective summarizes the most advanced achievements in this field, followed by the proposed opportunities in further research, including regulation of the magnetic moment, inter-atomic distance effect, strain engineering, atomic cluster (AC)/nanoparticle (NP) modification, etc. It is demonstrated that this perspective can contribute to the DAC application in Fenton or Fenton-like reactions with innovative design and mechanisms being put forward.

Iron oxide nanoparticles in the soil environment: Adsorption, transformation, and environmental risk.

Iron oxide nanoparticles (IONPs) have great application potential due to their multifunctional excellence properties, leading to the possibility of their release into soil environments. IONPs exhibit different adsorption properties toward environmental pollutants (e.g., heavy metals and organic compounds), thus the adsorption performance for various contaminants and the molecular interactions at the IONPs-pollutants interface are discussed. After solute adsorption, the change in the environmental behavior of IONPs is an important transformation process in the natural environments. The aggregation, aging process, and chemical/biological transformation of IONPs can be altered by soil solution chemistry, as well as by the presence of dissolved organic matter and microorganisms. Upon exposure to soil environments, IONPs have both positive and negative impacts on soil organisms (e.g., bacteria, plants, nematodes, and earthworms). Moreover, we compared the toxicity of IONPs alone to combined toxicity with environmental pollutants and pristine IONPs to aged IONPs, and the mechanisms of IONPs toxicity at the cellular level are also reviewed. Given the unanswered questions, future research should include prediction and design of IONPs, new characterization technology for monitoring IONPs transformation in soil ecosystems, and further refinement the environmental risk assessment of IONPs. This review will greatly enhance our knowledge of the performance and impact of IONPs in soil systems.

A Versatile Extended Stöber Approach to Monodisperse Sub-40 nm Carbon Nanospheres for Stabilizing Atomically Dispersed Fe─N4 Sites Toward Efficient Oxygen Reduction Electrocatalysis.

The development of atomically dispersed iron-nitrogen-carbon (Fe─N─C) catalysts as an alternative to precious platinum holds great potential for the substantial progress of a variety of oxygen reduction reaction (ORR)-associated energy conversion technologies. Nevertheless, the precise synthesis of Fe─N─C single atomic catalysts (SACs) with a high density of accessible active sites and pronounced electrocatalytic performance still remains an enormous challenge. Herein, an innovative extended Stöber method is designed for the controllable preparation of monodisperse small-sized N-doped carbon colloidal nanospheres (≈40 nm) anchoring atomically isolated Fe─N4 sites (abbreviated as Fe-SA@N-CNSs hereafter) with a narrow size distribution and high uniformity. Benefiting from the single Fe─N4 moieties and the unique spherical carbon substrate, the resultant Fe-SA@N-CNSs exhibit excellent ORR activity, outstanding long-term durability, and methanol tolerance in KOH electrolyte. More impressively, when further assembled into a flexible solid-state rechargeable zinc-air battery (ZAB), the Fe-SA@N-CNSs-driven ZAB delivers a higher open circuit voltage, a larger power density, and robust cycling/mechanical stability, outperforming the state-of-the-art Pt/C-based counterpart and further testifying the great potential of the as-prepared Fe-SA@N-CNSs in diverse ORR-related practical energy devices. The developed extended Stöber method provides an efficient and versatile avenue toward the preparation of a series of well-defined SACs for diverse electrocatalytic systems.

Potential contribution of chlorella vulgaris to carbon-nitrogen turnover in freshwater ecosystems after a great sandstorm event.

Urban lakes represent important land-water and nature-human dual interfaces that promote the cycling of elements from terrestrials to sediments and consequently modulating the stabilization of regional climate. However, whether disturbances caused by extreme weather events can have substantial effects on carbon-nitrogen (C-N) cycling in these ecosystems are vague. To explore the impact of phytoplankton on the ecological retention time of C-N, two kinds of freshwater (natural and landscape) were collected and conducted a microcosm experiment using a freshwater algal species Chlorella vulgaris. Sandstorm events increased dissolved inorganic carbon in freshwater (65.55 ± 3.09 and 39.46 ± 2.51 mg·L-1 for samples from Jinyang and Nankai, respectively) and significantly affected the relevant pathways of photosynthesis in Chlorella vulgaris, including enhancing chlorophyll fluorescence (The effective quantum yield of PSII at the fifth day of incubation was 0.34 and 0.35 for Nankai and Jinyang, respectively), promoting the synthesis of sugars and inhibiting the synthesis of glycine and serine related proteins. Besides, carbon from plant biomass accumulation and cellular metabolism (fulvic acid-like, polyaromatic-type humic acid and polycarboxylate-type humic acid, etc.) was enriched into residues and become a kind of energy source for the decomposer (TC mass increased by 1.63-2.13 times after 21 days of incubation). This means that the accumulation and consumption of carbon and nitrogen in the residue can be used to track the processes controlling the long-term C-N cycle. Our findings shed light on the plant residues were key factors contributing to the formation of water carbon pool, breaks the traditional theory that dissolved carbonates cannot produce carbon sinks.

Atomically Dispersed FeN2 P2 Motif with High Activity and Stability for Oxygen Reduction Reaction Over the Entire pH Range.

The past decade has witnessed the great potential of Fe-based single-atom electrocatalysis in catalyzing oxygen reduction reaction (ORR). However, it remains a grand challenge to substantially improve their intrinsic activity and long-term stability in acidic electrolytes. Herein, we report a facile chemical vapor deposition strategy, by which high-density Fe atoms (3.97 wt%) are coordinated with square-planar para-positioned nitrogen and phosphorus atoms in a hierarchical carbon framework. The as-crafted atomically dispersed Fe catalyst (denoted Fe-SA/PNC) manifests an outstanding activity towards ORR over the entire pH range. Specifically, the half-wave potential of 0.92 V, 0.83 V, and 0.86 V vs. reversible hydrogen electrode (RHE) are attained in alkaline, neutral, and acidic electrolytes, respectively, representing the high performance among reported catalysts to date. Furthermore, after 30,000 durability cycles, the Fe-SA/PNC remains to be stable with no visible performance decay when tested in 0.1 M KOH and 0.5 M H2 SO4 , and only a minor negative shift of 40 mV detected in 0.1 M HClO4 , significantly outperforming commercial Pt/C counterpart. The coordination motif of Fe-SA/PNC is validated by density functional theory (DFT) calculations. This work provides atomic-level insight into improving the activity and stability of non-noble metal ORR catalysts, opening up an avenue to craft the desired single-atom electrocatalysts.

Selective hydroxyl generation for efficient pollutant degradation by electronic structure modulation at Fe sites.

Hydrogen peroxide (H2O2) is an important green oxidant in the field of sewage treatment, and how to improve its activation efficiency and generate free radicals with stronger oxidation performance is a key issue in current research. Herein, we synthesized a Cu-doped α-Fe2O3 catalyst (7% Cu-Fe2O3) for activation of H2O2 under visible light for degradation of organic pollutants. The introduction of a Cu dopant changed the d-band center of Fe closer to the Fermi level, which enhanced the adsorption and activation of the Fe site for H2O2, and the cleavage pathway of H2O2 changed from heterolytic cleavage to homolytic cleavage, thereby improving the selectivity of •OH generation. In addition, Cu doping also promoted the light absorption ability of α-Fe2O3 and the separation of hole-electron pairs, which enhanced its photocatalytic activities. Benefiting from the high selectivity of •OH, 7% Cu-Fe2O3 exhibited efficient degradation activities against ciprofloxacin, the degradation rate was 3.6 times as much as that of α-Fe2O3, and it had good degradation efficiency for a variety of organic pollutants.

Microplastics Weaken the Adaptability of Cyanobacterium Synechococcus sp. to Ocean Warming.

Ocean warming (OW) caused by anthropogenic activities threatens ocean ecosystems. Moreover, microplastic (MP) pollution in the global ocean is also increasing. However, the combined effects of OW and MPs on marine phytoplankton are unclear. Synechococcus sp., the most ubiquitous autotrophic cyanobacterium, was used to evaluate the response to OW + MPs under two warming scenarios (28 and 32 °C compared to 24 °C). The enhancement of the cell growth rate and carbon fixation under OW were weakened by MP exposure. Specifically, OW + MPs reduced carbon fixation by 10.9 and 15.4% at 28 and 32 °C, respectively. In addition, reduction in photosynthesis pigment contents of Synechococcus sp. under OW was intensified under OW + MPs, supporting the lower growth rate and carbon fixation under OW + MPs. Transcriptome plasticity (the evolutionary and adaptive potential of gene expression in response to changing environments) enabled Synechococcus sp. to develop a warming-adaptive transcriptional profile (downregulation of photosynthesis and CO2 fixation) under OW. Nevertheless, the downregulation of photosynthesis and CO2 fixation were alleviated under OW + MPs to increase responsiveness to the adverse effect. Due to the high abundances of Synechococcus sp. and its contributions to primary production, these findings are important for understanding the effects of MPs on carbon fixation and ocean carbon fluxes under global warming.