Anthropogenic emissions alter biogenic secondary organic aerosol(SOA)formation from naturally emitted volatileorganic compounds(BVOCs).We review the major laboratory and field findings with regard to effects of anthro...Anthropogenic emissions alter biogenic secondary organic aerosol(SOA)formation from naturally emitted volatileorganic compounds(BVOCs).We review the major laboratory and field findings with regard to effects of anthropogenicpollutants(NO_(x),anthropogenic aerosols,SO_(2),NH_(3))on biogenic SOA formation.NO_(x) participate in BVOC oxidationthrough changing the radical chemistry and oxidation capacity,leading to a complex SOA composition and yield sensitivitytowards NO_(x) level for different or even specific hydrocarbon precursors.Anthropogenic aerosols act as an importantintermedium for gas-particle partitioning and particle-phase reactions,processes of which are influenced by the particlephase state,acidity,water content and thus associated with biogenic SOA mass accumulation.SO_(2)modifies biogenic SOAformation mainly through sulfuric acid formation and accompanies new particle formation and acid-catalyzedheterogeneous reactions.Some new SO_(2)-involved mechanisms for organosulfate formation have also been proposed.NH_(3)/amines,as the most prevalent base species in the atmosphere,influence biogenic SOA composition and modify theoptical properties of SOA.The response of SOA formation behavior to these anthropogenic pollutants varies amongdifferent BVOCs precursors.Investigations on anthropogenic-biogenic interactions in some areas of China that aresimultaneously influenced by anthropogenic and biogenic emissions are summarized.Based on this review,somerecommendations are made for a more accurate assessment of controllable biogenic SOA formation and its contribution tothe total SOA budget.This study also highlights the importance of controlling anthropogenic pollutant emissions witheffective pollutant mitigation policies to reduce regional and global biogenic SOA formation.展开更多
Elucidating the effects of anthropogenic pollutants on the photooxidation of biogenic volatile organic compounds is crucial to understanding the fundamental mechanisms of secondary organic aerosol(SOA)formation.Here,t...Elucidating the effects of anthropogenic pollutants on the photooxidation of biogenic volatile organic compounds is crucial to understanding the fundamental mechanisms of secondary organic aerosol(SOA)formation.Here,the impacts of NO_(2)and SO_(2)on SOA formation from the photooxidation of a representative monoterpene,β-pinene,were investigated by a number of laboratory studies.The results indicated NO_(2)enhanced the SOA mass concentrations and particle number concentrations under both low and highβ-pinene conditions.This could be rationalized that the increased O_(3)concentrations upon the NO_(x)photolysis was helpful for the generation of more amounts of O_(3)-oxidized products,which accelerated the SOA nucleation and growth.Combing with NO_(2),the promotion of the SOA yield by SO_(2)was mainly reflected in the increase of mass concentration,which might be due to the elimination of the newly formed particles by the initially formed particles.The observed low oxidation degree of SOA might be attributed to the fast growth of SOA,resulting in the uptake of less oxygenated gas-phase species onto the particle phase.The present findings have important implications for SOA formation affected by anthropogenic–biogenic interactions in the ambient atmosphere.展开更多
The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and hum...The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and human health.However,there are still large errors between air quality model simulation results and field observations.The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences.In this paper,we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging.And all these results were mainly based the studies of photochemical smog chamber simulation.Although the properties of precursor volatile organic compounds(VOCs),oxidants(such as OH radicals),and atmospheric environmental factors(such as NOx,SO2,NH3,light intensity,temperature,humidity and seed aerosols)jointly influence the products and yield of SOA,the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process.The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research.展开更多
Organosulfate (OSA) nanoparticles,as secondary organic aerosol (SOA) compositions,are ubiquitous in urban and rural environments.Hence,we systemically investigated the mechanisms and kinetics of aqueous-phase reaction...Organosulfate (OSA) nanoparticles,as secondary organic aerosol (SOA) compositions,are ubiquitous in urban and rural environments.Hence,we systemically investigated the mechanisms and kinetics of aqueous-phase reactions of 1-butanol/1-decanol (BOL/DOL) and their roles in the formation of OSA nanoparticles by using quantum chemical and kinetic calculations.The mechanism results show that the aqueous-phase reactions of BOL/DOL start from initial protonation at alcoholic OH^(-)groups to form carbenium ions (CBs),which engage in the subsequent esterification or oligomerization reactions to form OSAs/organosulfites (OSIs) or dimers.The kinetic results reveal that dehydration to form CBs for BOL and DOL reaction systems is the rate-limiting step.Subsequently,about 18%of CBs occur via oligomerization to dimers,which are difficult to further oligomerize because all reactive sites are occupied.The rate constant of BOL reaction system is one order of magnitude larger than that of DOL reaction system,implying that relative short-chain alcohols are more prone to contribute OSAs/OSIs than long-chain alcohols.Our results reveal that typical long-chain alcohols contribute SOA formation via esterification rather than oligomerization because OSA/OSI produced by esterification engages in nanoparticle growth through enhancing hygroscopicity.展开更多
Volatile organic compounds(VOCs)are the important precursors of the tropospheric ozone(O3)and secondary organic aerosols(SOA),both of which are known to harm human health and disrupt the earth’s climate system.In thi...Volatile organic compounds(VOCs)are the important precursors of the tropospheric ozone(O3)and secondary organic aerosols(SOA),both of which are known to harm human health and disrupt the earth’s climate system.In this study,VOC emission factors,O3 and SOA formation potentials were estimated for two types of industrial boilers:coal-fired boilers(n=3)and oil-fired boilers(n=3).Results showed that EVOCs concentrations were more than nine times higher for oil-fire d boilers compared to those for coal-fired boilers.Emission factors ofΣVOCs were found to be higher for oil-fired boilers(9.26-32.83 mg-VOC/kg)than for coal-fired boilers(1.57-4.13 mg-VOC/kg).Alkanes and aromatics were obtained as the most abundant groups in coal-fired boilers,while oxygenated organics and aromatics were the most contributing groups in oil-fired boilers.Benzene,n-hexane and o-ethyl toluene were the abundant VOC species in coal-fired boiler emissions,whereas toluene was the most abundant VOC species emitted from oil-fired boilers.O3 and SOA formation potentials were found 12 and 18 times,respectively,higher for oil-fired than for coal-fired boilers.Total OFP ranged from 3.99 to 11.39 mg-O3/kg for coal-fired boilers.For oil-fired boilers,total OFP ranged from 36.16 to 131.93 mg-O3/kg.Moreover,total secondary organic aerosol potential(SOAP)ranged from 65.4 to 122.5 mg-SOA/kg and 779.9 to 2252.5 mg-SOA/kg for the coal-fired and oil-fired boilers,respectively.展开更多
PM_(1)0 samples were collected from an urban/industrial site nearby Athens,where uncontrolled burning activities occur.PAHs,monocarboxylic,dicarboxylic,hydroxycarboxylic and aromatic acids,tracers from BVOC oxidation,...PM_(1)0 samples were collected from an urban/industrial site nearby Athens,where uncontrolled burning activities occur.PAHs,monocarboxylic,dicarboxylic,hydroxycarboxylic and aromatic acids,tracers from BVOC oxidation,biomass burning tracers and bisphenol A were determined.PAH,monocarboxylic acids,biomass burning tracers and bisphenol A were increased during autumn/winter,while BSOA tracers,dicarboxylic-and hydroxycarboxylic acids during summer.Regarding aromatic acids,different sources and formation mechanisms were indicated as benzoic,phthalic and trimellitic acids were peaked during summer whereas p-toluic,isophthalic and terephthalic were more abundant during autumn/winter.The Benzo[a]pyrene-equivalent carcinogenic power,carcinogenic and mutagenic activities were calculated showing significant(p<0.05)increases during the colder months.Palmitic,succinic and malic acids were the most abundant monocarboxylic,dicarboxylic and hydrocarboxylic acids during the entire sampling period.Isoprene oxidation was the most significant contributor to BSOA as the isoprene-SOA compounds were two times more abundant than the pinene-SOA(13.4±12.3 and 6.1±2.9 ng/m^3,respectively).Ozone has significant impact on the formation of many studied compounds showing significant correlations with:isoprene-SOA(r=0.77),hydrocarboxylic acids(r=0.69),pinene-SOA(r=0.63),dicarboxylic acids(r=0.58),and the sum of phthalic,benzoic and trimellitic acids(r=0.44).PCA demonstrated five factors that could explain sources including plastic enriched waste burning(30.8%),oxidation of unsaturated fatty acids(23.0%),vehicle missions and cooking(9.2%),biomass burning(7.7%)and oxidation of VOCs(5.8%).The results highlight the significant contribution of plastic waste uncontrolled burning to the overall air quality degradation.展开更多
Secondary organic aerosol(SOA)is a very important component of fine particulate matter(PM)in the atmosphere.However,the simulations of SOA,which could help to elucidate the detailed mechanism of SOA formation and quan...Secondary organic aerosol(SOA)is a very important component of fine particulate matter(PM)in the atmosphere.However,the simulations of SOA,which could help to elucidate the detailed mechanism of SOA formation and quantify the roles of various precursors,remains unsatisfactory,as SOA levels are frequently underestimated.It has been found that the performance of SOA formation models can be significantly improved by incorporating the emission and evolution of semivolatile and intermediate-volatility organic compounds(S/IVOCs).In order to explore the roles of S/IVOCs in SOA formation,this study reviews some simulation models which could consider S/IVOCs for SOA formation as well as the development of emission inventories of S/IVOCs and S/IVOC modules for SOA formation.In addition,the future research directions for simulations of the effect of S/IVOCs on SOA formation are suggested.展开更多
Primary and secondary organic aerosols in PM_(2.5)were investigated over a one-year campaign at Zouk Mikael and Fiaa,Lebanon.The n-alkanes concentrations were quite similar at both sites(26-29 ng/m^(3))and mainly expl...Primary and secondary organic aerosols in PM_(2.5)were investigated over a one-year campaign at Zouk Mikael and Fiaa,Lebanon.The n-alkanes concentrations were quite similar at both sites(26-29 ng/m^(3))and mainly explained by anthropogenic emissions rather than natural ones.The concentrations of total Polycyclic Aromatic Hydrocarbons(PAHs)were nearly three times higher at Zouk Mikael(2.56 ng/m^(3))compared to Fiaa(0.95 ng/m^(3)),especially for indeno[1,2,3-c,d]pyrene linked to the presence of the power plant.A characteristic indeno[1,2,3-c,d]pyrene/(indeno[1,2,3-c,d]pyrene+benzo[g,h,i]perylene)ratio in the range0.8-1.0 was determined for heavy fuel oil combustion from the power plant.Fatty acids and hopanes were also investigated and were assigned to cooking activities and vehicular emissions respectively.Phthalates were identified for the first time in Lebanon with high concentrations at Zouk and Fiaa(106.88 and 97.68 ng/m^(3) respectively).Moreover,the biogenic secondary aerosols revealed higher concentrations in summer.The total terpene concentration varied between 131 ng/m^(3) at Zouk Mikael in winter to 469 ng/m3 at Fiaa in summer.Additionnally,the concentrations of the dicarboxylic acids especially for adipic and phthalic acids were more influenced by anthropogenic sources.The analysis of molecular markers and diagnostic ratios indicated that the sites were strongly affected by anthropogenic sources such as waste open burning,diesel private generators,cooking activities,road transport,power plant,and industrial emissions.Moreover,results showed different pattern during winter and summer seasons.Whereas,higher concentrations of biogenic markers were clearly encountered during the summer period.展开更多
Fine particulate matter(PM_(2.5))and ozone(O_(3))pollutions are prevalent air quality issues in China.Volatile organic compounds(VOCs)have significant impact on the formation of O_(3)and secondary organic aerosols(SOA...Fine particulate matter(PM_(2.5))and ozone(O_(3))pollutions are prevalent air quality issues in China.Volatile organic compounds(VOCs)have significant impact on the formation of O_(3)and secondary organic aerosols(SOA)contributing PM_(2.5).Herein,we investigated 54 VOCs,O_(3)and SOA in Tianjin from June 2017 to May 2019 to explore the non-linear relationship among O_(3),SOA and VOCs.The monthly patterns of VOCs and SOA concentrations were characterized by peak values during October to March and reached a minimum from April to September,but the observed O_(3)was exactly the opposite.Machine learning methods resolved the importance of individual VOCs on O_(3)and SOA that alkenes(mainly ethylene,propylene,and isoprene)have the highest importance to O_(3)formation;alkanes(C_(n),n≥6)and aromatics were the main source of SOA formation.Machine learning methods revealed and emphasized the importance of photochemical consumptions of VOCs to O_(3)and SOA formation.Ozone formation potential(OFP)and secondary organic aerosol formation potential(SOAFP)calculated by consumed VOCs quantitatively indicated that more than 80%of the consumed VOCs were alkenes which dominated the O_(3)formation,and the importance of consumed aromatics and alkenes to SOAFP were 40.84%and 56.65%,respectively.Therein,isoprene contributed the most to OFP at 41.45%regardless of the season,while aromatics(58.27%)contributed the most to SOAFP in winter.Collectively,our findings can provide scientific evidence on policymaking for VOCs controls on seasonal scales to achieve effective reduction in both SOA and O_(3).展开更多
The atmospheric chemistry in complex air pollution remains poorly understood.In order to probe how environmental conditions can impact the secondary organic aerosol(SOA)formation from biomass burning emissions,we inve...The atmospheric chemistry in complex air pollution remains poorly understood.In order to probe how environmental conditions can impact the secondary organic aerosol(SOA)formation from biomass burning emissions,we investigated the photooxidation of 2,5-dimethylfuran(DMF)under different environmental conditions in a smog chamber.It was found that SO_(2)could promote the formation of SOA and increase the amounts of inorganic salts produced during the photooxidation.The formation rate of SOA and the corresponding SOA mass concentration increased gradually with the increasing DMF/OH ratio.The addition of(NH_(4))_(2)SO_(4)seed aerosol accelerated the SOA formation rate and significantly shortened the time for the reaction to reach equilibrium.Additionally,a relatively high illumination intensity promoted the formation of OH radicals and,correspondingly,enhanced the photooxidation of DMF.However,the enhancement of light intensity accelerated the aging of SOA,which led to a gradual decrease of the SOA mass concentration.This work shows that by having varying influence on atmospheric chemical reactions,the same environmental factor can affect SOA formation in different ways.The present study is helpful for us to better understand atmospheric complex pollution.展开更多
Herein,we use an oxidation flow reactor,Gothenburg:Potential Aerosol Mass(Go:PAM)reactor,to investigate the secondary organic aerosol(SOA)formation from wheat straw burning.Biomass burning emissions are exposed to hig...Herein,we use an oxidation flow reactor,Gothenburg:Potential Aerosol Mass(Go:PAM)reactor,to investigate the secondary organic aerosol(SOA)formation from wheat straw burning.Biomass burning emissions are exposed to high concentrations of hydroxyl radicals(OH)to simulate processes equivalent to atmospheric oxidation of 0-2.55 days.Primary volatile organic compounds(VOCs)were investigated,and particles were measured before and after the Go:PAM reactor.The influence of water content(i.e.5%and 11%)in wheat straw was also explored.Two burning stages,the flaming stage,and non-flaming stages,were identified.Primary particle emission factors(EFs)at a water content of 11%(~3.89 g/kg-fuel)are significantly higher than those at a water content of 5%(~2.26 g/kg-fuel)during the flaming stage.However,the water content showed no significant influence at the non-flaming stage.EFs of aromatics at a non-flaming stage(321.8±46.2 mg/kg-fuel)are larger than that at a flaming stage(130.9±37.1 mg/kg-fuel).The OA enhancement ratios increased with the increase in OH exposure at first and decreased with the additional increment of OH exposure.The maximum OA enhancement ratio is~12 during the non-flaming stages,which is much higher than~1.7 during the flaming stages.The mass spectrum of the primary wheat burning organic aerosols closely resembles that of resolved biomass burning organic aerosols(BBOA)based on measurements in ambient air.Our results show that large gap(0%-90%)still remains to estimate biomass burning SOA if only the oxidation of VOCs were included.展开更多
As Volatile Organic Compounds(VOCs)are one of the precursors of ozone,their distribution and variable concentrations are highly related to local ozone pollution control.In this study,we obtained vertical profiles of V...As Volatile Organic Compounds(VOCs)are one of the precursors of ozone,their distribution and variable concentrations are highly related to local ozone pollution control.In this study,we obtained vertical profiles of VOCs in Shanghai’s Jinshan district on 8 September and 9 September in 2016 to investigate their distribution and impact on local atmospheric oxidation in the near surface layer.Vertical samples were collected from heights between 50 m and 400 m by summa canisters using an unmanned aerial vehicle(UAV).Concentrations of VOCs(VOCs refers to the 52 species measured in this study)varied minimally below 200 m,and decreased by 21.2%from 100 m to 400 m.The concentrations of VOCs above 200 m decreased significantly in comparison to those below 200 m.The proportions of alkanes and aromatics increased from 55.2%and 30.5%to 57.3%and 33.0%,respectively.Additionally,the proportion of alkenes decreased from 13.2%to 8.4%.Toluene and m/p-xylene were the key species in the formation of SOA and ozone.Principal component analysis(PCA)revealed that the VOCs measured in this study mainly originated from industrial emissions.展开更多
Organic aerosol(OA)is a major component of atmospheric particulate matter(PM)with complex composition and formation processes influenced by various factors.Emission reduction can alter both precursors and oxidants whi...Organic aerosol(OA)is a major component of atmospheric particulate matter(PM)with complex composition and formation processes influenced by various factors.Emission reduction can alter both precursors and oxidants which further affects secondary OA formation.Here we provide an observational analysis of secondary OA(SOA)variation properties in Yangtze River Delta(YRD)of eastern China in response to large scale of emission reduction during Chinese New Year(CNY)holidays from 2015 to 2020,and the COVID-19 pandemic period from January to March,2020.We found a 17%increase of SOA proportion during the COVID lockdown.The relative enrichment of SOA is also found during multi-year CNY holidays with dramatic reduction of anthropogenic emissions.Two types of oxygenated OA(OOA)influenced by mixed emissions and SOA formation were found to be the dominant components during the lockdown in YRD region.Our results highlight that these emission-reduction-induced changes in organic aerosol need to be considered in the future to optimize air pollution control measures.展开更多
Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons.However,whether this technology efficiently removes the pollutants to prevent secondary pollution and health ...Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons.However,whether this technology efficiently removes the pollutants to prevent secondary pollution and health risk is still unclear.Here,the photodegradation processes of three xylenes were compared under designed reaction atmospheres and light sources.Xe lamp showed poor photodegradation ability toward xylenes,no matter in N_(2) or N_(2)+O_(2)system,while much higher photodegradation performance of xylenes were obtained under ultraviolet(UV)and vacuum ultraviolet(VUV)irradiation,especially in N_(2)+O_(2)+VUV system,where 97.9%of m-xylene,99.0%of o-xylene or 87.5%of p-xylene with the initial concentration of 860 mg/m^(3) was removed within 240 min.The xylenes underwent three processes of photo-isomerization,photodecomposition and photo-oxidation to produce intermediates of aromatics,alkanes and carbonyls.Among them,the photo-isomerization products showed the highest concentration percentage(e.g.,≥50%in o-xylene system),confirming that photo-isomerization reaction was the dominated photodegradation process of xylenes.Moreover,these isomerized products not only contributed about 97%and91%to the formation potential of O3(OFP)and secondary organic aerosols(SOAFP),but also displayed obvious non-carcinogenic risk,although one of photodecomposition product—benzene showed the highest occupational exposure risk.Therefore,the secondary pollution and health risks of photodegradation products of xylenes were non-ignorable,although the OFP,SOAFP and health risks of the generated products reduced at least 4.5 times in comparison with that of the degraded xylenes.The findings are helpful for the appropriate application of this technology in the purification of industrial organic waste gas.展开更多
Photochemical aging of volatile organic compounds(VOCs)in the atmosphere is an important source of secondary organic aerosol(SOA).To evaluate the formation potential of SOA at an urban site in Lyon(France),an outdoor ...Photochemical aging of volatile organic compounds(VOCs)in the atmosphere is an important source of secondary organic aerosol(SOA).To evaluate the formation potential of SOA at an urban site in Lyon(France),an outdoor experiment using a Potential Aerosol Mass(PAM)oxidation flow reactor(OFR)was conducted throughout entire days during JanuaryFebruary 2017.Diurnal variation of SOA formations and their correlation with OH radical exposure(OHexp),ambient pollutants(VOCs and particulate matters,PM),Relative Humidity(RH),and temperature were explored in this study.Ambient urban air was exposed to high concentration of OH radicals with OHexp in range of(0.2-1.2)×10^12 molecule/(cm^3·sec),corresponding to several days to weeks of equivalent atmospheric photochemical aging.The results informed that urban air at Lyon has high potency to contribute to SOA,and these SOA productions were favored from OH radical photochemical oxidation rather than via ozonolysis.Maximum SOA formation(36μg/m^3)was obtained at OHexp of about 7.4×10^11 molecule/(cm^3·sec),equivalent to approximately 5 days of atmospheric oxidation.The correlation between SOA formation and ambient environment conditions(RH&temperature,VOCs and PM)was observed.It was the first time to estimate SOA formation potential from ambient air over a long period in urban environment of Lyon.展开更多
Methylglyoxal(CH3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxy...Methylglyoxal(CH3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxyl radicals was studied in a 500 L smog chamber at(293±3)K,atmospheric pressure,(18±2)%relative humidity,and under different NOx and SO2.Particle size distribution was measured by using a scanning mobility particle sizer(SMPS)and the results showed that the addition of SO2 can promote SOA formation,while different NOx concentrations have different influences on SOA production.High NOx suppressed the SOA formation,whereas the particle mass concentration,particle number concentration and particle geometric mean diameter increased with the increasing NOx concentration at low NOx concentration in the presence of SO2.In addition,the products of the OH-initiated oxidation of MG and the functional groups of the particle phase in the MG/OH/SO2 and MG/OH/NOx/SO2 reaction systems were detected by gas chromatography mass spectrometry(GC-MS)and attenuated total reflection fourier transformed infrared spectroscopy(ATR-FTIR)analysis.Two products,glyoxylic acid and oxalic acid,were detected by GC-MS.The mechanism of the reaction of MG and OH radicals that follows two main pathways,H atom abstraction and hydration,is proposed.Evidence is provided for the formation of organic nitrates and organic sulfate in particle phase from IR spectra.Incorporation of NOx and SO2 influence suggested that SOA formation from anthropogenic hydrocarbons may be more efficient in polluted environment.展开更多
Volatile organic compounds(VOCs)are major contributors to air pollution.Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer fr...Volatile organic compounds(VOCs)are major contributors to air pollution.Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer from 21 July to 25 August 2016 in Beijing,the environmental impact and health risk of VOC were assessed.In the winter polluted days,the secondary organic aerosol formation potential(SOAP)of VOC(199.70±15.05 mg/m^3)was significantly higher than that on other days.And aromatics were the primary contributor(98.03%)to the SOAP during the observation period.Additionally,the result of the ozone formation potential(OFP)showed that ethylene contributed the most to OFP in winter(26.00%and 27.64%on the normal and polluted days).In summer,however,acetaldehyde was the primary contributor to OFP(22.00%and 21.61%on the normal and polluted days).Simultaneously,study showed that hazard ratios and lifetime cancer risk values of acrolein,chloroform,benzene,1,2-dichloroethane,acetaldehyde and 1,3-butadiene exceeded the thresholds established by USEPA,thereby presenting a health risk to the residents.Besides,the ratio of toluene-to-benzene indicated that vehicle exhausts were the main source of VOC pollution in Beijing.The ratio of m-/p-xylene-toethylbenzene demonstrated that there were more prominent atmospheric photochemical reactions in summer than that in winter.Finally,according to the potential source contribution function(PSCF)results,compared with local pollution sources,the spread of pollution from long-distance VOCs had a greater impact on Beijing.展开更多
Ship auxiliary engines contribute large amounts of air pollutants when at berth.Biodiesel,including that from waste cooking oil(WCO),can favor a reduction in the emission of primary pollutant when used with internal c...Ship auxiliary engines contribute large amounts of air pollutants when at berth.Biodiesel,including that from waste cooking oil(WCO),can favor a reduction in the emission of primary pollutant when used with internal combustion engines.This study investigated the emissions of gaseous intermediate-volatile organic compounds(IVOCs)between WCO biodiesel and marine gas oil(MGO)to further understand the differences in secondary organic aerosol(SOA)production of exhausts.Results revealed that WCO exhaust exhibited similar IVOC composition and volatility distribution to MGO exhaust,despite the differences between fuel contents.While WCO biodiesel could reduce IVOC emissions by 50%as compared to MGO,and thus reduced the SOA production from IVOCs.The compositions and volatility distributions of exhaust IVOCs varied to those of their fuels,implying that fuel-component-based SOA predicting model should be used with more cautions when assessing SOA production of WCO and MGO exhausts.WCO biodiesel is a cleaner fuel comparing to conventional MGO on ship auxiliary engines with regard to the reductions in gaseous IVOC emissions and corresponding SOA productions.Although the tests were conducted on test bench,the results could be considered as representative due to the widely applications of the test engine and MGO fuel on real-world ships.展开更多
Indoor particle release from toner printing equipment (TPE) is a major health concern and has received wide attention.In this study,nine printing centers were randomly selected and three working phases were simulated,...Indoor particle release from toner printing equipment (TPE) is a major health concern and has received wide attention.In this study,nine printing centers were randomly selected and three working phases were simulated,namely,non-working,normal printing/copying,and heavy printing/copying.The dynamics of the ozone (O_(3)),volatile organic compound (VOC),and particle emissions from TPE were determined by portable detectors.Results showed that particles,VOCs,and O_(3)were indeed discharged,and particles and VOCs concentrations remained at high levels.Among them,44%of the rooms represented high-level particle releases.Submicrometer-sized particles,especially nanoparticles,were positively correlated with VOCs,but were inversely proportional to the O_(3)concentration.Four elements,Ca,Al,Mg and Ni,were usually present in nanoparticles because of the discharge of paper.Si,Al,K,Ni and Pb were found in the submicrometer-sized particles and were consistent with the toner composition.The potential particle precursors were identified,which suggested that styrene was the most likely secondary organic aerosol (SOA) precursor.Overall,the use of the toner formulation and the discharge of paper attribute to the TPE-emitted particles,in which styrene is a specific monitoring indicator for the formation of SOA.展开更多
Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China.Thus,a large-scale outdoor atmospheric simulation smog chamber ...Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China.Thus,a large-scale outdoor atmospheric simulation smog chamber was constructed at Chinese Research Academy of Environmental Sciences(the CRAES Chamber),which was designed for simulating the atmospheric photochemical processes under the conditions close to the real atmospheric environment.The chamber consisted of a 56-m^(3) fluorinated ethylene propylene(FEP) Teflon film reactor,an electrically-driven stainless steel alloy shield,an auxiliary system,and multiple detection instrumentations.By performing a series of characterization experiments,we obtained basic parameters of the CRAES chamber,such as the mixing ability,the background reactivity,and the wall loss rates of gaseous compounds(propene,NO,NO_(2),ozone) and aerosols(ammonium sulfate).Oxidation experiments were also performed to study the formation of ozone and secondary organic aerosol(SOA),including α-pinene ozonolysis,propene and 1,3,5-trimethylbenzene photooxidation.Temperature and seed effects on the vapor wall loss and SOA yields were obtained in this work:higher temperature and the presence of seed could reduce the vapor wall loss;SOA yield was found to depend inversely on temperature,and the presence of seed could increase SOA yield.The seed was suggested to be used in the chamber to reduce the interaction between the gas phase and chamber walls.The results above showed that the CRAES chamber was reliable and could meet the demands for investigating tropospheric chemistry.展开更多
基金This work was supported by National Natural Science Foundation of China(Grant No.91644214)Youth Innovation Program of Universities in Shandong Province(Grant No.2019KJD007)Fundamental Research Fund of Shandong University(Grant No.2020QNQT012).
文摘Anthropogenic emissions alter biogenic secondary organic aerosol(SOA)formation from naturally emitted volatileorganic compounds(BVOCs).We review the major laboratory and field findings with regard to effects of anthropogenicpollutants(NO_(x),anthropogenic aerosols,SO_(2),NH_(3))on biogenic SOA formation.NO_(x) participate in BVOC oxidationthrough changing the radical chemistry and oxidation capacity,leading to a complex SOA composition and yield sensitivitytowards NO_(x) level for different or even specific hydrocarbon precursors.Anthropogenic aerosols act as an importantintermedium for gas-particle partitioning and particle-phase reactions,processes of which are influenced by the particlephase state,acidity,water content and thus associated with biogenic SOA mass accumulation.SO_(2)modifies biogenic SOAformation mainly through sulfuric acid formation and accompanies new particle formation and acid-catalyzedheterogeneous reactions.Some new SO_(2)-involved mechanisms for organosulfate formation have also been proposed.NH_(3)/amines,as the most prevalent base species in the atmosphere,influence biogenic SOA composition and modify theoptical properties of SOA.The response of SOA formation behavior to these anthropogenic pollutants varies amongdifferent BVOCs precursors.Investigations on anthropogenic-biogenic interactions in some areas of China that aresimultaneously influenced by anthropogenic and biogenic emissions are summarized.Based on this review,somerecommendations are made for a more accurate assessment of controllable biogenic SOA formation and its contribution tothe total SOA budget.This study also highlights the importance of controlling anthropogenic pollutant emissions witheffective pollutant mitigation policies to reduce regional and global biogenic SOA formation.
基金National Natural Science Foundation of China (Nos.22125303,92061203,and 22288201)the National Key Research and Development Program of China (No.2021YFA1400501)+3 种基金Innovation Program for Quantum Science and Technology (No.2021ZD0303304)Dalian Institute of Chemical Physics (No.DICP DCLS201702)Chinese Academy of Sciences (No.GJJSTD20220001)K.C.Wong Education Foundation (No.GJTD-2018-06)。
文摘Elucidating the effects of anthropogenic pollutants on the photooxidation of biogenic volatile organic compounds is crucial to understanding the fundamental mechanisms of secondary organic aerosol(SOA)formation.Here,the impacts of NO_(2)and SO_(2)on SOA formation from the photooxidation of a representative monoterpene,β-pinene,were investigated by a number of laboratory studies.The results indicated NO_(2)enhanced the SOA mass concentrations and particle number concentrations under both low and highβ-pinene conditions.This could be rationalized that the increased O_(3)concentrations upon the NO_(x)photolysis was helpful for the generation of more amounts of O_(3)-oxidized products,which accelerated the SOA nucleation and growth.Combing with NO_(2),the promotion of the SOA yield by SO_(2)was mainly reflected in the increase of mass concentration,which might be due to the elimination of the newly formed particles by the initially formed particles.The observed low oxidation degree of SOA might be attributed to the fast growth of SOA,resulting in the uptake of less oxygenated gas-phase species onto the particle phase.The present findings have important implications for SOA formation affected by anthropogenic–biogenic interactions in the ambient atmosphere.
基金supported by the Central Level,Scientific Research Institutes for Basic R&D Special Fund Business,China(No.2021-JY-16)the National Natural Science Foundation of China(Nos.42075182 and 2130721)+1 种基金the National Research Program for Key Issue in Air Pollution Control(No.DQGG2021101)the National Key Research and Development Program of China(No.2019YFC0214800)。
文摘The formation and aging mechanism of secondary organic aerosol(SOA)and its influencing factors have attracted increasing attention in recent years because of their effects on climate change,atmospheric quality and human health.However,there are still large errors between air quality model simulation results and field observations.The currently undetected components during the formation and aging of SOA due to the limitation of current monitoring techniques and the interactions among multiple SOA formation influencing factors might be the main reasons for the differences.In this paper,we present a detailed review of the complex dynamic physical and chemical processes and the corresponding influencing factors involved in SOA formation and aging.And all these results were mainly based the studies of photochemical smog chamber simulation.Although the properties of precursor volatile organic compounds(VOCs),oxidants(such as OH radicals),and atmospheric environmental factors(such as NOx,SO2,NH3,light intensity,temperature,humidity and seed aerosols)jointly influence the products and yield of SOA,the nucleation and vapor pressure of these products were found to be the most fundamental aspects when interpreting the dynamics of the SOA formation and aging process.The development of techniques for measuring intermediate species in SOA generation processes and the study of SOA generation and aging mechanism in complex systems should be important topics of future SOA research.
基金financially supported by the Natural Science Foundation of Guangdong Province,China (No.2019B151502064)the National Natural Science Foundation of China (Nos.42077189 and 4201001008)+2 种基金the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (No.2017BT01Z032)the Innovation Team Project of Guangdong Provincial Department of Education(No.2017KCXTD012)the Science and Technology Key Project of Guangdong Province,China (No.2019B110206002)。
文摘Organosulfate (OSA) nanoparticles,as secondary organic aerosol (SOA) compositions,are ubiquitous in urban and rural environments.Hence,we systemically investigated the mechanisms and kinetics of aqueous-phase reactions of 1-butanol/1-decanol (BOL/DOL) and their roles in the formation of OSA nanoparticles by using quantum chemical and kinetic calculations.The mechanism results show that the aqueous-phase reactions of BOL/DOL start from initial protonation at alcoholic OH^(-)groups to form carbenium ions (CBs),which engage in the subsequent esterification or oligomerization reactions to form OSAs/organosulfites (OSIs) or dimers.The kinetic results reveal that dehydration to form CBs for BOL and DOL reaction systems is the rate-limiting step.Subsequently,about 18%of CBs occur via oligomerization to dimers,which are difficult to further oligomerize because all reactive sites are occupied.The rate constant of BOL reaction system is one order of magnitude larger than that of DOL reaction system,implying that relative short-chain alcohols are more prone to contribute OSAs/OSIs than long-chain alcohols.Our results reveal that typical long-chain alcohols contribute SOA formation via esterification rather than oligomerization because OSA/OSI produced by esterification engages in nanoparticle growth through enhancing hygroscopicity.
文摘Volatile organic compounds(VOCs)are the important precursors of the tropospheric ozone(O3)and secondary organic aerosols(SOA),both of which are known to harm human health and disrupt the earth’s climate system.In this study,VOC emission factors,O3 and SOA formation potentials were estimated for two types of industrial boilers:coal-fired boilers(n=3)and oil-fired boilers(n=3).Results showed that EVOCs concentrations were more than nine times higher for oil-fire d boilers compared to those for coal-fired boilers.Emission factors ofΣVOCs were found to be higher for oil-fired boilers(9.26-32.83 mg-VOC/kg)than for coal-fired boilers(1.57-4.13 mg-VOC/kg).Alkanes and aromatics were obtained as the most abundant groups in coal-fired boilers,while oxygenated organics and aromatics were the most contributing groups in oil-fired boilers.Benzene,n-hexane and o-ethyl toluene were the abundant VOC species in coal-fired boiler emissions,whereas toluene was the most abundant VOC species emitted from oil-fired boilers.O3 and SOA formation potentials were found 12 and 18 times,respectively,higher for oil-fired than for coal-fired boilers.Total OFP ranged from 3.99 to 11.39 mg-O3/kg for coal-fired boilers.For oil-fired boilers,total OFP ranged from 36.16 to 131.93 mg-O3/kg.Moreover,total secondary organic aerosol potential(SOAP)ranged from 65.4 to 122.5 mg-SOA/kg and 779.9 to 2252.5 mg-SOA/kg for the coal-fired and oil-fired boilers,respectively.
文摘PM_(1)0 samples were collected from an urban/industrial site nearby Athens,where uncontrolled burning activities occur.PAHs,monocarboxylic,dicarboxylic,hydroxycarboxylic and aromatic acids,tracers from BVOC oxidation,biomass burning tracers and bisphenol A were determined.PAH,monocarboxylic acids,biomass burning tracers and bisphenol A were increased during autumn/winter,while BSOA tracers,dicarboxylic-and hydroxycarboxylic acids during summer.Regarding aromatic acids,different sources and formation mechanisms were indicated as benzoic,phthalic and trimellitic acids were peaked during summer whereas p-toluic,isophthalic and terephthalic were more abundant during autumn/winter.The Benzo[a]pyrene-equivalent carcinogenic power,carcinogenic and mutagenic activities were calculated showing significant(p<0.05)increases during the colder months.Palmitic,succinic and malic acids were the most abundant monocarboxylic,dicarboxylic and hydrocarboxylic acids during the entire sampling period.Isoprene oxidation was the most significant contributor to BSOA as the isoprene-SOA compounds were two times more abundant than the pinene-SOA(13.4±12.3 and 6.1±2.9 ng/m^3,respectively).Ozone has significant impact on the formation of many studied compounds showing significant correlations with:isoprene-SOA(r=0.77),hydrocarboxylic acids(r=0.69),pinene-SOA(r=0.63),dicarboxylic acids(r=0.58),and the sum of phthalic,benzoic and trimellitic acids(r=0.44).PCA demonstrated five factors that could explain sources including plastic enriched waste burning(30.8%),oxidation of unsaturated fatty acids(23.0%),vehicle missions and cooking(9.2%),biomass burning(7.7%)and oxidation of VOCs(5.8%).The results highlight the significant contribution of plastic waste uncontrolled burning to the overall air quality degradation.
基金supported by the State Key Program of National Natural Science Foundation of China(No.91644215)the National Key Research and Development Program of China(Nos.2017YFC0210106 and 2016YFC0202206)+3 种基金the National Natural Science Foundation of China(No.41775114)the Pearl River Science&Technology Nova Program of Guangzhou(No.201806010146)the Fundamental Research Funds for the Central Universities(No.19lgzd06)the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province(No.2019B121205004)
文摘Secondary organic aerosol(SOA)is a very important component of fine particulate matter(PM)in the atmosphere.However,the simulations of SOA,which could help to elucidate the detailed mechanism of SOA formation and quantify the roles of various precursors,remains unsatisfactory,as SOA levels are frequently underestimated.It has been found that the performance of SOA formation models can be significantly improved by incorporating the emission and evolution of semivolatile and intermediate-volatility organic compounds(S/IVOCs).In order to explore the roles of S/IVOCs in SOA formation,this study reviews some simulation models which could consider S/IVOCs for SOA formation as well as the development of emission inventories of S/IVOCs and S/IVOC modules for SOA formation.In addition,the future research directions for simulations of the effect of S/IVOCs on SOA formation are suggested.
基金funded by the Research Council and the Faculty of Sciences of Saint Joseph University of Beirut–LebanonThe“Unitéde Chimie Environnementale et Interactions sur le Vivant”(UCEIV-UR4492)participates in the CLIMIBIO project,which is financially supported by the Hauts-de-France Region Council,the French Ministry of Higher Education and Researchthe European Regional Development Funds。
文摘Primary and secondary organic aerosols in PM_(2.5)were investigated over a one-year campaign at Zouk Mikael and Fiaa,Lebanon.The n-alkanes concentrations were quite similar at both sites(26-29 ng/m^(3))and mainly explained by anthropogenic emissions rather than natural ones.The concentrations of total Polycyclic Aromatic Hydrocarbons(PAHs)were nearly three times higher at Zouk Mikael(2.56 ng/m^(3))compared to Fiaa(0.95 ng/m^(3)),especially for indeno[1,2,3-c,d]pyrene linked to the presence of the power plant.A characteristic indeno[1,2,3-c,d]pyrene/(indeno[1,2,3-c,d]pyrene+benzo[g,h,i]perylene)ratio in the range0.8-1.0 was determined for heavy fuel oil combustion from the power plant.Fatty acids and hopanes were also investigated and were assigned to cooking activities and vehicular emissions respectively.Phthalates were identified for the first time in Lebanon with high concentrations at Zouk and Fiaa(106.88 and 97.68 ng/m^(3) respectively).Moreover,the biogenic secondary aerosols revealed higher concentrations in summer.The total terpene concentration varied between 131 ng/m^(3) at Zouk Mikael in winter to 469 ng/m3 at Fiaa in summer.Additionnally,the concentrations of the dicarboxylic acids especially for adipic and phthalic acids were more influenced by anthropogenic sources.The analysis of molecular markers and diagnostic ratios indicated that the sites were strongly affected by anthropogenic sources such as waste open burning,diesel private generators,cooking activities,road transport,power plant,and industrial emissions.Moreover,results showed different pattern during winter and summer seasons.Whereas,higher concentrations of biogenic markers were clearly encountered during the summer period.
基金financially supported by the National Key Research and Development Program of China(No.2018 YFE0106900)supported by National Natural Science Foundation of China(Nos.42077191,41775149)+2 种基金Fundamental Research Funds for the Central Universities(No.63213072)National Research Program for Key Issues in Air Pollution Control(No.DQGG-05-30)the Blue Sky Foundation
文摘Fine particulate matter(PM_(2.5))and ozone(O_(3))pollutions are prevalent air quality issues in China.Volatile organic compounds(VOCs)have significant impact on the formation of O_(3)and secondary organic aerosols(SOA)contributing PM_(2.5).Herein,we investigated 54 VOCs,O_(3)and SOA in Tianjin from June 2017 to May 2019 to explore the non-linear relationship among O_(3),SOA and VOCs.The monthly patterns of VOCs and SOA concentrations were characterized by peak values during October to March and reached a minimum from April to September,but the observed O_(3)was exactly the opposite.Machine learning methods resolved the importance of individual VOCs on O_(3)and SOA that alkenes(mainly ethylene,propylene,and isoprene)have the highest importance to O_(3)formation;alkanes(C_(n),n≥6)and aromatics were the main source of SOA formation.Machine learning methods revealed and emphasized the importance of photochemical consumptions of VOCs to O_(3)and SOA formation.Ozone formation potential(OFP)and secondary organic aerosol formation potential(SOAFP)calculated by consumed VOCs quantitatively indicated that more than 80%of the consumed VOCs were alkenes which dominated the O_(3)formation,and the importance of consumed aromatics and alkenes to SOAFP were 40.84%and 56.65%,respectively.Therein,isoprene contributed the most to OFP at 41.45%regardless of the season,while aromatics(58.27%)contributed the most to SOAFP in winter.Collectively,our findings can provide scientific evidence on policymaking for VOCs controls on seasonal scales to achieve effective reduction in both SOA and O_(3).
基金supported by National Natural Science Foundation of China(No.91644214)Youth Innovation Program of Universities in Shandong Province(No.2019KJD007)Fundamental Research Fund of Shandong University(No.2020QNQT012)
文摘The atmospheric chemistry in complex air pollution remains poorly understood.In order to probe how environmental conditions can impact the secondary organic aerosol(SOA)formation from biomass burning emissions,we investigated the photooxidation of 2,5-dimethylfuran(DMF)under different environmental conditions in a smog chamber.It was found that SO_(2)could promote the formation of SOA and increase the amounts of inorganic salts produced during the photooxidation.The formation rate of SOA and the corresponding SOA mass concentration increased gradually with the increasing DMF/OH ratio.The addition of(NH_(4))_(2)SO_(4)seed aerosol accelerated the SOA formation rate and significantly shortened the time for the reaction to reach equilibrium.Additionally,a relatively high illumination intensity promoted the formation of OH radicals and,correspondingly,enhanced the photooxidation of DMF.However,the enhancement of light intensity accelerated the aging of SOA,which led to a gradual decrease of the SOA mass concentration.This work shows that by having varying influence on atmospheric chemical reactions,the same environmental factor can affect SOA formation in different ways.The present study is helpful for us to better understand atmospheric complex pollution.
基金supported by National Natural Science Foundation of China(Nos.51636003,91844301,41977179)Beijing Municipal Science and Technology Commission(No.Z201100008220011)+2 种基金Natural Science Foundation of Beijing(No.8192022)China Postdoctoral Science Foundation(No.2020M680242)the Open Research Fund of State Key Laboratory of Multi-phase Complex Systems(No.MPCS-2021-D-12)
文摘Herein,we use an oxidation flow reactor,Gothenburg:Potential Aerosol Mass(Go:PAM)reactor,to investigate the secondary organic aerosol(SOA)formation from wheat straw burning.Biomass burning emissions are exposed to high concentrations of hydroxyl radicals(OH)to simulate processes equivalent to atmospheric oxidation of 0-2.55 days.Primary volatile organic compounds(VOCs)were investigated,and particles were measured before and after the Go:PAM reactor.The influence of water content(i.e.5%and 11%)in wheat straw was also explored.Two burning stages,the flaming stage,and non-flaming stages,were identified.Primary particle emission factors(EFs)at a water content of 11%(~3.89 g/kg-fuel)are significantly higher than those at a water content of 5%(~2.26 g/kg-fuel)during the flaming stage.However,the water content showed no significant influence at the non-flaming stage.EFs of aromatics at a non-flaming stage(321.8±46.2 mg/kg-fuel)are larger than that at a flaming stage(130.9±37.1 mg/kg-fuel).The OA enhancement ratios increased with the increase in OH exposure at first and decreased with the additional increment of OH exposure.The maximum OA enhancement ratio is~12 during the non-flaming stages,which is much higher than~1.7 during the flaming stages.The mass spectrum of the primary wheat burning organic aerosols closely resembles that of resolved biomass burning organic aerosols(BBOA)based on measurements in ambient air.Our results show that large gap(0%-90%)still remains to estimate biomass burning SOA if only the oxidation of VOCs were included.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41830106,21607104)the National Key Research and Development Plan(Grant Nos.2017YFC0210004,2018YFC0213801)+1 种基金the Shanghai Science and Technology Commission of Shanghai Municipality(18QA 403600)the Shanghai Environmental Protection Bureau(2017-2).
文摘As Volatile Organic Compounds(VOCs)are one of the precursors of ozone,their distribution and variable concentrations are highly related to local ozone pollution control.In this study,we obtained vertical profiles of VOCs in Shanghai’s Jinshan district on 8 September and 9 September in 2016 to investigate their distribution and impact on local atmospheric oxidation in the near surface layer.Vertical samples were collected from heights between 50 m and 400 m by summa canisters using an unmanned aerial vehicle(UAV).Concentrations of VOCs(VOCs refers to the 52 species measured in this study)varied minimally below 200 m,and decreased by 21.2%from 100 m to 400 m.The concentrations of VOCs above 200 m decreased significantly in comparison to those below 200 m.The proportions of alkanes and aromatics increased from 55.2%and 30.5%to 57.3%and 33.0%,respectively.Additionally,the proportion of alkenes decreased from 13.2%to 8.4%.Toluene and m/p-xylene were the key species in the formation of SOA and ozone.Principal component analysis(PCA)revealed that the VOCs measured in this study mainly originated from industrial emissions.
基金supported by National Natural Science Foundation of China(No.42005082).
文摘Organic aerosol(OA)is a major component of atmospheric particulate matter(PM)with complex composition and formation processes influenced by various factors.Emission reduction can alter both precursors and oxidants which further affects secondary OA formation.Here we provide an observational analysis of secondary OA(SOA)variation properties in Yangtze River Delta(YRD)of eastern China in response to large scale of emission reduction during Chinese New Year(CNY)holidays from 2015 to 2020,and the COVID-19 pandemic period from January to March,2020.We found a 17%increase of SOA proportion during the COVID lockdown.The relative enrichment of SOA is also found during multi-year CNY holidays with dramatic reduction of anthropogenic emissions.Two types of oxygenated OA(OOA)influenced by mixed emissions and SOA formation were found to be the dominant components during the lockdown in YRD region.Our results highlight that these emission-reduction-induced changes in organic aerosol need to be considered in the future to optimize air pollution control measures.
基金supported by the National Natural Science Foundation of China (Nos.42177354 and 21777032)the National Key R&D Program of China (No.2019YFC0214402)the Guangdong Basic and Applied Basic Research oundation (No.2019B151502064)。
文摘Photodegradation technology has been widely applied in the purification of industrial aromatic hydrocarbons.However,whether this technology efficiently removes the pollutants to prevent secondary pollution and health risk is still unclear.Here,the photodegradation processes of three xylenes were compared under designed reaction atmospheres and light sources.Xe lamp showed poor photodegradation ability toward xylenes,no matter in N_(2) or N_(2)+O_(2)system,while much higher photodegradation performance of xylenes were obtained under ultraviolet(UV)and vacuum ultraviolet(VUV)irradiation,especially in N_(2)+O_(2)+VUV system,where 97.9%of m-xylene,99.0%of o-xylene or 87.5%of p-xylene with the initial concentration of 860 mg/m^(3) was removed within 240 min.The xylenes underwent three processes of photo-isomerization,photodecomposition and photo-oxidation to produce intermediates of aromatics,alkanes and carbonyls.Among them,the photo-isomerization products showed the highest concentration percentage(e.g.,≥50%in o-xylene system),confirming that photo-isomerization reaction was the dominated photodegradation process of xylenes.Moreover,these isomerized products not only contributed about 97%and91%to the formation potential of O3(OFP)and secondary organic aerosols(SOAFP),but also displayed obvious non-carcinogenic risk,although one of photodecomposition product—benzene showed the highest occupational exposure risk.Therefore,the secondary pollution and health risks of photodegradation products of xylenes were non-ignorable,although the OFP,SOAFP and health risks of the generated products reduced at least 4.5 times in comparison with that of the degraded xylenes.The findings are helpful for the appropriate application of this technology in the purification of industrial organic waste gas.
基金the Institute for Research on Catalysis and the Environment of Lyon(IRCELYON)supported by the"Investissement d’Avenir"PEPS Program Project(ASTRAL)of the University of Lyon and French National center for Scientific Research(French:center national de la recherche scientifique,CNRS)as part of the ANR-11-IDEX-0007 programby the European Research Council under the Horizon 2020 Research and Innovation Program Project of the European Union under Convention N°690958(MARSU)。
文摘Photochemical aging of volatile organic compounds(VOCs)in the atmosphere is an important source of secondary organic aerosol(SOA).To evaluate the formation potential of SOA at an urban site in Lyon(France),an outdoor experiment using a Potential Aerosol Mass(PAM)oxidation flow reactor(OFR)was conducted throughout entire days during JanuaryFebruary 2017.Diurnal variation of SOA formations and their correlation with OH radical exposure(OHexp),ambient pollutants(VOCs and particulate matters,PM),Relative Humidity(RH),and temperature were explored in this study.Ambient urban air was exposed to high concentration of OH radicals with OHexp in range of(0.2-1.2)×10^12 molecule/(cm^3·sec),corresponding to several days to weeks of equivalent atmospheric photochemical aging.The results informed that urban air at Lyon has high potency to contribute to SOA,and these SOA productions were favored from OH radical photochemical oxidation rather than via ozonolysis.Maximum SOA formation(36μg/m^3)was obtained at OHexp of about 7.4×10^11 molecule/(cm^3·sec),equivalent to approximately 5 days of atmospheric oxidation.The correlation between SOA formation and ambient environment conditions(RH&temperature,VOCs and PM)was observed.It was the first time to estimate SOA formation potential from ambient air over a long period in urban environment of Lyon.
基金supported by the National Natural Science Foundation of China(No.91644214)the Shandong Natural Science Fund for Distinguished Young Scholars(No.JQ201705)。
文摘Methylglyoxal(CH3COCHO,MG),which is one of the most abundant α-dicarbonyl compounds in the atmosphere,has been reported as a major source of secondary organic aerosol(SOA).In this work,the reaction of MG with hydroxyl radicals was studied in a 500 L smog chamber at(293±3)K,atmospheric pressure,(18±2)%relative humidity,and under different NOx and SO2.Particle size distribution was measured by using a scanning mobility particle sizer(SMPS)and the results showed that the addition of SO2 can promote SOA formation,while different NOx concentrations have different influences on SOA production.High NOx suppressed the SOA formation,whereas the particle mass concentration,particle number concentration and particle geometric mean diameter increased with the increasing NOx concentration at low NOx concentration in the presence of SO2.In addition,the products of the OH-initiated oxidation of MG and the functional groups of the particle phase in the MG/OH/SO2 and MG/OH/NOx/SO2 reaction systems were detected by gas chromatography mass spectrometry(GC-MS)and attenuated total reflection fourier transformed infrared spectroscopy(ATR-FTIR)analysis.Two products,glyoxylic acid and oxalic acid,were detected by GC-MS.The mechanism of the reaction of MG and OH radicals that follows two main pathways,H atom abstraction and hydration,is proposed.Evidence is provided for the formation of organic nitrates and organic sulfate in particle phase from IR spectra.Incorporation of NOx and SO2 influence suggested that SOA formation from anthropogenic hydrocarbons may be more efficient in polluted environment.
基金supported by the National Key R&D Program of China(No.2016YFC0202500)the National Natural Science Foundation of China(Nos.21677163 and 21876193)+1 种基金the Chengdu Science and Technology Project(No.2018-ZM01-00019-SN)the Youth Innovation Promotion Association CAS。
文摘Volatile organic compounds(VOCs)are major contributors to air pollution.Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer from 21 July to 25 August 2016 in Beijing,the environmental impact and health risk of VOC were assessed.In the winter polluted days,the secondary organic aerosol formation potential(SOAP)of VOC(199.70±15.05 mg/m^3)was significantly higher than that on other days.And aromatics were the primary contributor(98.03%)to the SOAP during the observation period.Additionally,the result of the ozone formation potential(OFP)showed that ethylene contributed the most to OFP in winter(26.00%and 27.64%on the normal and polluted days).In summer,however,acetaldehyde was the primary contributor to OFP(22.00%and 21.61%on the normal and polluted days).Simultaneously,study showed that hazard ratios and lifetime cancer risk values of acrolein,chloroform,benzene,1,2-dichloroethane,acetaldehyde and 1,3-butadiene exceeded the thresholds established by USEPA,thereby presenting a health risk to the residents.Besides,the ratio of toluene-to-benzene indicated that vehicle exhausts were the main source of VOC pollution in Beijing.The ratio of m-/p-xylene-toethylbenzene demonstrated that there were more prominent atmospheric photochemical reactions in summer than that in winter.Finally,according to the potential source contribution function(PSCF)results,compared with local pollution sources,the spread of pollution from long-distance VOCs had a greater impact on Beijing.
基金financially supported by the National Natural Science Foundation of China(Nos.41403084,41807341,4171101108 and 41603090)the Project from Shanghai Committee of Science and Technology(No.16ZR1414800)
文摘Ship auxiliary engines contribute large amounts of air pollutants when at berth.Biodiesel,including that from waste cooking oil(WCO),can favor a reduction in the emission of primary pollutant when used with internal combustion engines.This study investigated the emissions of gaseous intermediate-volatile organic compounds(IVOCs)between WCO biodiesel and marine gas oil(MGO)to further understand the differences in secondary organic aerosol(SOA)production of exhausts.Results revealed that WCO exhaust exhibited similar IVOC composition and volatility distribution to MGO exhaust,despite the differences between fuel contents.While WCO biodiesel could reduce IVOC emissions by 50%as compared to MGO,and thus reduced the SOA production from IVOCs.The compositions and volatility distributions of exhaust IVOCs varied to those of their fuels,implying that fuel-component-based SOA predicting model should be used with more cautions when assessing SOA production of WCO and MGO exhausts.WCO biodiesel is a cleaner fuel comparing to conventional MGO on ship auxiliary engines with regard to the reductions in gaseous IVOC emissions and corresponding SOA productions.Although the tests were conducted on test bench,the results could be considered as representative due to the widely applications of the test engine and MGO fuel on real-world ships.
基金supported by the National Natural Science Foundation of China (No.81973003)the Army Logistics Research Plan of China (No.AEP14C001)。
文摘Indoor particle release from toner printing equipment (TPE) is a major health concern and has received wide attention.In this study,nine printing centers were randomly selected and three working phases were simulated,namely,non-working,normal printing/copying,and heavy printing/copying.The dynamics of the ozone (O_(3)),volatile organic compound (VOC),and particle emissions from TPE were determined by portable detectors.Results showed that particles,VOCs,and O_(3)were indeed discharged,and particles and VOCs concentrations remained at high levels.Among them,44%of the rooms represented high-level particle releases.Submicrometer-sized particles,especially nanoparticles,were positively correlated with VOCs,but were inversely proportional to the O_(3)concentration.Four elements,Ca,Al,Mg and Ni,were usually present in nanoparticles because of the discharge of paper.Si,Al,K,Ni and Pb were found in the submicrometer-sized particles and were consistent with the toner composition.The potential particle precursors were identified,which suggested that styrene was the most likely secondary organic aerosol (SOA) precursor.Overall,the use of the toner formulation and the discharge of paper attribute to the TPE-emitted particles,in which styrene is a specific monitoring indicator for the formation of SOA.
基金supported by the China Postdoctoral Science Foundation (No.2019M660752)the Beijing Municipal Science&Technology Commission (No.Z181100005418015),LAC/CMA (No.2019B08)+2 种基金the Fundamental Research Funds for Central Public Welfare Scientific Research Institutes of ChinaChinese Research Academy of Environmental Sciences (Nos.GYG5051201,2009GGQD18,2019YSKY-018,2019YSKY-012)the Chinese Academy of Sciences Strategic Leading Science and Technology Project (Class B)(No.XDB05010200)。
文摘Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China.Thus,a large-scale outdoor atmospheric simulation smog chamber was constructed at Chinese Research Academy of Environmental Sciences(the CRAES Chamber),which was designed for simulating the atmospheric photochemical processes under the conditions close to the real atmospheric environment.The chamber consisted of a 56-m^(3) fluorinated ethylene propylene(FEP) Teflon film reactor,an electrically-driven stainless steel alloy shield,an auxiliary system,and multiple detection instrumentations.By performing a series of characterization experiments,we obtained basic parameters of the CRAES chamber,such as the mixing ability,the background reactivity,and the wall loss rates of gaseous compounds(propene,NO,NO_(2),ozone) and aerosols(ammonium sulfate).Oxidation experiments were also performed to study the formation of ozone and secondary organic aerosol(SOA),including α-pinene ozonolysis,propene and 1,3,5-trimethylbenzene photooxidation.Temperature and seed effects on the vapor wall loss and SOA yields were obtained in this work:higher temperature and the presence of seed could reduce the vapor wall loss;SOA yield was found to depend inversely on temperature,and the presence of seed could increase SOA yield.The seed was suggested to be used in the chamber to reduce the interaction between the gas phase and chamber walls.The results above showed that the CRAES chamber was reliable and could meet the demands for investigating tropospheric chemistry.
