Hydroxylamine-induced activation of permanganate for enhanced oxidation of sulfamethoxazole: Mechanism and products.

Recently, many reagents have been introduced to accelerate the formation of highly reactive intermediate Mn species from permanganate (KMnO4), thereby improving the oxidation activity of KMnO4 towards pollutants. However, most studies have mainly focused on sulfur-containing reducing agents (e.g., bisulfite and sodium sulfite), with little attention paid to nitrogen-containing reducing agents. This study found that hydroxylamine (HA) and hydroxylamine derivatives (HAs) can facilitate KMnO4 in pollutant removal. Taking sulfamethoxazole (SMX) as a target contaminant, the effect of pH, SMX concentration, KMnO4 and HA dosages, and the molar ratio of HA and KMnO4 on the degradation of SMX in the KMnO4/HA process was systematically investigated. Quenching experiments and probe analysis revealed MnO2-catalyzed KMnO4 oxidation, Mn(III) and reactive nitrogen species as the primary active species responsible for SMX oxidation in the KMnO4/HA system. Proposed transformation pathways of SMX in the KMnO4/HA system mainly involve hydroxylation and cleavage reactions. The KMnO4/HA system was more conducive to selective oxidation of SMX, 2,4-dichlorophenol, and several other pollutants, but reluctant to bisphenol S (BPS). Overall, this study proposed an effective system for eliminating pollutants, while providing mechanistic insight into HA-driven KMnO4 activation for environmental remediation.

Bioprotective Respirator Assembled by Defective Carbon Nitride for Long-Term Light Triggered Health Protection.

Wearing face masks is the best way to stop the spread of respiratory infections. However, if masks are not sterilized, changing them too frequently can actually increase the risk of cross-contamination. Herein, the construction of an antipathogen photocatalytic mask with carbon vacancy-modified carbon nitride nanosheets (g-C3N4-VC Ns) coated on the non-woven fabrics of the out layer of the mask, offering effective and long-term protection against damaging pathogens when exposed to light is reported. The introduced carbon vacancies are found capable of creating energy-disordered sites and inducing energetic electric force to overcome the Coulomb interactions between electron-hole pairs, thus promoting the electron-hole separation to achieve a high generation of reactive oxygen species (ROS). Thanks to its high activity in generating ROS upon exposure to light, the as-prepared photocatalytic mask shows high pathogen sterilization performance. This, in turn, prolongs the mask's protective lifetime, decreases the need for regular replacement, and decreases medical waste production. The work demonstrated here opens new viewpoints in designing pathogens biocidal protective devices for health protection, offering significant promise in specific environment self-protection.

Novel enhanced defluorination of perfluorooctanoic acids by biochar-assisted ultrasound coupling ferrate: Performance and mechanism.

An ultrasound (US)/biochar (BC)/ferrate (Fe (VI)) system was firstly proposed to enhance perfluorooctanoic acid (PFOA) defluorination. It achieved 93 % defluorination optimally, higher than the sum of 77 % (28 % and 49 % for US/BC and US/Fe (VI) respectively), implying synergistic effect. Besides, the mechanism study confirmed that, this system can not only increase the specific surface area of BC and the generation of reactive oxidant species (ROS), enriching the active sites and forming new oxygen-containing functional groups, but also promote the formation of intermediate iron species. The PFOA degradation in the US/BC/Fe (VI) was probably an adsorption-degradation process, both ROS and electron transfer promoted the defluorination. Additionally, its sustainability was also demonstrated with 14 % reduced defluorination percentage after five cycles of BC. Overall, the synergistic effect of the US/BC/Fe (VI) and its enhancing mechanism for PFOA defluorination were clarified firstly, which contributes to the development of biochar for assisting polyfluoroalkyl substances degradation.

Restricted reaction of layered double hydroxide nanoparticles with phosphate in a confined microsphere space.

Over the past decades, considerable efforts have been made to find useful solutions for phosphate pollution control. The state transition of nanomaterials from freely dispersed to encapsulated provides a realizable route for their application in phosphate elimination. The separation convenience offered by encapsulation has been widely recognized, however, the unique binding mode of nanostructures and phosphate in the confined space remains unclear, limiting its further development. Here, carboxymethyl cellulose (CMC) microspheres were used as hosts to deploy layered double hydroxide (LDH) nanoparticles. On this basis, we described an attempt to explore the adsorption behavior of LDH and phosphate in the microsphere space. Compared to their freely dispersed analogues, LDH particles exhibited higher structural stability, wider pH adaptability, and better phosphate selectivity when spatially confined in the CMC microsphere. Nevertheless, the kinetic process was severely inhibited by three orders of magnitude. Besides, the saturated phosphate adsorption capacity was also reduced to 74.6 % of the freely dispersed system. A combinative characterization revealed that the highly electronegative CMC host not only causes electrostatic repulsion to phosphate, but also extracts the electron density of the metal center of LDH, weakening its ability to act as a Lewis acid site for phosphate binding. Meanwhile, the microsphere encapsulation also hinders the ion exchange function of interlayer anions and phosphate. This study offers an objective insight into the reaction of LDH and phosphate in the confined microsphere space, which may contribute to the advanced design of encapsulation strategies for nanoparticles.

Ultrasound-based advanced oxidation processes for landfill leachate treatment: Energy consumption, influences, mechanisms and perspectives.

Advanced oxidation processes (AOPs) based on ultrasound (US) have attracted considerable attention in recent years due to its advantages in the degradation of landfill leachate. The review summarizes the existing treatment methods of leachate from lab-scale, compares their advantages and disadvantages by focusing on the degradation of emerging contaminants (ECs) in the leachate. Then the US-based AOPs are introduced emphatically, including their degradation mechanisms, influencing factors, energy consumption, further optimization methods as well as the possibility of field-scale application are systematically described. Moreover, this review also expounds on the advantages of dual-frequency US (DFUS) technology compared with single-frequency US, and a theoretically feasible DFUS process is proposed to treat ECs in the leachate. Finally, suggestions and prospects for US technologies in treating landfill leachate are put forward to aid future research on landfill leachate treatment. Meaningfully, this manuscript will provide reference values of US-based technologies in landfill leachate treatment for the practical use, facilitating the development of US-based AOPs in landfill leachate management and disposal.

The factors controlling antibiotic resistance genes in different treatment processes of mainstream full-scale wastewater treatment plants.

The alteration of antibiotic resistance genes (ARGs) in wastewater has been less studied in wastewater treatment plants (WWTPs), making it difficult to assess ARGs' spreading risk comprehensively. Therefore, this study investigated the distribution and reduction of ARGs in the main process (Anaerobic-Anoxic-Oxic with Membrane Bio-Reactor (A2/O + MBR), Oxidation Ditch with sedimentation (OD), and Cyclic Activated Sludge System (CASS) with sedimentation) and disinfection process (Ultra-violet and Chlorination) of full-scale WWTPs. The wastewater was sampled before and after the different main process and disinfection process; then, the diversity and abundance of ARGs and mobile genetic genes (MGEs, helping the horizontal transfer of ARGs) in wastewater of different treatment stages were determined by a real-time high-throughput quantitative PCR (HT-qPCR) system. It was found that similar influents would result in similar ARGs in wastewater samples, independent of the treatment processes used. The main process could effectively reduce the abundance of ARGs and MGEs by 1.80-2.12 and 1.46-2.18 logarithm units, respectively. The main factors affecting ARGs were mainly wastewater quality index, especially COD, and MGEs like transposase and insertion sequences which were significantly associated with 66 and 48 subtypes of ARGs, respectively. Moreover, disinfection was more effective than the main process in inactivating antibiotic resistance bacteria (ARB), and the removal rate of ARB by disinfection reached 43.53 %-100 %. However, there are still risks of ARB regeneration (up to 4.22 log units) in the effluent of WWTPs. In the future, nutrient removal and disinfection process improvement is necessary to benefit ARG and ARB removal.

Allelopathic effect of pyrogallic acid on cyanobacterium Microcystis aeruginosa: The regulatory role of nitric oxide and its significance for controlling harmful algal blooms (HABs).

Utilization of allelochemicals to inhibit overgrowth of toxic cyanobacteria is considered to be an environmentally friendly approach. However, the regulatory role of the signaling molecule nitric oxide (NO) on cyanobacteria under allelopathic stress remains unanswered. Here we demonstrate that the effect of NO on the cyanobacterium Microcystis aeruginosa depends on allelopathic stress of pyrogallic acid (PA). The experimental results revealed that general stimulation of M. aeruginosa by PA occurred within the concentration range 0.4-0.8 mg/L. In parallel with increasing concentration of PA (1.6-16.0 mg/L), the growth of M. aeruginosa was observed to decrease. The effect of NO on M. aeruginosa was evaluated by addition of the NO scavenger hemoglobin. In the stimulation stage, intracellular NO was seen to decreased to modulate the level of reactive oxygen species (ROS) and to maintain redox homeostasis of the cells. In the inhibition stage, the physiological characteristics of M. aeruginosa were changed significantly. Additionally, the accumulation of S-nitrosothiol by M. aeruginosa indicated that the high concentrations of PA induced nitric oxidative stress in M. aeruginosa. This study provides a new thought to understand the role of NO in controlling harmful algal blooms through the allelopathic effect of aquatic macrophytes.

Nitrogen addition may promote soil organic carbon storage and CO2 emission but reduce dissolved organic carbon in Zoige peatland.

With the increase of nitrogen (N) deposition, N input can affect soil C cycling since microbes may trigger a series of activities to balance the supply and demand of nutrients. However, as one of the largest C sinks on earth, the role of extra N addition in affecting peatland soil C and its potential mechanism remains unclear and debated. Therefore, this study chose the largest peatland in China (i.e., Zoige, mostly N-limited) to systematically explore the potential changes of soil C, microbes, and ecoenzymes caused by extra N input at the lab scale incubation. Three different types of soils were collected and incubated with different levels of NH4NO3 solution for 45 days. After incubation, N input generally increased soil organic C (SOC) but decreased dissolved organic carbon (DOC) in Zoige peatland soils. Moreover, CO2 and CH4 emissions were significantly increased after high N input (equal to 5 mg NH4NO3 g-1 dry soils). Through a series of analyses, it was observed that microbial communities and ecoenzyme activities mainly influenced the changes of different C components. Collectively, this study implied that the increasing N deposition might help C sequestration in N-limited peatland soils; simultaneously, the risk of increased CO2 and CH4 by N input in global warming should not be ignored.

Quantitative assessment of interactions of hydrophilic organic contaminants with microplastics in natural water environment.

The interaction between microplastics (MPs) and hydrophilic organic contaminants (HOCs) in natural water environment has recently raised great public attentions due to the potential toxicity to humans. However, the quantitative assessment is less studied. In this study, the interaction between ciprofloxacin (CIP) and ofloxacin (OFL) (two important HOCs) and virgin and aged polystyrene (PS) was investigated. The aged PS showed higher adsorption rate and capacity than the virgin PS, due to its larger surface area and more O-containing groups. The pH-dependent adsorption of CIP was higher than OFL on both virgin and aged PS; the maximum adsorption for both HOCs occurred at pH 5. The sequential orders of functional groups for the adsorption were discovered according to the study by the 2D correlation Fourier transform infrared spectroscopy. Several mechanisms existed for the interaction: (1) at 3.0 < pH < 5.0, the electrostatic attraction (EA) was inhibited while H-bond (HB) was dominant, accounting for > 60% of the total uptake; (2) at 5.0 < pH < 8.0, the contribution of EA increased to around 50-60% while HB decreased to 30-40%; (3) at 8.0 < pH < 10.0, EA, HB and π-π conjugation caused 30-40%, 25-40% and 20-45% of the total uptake, respectively; (4) at 10.0 < pH < 12.0, π-π conjugation accounted for 90-100%. Notably, higher adsorption of CIP was mainly attributed to the presence of secondary amino groups and its higher pKa value, correspondingly leading to the additional ordinary HB and negative charge-assisted HB, and EA interactions with PS. This study further provides clear evidences on the risk of MPs and HOCs on humans and aqueous living organisms.

Techno-ecological synergies of hydropower plants: Insights from GHG mitigation.

Hydropower is a source of climate-friendly energy; however, its ecological impacts have been criticized. Few studies have considered the greenhouse gas (GHG) emissions resulting from ecosystem restoration. This study proposes a techno-ecological synergy framework based on life cycle assessment (LCA) to evaluate 34 hydropower plants (HPs) in the upper reaches of the Yangtze River from GHG supply and demand side perspectives. Our results show that the demand unit carbon footprint of the 34 HPs ranged from 5.43 to 49.36 g CO2-eq/kWh, while the imputed GHG emissions from ecosystem restoration occupied 1.22 % to 30.35 %. The unit carbon footprint of large HPs were larger than those of small HPs, and both were positively correlated with the installed capacity of the HPs. All the HPs were unsustainable at the local scale and relied on regional ecosystem supplies. The Sobol' sensitivity analysis and Monte Carlo simulations demonstrated the reliability of our results. Finally, our results were used to consider the related policy implications.

The silicon active sites driven by oxygen vacancies in iron silicate for activating peroxymonosulfate.

Most metal sites and some non-metallic sites such as carbon and nitrogen are usually considered to be traditional active sites during peroxymonosulfate (PMS) activation. However, as an important non-metallic element, the actual role of silicon (Si) in PMS activation still remains unclear. In this work, taking iron silicate (FeSi) as an example, the role of the Si region in PMS activation was clearly revealed. The experiments and density functional theory (DFT) calculation results showed that besides the traditional Fe sites, the Si also played a non-negligible role during PMS activation. In FeSi containing oxygen vacancies (Ovac), Fe-Si was the active site instead of Fe-Fe. The Bard charge results implied that the presence of Ovac tuned the electronic properties of FeSi, making the Si participate in PMS activation. This work deepened understanding of the role of Si in silicates for PMS activation and provided a theoretical basis for the development of excellent Si-based catalysts.

Carbon Quantum Dots-Functionalized UiO-66-NH2 Enabling Efficient Infrared Light Conversion of 5-Hydroxymethylfurfuryl with Waste Ethanol into 5-Ethoxymethylfurfural.

The catalytic etherification of 5-hydroxymethylfurfural (HMF) with the waste ethanol into high-energy-density 5-ethoxymethylfurfural (EMF) has been considered as a promising way to simultaneously alleviate the energy crisis and environmental pollution. However, the energy consumption is rather high as the synthesis of EMF requires a high temperature to open the etherification reaction. Herein, we demonstrate a clever design and construction of acidified biomass-derived carbon quantum dots (BCQDs)-modified UiO-66-NH2 that is immobilized on cermasite (H+/BCQDs/UiO-66-NH2@ceramsite), which can use the IR light as driven energy and wasted ethanol to trigger the catalytic conversion of HMF into EMF. The temperature on the surface of the immobilized catalyst could reach as high as 139 °C within 15 min IR irradiation. Due to the aforementioned advantages, the as-prepared catalyst exhibited excellent IR-triggered catalytic performance toward EMF production, where the EMF yields and selectivity were as high as 45% and 65%, respectively. The high catalytic performance originates from the outstanding photo-to-thermal conversion by the introduction of BCQDs, as well as the strong interactions between BCQDs and UiO-66-NH2 that boosts the etherification reactions. The immobilization of catalyst on cermasite not only benefits catalyst recycling, but more importantly reduces catalyst loss during practical applications. The conceptual study shown here provides new viewpoints in designing energy-effective materials for the conversion of wastes into high-value-added resources.

A novel way to facilely degrade organic pollutants with the tail-gas derived from PHP (phosphoric acid plus hydrogen peroxide) pretreatment of lignocellulose.

The abundantly released tail-gas from lignocellulose pretreatment with phosphoric acid plus hydrogen peroxide (PHP) was found to accelerate the aging of latex/silicone textural accessories of the pretreatment device. Inspired by this, tail-gas was utilized to control organic pollutants. Methylene blue (MB), as a model pollutant, was rapidly decolorized by the tail-gas, and oxidative degradation was substantially proven by full-wavelength scanning with a UV-visible spectrometer. The tail-gas from six typical lignocellulosic feedstocks produced 68.0-98.3% MB degradation, suggesting its wide feedstock compatibility. Three other dyes, including rhodamine B, methyl orange and malachite green, obtained 97.5-99.5% degradation; moreover, tetracycline, resorcinol and hexachlorobenzene achieved 73.8-93.7% degradation, suggesting a superior pollutant compatibility. In a cytotoxicity assessment, the survival rate of the degraded MB was 103.5% compared with 80.4% for the untreated MB, implying almost no cytotoxicity after MB degradation. Mechanism investigations indicated that the self-exothermic reaction in PHP pretreatment drove the self-generated peroxy acids into tail-gas. Moreover, it heated the pollutant solution and thermally activated peroxy acids as free radicals for efficient pollutant degradation. Here, a brand-new technique for degrading organic pollutants with a "Win-Win-Win" concept was purposed for lignocellulose valorization, pollutant control by waste tail-gas, and biofuel production.

Insights into lignocellulosic waste fractionation for lignin nanospheres fabrication using acidic/alkaline deep eutectic solvents.

Facile fractionation of lignocellulosic waste into useable forms is essential to achieve a multi-product treatment process especially when the resulting lignin streams are expected for high-value materials valorization. Despite acidic/alkaline deep eutectic solvents (DESs) are promising solvents for lignocellulosic waste fractionation, there is little information about their differences in the fractionation and lignin extraction profiles. In this work, four DESs that were cataloged to acidic types (formic acid-choline chloride, lactic acid-choline chloride) and alkaline types (monoethanolamine-choline chloride, glycerol-K2CO3) were investigated to compare their abilities of bamboo waste fractionation. Physicochemical properties of these resulting cellulose, lignin and derived lignin nanospheres (LNPs) were also assessed. Results showed that DESs could selectively extract lignin via cleaving lignin-carbohydrate linkages and lignin ether bonds. Acidic DESs pretreatments were more effective in biomass delignification (~95.0 %), while alkaline DESs showed better polysaccharide retention. Glycerol-K2CO3 LNPs exhibited much smaller sphere size (50-100 nm) while acidic DESs LNPs showed higher thermal stability due to higher extent of lignin condensation. In addition, MEA-ChCl could introduce amine groups onto lignin hydroxyl. This work provided insightful information for tailoring technique routes to selective lignocellulosic waste fractionation, while facilitating the downstream applications of the obtained cellulose/lignin.

Paper mulberry fruit juice: a novel biomass resource for bioethanol production.

By way of broadening the use of diverse sustainable bioethanol feedstocks, the potentials of Paper mulberry fruit juice (PMFJ), as a non-food, sugar-based substrate, were evaluated for fuel ethanol production. The suitability of PMFJ was proven, as maximum ethanol concentration (56.4 g/L) and yield (0.39 g/g) were achieved within half a day of the start of fermentation, corresponding to very high ethanol productivity of 4.7 g/L/hr. The established potentials were further optimally maximized through the response surface methodology (RSM). At the optimal temperature of 30 °C, yeast concentration of 0.55 g/L, and pH of 5, ethanol concentration, productivity, and yield obtained were 73.69 g/L, 4.61 g/L/hr, and 0.48 g/g, respectively. Under these ideal conditions, diverse metal salts were afterward screened for their effects on PMFJ fermentation. Based on a two-level fractional factorial design, nutrient addition had no positive impact on ethanol production. Thus, under the optimal process conditions, and without any external nutrient supplementation, bioethanol from PMFJ compared favorably with typical sugar-based energy crops, highlighting its resourcefulness as a high-value biomass resource for fuel ethanol production.

Self-generated peroxyacetic acid in phosphoric acid plus hydrogen peroxide pretreatment mediated lignocellulose deconstruction and delignification.

BACKGROUND: Peroxyacetic acid involved chemical pretreatment is effective in lignocellulose deconstruction and oxidation. However, these peroxyacetic acid are usually artificially added. Our previous work has shown that the newly developed PHP pretreatment (phosphoric acid plus hydrogen peroxide) is promising in lignocellulose biomass fractionation through an aggressive oxidation process, while the information about the synergistic effect between H3PO4 and H2O2 is quite lack, especially whether some strong oxidant intermediates is existed. In this work, we reported the PHP pretreatment system could self-generate peroxyacetic acid oxidant, which mediated the overall lignocellulose deconstruction, and hemicellulose/lignin degradation. RESULTS: The PHP pretreatment profile on wheat straw and corn stalk were investigated. The pathways/mechanisms of peroxyacetic acid mediated-PHP pretreatment were elucidated through tracing the structural changes of each component. Results showed that hemicellulose was almost completely solubilized and removed, corresponding to about 87.0% cellulose recovery with high digestibility. Rather high degrees of delignification of 83.5% and 90.0% were achieved for wheat straw and corn stalk, respectively, with the aid of peroxyacetic acid oxidation. A clearly positive correlation was found between the concentration of peroxyacetic acid and the extent of lignocellulose deconstruction. Peroxyacetic acid was mainly self-generated through H2O2 oxidation of acetic acid that was produced from hemicellulose deacetylation and lignin degradation. The self-generated peroxyacetic acid then further contributed to lignocellulose deconstruction and delignification. CONCLUSIONS: The synergistic effect of H3PO4 and H2O2 in the PHP solvent system could efficiently deconstruct wheat straw and corn stalk lignocellulose through an oxidation-mediated process. The main function of H3PO4 was to deconstruct biomass recalcitrance and degrade hemicellulose through acid hydrolysis, while the function of H2O2 was to facilitate the formation of peroxyacetic acid. Peroxyacetic acid with stronger oxidation ability was generated through the reaction between H2O2 and acetic acid, which was released from xylan and lignin oxidation/degradation. This work elucidated the generation and function of peroxyacetic acid in the PHP pretreatment system, and also provide useful information to tailor peroxide-involved pretreatment routes, especially at acidic conditions.

Bacterial cellulose/lignin nanoparticles composite films with retarded biodegradability.

In practical applications, the full biodegradability of all-biomass-based bacterial cellulose (BC) composites enhances their environmentally friendliness but results in the poor durability especially at humid conditions. This work prepared BC/lignin nanoparticles (LNPs) composite films with retarded biodegradability, which could broaden their application area. Three LNPs were fabricated using technical lignins extracted by deep eutectic solvent (DES), ethanol organosolv, soda/anthraquinone from poplar. LNPs involvement during BC fermentation showed limited influence on its productivity but significantly retarded the biodegradation of composite films. The potential inhibition mechanism was physical barrier and non-productive binding of LNPs. The BC/Soda LNPs showed much higher retarded degradation property (~58 wt% degradation) compared to BC/Organosolv LNPs and BC/DES LNPs (~85 wt% and ~ 97 wt% degradation respectively) at high enzyme loadings of 5 mg g-1 BCE. While at low enzyme loadings of 1 mg g-1 BCE, all these three composite films showed comparable retarded degradation property of ~60 wt%.

Mechanistic insight into different adsorption of norfloxacin on microplastics in simulated natural water and real surface water.

Microplastics (MPs) as carriers of various contaminants have attracted more attentions in water environments. However, the interactions between typical MPs and norfloxacin (NOR) in natural water environments were still not systematically studied. In this study, the adsorption of NOR onto four typical types of MPs (polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyvinyl chloride (PVC)) was investigated in simulated natural water and real surface water, and the adsorption mechanisms were deeply explored to provide fundamental understandings of the MPs-NOR complicated pollution. The results showed that the kinetics of NOR onto all MPs obeyed pseudo-second-order model, and was greatly slowed down at lower temperature or higher salinity. The intrinsic structure and surface area of MPs played important roles in the adsorption behaviors of NOR on these four types of MPs. The adsorption isotherm of NOR onto all MPs could be well described by linear model, with the Kd values following the order of PVC > PS > PE > PP (i.e. 6.229-11.901 L/µg) in simulated natural water. However, in surface water the adsorption isotherms of NOR on all MPs could be well fitted by Freundlich model. For all MPs, the adsorption of NOR was quite pH-dependent due to the electrostatic interactions. Furthermore, the salinity and the presence of dissolved organic matter (DOM) had significantly hindered the NOR adsorption. More importantly, compared with adsorption behaviors in simulated natural water, the competition of coexisting substances such as cations and NOM for adsorption sites and higher water pH dramatically reduced the adsorption of NOR onto all types of MPs in Jiang'an River, with the reduction rate of 19.7-41.2%. Finally, the mechanism studies indicated that the electrostatic attractions played a key role in the adsorption of NOR onto MPs, and π-π, H-bonding, polar-polar, and Van Der Waals interactions were also involved in adsorption processes.

Dynamics of sediment phosphorus affected by mobile aeration: Pilot-scale simulation study in a hypereutrophic pond.

Controlling the release of phosphorus (P) in sediments is important to prevent eutrophication and harmful algal blooms in water bodies. Here we explored the effect of mobile aerators on the control of P release from sediments in a eutrophic pond. The dissolved oxygen in the water body recovered significantly after six months of aeration, becoming 4.2-5.8 times higher than in the control. The pH and Eh values at the sediment-water interface considerably increased, while the concentration of soluble reactive phosphorus (SRP) in pore water significantly decreased, resulting in the alteration of SRP fluxes from 1.69 mg/m2 d to -53.49 mg/m2 d. Moreover, the inert P in sediments increased by 5.2% of the total P at the end of the study compared with the initial state, and the calcium-bound phosphorus (HCl-P) increased by 96.6%. However, although aeration reduced the concentration of SRP in the water column, the total P concentration was 2.45 times higher than that of the control, and the content of redox-sensitive P (BD-P) in the sediment also increased by 200%. Overall, although mobile aeration can maintain the microenvironment of the sediment interface and increase the inert P content in the sediment to reduce the P flux, it cannot reduce the risk of release of mobile P.

Polar organic aerosol tracers in two areas in Beijing-Tianjin-Hebei region: Concentration comparison before and in the sept. Third Parade and sources.

A total of 106 24-h PM2.5 aerosol samples were collected in an urban area (Shijiazhuang, SJZ) and a suburban area (Liulihe, LLH, Fangshan County, Beijing) in the Beijing-Tianjin-Hebei (BTH) region in 2 periods: the first is from 10 July to 10 August, which is before Sept. Third Parade (Period I); the second is from 20 Aug. to 6 Sept. 2015, which is during Sept. Third Parade (Period II). Polar organic tracers, including isoprene, α-pinene, ß-caryophyllene and toluene oxidation products, as well as sugars and carboxylic acids were measured. In Period II, rigorous emission-reduction measures were taken in the BTH region. With the anthropogenic emission being cut down significantly, the average concentrations of isoprene, α-pinene, ß-caryophyllene and toluene oxidation products and all carboxylic acids (except tetradecanoic, palmitic, and stearic acids), were lower in Period II than those in Period I in LLH, indicating that the SOA tracers were decreased with precursor emission volumes and yields in the atmosphere. Moreover, sugar compounds were shown with comparable levels during the two periods in LLH, suggesting that no measures were taken to reduce the intensities of the biogenic sources. On the contrary, tetradecanoic, palmitic, and stearic acids were shown with obviously higher concentrations in Period II than those in Period I, demonstrating that cooking fumes increased during Sept. Third Parade period. The positive matrix factorization (PMF) model combining with tracer-based method was applied to explore the sources of secondary organic carbon (SOC). It reveals that the sources of SOC include isoprene, α-pinene, ß-caryophyllene and toluene oxidation products, fossil fuel combustion, cooking fumes and regionally transferred aged aerosols. These sources accounted for 11.3%, 9.0%, 15.5%, 10.9%, 29.2%, 2.9%, 21.1% of SOC for SJZ, and 12.7%, 11.2%, 9.7%, 14.4%, 25.3%, 0%, 26.7% of SOC for LLH, during the whole sampling periods respectively.