二硫化碳气体近紫外吸收截面积测定

利用二极管阵列光谱仪,室温条件下,在波长220～380 nm的波段内,测量了CS2的紫外吸收截面积。发现CS2在315 nm处具有较大吸收,其值为σ=7.184×10-20cm2.molecule-1。与文献报道进行了比对,吻合较好,并利用所获得的数据对CS2大气光解寿命进行了评估。

A study on wildfire impacts on greenhouse gas emissions and regional air quality in South of Orléans,France

Wildfire events are increasing globally which may be partly associated with climate change,resulting in significant adverse impacts on local,regional air quality and global climate.In September 2020,a small wildfire(burned area:36.3 ha)event occurred in Souesmes(Loiret-Cher,Sologne,France),and its plume spread out over 200 km on the following day as observed by the MODIS satellite.Based on measurements at a suburban site(~50 km northwest of the fire location)in Orléans and backward trajectory analysis,young wildfire plumes were characterized.Significant increases in gaseous pollutants(CO,CH_(4),N_(2)O,VOCs,etc.)and particles(including black carbon)were found within the wildfire plumes,leading to a reduced air quality.Emission factors,defined as EF(X)=ΔX/ΔCO(where,X represents the target species),of various trace gases and black carbon within the young wildfire plumes were determined accordingly and compared with previous studies.Changes in the ambient ions(such as ammonium,sulfate,nitrate,chloride,and nitrite in the particle-and gasphase)and aerosol properties(e.g.,aerosol water content,aerosol p H)were also quantified and discussed.Moreover,we estimated the total carbon and climate-related species(e.g.,CO_(2),CH_(4),N_(2)O,and BC)emissions and compared them with fire emission inventories.Current biomass burning emission inventories have uncertainties in estimating small fire burned areas and emissions.For instance,we found that the Global Fire Assimilation System(GFAS)may underestimate emissions(e.g.,CO)of this small wildfire while other inventories(GFED and FINN)showed significant overestimation.Considering that it is the first time to record wildfire plumes in this region,related atmospheric implications are presented and discussed.

Levels,sources and health risks of carbonyls and BTEX in the ambient air of Beijing,China

The atmospheric concentrations of carbonyls and BTEX （benzene,toluene,ethylbenzene,m,p-xylene and o-xylene） were measured simultaneously at a same sampling site in Beijing from September 2008 to August 2010.The average concentrations of the total measured carbonyls during autumn,winter,spring,and summer were 37.7,31.3,39.7,50.5 μg/m 3,respectively,and maximal values for their diurnal variations usually happened at noontime.In contrast to carbonyls,the average concentrations of the total measured BTEX during the four seasons were 27.2,31.9,23.2,19.1 μg/m 3,respectively,andminimal values for their diurnal variations always occurred in the early afternoon.The average concentration for carbonyls increased about 24% from September 2008–August 2009 to September 2009–August 2010,for BTEX,increased about 15%.Integrated life time cancer risks for three carcinogens （benzene,formaldehyde and acetaldehyde） in Beijing exceeded the value of 1E-06,and the hazard quotient （HQ） of non-cancer risk of exposure to formaldehyde exceeded unity.

Characterization of peroxyacetyl nitrate(PAN)under different PM_(2.5) concentration in wintertime at a North China rural site

As a secondary pollutant of photochemical pollution,peroxyacetyl nitrate(PAN)has attracted a close attention.A four-month campaign was conducted at a rural site in North China Plain(NCP)including the measurement of PAN,O_(3),NO_(x),PM_(2.5),oxygenated volatile organic compounds(OVOCs),photolysis rate constants of NO_(2)and O_(3)and meteorological parameters to investigate the wintertime characterization of photochemistry from November 2018 to February 2019.The results showed that the maximum and mean values of PAN were 4.38 and 0.93±0.67 ppbv during the campaign,respectively.The PAN under different PM_(2.5)concentrations from below 75μg/m^(3)up to 250μg/m^(3),showed different diurnal variation and formation rate.In the PM_(2.5)concentration range of above 250μg/m^(3),PAN had the largest daily mean value of 0.64 ppbv and the fastest production rate of 0.33 ppbv/hr.From the perspective of PAN’s production mechanism,the light intensity and precursors concentrations under different PM_(2.5)pollution levels indicated that there were sufficient light intensity and high volatile organic compounds(VOCs)and NO_(x)precursors concentration even under severe pollution level to generate a large amount of PAN.Moreover,the bimodal staggering phenomenon of PAN and PM_(2.5)provided a basis that PAN might aggravate haze through secondary organic aerosols(SOA)formation.

A large-scale outdoor atmospheric simulation smog chamber for studying atmospheric photochemical processes:Characterization and preliminary application

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.

Seasonal,diurnal and nocturnal variations of carbonyl compounds in the semi-urban environment of Orléans,France

Atmospheric carbonyls were measured at a semi-urban site in Orléans, France, from October 2010to July2011. Formaldehyde, acetaldehyde and acetone were found to be the most abundant carbonyls, with average concentrations of 3.1, 1.0, 2.0 ppb, respectively in summer, 2.3, 0.7, 2.2 ppb, respectively in autumn, 2.2, 1.0, 2.1 ppb, respectively in spring,and 1.5, 0.7, 1.1 ppb, respectively in winter. Photo-oxidation of volatile organic compounds（VOCs） was found to make a remarkable contribution to atmospheric carbonyls in the semi-urban site based on the distinct seasonal and diurnal variations of the carbonyls, as well as the significantly positive correlations between the carbonyls and ozone. The significantly negative correlations between NO x and O_3 as well as the carbonyls and the positive correlations between wind speed and O_3 as well as the carbonyls implied that the carbonyls and O_3 at the semi-urban site were probably formed during air mass transport from neighboring cities.

Kinetic and product studies of Cl atoms reactions with a series of branched Ketones

The rate constants for the C1 atom reaction with three branched ketones have been measured at 298 ± 2 K and 760 Torr using the relative rate method in the absence of NO. The rate constants values obtained （in units of 10^-10 cm^3/（molecule.sec）） are： k（2-methyl-3-pentanone） = 1.07 ± 0.26, k（3-methyl-2-pentanone） =1.21 ± 0.26, and k（4-methyl-2-pentanone） = 1.35 ± 0.27. Combining the chemical kinetic data obtained by this study with those reported for other ketones, a revised Structure Activity Relationship （SAR） parameter and R group reactivity （kR of R（O）R＇ and CHx （x = 1, 2, 3） group reactivity （kCHx） toward C1 atoms were proposed. In addition, the products from the three reactions in the presence of NO were also identified and quantified by using PTR-ToF-MS and GC-FID, and the yields of the identified products are： acetone （39% ± 8%） ＋ ethanal （78% ± 12%）, 2-butanone （22% ± 2%） ＋ ethanal （75% ± 10%） ＋ propanal （14% ± 1%） and acetone （26% ± 3%） ＋ 2-methylpmpanal （24% ± 2%）, for C1 atoms reaction with 2-methyl-3-pentanone, 3-methyl-2-pentanone and 4-methyl-2-pentanone, respectively. Based on the obtained results, the reaction mechanisms of C1 atoms with these three ketones are proposed.

Kinetic and product studies of the reactions of NO3 with a series of unsaturated organic compounds

Rate coefficients for the reaction of N03 radicals with 6 unsaturated volatile organic compounds(VOCs) in a 7300 L simulation chamber at ambient temperature and pressure have been determined by the relative rate method.The resulting rate coefficients were determined for isoprene,2-carene,3-carene,methyl vinyl ketone(MVK),methacrolein(MACR)and crotonaldehyde(CA),as(6.6±0.8)×10-13,(1.8±0.6)×10-11,(8.7±0.5)×10-12,(1.24±1.04)×10-16,(3.3±0.9)×10-15 and(5.7±1.2)×10-15 cm3/(molecule·sec),respectively.The experiments indicate that NO3 radical reactions with all the studied unsaturated VOGs proceed through addition to the olefinic bond,however,it indicates that the introduction of a carbonyl group into unsaturated VOGs can deactivate the neighboring olefinic bond towards reaction with the NO3 radical,which is to be expected since the presence of these electronwithdrawing substituents will reduce the electron density in the π orbitals of the alkenes,and will therefore reduce the rate coefficient of these electrophilic addition reactions.In addition,we investigated the product formation from the reactions of 2-carene and 3-carene with the NO3 radical.Qualitative identification of an epoxide(C10H16OH+),caronaldehyde(C10H16O2 H+) and nitrooxy-ketone(C10H16O4 NH+) was achieved using a proton transfer reaction time-of-flight mass spectrometer(PTR-TOF-MS) and a reaction mechanism is proposed.

Preface

Air pollution as well as climate change and their possible effects on the environment, ecosystems and human health, are pressing challenges. Nowadays, it is dear that sustainable societal development cannot remain solely wealth-oriented, but must take into account the present and future environmental issues. However, this approach is possible only if scientifically sound knowledge in all environmental areas becomes available to our societies and decision makers, which requires a firm scientific basis to our understanding of the processes guiding the atmospheric compositions.

Hygroscopicity and optical properties of alkylaminium sulfates

The hygroscopicity and optical properties of alkylaminium sulfates （AASs） were investigated using a hygroscopicity tandem differential mobility analyzer coupled to a cavity ring-down spectrometer and a nephelometer. AAS particles do not exhibit a deliquescence phenomenon and show a monotonic increase in diameter as the relative humidity （RH） ascends. Hygroscopic growth factors （GFs） for 40, 100 and 150 nm alkylaminium sulfate particles do not show an apparent Kelvin effect when RH is less than 45%, whereas GFs of the salt aerosols increase with initial particle size when RH is higher than 45%. Calculation using the Zdanovskii-Stokes-Robinson mixing rule suggests that hygroscopic growth of triethylaminium sulfate-ammonium sulfate mixtures is non-deliquescent, occurring at very low RH, implying that the displacement of ammonia by amine will significantly enhance the hygroscopicity of （NH4）2SO4 aerosols. In addition, light extinction of AAS particles is a combined effect of both scattering and absorption under dry conditions, but is dominated by scattering under wet conditions.

Impact of photocatalytic remediation of pollutants on urban air quality

In the recent years, photocatalytic self-cleaning and ＂depolluting＂ materials have been suggested as a remediation technology mainly for NOx and aromatic VOCs in urban areas. A number of products incorporating the aforementioned technology have been made commercially available with the aim to improve urban air quality. These commercial products are based on the photocatalytic properties of a thin layer of TiO2 at the surface of the material （such as glass, pavement, etc.） or embedded in paints or concrete. The use of TiO2 photocatalysts as an emerging air pollution control technology has been reported in many locations worldwide. However, up to now, the effectiveness measured in situ and theexpected positive impact on air quality of this relatively new technology has only been demonstrated in a limited manner. Assessing and demonstrating the effectiveness of these depolluting techniques in real scale applications aims to create a real added value, in terms of policy making （i.e., implementing air quality strategies） and economics （by providing a demonstration of the actual performance of a new technique）.

Diverse bacterial populations of PM_(2.5) in urban and suburb Shanghai,China

Airborne bacteria play key roles in terrestrial and marine ecosystems and human health,yet our understanding of bacterial communities and their response to the environmental variables lags significantly behind that of other components of PM_(2.5).Here,atmospheric fine particles obtained from urban and suburb Shanghai were analyzed by using the qPCR and Illumina Miseq sequencing.The bacteria with an average concentration of 2.12× 10^(3 )cells/m^(3),were dominated by Sphingomonas,Curvibacter,Acinetobacter,Bradyrhizobium,Methylobacterium,Halomonas,Aliihoeflea,and Phyllobacterium,which were related to the nitrogen,carbon,sulfur cycling and human health risk.Our results provide a global survey of bacterial community across urban,suburb,and high-altitude sites.In Shanghai(China),urban PM2.5 harbour more diverse and dynamic bacterial populations than that in the suburb.The structural equation model explained about 27%,41%,and 20%^78%of the variance found in bacteria diversity,concentration,and discrepant genera among urban and suburb sites.This work furthered the knowledge of diverse bacteria in a coastal Megacity in the Yangtze river delta and emphasized the potential impact of environmental variables on bacterial community structure.

The Second Sino-French Workshop on Atmospheric Environment (Orleans,December 2010):Preface

A sound scientific understanding of the factors affecting the environment is essential to guarantee the sustainable development of the world＇s economic and societal activities. Many environmental issues,such as air quality and climate

Reactive uptake of NO2 on volcanic particles: A possible source of HONO in the atmosphere

The heterogeneous degradation of nitrogen dioxide(NO2) on five samples of natural Icelandic volcanic particles has been investigated.Laboratory experiments were carried out under simulated atmospheric conditions using a coated wall flow tube(CWFT).The CWFT reactor was coupled to a blue light nitrogen oxides analyzer(NOx analyzer),and a long path absorption photometer(LOPAP) to monitor in real time the concentrations of NO2,NO and HONO,respectively.Under dark and ambient relative humidity conditions,the steady state uptake coefficients of NO2 varied significantly between the volcanic samples probably due to differences in magma composition and morphological variation related with the density of surface OH groups.The irradiation of the surface with simulated sunlight enhanced the uptake coefficients by a factor of three indicating that photo-induced processes on the surface of the dust occur.Furthermore,the product yields of NO and HONO were determined under both dark and simulated sunlight conditions.The relative humidity was found to influence the distribution of gaseous products,promoting the formation of gaseous HONO.A detailed reaction mechanism is proposed that supports our experimental observations.Regarding the atmospheric implications,our results suggest that the NO2 degradation on volcanic particles and the corresponding formation of HONO is expected to be significant during volcanic dust storms or after a volcanic eruption.

Preface

One of the most important challenges the world is facing in this century is how to achieve sustained global development while balancing economic, societal and environmental considerations. It is clear that providing everyone a healthy and wealthy society can only be achieved if upcoming policies and initiatives from policy makers are based on the most up-todate and validated scientific knowledge.

Sources,chemistry,impacts and regulations of complex air pollution：Preface

Clean air is essential to people＇s health and that of the environment.Since the industrial revolution,however,the quality of the air that people breathe has deteriorated considerably—mainly as a result of human activities.Rising industrial and energy production,the burning of fossil fuels and the dramatic rise in traffic all contribute to air pollution in our cities which,in turn,