In-situ construction of abundant active centers on hierarchically porous carbon electrode toward high-performance phosphate electrosorption: Synergistic effect of electric field and capture sites

Phosphate removal is crucial for eutrophication control and water quality improvement.Electro-assisted adsorption,an eco-friendly elec-trosorption process,exhibited a promising potential for wastewater treatment.However,there are few works focused on phosphate electro-sorption,and reported electrodes cannot attach satisfactory removal capacities and rates.Herein,electro-assisted adsorption of phosphate via in-situ construction of La active centers on hierarchically porous carbon(LaPC)has been originally demonstrated.The resulted LaPC composite not only possessed a hierarchically porous structure with uniformly dispersed La active sites,but also provided good conductivity for interfacial electron transfer.The LaPC electrode achieved an ultrahigh phosphate electrosorption capability of 462.01 mg g^(-1) at 1 V,outperforming most existing electrodes.The superior phosphate removal performance originates from abundant active centers formed by the coupling of electricfield and capture sites.Besides,the stability and selectivity toward phosphate capture were maintained well even under comprehensive conditions.Moreover,a series of kinetics and isotherms models were employed to validate the electrosorption process.This work demonstrates a deep understanding and promotes a new level of phosphate electrosorption.

Achieving high-efficient photocatalytic persulfate-activated degradation of tetracycline via carbon dots modified MIL-101(Fe)octahedrons

The synergistic reaction of photocatalysis and advanced oxidation is a valid strategy for the degradation of harmful antibiotic wastewater.Herein,carbon dots(CDs)modified MIL-101(Fe)octahedrons to form CDs/MIL-101(Fe)composite photocatalyst was synthesized for visible light-driven photocatalytic/persulfate(PS)-activated tetracycline(TC)degradation.The electron spin resonance(ESR)spectra,scavenging experiment and electrochemical analysis were carried out to reveal that the high visible light-driven photocatalytic degradation activity of TC over CDs/MIL-101(Fe)photocatalysts is not only ascribed to the production of free active radicals in the CDs/MIL-101(Fe)/PS system(·OH,·SO_(4-),^(1)O_(2),h^(+)and·O_(2)^(-))but also attributed to the consumption of electrons caused by the PS,which can suppress the recombination of photo-generated carriers as well as strong light scattering and electron trapping effects of CDs.Finally,the possible degradation pathways were proposed by analyzing intermediates via liquid chromatography-mass spectrometry technique.This research presents a rational design conception to construct a CDs/PS-based photocatalysis/advanced oxidation technology with high-efficient degradation activity for the remediation of organic antibiotic pollutant wastewater and for the improvement of carrier transport kinetics of photocatalysts.

Free radicals trigger the closure of open pores in lignin-derived hard carbons toward improved sodium-storage capacity

The chemical activation of various precursors is effective for creating additional closed pores in hard carbons for sodium storage.However,the formation mechanism of closed pores under the influence of pore-forming agents is not well understood.Herein,an effective chemical activation followed by a high-temperature self-healing strategy is employed to generate interconnected closed pores in lignin-derived hard carbon(HCs).By systematic experimental design combined with electron paramagnetic res-onance spectroscopy,it can be found that the content of free radicals in the carbon matrix influences the closure of open pores at high temperatures.Excessively high activation temperature(>700 C)leads to a low free radical concentration,making it difficult to achieve self-healing of open pores at high tempera-tures.By activation at 700°C,a balance between pore making and self-healing is achieved in the final hard carbon.A large number of free radicals triggers rapid growth and aggregation of carbon microcrys-tals,blocking pre-formed open micropores and creating additional interconnected closed pores in as-obtained hard carbons.As a result,the optimized carbon anode(LK-700-1300)delivers a high reversible capacity of 330.8 mA h g^(-1) at 0.03 A g^(-1),which is an increase of 86 mA h g^(-1) compared to the pristine lignin-derived carbon anode(L-700-1300),and exhibits a good rate performance(202.1 mA h g^(-1) at 1 A g^(-1)).This work provides a universal and effective guidance for tuning closed pores of hard carbons from otherprecursors.

Effects of elevated CO_2 concentration and nitrogen supply on biomass and active carbon of freshwater marsh after two growing seasons in Sanjiang Plain, Northeast China

An experiments were carried out with treatments differing in nitrogen supply （0, 5 and 15 g N/m^2） and CO2 levels （350 and 700 μmol/mol） using OTC （open top chamber） equipment to investigate the biomass of Calamagrostis angustifolia and soil active carbon contents after two years. The results showed that elevated CO2 concentration increased the biomass of C. angustifolia and the magnitude of response varied with each growth period. Elevated CO2 concentration has increased aboveground biomass by 16.7% and 17.6% during the jointing and heading periods and only 3.5% and 9.4% during dough and maturity periods. The increases in belowground biomass due to CO2 elevation was 26.5%, 34.0% and 28.7% during the heading, dough and maturity periods, respectively. The responses of biomass to enhanced CO2 concentrations are differed in N levels. Both the increase of aboveground biomass and belowground biomass were greater under high level of N supply （15 g N/m^2）. Elevated CO2 concentration also increased the allocation of biomass and carbon in root. Under elevated CO2 concentration, the average values of active carbon tended to increase. The increases of soil active soil contents followed the sequence of microbial biomass carbon （10.6%） 〉 dissolved organic carbon （7.5%） 〉 labile oxidable carbon （6.6%） 〉 carbohydrate carbon （4.1%）. Stepwise regressions indicated there were significant correlations between the soil active carbon contents and plant biomass. Particularly, microbial biomass carbon, labile oxidable carbon and carbohydrate carbon were found to be correlated with belowground biomass, while dissolved organic carbon has correlation with aboveground biomass. Therefore, increased biomass was regarded as the main driving force for the increase in soil active organic carbon under elevated CO2 concentration.

Invertebrate community characteristics in biologically active carbon filter

Biologically active carbon （BAC） system was set up in a water plant of South China during January to December 2007,to study the invertebrate community characteristics of BAC filter.Thirty-seven invertebrate species were found,of which 28 belonging to rotifers.Filter operation could lead to an output of invertebrates in high abundances with the filtrate,and the maximum density could reach 5608 individuals/m 3.Average abundances in the effluent water increased in 27-33 folds in comparison to the influent water during the sampling period.Invertebrate community succession had the following trend：filter-feeding animals → small benthic invertebrates → large benthic and resistant invertebrates.Abundances of large-sized invertebrates （copepod adult and oligochaete） at bigger-media column were significantly higher than that at small-media column.The results implied the abundant species diversity of invertebrate in BAC filter.The relationship between invertebrate and biofilm still remain to be studied in detail.

Coupling dehydrogenation of isobutane in the presence of carbon dioxide over chromium oxide supported on active carbon

The dehydrogenation of isobutane （IB） to produce isobutene coupled with reverse water gas shift in the presence of carbon dioxide was investigated over the catalyst Cr2O3 supported on active carbon （Cr2O3/AC）. The results illustrated that isobutane conversion and isobutene yield can be enhanced through the reaction coupling in the presence of carbon dioxide. Moreover, carbon dioxide can partially eliminate carbonaceous deposition on the catalyst and keep the active phase （Cr2O3）, which are then helpful to alleviate the catalyst deactivation.

Treatment of simulated wastewater containing Reactive Red 195 by zero-valent iron/activated carbon combined with microwave discharge electrodeless lamp/sodium hypochlorite

A comparative study of treatment of simulated wastewater containing Reactive Red 195 using zero-valent iron/activated carbon （ZVI/AC）, microwave discharge electrodeless lamp/sodium hypochlorite （MDEL/NaCIO） and the combination of ZVI/AC- MDEL/NaCIO was conducted. The preliminary results showed the two steps method of ZVI/AC-MDEL/NaCIO had much higher degradation efficiency than both single steps. The final color removal percentage was nearly up to 100% and the chemical oxygen demand reduction percentage was up to approximately 82%. The effects of operational parameters, including initial pH value of simulated wastewater, ZVI/AC ratio and particle size of ZVI were also investigated. In addition, from the discussion of synergistic effect between ZVI/AC and MEDL/NaCIO, we found that in the ZVI/AC-MEDL/NaCIO process, ZVI/AC could break the azo bond firstly and then MEDLfNaCIO degraded the aromatic amine products effectively. Reversing the order would reduce the degradation efficiency.

Synthesis of acetals and ketals catalyzed by tungstosilicic acid supported on active carbon

Catalytic activity of activated carbon supported tungstosilicic acidin synthesizing 2-methyl-2-ethoxycarbonylmethyl- 1,3-dioxolane, 2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane, cyclohexanone ethylene ketal, cyclohexanone 1,2-propa- nediol ketal, butanone ethylene ketal, butanone 1,2-propanediol ketal, 2-phenyl-1,3-dioxolane, 4-methyl-2-phenyl-1,3-dioxolane, 2-propyl-1,3-dioxolane, 4-methyl-2-propyl-1,3-dioxolane was reported. It has been demonstrated that activated carbon supported tungstosilicic acid is an excellent catalyst. Various factors involved in these reactions were investigated. The optimum conditions found were: molar ratio of aldehyde/ketone to glycol is 1/1.5, mass ratio of the catalyst used to the reactants is 1.0%, and reaction time is 1.0 h. Under these conditions, the yield of 2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane is 61.5%, of 2,4-dimethyl- 2-ethoxycarbonylmethyl-1,3-dioxolane is 69.1%, of cyclohexanone ethylene ketal is 74.6%, of cyclohexanone 1,2-propanediol ketal is 80.1%, of butanone ethylene ketal is 69.5%, of butanone 1,2-propanediol ketal is 78.5%, of 2-phenyl-1,3-dioxolane is 56.7%, of 4-methyl-2-phenyl-1,3-dioxolane is 86.2%, of 2-propyl-1,3-dioxolane is 87.5%, of 4-methyl-2-propyl-1,3-dioxolane is 87.9%.

Effect of fire disturbance on active organic carbon of Larix gmelinii forest soil in Northeastern China

Active organic carbon in soil has high biological activity and plays an important role in forest soil ecosystem structure and function. Fire is an important disturbance factor in many forest ecosystems and occurs frequently over forested soils. However, little is known about its impact on soil active organic carbon (SAOC), which is important to the global carbon cycle. To investigate this issue, we studied the active organic carbon in soils in the Larix gmelinii forests of the Da Xing'an Mountains (Greater Xing'an Mountains) in Northeastern China, which had been burned by high-intensity wildfire in two different years (2002 and 2008). Soil samples were collected monthly during the 2011 growing season from over 12 sample plots in burned and unburned soils and then analyzed to examine the dynamics of SAOC. Our results showed that active organic carbon content changed greatly after fire disturbance in relation to the amount of time elapsed since the fire. There were significant differences in microbial biomass carbon, dissolved organic carbon, light fraction organic carbon, particulate organic carbon between burned and unburned sample plots in 2002 and 2008 (p < 0.05). The correlations between active organic carbon and environmental factors such as water content, pH value and temperature of soils, and correlations between each carbon component changed after fire disturbance, also in relation to time since the fire. The seasonal dynamics of SAOC in all of the sample plots changed after fire disturbance; peak values appeared during the growing season. In plots burned in 2002 and 2008, the magnitude and occurrence time of peak values differed. Our findings provide basic data regarding the impact of fire disturbance on boreal forest soil-carbon cycling, carbon-balance mechanisms, and carbon contributions of forest ecosystem after wildfire disturbance.

Highly active catalyst for vinyl acetate synthesis by modified activated carbon

A new zinc acetate catalyst which was prepared from modified activated carbon exhibited extreme activity towards the synthesis of vinyl acetate. The activated carbon was modified by nitric acid, vitriol and peroxyacetic acid （PAA）. The effect on specific area, structure, pH and surface acidity groups of carders by modification was discussed. Amount of carbonyl and carboxyl groups in activated carbon was increased by peroxyacetic acid treatment. The productivity of the new catalyst was 14.58% higher than that of catalyst prepared using untreated activated carbon. The relationship between amount of carbonyl and carboxyl groups （m） and catalyst productivity （P） was P = 1.83 ＋ 2.26 × 10^-3＊e^3.17m. Reaction mechanism was proposed. C 2009 Liang Rong Feng. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Performance of Electric Double Layer Capacitors using Active Carbons Prepared from Petroleum Coke by KOH and Vapor Re-Etching

The electrochemical storage of energy in a special kind of active carbon materials used as capacitor electrodes is considered. Petroleum coke was used for preparation of carbons with different porosities by KOH and vapor etching with catalysis of FeCI3 in turn. Carbon electrodes were fabricated and used as electrodes of double layer capacitors. Nitrogen adsorption was used to characterize the porous structure of the carbons. The electrochemical performance of the capacitors in 6 mol/L KOH was investigated with constant current charge and discharge experiments. A specific capacitance larger than 160 F/g was achieved with an electrode composed of 75% active carbon with a specific surface area of 1180 m2/g and 20% graphite as conductive agent. Evaluation of capacitor performance was conducted by different techniques, e.g. voltammetry and impedance spectroscopy. Characteristics of the capacitor were also discussed. A hybrid power source consisting of nickel- hydrogen and double layer capacitor was demonstrated by powering successfully a simulated power load encountered in communication equipment.

Preparation of active carbons from corn stalk for butanol vapor adsorption

Active carbons(ACs) were prepared through chemical activation of biochar from whole corn stalk(WCS)and corn stalk pith(CSP) at varying temperatures using potassium hydroxide as the activating agent. ACs were characterized via pore structural analysis and scanning electron microscopy(SEM). These adsorbents were then assessed for their adsorption capacity for butanol vapor. It was found that WCS activated at900 °C for 1 h(WCS-900) had optimal butanol adsorption characteristics. The BET surface area and total pore volume of the WCS-900 were 2330 m2/g and 1.29 cm3/g, respectively. The dynamic adsorption capacity of butanol vapor was 410.0 mg/g, a 185.1% increase compared to charcoal-based commercial AC(143.8 mg/g).

CoN_(x)C active sites-rich three-dimensional porous carbon nanofibers network derived from bacterial cellulose and bimetal-ZIFs as efficient multifunctional electrocatalyst for rechargeable Zn–air batteries

In this work, a CoNxC active sites-rich three-dimensional porous carbon nanofibers network derived from bacterial cellulose and bimetal-ZIFs is prepared via a nucleation growth strategy and a pyrolysis process.The material displays excellent electrocatalytic activity for the oxygen reduction reaction, reaching a high limiting diffusion current density of -7.8 mA cm^(-2), outperforming metal–organic frameworks derived multifunctional electrocatalysts, and oxygen evolution reaction and hydrogen evolution reaction with low overpotentials of 380 and 107 mV, respectively. When the electrochemical properties are further evaluated, the electrocatalyst as an air cathode for Zn-air batteries exhibits a high cycling stability for63 h as well as a maximum power density of 308 mW cm^(-2), which is better than those for most Zn-air batteries reported to date. In addition, a power density of 152 mW cm^(-2) is provided by the solid-state Zn-air batteries, and the cycling stability is outstanding for 24 h. The remarkable electrocatalytic properties are attributed to the synergistic effect of the 3 D porous carbon nanofibers network and abundant inserted CoNxC active sites, which enable the fast transmission of ions and mass and simultaneously provide a large contact area for the electrode/electrolyte.

Thermal pretreatment of willow branches impacts yield and pore development of activated carbon in subsequent activation with ZnCl_(2) via modifying cellulose structure

Development of pore structures of activated carbon(AC)from activation of biomass with ZnCl_(2) relies on content and structure of cellulose/hemicellulose in the feedstock.Thermal pretreatment of biomass could induce dehydration and/or aromatization to change the structure of cellulose/hemicellulose.This might interfere with evolution of structures of AC,which was investigated herein via thermal pretreatment of willow branch(WB)from 200 to 360℃and the subsequent activation with ZnCl_(2) at 550℃.The results showed that thermal pretreatment at 360℃(WB-360)could lead to substantial pyrolysis to form biochar,with a yield of 31.9%,accompanying with nearly complete destruction of cellulose crystals and remarkably enhanced aromatic degree.However,cellulose residual in WB-360 could still be activated to form AC-360 with specific surface area of 1837.9 m~2·g^(-1),which was lower than that in AC from activation of untreated WB(AC-blank,2077.8 m~2·g^(-1)).Nonetheless,the AC-200 from activation of WB-200 had more developed pores(2113.9 m~2·g^(-1))and superior capability for adsorption of phenol,due to increased permeability of ZnCl_(2) to the largely intact cellulose structure in WB-200.The thermal pretreatment did increase diameters of micropores of AC but reduced the overall yield of AC(26.8%for AC-blank versus 18.0%for AC-360),resulting from accelerated cracking but reduced intensity of condensation.In-situ infrared characterization of the activation showed that ZnCl_(2) mainly catalyzed dehydration,dehydrogenation,condensation,and aromatization but not cracking,suppressing the formation of derivatives of cellulose and lignin in bio-oil.The thermal pretreatment formed phenolic-OH and C=O with higher chemical innerness,which changed the reaction network in activation,shifting morphology of fibrous structures in AC-blank to“melting surface”in AC-200 or AC-280.

Properties of Activated Carbons from Sugarcane Leaves and Rice Straw Derived Charcoals by Activation at Low Temperature via KMnO_(4)Pre-Oxidation-Hydrolysis

Activated carbon preparation from sugarcane leaves and rice straw by carbonization(250℃–400℃)and activation at 500℃were studied.The effects of pre-oxidation,hydrolysis of derived charcoals by boiled KMnO4 aqueous solution were evaluated.The derived charcoals products were pretreated using oxidation-hydrolysis with 1–5 wt.%KMnO4 at 100℃and then activated at 500℃.The derived charcoal and activated carbon products were characterized by FTIR,XRD,SEM-EDS and BET.Iodine number and methylene blue number of derived products were also used for the analysis of the products.It was found that fabricated charcoal materials made at 350℃–400℃possess good characteristics with low content of surface functional groups and high carbon content.After pre-oxidation-hydrolysis and activation at 500℃,the resulting derived activated carbon materials from charcoals with 400℃carbonization temperature have high content of oxygen containing surface functional groups such as Mn-O,Si-O,Si-O-Si,C-O,or O-H.In addition,MnO_(2) accumulated on the surface of the derived activated carbon products.The surface area and pore volume of the activated carbon products have also increased with increasing of KMnO_(4) concentration from 1 to 3 wt.%and then decreased with 5 wt.%used during activation.Therefore,activated carbon products made by pre-oxidation-hydrolysis with 3 wt.%KMnO_(4) were used for Fe(Ⅲ)adsorption experiments.It was found that Fe(Ⅲ)adsorption on the activated carbon materials can be fitted with both the Freundlich and the Langmuir models.The calculated maximum Fe(Ⅲ)adsorption capacities of sugarcane leaves derived activated carbon and rice straw derived activated carbon products were 50.00 and 39.37 mg/g,respectively.It was shown that the effect of pre-oxidation-hydrolysis by KMnO_(4) and activation at 500℃are beneficial for activated carbon preparation with environmentally friendly and low-cost simplified operation.

Ultra-high specific surface area activated carbon from Taihu cyanobacteria via KOH activation for enhanced methylene blue adsorption

Cyanobacteria-based activated carbon(CBAC)was successfully prepared by pyrolysis-activation of Taihu cyanobacteria.When the impregnation ratio and activated temperature were 2 and 800-C,respectively,the optimal CBACs possessed an ultra-high specific surface(2178.90 m^(2)·g^(-1))and plenty of micro-and meso-pores,as well as a high pore volume(1.01 cm^(3)·g^(-1)).Ascribed to ultra-high surface area,π-π interaction,electrostatic interaction,as well as hydrogen-bonding interactions,the CBACs displayed huge superiority in efficient dye removal.The saturated methylene blue adsorption capacity by CBACs could be as high as 1143.4 mg·g^(-1),superior to that of other reported biomass-activated carbons.The adsorption was endothermic and modeled well by the pseudo-second-order kinetic,intra-particle diffusion,and Langmuir models.This work presented the effectiveness of Taihu cyanobacteria adsorbent ascribed to its super large specific surface area and high adsorption ability.

Active forest management accelerates carbon storage in plantation forests in Lishui,southern China

Background:China has committed to achieving peak CO_(2)emissions before 2030 and carbon neutrality before 2060;therefore,accelerated efforts are needed to better understand carbon accounting in industry and energy fields as well as terrestrial ecosystems.The carbon sink capacity of plantation forests contributes to the mitigation of climate change.Plantation forests throughout the world are intensively managed,and there is an urgent need to evaluate the effects of such management on long-term carbon dynamics.Methods:We assessed the carbon cycling patterns of ecosystems characterized by three typical plantation species(Chinese fir(Cunninghamia lanceolata(Lamb.)Hook.),oak(Cyclobalanopsis glauca(Thunb.)Oerst.),and pine(Pinus massoniana Lamb.))in Lishui,southern China,by using an integrated biosphere simulator(IBIS)tuned with localized parameters.Then,we used the state-and-transition simulation model(STSM)to study the effects of active forest management(AFM)on carbon storage by combining forest disturbance history and carbon cycle regimes.Results:1)The carbon stock of the oak plantation was lower at an early age(<50 years)but higher at an advanced age(>50 years)than that of the Chinese fir and pine plantations.2)The carbon densities of the pine and Chinese fir plantations peaked at 70 years(223.36 Mg⋅ha^(‒1))and 64 years(232.04 Mg⋅ha^(‒1)),respectively,while the carbon density in the oak plantation continued increasing(>100 years).3)From 1989 to 2019,the total carbon pools of the three plantation ecosystems followed an upward trend(an annual increase of 0.16–0.22 Tg C),with the largest proportional increase in the aboveground biomass carbon pool.4)AFM increased the recovery of carbon storage after 1996 and 2009 in the pine and Chinese fir plantations,respectively,but did not result in higher growth in the oak plantation.5)The proposed harvest planning is reasonable and conducive to maximizing the carbon sequestration capacity of the forest.Conclusions:This study provides an example of a carbon cycle coupling model that is potentially suitable for simulating China's plantation forest ecosystems and supporting carbon accounting to monitor peak CO_(2)emissions and reach carbon neutrality.

High adsorption selectivity of activated carbon and carbon molecular sieve boosting CO_(2)/N_(2) and CH_(4)/N_(2) separation

Flue gas and coal bed methane are two important sources of greenhouse gases.Pressure swing adsorption process has a wide range of application in the field of gas separation,and the selection of adsorbent is crucial.In this regard,in order to assess the better adsorbent for separating CO_(2) from flue gas and CH_(4) from coal bed methane,adsorption isotherms of CO_(2),CH_(4) and N_(2) on activated carbon and carbon molecular sieve are measured at 303.15,318.15 and 333.15 K,and up to 250 kPa.The experimental data fit better with Langmuir 2 compared to Langmuir 3 and Langmuir-Freundlich models,and Clausius-Clapeyron equation was used to calculate the isosteric heat.Both the order of the adsorbed amount and the adsorption heat on the two adsorbents are CO_(2)>CH_(4)>N_(2).The adsorption kinetics are calculated by the pseudo-first kinetic model,and the order of adsorption rates on activated carbon is N_(2)-CH_(4)>CO_(2),while on carbon molecular sieve,it is CO_(2)-N_(2)>CH_(4).It is shown that relative molecular mass and adsorption heat are the primary effect on kinetics for activated carbon,while kinetic diameter is the main resistance factor for carbon molecular sieve.Moreover,the adsorption selectivity of CH_(4)/N_(2) and CO_(2)/N_(2) were estimated with the ideal adsorption solution theory,and carbon molecular sieve performed best at 318.15 K for both CO_(2) and CH_(4) separation.The study suggested that activated carbon is a better choice for separating flue gas and carbon molecular sieve can be a strong candidate for separating coal bed methane.

Effects of desert plant communities on soil enzyme activities and soil organic carbon in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia,China

It is of great significance to study the effects of desert plants on soil enzyme activities and soil organic carbon(SOC)for maintaining the stability of the desert ecosystem.In this study,we studied the responses of soil enzyme activities and SOC fractions(particulate organic carbon(POC)and mineral-associated organic carbon(MAOC))to five typical desert plant communities(Convolvulus tragacanthoides,Ephedra rhytidosperma,Stipa breviflora,Stipa tianschanica var.gobica,and Salsola laricifolia communities)in the proluvial fan in the eastern foothills of the Helan Mountain in Ningxia Hui Autonomous Region,China.We recorded the plant community information mainly including the plant coverage and herb and shrub species,and obtained the aboveground biomass and plant species diversity through sample surveys in late July 2023.Soil samples were also collected at depths of 0–10 cm(topsoil)and 10–20 cm(subsoil)to determine the soil physicochemical properties and enzyme activities.The results showed that the plant coverage and aboveground biomass of S.laricifolia community were significantly higher than those of C.tragacanthoides,S.breviflora,and S.tianschanica var.gobica communities(P<0.05).Soil enzyme activities varied among different plant communities.In the topsoil,the enzyme activities of alkaline phosphatase(ALP)andβ-1,4-glucosidas(βG)were significantly higher in E.rhytidosperma and S.tianschanica var.gobica communities than in other plant communities(P<0.05).The topsoil had higher POC and MAOC contents than the subsoil.Specifically,the content of POC in the topsoil was 18.17%–42.73%higher than that in the subsoil.The structural equation model(SEM)indicated that plant species diversity,soil pH,and soil water content(SWC)were the main factors influencing POC and MAOC.The soil pH inhibited the formation of POC and promoted the formation of MAOC.Conversely,SWC stimulated POC production and hindered MAOC formation.Our study aimed to gain insight into the effects of desert plant communities on soil enzyme activities and SOC fractions,as well as the drivers of SOC fractions in the proluvial fan in the eastern foothills of the Helan Mountain and other desert ecosystems.

Fate and Behavior of Tetracycline Resistance Genes in Activated Carbon Adsorption

The accessibility of tetracycline resistance gene (tetG) into the pores of activated carbon (AC), as well as the impact of the pore size distribution (PSD) of AC on the uptake capacity of tetG, were investigated using eight types of AC (four coal-based and four wood-based). AC showed the capability to admit tetG and the average reduction of tetG for coal-based and wood-based ACs at the AC dose of 1 g·L-1 was 3.12 log and 3.65 log, respectively. The uptake kinetic analysis showed that the uptake of the gene followed the pseudo-second-order kinetics reaction, and the uptake rate constant for the coal-based and wood-based ACs was in the range of 5.97 × 10-12 - 4.64 × 10-9 and 7.02 × 10-11 - 1.59 × 10-8 copies·mg-1·min-1, respectively. The uptake capacity analysis by fitting the obtained experiment data with the Freundlich isotherm model indicated that the uptake constant (KF) values were 1.71 × 103 - 8.00 × 109 (copies·g-1)1-1/n for coal-based ACs and 7.00 × 108 - 3.00 × 1010 (copies·g-1)1-1/n for wood-based ones. In addition, the correlation analysis between KF values and pore volume as well as pore surface at different pore size regions of ACs showed that relatively higher positive correlation was found for pores of 50 - 100 Å, suggesting ACs with more pores in this size region can uptake more tetG. The findings of this study are valuable as reference for optimizing the adsorption process regarding antibiotic resistance-related concerns in drinking water treatment.