Cu-optimized long-range interaction between Co nanoparticles and Co single atoms: Improved Fenton-like reaction activity.

The interplay between multi-atom assembly configurations and single atoms (SAs) has been gaining attention in research. However, the effect of long-term range interactions between SAs and multi-atom assemblies on the orbital filling characteristics has yet to be investigated. In this context, we introduced copper (Cu) doping to strengthen the interaction between cobalt (Co) nanoparticles (NPs) and Co SAs by promoting the spontaneous formation of Co-Cu alloy NPs that tends toward aggregation owing to its negative cohesive energy (-0.06454), instead of forming Cu SAs. The incorporation of Cu within the Co-Cu alloy NPs, compared to the pure Co NPs, significantly expedites the kinetics of peroxymonosulfate (PMS) oxidation processes on Co SAs. Unlike Co NPs, Co-Cu NPs facilitate electron rearrangement in the d orbitals (especially dz2 and dxz) near the Fermi level in Co SAs, thereby optimizing the dz2-O (PMS) and dxz-O (SO5-) orbital interaction. Eventually, the Co-Cu alloy NPs embedded in nitrogen-doped carbon (CC@CNC) catalysts rapidly eliminated 80.67% of 20 mg/L carbamazepine (CBZ) within 5 min. This performance significantly surpasses that of catalysts consisting solely of Co NPs in a similar matrix (C@CNC), which achieved a 58.99% reduction in 5 min. The quasi in situ characterization suggested that PMS acts as an electron donor and will transfer electrons to Co SAs, generating 1O2 for contaminant abatement. This study offers valuable insights into the mechanisms by which composite active sites formed through multi-atom assembly interact at the atomic orbital level to achieve high-efficiency PMS-based advanced oxidation processes at the atomic orbital level.

The pivotal role of phosphorus level gradient in regulating nitrogen cycle in wetland ecosystem.

Phosphorus (P) is one of key drivers in Earth's nitrogen (N) cycle, however, the global overview of the P-regulated microbial community structure and gene abundance carrying wetland N process remains to be investigated. The key environmental factors that influenced wetland N cycle were initially screened, verifying the central role P. More complex and stable community interaction can be established in rich (20 mg/kg < P ≤ 100 mg/kg) and surplus P groups (P > 100 mg/kg) compared to that in deficient P group (P ≤ 20 mg/kg), with enhanced participation of betaproteobacteria and actinobacteria (i.e., changed hub microorganisms). Accordingly, P-mediated variations in gene expression patterns can be expected. On the one hand, the gene responses to carbon (C), N, and P factors presented nearly synchronous variation, highlighting the potential C-N-P coupling cycle in wetland ecosystem. On the other hand, the gene sensitivity towards environmental factors was changed at different P levels. Overall, the P level gradient can influence N cycle in direct (i.e., influences on gene abundances) and indirect (i.e., influences on gene response to environmental factors) manners. These findings provide important insights for controlling the N cycle in wetland ecosystems, particularly in cases where P levels are limiting factors.

Bioelectrochemical anaerobic digestion mitigates microplastic pollution and promotes methane recovery of wastewater treatment in biofilm system.

Bioelectrochemical systems (BES) offer significant potential for treating refractory waste and recovering bioenergy. However, their ability to mitigate microplastic pollution in wastewater remains unexplored. This study showed that BES facilitated the treatment of polyethylene (PE), polyvinyl chloride (PVC), and Mix (PE+PVC) microplastic wastewater and the methane recovery (40.61%, 20.02%, 21.19%, respectively). The lactate dehydrogenase (LDH), adenosine triphosphate (ATP), cytochrome c, and nicotinamide adenine dinucleotide (NADH/NAD+) ratios were elevated with electrical stimulation. Moreover, the applied voltage improved the polysaccharides content of the extracellular polymeric substances (EPS) in the PE-BES but decreased in PVC-BES, while the proteins showed the opposite trend. Metatranscriptomic sequencing showed that the abundance of fermentation bacteria, acetogens, electrogens, and methanogens was greatly enhanced by applying voltage, especially at the anode. Methane metabolism was dominated by the acetoclastic methanogenic pathway, with the applied voltage promoting the enrichment of Methanothrix, resulting in the direct conversion of acetate to acetyl-CoA via acetate-CoA ligase (EC: 6.2.1.1), and increased metabolic activity in the anode. Moreover, applied voltage greatly boosted the function genes expression level related to energy metabolism, tricarboxylic acid (TCA) cycle, electron transport, and transporters on the anode biofilm. Overall, these results demonstrate that BES can mitigate microplastic pollution during wastewater treatment.

Gallic Acid Can Promote Low-Density Lipoprotein Uptake in HepG2 Cells via Increasing Low-Density Lipoprotein Receptor Accumulation.

Gallic acid (GA) is a type of polyphenolic compound that can be found in a range of fruits, vegetables, and tea. Although it has been confirmed it improves non-alcoholic fatty liver disease (NAFLD), it is still unknown whether GA can improve the occurrence of NAFLD by increasing the low-density lipoprotein receptor (LDLR) accumulation and alleviating cholesterol metabolism disorders. Therefore, the present study explored the effect of GA on LDLR and its mechanism of action. The findings indicated that the increase in LDLR accumulation in HepG2 cells induced by GA was associated with the stimulation of the epidermal growth factor receptor-extracellular regulated protein kinase (EGFR-ERK1/2) signaling pathway. When the pathway was inhibited by EGFR mab cetuximab, it was observed that the activation of the EGFR-ERK1/2 signaling pathway induced by GA was also blocked. At the same time, the accumulation of LDLR protein and the uptake of LDL were also suppressed. Additionally, GA can also promote the accumulation of forkhead box O3 (FOXO3) and suppress the accumulation of hepatocyte nuclear factor-1α (HNF1α), leading to the inhibition of proprotein convertase subtilisin/kexin 9 (PCSK9) mRNA expression and protein accumulation. This ultimately results in increased LDLR protein accumulation and enhanced uptake of LDL in cells. In summary, the present study revealed the potential mechanism of GA's role in ameliorating NAFLD, with a view of providing a theoretical basis for the dietary supplementation of GA.

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.

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.

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.

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.

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.

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.

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.

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.