Oxygen and hydrogen isotope exchange of geopressured thermal water in the central Guanzhong basin

Geothermal water of Xi'an and Xianyang in the central Guanzhong basin is typically geopressured thermal water in China. δ18O and δD data of geopressured thermal water in Xi'an and Xianyang, combined with data from the perimeter of the basin, are analyzed to study features of hydrogen and oxygen shifts. The results show that 18O exchange of geothermal water at the perimeter of the basin and in the non-geopressured thermal water in the center of the basin is not evident, while in most of the geopressured thermal water in the central basin, in cities such as Xi'an and Xianyang, significant oxygen exchange had taken place as well as hydrogen exchange, suggesting that isotope exchanges would slowly move the geothermal water system towards equilib-rium. Thermal water reservoirs in the central basin have passed through significant water-rock reactions. Moreover, the geothermal reservoir of Xianyang city is relatively much more enclosed than that of Xi'an city. It has been observed that the more enclosed the geological environment of geothermal water is, the more obvious the oxygen shifts are. With the increasing of the depth, residence time, total amounts of dissolute solids and temperatures of geothermal waters, the oxygen exchange accelerates.

Preparation and Fluorescence Properties of TiO_2∶Eu Nano-Materia ls

A series of europium-doped titanium dioxide (TiO 2) fluorescent nano-material s prepared by sol-gel method is presented. The phase structure and crystalline sizes of TiO 2∶Eu, which is doped with different europium content and then he at-treated at different temperature, were investigated by XRD,TG,DTA and TEM. The results show that europium could be introduced into TiO 2 under high temper ature and it can suppress the structural phase transition from anatase to rutile and the crystal growth of TiO 2 in TiO 2∶Eu nano-materials. The fluorescenc e spectra were examined by fluorescence spectrophotometer, and the results show that the fluorescence intensity is the strongest when europium content is 2.68%( mole fraction) and the heat-treated temperature is 700 ℃. From the measurement results of the fluorescence lifetimes, it can be seen that the fluorescence lifetime c ould be prolonged when europium is incorporated in TiO 2.

Thermodynamic behaviors of Cu in interaction with chlorine, sulfur, phosphorus and minerals during sewage sludge co-incineration

Thermodynamic equilibrium calculations were performed to reveal effects of interactions among Cl, S, P and other minerals on Cu migration. Our results showed that HCl(g), SO2(g) and(P_2O_5)_2(g) were released from the sewage sludge co-incineration. Cl was found to weaken adsorption of Cu by Al_2O_3, CaO and Fe_2O_3, while S delayed reactions of Fe_2O_3 and Al_2O_3 with Cu, with P having no effect on reactions between the minerals and Cu.Among the coupled systems of Cl, S and P, the co-existences of Cl and S, and Cl, S and P were determined to inhibit Cu volatilization, and the co-existence of Cl and P had an enhancing effect. Cu migration was affected only by S in the S and P system. With the SiO_2, CaO and Al_2O_3 system, both Cl alone and Cl and P led to failed reactions between the minerals and Cu. In the systems of S, S and Cl, S and P, and S, Cl and P, the migration behavior of Cu was mainly affected by S at low temperatures and by Cl at high temperatures, whereas P had no effect on Cu migration during the entire process.

Reclaim nickel and remove organics from the spent electroless nickel-plating bath by electrolysis

Typical wastes from nickel plating operations include excess drag-out solution. An electrochemical approach was made to recover the nickel and remove the organic pollutants from the spent electroless nickel-plating bath. An electrolyte cell which was constructed by the cathode of porous nickel foam and the anode of Ti/RuO2 was used. During electrolysis, the nickel ion was electrodeposited at the cathode and the oxidation of the organics in the bath was conducted at the anode. The current（i）, time（t）, temperature（T） and pH of the solution affected the recovery efficiency of nickel with constant potential electrolysis. With the optimum experimental conditions of pH=7.6, i=0.45 A, T=65 ℃ and t=2 h, the concentration of nickel ion was reduced from 2.09 g/L to 0.053 g/L and the recovery rate of nickel, the current efficiency and the consumed energy were 97.5%, 17.1%, 12.2 kWh/kg Ni, respectively. Meanwhile, total organic carbon （TOC） of the bath was reduced from 5 800 mg/L to 152.5 mg/L and the removal efficiency of TOC was 97.3%. The recovery rate of nickel could keep to about 97% when electrodeposit was used to recover nickel for 40 hours in a laboratory batch reactor containing the spent bath. Dull nickel containing phosphorus was obtained on the cathode.

Specialissue:Environmental photocatalysis

As the rapid development of industrial economy,massiveconsumption of fossil energy leads to increasingly seriousenvironmental pollution.Thus.it is highly obliged to developgreen,efficient and robust technologies for fuel production andpollution remediation.Semiconductor-based photocatalysiscould realize the production of fuel chemicals,selectivetransformation/degradation of organic pollutants and eveninactivation of microorganisms by using the solar-to-chemicalenergy conversion hence possesses scientific significance andgreat application potential.Besides,multidisciplinarilyinvolving semiconductor physics.catalysis and surface science,photocatalysis has become one of the most attractive andpioneering research fields all over the world.

Feasibility of low-intensity ultrasound treatment with hydroxylamine to accelerate the initiation of partial nitrification and allow operation under intermittent aeration

Partial nitrification is a key aspect of efficient nitrogen removal,although practically it suf-fers from long start-up cycles and unstable long-term operational performance.To address these drawbacks,this study investigated the effect of low intensity ultrasound treatment combined with hydroxylamine(NH2OH)on the performance of partial nitrification.Results showthat compared with the control group,low-intensity ultrasound treatment(0.10W/mL,15 min)combined with NH2OH(5 mg/L)reduced the time required for partial nitrification initiation by 6 days,increasing the nitrite accumulation rate(NAR)and ammonia nitro-gen removal rate(NRR)by 20.4% and 6.7%,respectively,achieving 96.48% NRR.Mechanis-tic analysis showed that NH2OH enhanced ammonia oxidation,inhibited nitrite-oxidizing bacteria(NOB)activity and shortened the time required for partial nitrification initiation.Furthermore,ultrasonication combined with NH2OH dosing stimulated EPS(extracellular polymeric substances)secretion,increased carbonyl,hydroxyl and amine functional group abundances and enhanced mass transfer.In addition,16S rRNA gene sequencing results showed that ultrasonication-sensitive Nitrospira disappeared from the ultrasound+NH_(2)OH system,while Nitrosomonas gradually became the dominant group.Collectively,the results of this study provide valuable insight into the enhancement of partial nitrification start-up during the process of wastewater nitrogen removal.

Status and trends of carbon emissions research at the county level in China

This study provides a comprehensive overview of the challenges to achieving carbon neutrality at the county level in China and offers targeted recommendations,laying the groundwork for future specialized research in this area.A total of 283 relevant studies(2004-2023)were analyzed to assess county-level carbon emissions through three phases:bibliometric analysis,frontier analysis,and future prospects.Bibliometric findings reveal that publication trends were largely influenced by domestic and foreign policies.Keyword cluster discerns ten primary themes,ranging from conceptual frameworks to research methodologies.The frontier analysis of the literature highlights the leading research areas,which include carbon neutrality pathway,driving factors,spatiotemporal variation of carbon emissions,the co-effects of pollutants and carbon reduction,and carbon emissions in China's rural areas.Drawing from the results of bibliometric and frontier analyses,this study elucidates the recommendations for achieving carbon neutrality at the county level from three perspectives:effective regional policy guidance,emphasis on ecological conservation,and the deployment of advanced carbon reduction and sequestration technologies.This study enriches the body of knowledge on carbon emissions at the county level and holds significant implications for China's comprehensive push towards achieving its carbon neutrality objectives.

The exposure risks associated with pathogens and antibiotic resistance genes in bioaerosol from municipal landfill and surrounding area

Pathogenic microbes with antibiotic resistance can thrive on municipal solid waste as nutrients and be aerosolized and transported to vicinities during waste disposal processes.However,the characterization of pathogenic bioaerosols and assessment of their exposure risks are lacking.Herein,particle size,concentration,activity,antibiotic resistance,and pathogenicity of airborne microorganisms were assessed in different sectors of a typical landfill.Results showed that active sector in downwind direction has the highest bioaerosol level(1234 CFU/m3),while residential area has the highest activity(14.82 mg/L).Botanical deodorizer from mist cannon can effectively remove bioaerosol.Most bioaerosols can be inhaled into respiratory system till bronchi with sizes ranging from 2.1−3.3 and 3.3−4.7μm.Pathogenic bacteria(Bacilli,Bacillus,and Burkholderia-Paraburkholderia)and allergenic fungi(Aspergillus,Cladosporium,and Curvularia)prevailed in landfill.Although high abundance of microbial volatile organic compounds(mVOCs)producing bioaerosols were detected,these mVOCs contributed little to odor issues in landfill.Notably,surrounding areas have higher levels of antibiotic-resistance genes(ARGs)than inner landfill with tetC,acrB,acrF,mdtF,and bacA as dominant ones.Most ARGs were significantly correlated with bacterial community,while environmental parameters mainly influenced fungal prevalence.These findings can assist in reducing and preventing respiratory allergy or infection risks in occupational environments relating to waste management.

Multiple evaluations of atmospheric behavior between Criegee intermediates and HCHO: Gas-phase and air-water interface reaction

Given the high abundance of water in the atmosphere,the reaction of Criegee intermediates(CIs)with(H_(2)O)_(2) is considered to be the predominant removal pathway for CIs.However,recent experimental findings reported that the reactions of CIs with organic acids and carbonyls are faster than expected.At the same time,the interface behavior between CIs and carbonyls has not been reported so far.Here,the gas-phase and air-water interface behavior between Criegee intermediates and HCHO were explored by adopting high-level quantum chemical calculations and Born-Oppenheimer molecular dynamics(BOMD)simulations.Quantum chemical calculations evidence that the gas-phase reactions of CIs+HCHO are submerged energy or low energy barriers processes.The rate ratios speculate that the HCHO could be not only a significant tropospheric scavenger of CIs,but also an inhibitor in the oxidizing ability of CIs on SO_(x) in dry and highly polluted areas with abundant HCHO concentration.The reactions of CH_(2)OO with HCHO at the droplet’s surface follow a loop structure mechanism to produce i)SOZ(■),ii)BHMP(HOCH_(2)OOCH_(2)OH),and iii)HMHP(HOCH_(2)OOH).Considering the harsh reaction conditions between CIs and HCHO at the interface(i.e.,the two molecules must be sufficiently close to each other),the hydration of CIs is still their main atmospheric loss pathway.These results could help us get a better interpretation of the underlying CIs-aldehydes chemical processes in the global polluted urban atmospheres.

大气细颗粒物中环境持久性自由基的分子特征与形成机理的研究

Aerosol-bound organic radicals,including environmentally persistent free radicals(EPFRs),are key components that affect climate,air quality,and human health.While putative structures have been proposed,the molecular characteristics of EPFRs remain unknown.Here,we report a surrogate method to characterize EPFRs in real ambient samples using mass spectrometry.The method identifies chemically relevant oxygenated polycyclic aromatic hydrocarbons(OxPAH)that interconvert with oxygen-centered EPFR(OC-EPFR).We found OxPAH compounds most relevant to OC-EPFRs are structurally rich and diverse quinones,whose diversity is strongly associated with OC-EPFR levels.Both atmospheric oxidation and combustion contributed to OC-EPFR formation.Redundancy analysis and photochemical aging model show pyrolytic sources generated more oxidized OC-EPFRs than photolytic sources.Our study reveals the detailed molecular characteristics of OC-EPFRs and shows that oxidation states can be used to identify the origins of OC-EPFRs,offering a way to track the development and evolution of aerosol particles in the environment.

Predicting microbial extracellular electron transfer activity in paddy soils with soil physicochemical properties using machine learning

Soil extracellular electron transfer(EET)is a pivotal biological process within the realm of soil.Unfortunately,EET suffers from a lack of predictive models.Herein,an intricately crafted machine learning model has been developed for the purpose of predicting soil EET by using the physicochemical properties of soil as independent input variables and the EET capabilities in terms of current density(j_(max))and Coulombic charge(C_(out))as dependent output variables.An autoencoder ensemble stacking(AES)model was developed to address the aforementioned issue by integrating support vector machine,multilayer perceptron,extreme gradient boosting,and light gradient boosting machine algorithms as the stacking algorithms.With 10-fold crossvalidation,the AES model exhibited notable improvements in predicting j_(max)and C_(out),with average test R^(2)values of 0.83 and 0.84,respectively,surpassing those of single machine learning(ML)models and the basic ensemble model.By utilizing partial correlation plots(PDPs),Shapley Additive explanations(SHAP)values,and SHAP decision plots,we quantitatively explained the impact and contribution of the input molecules on the AES model’s predictions of j_(max)and C_(out).In the context of the SHAP method for the AES model,total carbon(TC)was identified as the most correlated descriptor for j_(max),while total organic carbon(TOC)stood out as the most relevant descriptor for C_(out).In the prediction tasks of j_(max)and C_(out)within the AES model,employing a multitask ML approach allowed the model to benefit from the shared information of input variables,thereby enhancing its overall generalizability.This study provides a feasible tool for the prediction of soil EET from soil physiochemical properties and an advanced understanding of the relationship between soil physiochemical properties and EET capability.

Research on the conversion relationships between the river and groundwater in the Yellow River drainage area

Conversion relationships between the river and groundwater in the Yellow River drainage area are studied in this paper based on the geologic and physiognomy conditions and the data of the groundwater regime, isotope, groundwater flow field and field survey. Then eight recharge and discharge modes on the relationships are put forward and the hydraulic characteristics of the modes are analysed, which provides a scientific basis for quantitatively simulating and assessing the conversion relationships, maintenance mechanism of the Yellow River and the regeneration ability of the groundwater in the area.

Photocatalytic defluorination of perfluorooctanoic acid by surface defective BiOCl:Fast microwave solvothermal synthesis and photocatalytic mechanisms

There is an urgent need for developing cost-effective methods for the treatment of perfluorooctanoic acid(PFOA)due to its global emergence and potential risks.In this study,taking surface-defective BiOCl as an example,a strategy of surface oxygen vacancy modulation was used to promote the photocatalytic defluorination efficiency of PFOA under simulated sunlight irradiation.The defective BiOCl was fabricated by a fast microwave solvothermal method,which was found to induce more surface oxygen vacancies than conventional solvothermal and precipitation methods.As a result,the asprepared BiOCl showed significantly enhanced defluorination efficiency,which was 2.7 and33.8 times higher than that of BiOCl fabricated by conventional solvothermal and precipitation methods,respectively.Mechanistic studies indicated that the defluorination of PFOA follows a direct hole(h^+)oxidation pathway with the aid of·OH,while the oxygen vacancies not only promote charge separation but also facilitate the intimate contact between the photocatalyst surface and PFOA by coordinating with its terminal carboxylate group in a bidentate or bridging mode.This work will provide a general strategy of oxygen vacancy modulation by microwave-assisted methods for efficient photocatalytic defluorination of PFOA in the environment using sunlight as the energy source.

Understanding unusually high levels of peroxyacetyl nitrate(PAN) in winter in Urban Jinan,China

Peroxyacetyl nitrate （PAN）, as a major secondary pollutant, has gained increasing worldwide attentions, but relevant studies in China are still quite limited. During winter of 2015 to summer of 2016, the ambient levels of PAN were measured continuously by an automatic gas chromatograph equipped with an electron capture detector （GC-ECD） analyzer at an urban site in Jinan （China）, with related parameters including concentrations of 03, NO, NO2, PM2.5, HONO, the photolysis rate constant of NO2 and meteorological factors observed concurrently. The mean and maximum values of PAN concentration were （1.89 ± 1.42） and 9.61 ppbv respectively in winter, and （2.54 ± 1.44） and 13.47 ppbv respectively in summer. Unusually high levels of PAN were observed during severe haze episodes in winter, and the formation mechanisms of them were emphatically discussed, Study showed that high levels of PAN in winter were mainly caused by local accumulation and strong photochemical reactions during haze episodes, while mass transport played only a minor role. Accelerated photochemical reactions （compared to winter days without haze） during haze episodes were deduced by the higher concentrations but shorter lifetimes of pAN, which was further supported by the sufficient solar radiation in the photolysis band along with the high concentrations of precursors （NO2, VOCs） and HONO during haze episodes. In addition, significant PAN accumulation during calm weather of haze episodes was verified by meteorological data.

Conversion characteristics and mechanism analysis of gaseous dichloromethane degraded by a VUV light in different reaction media

The photodegradation of gaseous dichloromethane （DCM） by a vacuum ultraviolet （VUV） light in a spiral reactor was investigated with different reaction media and initial concentrations. Through the combination of direct photolysis, O3 oxidation and HO. oxidation, DCM was ultimately mineralized into inorganic compounds （such as HC1, CO2, H20, etc.） in the air with relative humidity （RH） of 75%-85%. During the photodegradation process, some small organic acids （including formic acid, acetic acid） were also detected and the intermediates were more soluble than DCM, providing a possibility for its combination with subsequent biodegradation. Based on the detected intermediates and the confirmed radicals, a photodegradation pathway of DCM by VUV was proposed. With RH 75%- 80% air as the reaction medium, the DCM removal followed the second-order kinetic model at inlet concentration of 100-1000 mg/m3. Kinetic analysis showed that the reaction media affected the kinetic constants of DCM conversion by a large extent, and RH 80% air could cause a much lower half-life for its conversion. Such results supported the possibility that VUV photodegradation could be used not only for the mineralization of DCM but also as a pretreatment before biodegradation.

Sources and health risks of PM2.5-bound polychlorinated biphenyls(PCBs) and organochlorine pesticides(OCPs) in a North China rural area

Polychlorinated biphenyls(PCBs) and organochlorine pesticides(OCPs) are typical persistent organic pollutants(POPs),which have high toxicity,bioaccumulation and long-distance transfer capability.Daily variation,sources of PcBs and OcPs in PM2.5 are rarely explored in polluted rural area.Here,the sources and health risks of the PcBs and OcPs were evaluated for 48 PM2.5 samples collected in winter 2017 in Wangdu,a heavy polluted rural area in the North China Plain.The average diurnal and nocturnal concentrations of E18 PCBs and∑15OCPs were 1.74-24.37 and 1.77-100.49,11.67-408.81 and 16.89-865.60 pg/m3,respectively.Hexa-CBs and penta-CBs accounted for higher proportions(29.0% and 33.6%) of clean and polluted samples,respectively.Hexachlorobenzene(HCB) was the dominant contributor to OCPs with an average concentration of 116.17 pg/m3.Hexachlorocyclohexane(EHCHs) and dichlorodiphenyltrichloroethane(EDDTs) were the other two main classes in OCPs with the average concentrations of 4.33 and 15.89 pg/m3,respectively.β-HCH and p,p’-DDE were the main degradation products of HCHs and DDTs,respectively.The principal component analysis and characteristic ratio method indicated both waste incineration and industrial activities were the main sources of PCBs,contributing 76.8% and 12.7%,respectively.The loadings of OCPs were attributed to their application characteristics and the characteristic ratio method reflected a current or past use of OCPs.Health risk assessment showed that the respiratory exposure quantity of doxin-like PCBs(DL-PCBs) and the lifetime cancer risk from airborne OCPs exposure was negligible,while the other exposure modes may pose a risk to human bodies.

A collaborative strategy for enhanced reduction of Cr(Ⅵ) by Fe(0) in the presence of oxalate under sunlight:Performance and mechanism

Nanometer-size zero-valent iron(NZVI)is an efficient reducing agent,but its surface is easily passivated with an oxide layer,leading to reaction inefficiency.In our study,oxalate(OA)was introduced into this heterogeneous system of NZVI,which could form ferrioxalate complexes with the NZVI surface-bound Fe3+and dissolved Fe3+in the solution.Photolysis of ferrioxalate complexes can facilitate the generation of Fe2+from Fe3+and CO2·-radical,both species have strong reduction capacity.Hence,a"photo-oxalate-Fe(0)"system through sunlight induction was established,which not only prohibited the formation of a surface passivation layer,but also displayed a synergetic mechanism of ferrioxalate photolysis to enhance reduction,exhibiting remarkably higher degradation activity(several times faster)toward the model pollutant Cr(Ⅵ)than the mechanism with NZVI alone.Factor tests suggested that both NZVI dosage and OA content markedly affected the reduction rate.Low pH was beneficial to the reduction efficiency.Moreover,recyclability experiment showed that the reduction rate decreased from 0.21706 to 0.03977 min-1 after three cycles of reuse due to the NZVI losing reaction activity generally,but the system still maintained considerable reduction capacity.Finally,a mechanism was revealed whereby NZVI would transform to Fe oxides after the exhaustion of its reductive power,and the photolysis of ferrioxalate to promote the cycling of iron species played the predominant role in providing extra reduction ability.These features confirm that introduction of OA into Cr(Ⅵ)reduction by NZVI through sunlight induction is advantageous and promising.

Investigation of PM_(2.5) pollution during COVID-19 pandemic in Guangzhou,China

The COVID-19 pandemic has raised awareness about various environmental issues,includ-ing PM_(2.5) pollution.Here,PM_(2.5) pollution during the COVID-19 lockdown was traced and an-alyzed to clarify the sources and factors influencing PM_(2.5) in Guangzhou,with an emphasis on heavy pollution.The lockdown led to large reductions in industrial and traffic emissions,which significantly reduced PM_(2.5) concentrations in Guangzhou.Interestingly,the trend of PM_(2.5) concentrations was not consistent with traffic and industrial emissions,as minimum concentrations were observed in the fourth period(3/01-3/31,22.45 μg/m^(3))of the lockdown.However,the concentrations of other gaseous pollutants,e.g.,SO_(2),NO_(2) and CO,were corre-lated with industrial and traffic emissions,and the lowest values were noticed in the sec-ond period(1/24-2/0_(3))of the lockdown.Meteorological correlation analysis revealed that the decreased PM_(2.5) concentrations during COVID-19 can be mainly attributed to decreased in-dustrial and traffic emissions rather than meteorological conditions.When meteorological factors were included in the PM_(2.5) composition and backward trajectory analyses,we found that long-distance transportation and secondary pollution offset the reduction of primary emissions in the second and third stages of the pandemic.Notably,industrial PM_(2.5) emis-sions from western,southern and southeastern Guangzhou play an important role in the formation of heavy pollution events.Our results not only verify the importance of control-ling traffic and industrial emissions,but also provide targets for further improvements in PM_(2.5) pollution.

The source and transport of bioaerosols in the air:A review

Recent pandemic outbreak of the corona-virus disease 2019(COVID-19)has raised widespread concerns about the importance of the bioaerosols.They are atmospheric aerosol particles of biological origins,mainly including bacteria,fungi,viruses,pollen,and cell debris.Bioaerosols can exert a substantial impact on ecosystems,climate change,air quality,and public health.Here,we review several relevant topics on bioaerosols,including sampling and detection techniques,characterization,effects on health and air quality,and control methods.However,very few studies have focused on the source apportionment and transport of bioaerosols.The knowledge of the sources and transport pathways of bioaerosols is essential for a comprehensive understanding of the role microorganisms play in the atmosphere and control the spread of epidemic diseases associated with them.Therefore,this review comprehensively summarizes the up to date progress on the source characteristics,source identification,and diffusion and transport process of bioaerosols.We intercompare three types of diffusion and transport models,with a special emphasis on a widely used mathematical model.This review also highlights the main factors affecting the source emission and transport process,such as biogeographic regions,land-use types,and environmental factors.Finally,this review outlines future perspectives on bioaerosols.

Effect of relative humidity and the presence of aerosol particles on the α-pinene ozonolysis

The α-pinene ozonolysis under the different environmental conditions were observed in a smog chamber. The second-order rate constant （k） was determined to be （7.25 ± 0.06） x 10^-17 cm^3/（molecule.sec） under 20% of relative humidity （RH） and room temperature. RH showed a marked influence on the α-pinene ozonolysis. The value of k increased with KH increase, which was 1.6 times faster at RH = 80% than that at RH = 20%. Additionally, the value of k apparently changed in the presence of the aerosol particles. The diesel soot increased the k value. The fly ash prohibited the reaction, however, H2SO4-treated fly ash promoted the reaction. The information of products gained using FT-IR and SPAMS showed that pinonic acid, 10-hydroxy-pinonic acid and pinic acid could be generated during the α- pinene ozonolysis. Water molecules could take part in the formation of the products, and play a vital role in the degradation of α-pinene. The atmospheric residence time calculation showed that the ozonolysis in the atmosphere is an important way of the α-pinene consumption as compared to that reacted with OH during daytime. The results suggested that the degradation of α-pinene via the ozonization in the atmosphere may be affected greatly by RH, as well as the presence of aerosol particles. The ozonolysis reaction may be an important way of the a-pinene consumption during daytime.