To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summ...To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summer and winter,respectively.The results showed that,apart from O_(3),the concentrations of other pollutants(CO,NO_(2),SO_(2),PM_(2.5)and PM_(10))were significantly higher in winter than in summer.All single particle aerosols were divided into seven categories:biomass burning(BB),coal combustion(CC),Dust,vehicle emission(VE),K mixedwith nitrate(K-NO_(3)),Kmixed with sulfate and nitrate(K-SN),and K mixedwith sulfate(K-SO_(4))particles.The highest contributions in both seasons were VE particles(24%).The higher contributions of K-SO_(4)(16%)and K-NO_(3)(10%)particles occurred in summer and winter,respectively,as a result of their different formation mechanisms.S-containing(KSO_(4)and K-SN),VE,and BB particles caused the evolution of pollution in both seasons,and they can be considered as targets for future pollution reduction.The mixing of primary sources particles(VE,Dust,CC,and BB)with secondary components was stronger in winter than in summer.In summer,as pollution worsens,the mixing of primary sources particles with 62[NO_(3)]−weakened,but themixing with 97[HSO_(4)]−increased.However,in winter,the mixing state of particles did not exhibit an obvious evolution rules.The potential source areas in summer were mainly distributed in the southern region of Sichuan,while in winter,besides the southern region,the contribution of the western region cannot be ignored.展开更多
Ultrasonic humidifiers are commonly used in households to maintain indoor humidity and generate a large number of droplets or spray aerosols.However,there have been various health concerns associated with humidifier u...Ultrasonic humidifiers are commonly used in households to maintain indoor humidity and generate a large number of droplets or spray aerosols.However,there have been various health concerns associated with humidifier use,largely due to aerosols generated during operation.Here,we investigated the size distribution,chemical composition,and charged fraction of aerosol particles emitted from commercial ultrasonic humidifiers.Heavy metals in water used for humidifiers were found to be highly enriched in the ultrasonic humidifier aerosols(UHA),with the enrichment factors ranging from 102 to 107.This enrichment may pose health concerns for the building occupants,as UHA concentrations of up to 106 particles/cm^(3) or 3 mg/m^(3) were observed.Furthermore,approximately 90%of UHA were observed to be electrically charged,for the first time according to our knowledge.Based on this discovery,we proposed and tested a newmethod to remove UHA by using a simple electrical field.The designed electrical field in this work can efficiently remove 81.4%of UHA.Therefore,applying this electrical field could be an effective method to significantly reduce the health risks by UHA.展开更多
With the rapid development of the world economy,complex air pollution has increasingly become a serious threat;for example,with haze events occurring frequently in various regions of the globe.Recent evidence has indi...With the rapid development of the world economy,complex air pollution has increasingly become a serious threat;for example,with haze events occurring frequently in various regions of the globe.Recent evidence has indicated that secondary aerosols play an important role in haze formation,and that heterogeneous processes are among the main forces driving their explosive growth.In this regard,this paper reviews recent advances in the understanding of the impact of heterogeneous processes on haze chemistry,including the impact on NO_(2)chemistry,marine aerosols,and the hygroscopicity and optical properties of atmospheric aerosols.It is distinguished from past reviews on this topic by focusing mainly on new insights from the past five years.We summarize the main findings of the impacts of heterogeneous processes on NO_(2)chemistry,marine aerosols,and the physicochemical properties of atmospheric aerosols,and propose several future research directions.展开更多
The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the...The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the influence of continental and marine air masses over the Pearl River Estuary(PRE)region in winter 2021.The sum concentration of SOA tracers was 6.2–132.8 ng m^(−3),with SOAM and SOAI as the main components in both continental(scenarios A1 and A2)and marine air masses(scenario A3),as well as their combination(scenario A4).The highest and lowest levels of SOAM were observed in A1 and A3,respectively,which were mainly related to the variations in meteorological conditions,precursor concentrations,and the degree of photochemical processes.Higher MBTCA/HGA(3-methyl-1,2,3-butanetricarboxylic acid/3-hydroxyglutaric acid)ratios suggested a less significant contribution fromα-pinene to SOAM.The variations of SOAI in the different scenarios were associated with differences in relative humidity,particle acidity,and isoprene/NOx ratios.The respective highest and lowest concentrations of aromatics SOA tracers in A1 and A3 revealed the influence of anthropogenic precursors from upwind continental areas,which was confirmed by the correlation among biogenic and anthropogenic precursors.The results of the tracer-based-method suggested dominant contributions of SOAs from aromatics and monoterpenes,with the highest concentrations in A1.A WRF-Chem simulation revealed that the SOAs from the above precursors only contributed 12%–25%to the total SOA at DWS,while the spatial distributions of SOAs further highlighted that the abundance of SOAs over the PRE region in winter is highly associated with air masses transported from upwind continental areas.展开更多
The impact of aerosols on clouds,which remains one of the largest aspects of uncertainty in current weather forecasting and climate change research,can be influenced by various factors,such as the underlying surface t...The impact of aerosols on clouds,which remains one of the largest aspects of uncertainty in current weather forecasting and climate change research,can be influenced by various factors,such as the underlying surface type,cloud type,cloud phase,and aerosol type.To explore the impact of different underlying surfaces on the effect of aerosols on cloud development,this study focused on the Yangtze River Delta(YRD)and its offshore regions(YRD sea)for a comparative analysis based on multi-source satellite data,while also considering the variations in cloud type and cloud phase.The results show lower cloud-top height and depth of single-layer clouds over the ocean than land,and higher liquid cloud in spring over the ocean.Aerosols are found to enhance the cumulus cloud depth through microphysical effects,which is particularly evident over the ocean.Aerosols are also found to decrease the cloud droplet effective radius in the ocean region and during the mature stage of cloud development in the land region,while opposite results are found during the early stage of cloud development in the land region.The quantitative results indicate that the indirect effect is positive(0.05)in the land region at relatively high cloud water path,which is smaller than that in the ocean region(0.11).The findings deepen our understanding of the influence aerosols on cloud development and the mechanisms involved,which could then be applied to improve the ability to simulate cloud-associated weather processes.展开更多
We conducted a comprehensive analysis of seasonal and long-term variations in organic carbon(OC),elemental carbon(EC),primary organic carbon(POC),and secondary organic carbon(SOC)among total suspended particles on Hua...We conducted a comprehensive analysis of seasonal and long-term variations in organic carbon(OC),elemental carbon(EC),primary organic carbon(POC),and secondary organic carbon(SOC)among total suspended particles on Huaniao Island,China,from 2011 to 2020.The highest OC and EC concentrations were observed in 2014(OC,4.13μg/m^(3))and 2013(EC,1.21μg/m^(3)),respectively;for both,the lowest concentrations occurred in 2017(OC,1.56μg/m^(3);EC,0.69μg/m^(3)).OC and EC exhibited seasonal variations,such that the highest and lowest values for both occurred in winter and summer,respectively;particularly high concentrations were observed in the winter of 2014 on Huaniao Island.By 2020,winter OC and EC concentrations had decreased by 43%and 36%,whereas autumn OC and EC concentrations increased by 38%and 160%compared with 2014.In terms of carbon components,the proportions of OC4 and EC1 significantly declined,whereas the proportions of OC3 and OC2 increased,during the study period.Higher POC and SOC concentrations were mainly observed during the autumn–winter and winter–spring transition periods.POC was most strongly correlated with OC2,followed by OC4 and EC1.SOC was strongly correlated with OC3,especially in winter.These findings highlight the characteristics of temporal variations in individual carbon components,as well as possible associations with POC and SOC.展开更多
Carbon dioxide(CO_(2))is often monitored as a convenient yardstick for indoor air safety,yet its ability to stand in for pathogen-laden aerosols has never been settled.To probe the question,we reproduced an open-plan ...Carbon dioxide(CO_(2))is often monitored as a convenient yardstick for indoor air safety,yet its ability to stand in for pathogen-laden aerosols has never been settled.To probe the question,we reproduced an open-plan office at full scale(7.2m×5.2m×2.8m)and introduced a breathing plume that carried 4% CO_(2),together with a polydisperse aerosol spanning 0.5–10μm(1320 particles s^(−1)).Inlet air was supplied at 0.7,1.4,and 2.1 m s^(−1),and the resulting fields were simulated with a Realisable k–εRANS model coupled to Lagrangian particle tracking.Nine strategically placed probes provided validation;the calibrated solution deviated fromthe experiment by 58 ppm for CO_(2)(8.1%RMSE)and 0.008 m s^(−1)for velocity(15.7%RMSE).Despite this agreement,gas and particles behaved in sharply different ways.Room-averaged CO_(2)varied by<15%,whereas the aerosol mass rose to almost three-fold the background within slowmoving corner vortices.Sub-micron particles stayed aloft along streamlines,while those≥5μmpeeled away and settled on nearby surfaces.The divergence shows that neither the CO_(2)level nor themeanageof air,taken in isolation,delineates all high-exposure zones.We therefore recommend that ventilation design be informed by a composite diagnosis that couples gas data,size-resolved particle measurements,and rapid CFD appraisal.展开更多
Researchers from the National Institute for Occupational Safety and Health(NIOSH)conducted a study in an isolated zone of an underground mine to characterize aerosols generated by:(1)a diesel-powered personnel carrier...Researchers from the National Institute for Occupational Safety and Health(NIOSH)conducted a study in an isolated zone of an underground mine to characterize aerosols generated by:(1)a diesel-powered personnel carrier vehicle operated over a simulated light-duty cycle and(2)the simulated repair of existing equipment using manual metal arc welding(MMAW).Both the diesel-powered vehicle and MMAW process contributed to concentrations of nano and ultrafine aerosols in the mine air.The welding process also contributed to aerosols with electrical mobility and aerodynamic mobility count median diameters of approximately 140 and 480 nm,respectively.The welding particles collected on the filters contained carbon,iron,manganese,calcium,and aluminum.展开更多
PM2.5 aerosols were collected in forests along north latitude in boreal-temperate, temperate, subtropical and tropical climatic zones in eastern China, i.e., Changbai Mountain Nature Reserve （CB）, Dongping National ...PM2.5 aerosols were collected in forests along north latitude in boreal-temperate, temperate, subtropical and tropical climatic zones in eastern China, i.e., Changbai Mountain Nature Reserve （CB）, Dongping National Forest Park in Chongming Island （CM）, Dinghu Mountain Nature Reserve （DH）, Jianfengling Nature Reserve in Hainan Island （HN）. The mass concentrations of PM2.5, organic carbon （OC）, elemental carbon （EC）, water soluble organic carbon （WSOC） as well as concentrations of ten inorganic ions （F？, Cl？, NO3？, SO42？, C2O42？, NH4＋, Na＋, K＋, Ca2＋, Mg2＋） were determined. Aerosol chemical mass closures were achieved. The 24-hr average concentrations of PM2.5 were 38.8, 89.2, 30.4, 18 μg/m3 at CB, CM, DH and HN, respectively. Organic matter and EC accounted for 21%–33% and 1.3%–2.3% of PM2.5 mass, respectively. The sum of three dominant secondary ions （SO42-, NO3-, NH4＋） accounted for 44%, 50%, 45% and 16% of local PM2.5 mass at CB, CM, DH and HN, respectively. WSOC comprised 35%–65% of OC. The sources of PM2.5 include especially important regional anthropogenic pollutions at Chinese forest areas.展开更多
As part of the development work of the Chinese new regional climate model (RIEMS), the radiative process of black carbon (BC) aerosols has been introduced into the original radiative procedures of RIEMS, and the trans...As part of the development work of the Chinese new regional climate model (RIEMS), the radiative process of black carbon (BC) aerosols has been introduced into the original radiative procedures of RIEMS, and the transport model of BC aerosols has also been established and combined with the RIEMS model. Using the new model system, the distribution of black carbon aerosols and their radiative effect over the China region are investigated. The influences of BC aerosole on the atmospheric radiative transfer and on the air temperature, land surface temperature, and total rainfall are analyzed. It is found that BC aerosols induce a positive radiative forcing at the top of the atmosphere (TOA), which is dominated by shortwave radiative forcing. The maximum radiative forcing occurs in North China in July and in South China in April. At the same time, negative radiative forcing is observed on the surface. Based on the radiative forcing comparison between clear sky and cloudy sky, it is found that cloud can enforce the TOA positive radiative forcing and decrease the negative surface radiative forcing. The responses of the climate system in July to the radiative forcing due to BC aerosols are the decrease in the air temperature in the middle and lower reaches of the Changjiang River and Huaihe area and most areas of South China, and the weak increase or decrease in air temperature over North China. The total rainfall in the middle and lower reaches of the Changjiang River area is increased, but it decreased in North China in July.展开更多
Using observed daily precipitation data to classify five levels of rainy days by strength in South China （SC）,with an emphasis on the Pearl River Delta （PRD） region,the spatiotemporal variation of different grades...Using observed daily precipitation data to classify five levels of rainy days by strength in South China （SC）,with an emphasis on the Pearl River Delta （PRD） region,the spatiotemporal variation of different grades of precipitation during the period 1960-2010 was analyzed and the possible link with anthropogenic aerosols examined.Statistical analysis showed that drizzle and small precipitation has significantly decreased,whereas medium to heavy precipitation has increased slightly over the past 50 years （although not statistically significant）.Further data analysis suggested that the decline in drizzle and small precipitation probably has a strong link to increased concentrations of anthropogenic aerosols produced by large-scale human activities related to the rapid socioeconomic development of the PRD region.These aerosols may also have led to the obvious decreasing trend in horizontal visibility and sunshine duration in SC,which is statistically significant according to the t-test.展开更多
Secondary organic aerosols(SOAs) are an important component of particulates, but whether biogenic SOAs(BSOAs) or anthropogenic SOAs(ASOAs) are the dominant contributors to haze pollution remains poorly characterized. ...Secondary organic aerosols(SOAs) are an important component of particulates, but whether biogenic SOAs(BSOAs) or anthropogenic SOAs(ASOAs) are the dominant contributors to haze pollution remains poorly characterized. In this study, particulate samples were collected from September 2014 to August 2015 at an urban site in Jinan, which is the capital of Shandong Province and a typical city in the North China Plain. The PM2.5 samples were analyzed for BSOA(isoprene(SOAI) and monoterpenes(SOAM)) and ASOA(aromatic(SOAA)) tracers. The concentrations of the SOAAtracer(1.1 ± 1.0 ng/m3) were lowest, and those of SOAItracers(41.8 ± 86.2 ng/m3) were highest, with the concentrations of SOAMtracers(19.4 ± 9.9 ng/m3) being intermediate. The SOAItracers were more abundant in the summer and less abundant in the winter. Both SOAIand SOAMincreased with increasing ozone level but decreased with increasing NOx level. Correlation analysis revealed a good correlation between 2,3-dihydroxy-4-oxopentanoic acid and levoglucosan levels in three seasons. These results suggested that biomass burning activities occurring in the NCP can enhance the emissions of aromatics and should be controlled, especially in the autumn and winter. SOA tracers were classified according to pollution degree, and the results showed that as pollution increases, the contributions of SOAAincrease. These results indicate that reducing anthropogenic emissions is necessary to prevent SOA pollution, especially during heavy pollution episodes.展开更多
Size-resolved biogenic secondary organic aerosols （BSOA） derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau （a continental background site） and five cities of China were measured...Size-resolved biogenic secondary organic aerosols （BSOA） derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau （a continental background site） and five cities of China were measured using gas chromatography/mass spectrometry （GC/MS）. Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations （R^2 = 0.44-0.90） between BSOA and sulfate were found at the six sites, suggesting that anthropogenic pollution （i.e., sulfate） could enhance SOA formation, because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. Size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode （〈3.3 μm） except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse （〉3.3 μm） modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.展开更多
A simple, sensitive and convenient ion chromatography(IC) method was established for the simultaneous determination of twelve water-soluble inorganic anions(F -, Cl -, NO - 2, NO - 3, SO 2- 3, SO 2- ...A simple, sensitive and convenient ion chromatography(IC) method was established for the simultaneous determination of twelve water-soluble inorganic anions(F -, Cl -, NO - 2, NO - 3, SO 2- 3, SO 2- 4, PO 3- 4), and fifteen water-soluble organic ions(formate, acetate, MSA, oxalate, malonate, succinate, phthalates, etc.) in atmospheric aerosols. The linear concentrations ranged from 0.005 μg/m 3 to 500 μg/m 3(r = 0.999—0.9999). The relative standard deviation(RSD) were 0.43%—2.00% and the detection limits were from 2.7 ng/m 3 to 88 ng/m 3. The proposed method was successfully applied to the simultaneous determination of those inorganic ions and organic ions in PM 2.5 of Beijing.展开更多
A hygroscopic tandem differentialmobility analyser(H-TDMA)was used to observe the sizeresolved hygroscopic characteristics of submicron particles in January and April 2018 in urban Beijing.The probability distribution...A hygroscopic tandem differentialmobility analyser(H-TDMA)was used to observe the sizeresolved hygroscopic characteristics of submicron particles in January and April 2018 in urban Beijing.The probability distribution of the hygroscopic growth factor(HGF-PDF)in winter and spring usually showed a bimodal pattern,with more hygroscopic mode(MH)being more dominant.The seasonal variation in particle hygroscopicity was related to the origin of air mass,which received polluted southerly air masses in spring and clean northwesterly air masses in winter.Particles showed stronger hygroscopic behaviour during heavy pollution episodes(HPEs)with elevated concentrations of secondary aerosols,especially higher mass fraction of nitrate,which were indicated using the PM2.5(particulate matter with diameter below 2.5μm)mass concentration normalised by CO mass concentration.The hygroscopic parameter(κ)values were calculated using H-TDMA(κhtdma)and chemical composition(κchem).The closure study showed thatκchem was overestimated in winter afternoon when compared withκhtdma,because the organic particle hygroscopic parameter(κorg)was overestimated in the calculations.It was influenced by the presence of a high concentration of hydrocarbon-like organic aerosol(HOA)with a weak water uptake ability.A positive relationship was observed betweenκorg and the ratio of oxygenated organic aerosol(OOA)and HOA,thereby indicating that the strong oxidation state enhanced the hygroscopicity of the particles.This study revealed the effect of local emission sources and secondary aerosol formation processes on particle hygroscopicity,which is of great significance for understanding the pollution formation mechanism in the North China Plain.展开更多
The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/ aerosol model, which includes major anthropogenic aerosols （s...The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/ aerosol model, which includes major anthropogenic aerosols （sulfate, black carbon, and organic carbon） and natural aerosols （soil dust and sea salt）. Anthropogenic emissions used in model simulation are from a global emission inventory prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report （IPCC AR5）, whereas natural aerosols are calculated online in the model. The simulated 20-year average direct solar radiative effect due to aerosols at the surface was estimated to be in a range of-9- -33 W m-2 over most areas of China, with maxima over the Gobi desert of West China, and-12 W m-2 to -24 W m-2 over the Sichuan Basin, the middle and lower reaches of the Yellow River and the Yangtze River. Aerosols caused surface cooling in most areas of East Asia, with maxima of-0.8℃ to -1.6℃ over the deserts of West China, the Sichuan Basin, portions of central China, and the middle reaches of the Yangtze River. Aerosols induced a precipitation decrease over almost the entire East China, with maxima of-90 mm/year to -150 mm/year over the Sichuan Basin, the middle reaches of the Yangtze River and the lower reaches of the Yellow River. Interdecadal variation of the climate response to the aerosol direct radiative effect is evident, indicating larger decrease in surface air temperature and stronger per- turbation to precipitation in the 1990s than that in the 1980s, which could be due to the interdecadal variation of anthropogenic emissions.展开更多
Continuous aggravated surface O_(3) over North China Plain(NCP)has attracted widely public concern.Herein,we evaluated the effects of changes in aerosols,precursor emissions,and meteorology on O_(3) in summer(June)of ...Continuous aggravated surface O_(3) over North China Plain(NCP)has attracted widely public concern.Herein,we evaluated the effects of changes in aerosols,precursor emissions,and meteorology on O_(3) in summer(June)of 2015–2019 over NCP via 8 scenarios with WRF-Chem model.The simulated mean MDA8 O_(3) in urban areas of 13 major cities in NCP increased by 17.1%∼34.8%,which matched well with the observations(10.8%∼33.1%).Meanwhile,the model could faithfully reproduce the changes in aerosol loads,precursors,and meteorological conditions.A relatively-even O_(3) increase(+1.2%∼+3.9%for 24-h O_(3) and+1.0%∼+3.8%for MDA8 O_(3))was induced by PM_(2.5) dropping,which was consistent with the geographic distribution of regional PM_(2.5) reduction.Meanwhile,the NO_(2) reduction coupled with a nearconstant VOCs led to the elevated VOCs/NOx ratios,and then caused O_(3) rising in the areas under VOCs-limited regimes.Therein,the pronounced increases occurred in Handan,Xingtai,Shijiazhuang,Tangshan,and Langfang(+10.7%∼+13.6%for 24-h O_(3) and+10.2%∼+12.2%forMDA8 O_(3));while the increases in other citieswere 5.7%∼10.5%for 24-h O_(3) and 4.9%∼9.2%for MDA8 O_(3).Besides,the meteorological fluctuations brought about the more noticeable O_(3) increases in northern parts(+12.5%∼+13.5%for 24-h O_(3) and+11.2%∼+12.4%for MDA8 O_(3))than those in southern and central parts(+3.2%∼+9.3%for 24-h O_(3) and+3.7%∼+8.8%for MDA8 O_(3)).The sum of the impacts of the three drivers reached 16.7%∼21.9%,which were comparable to the changes of the observed O_(3).Therefore,exploring reasonable emissionsreduction strategies is essential for the ozone pollution mitigation over this region.展开更多
This study estimates direct radiative forcing by tropospheric ozone and all aerosols between the years 1850 and 2000, using the new IPCC AR5 （the Intergovernmental Panel on Climate Change Fifth Assessment Report） em...This study estimates direct radiative forcing by tropospheric ozone and all aerosols between the years 1850 and 2000, using the new IPCC AR5 （the Intergovernmental Panel on Climate Change Fifth Assessment Report） emissions inventories and a fully coupled chemistry-aerosol general circulation model. As compared to the previous Global Emissions Inventory Activity （GEIA） data, that have been commonly used for forcing estimates since 1990, the IPCC AR5 emissions inventories report lower anthropogenic emissions of organic carbon and black carbon aerosols and higher sulfur and NOx emissions. The simulated global and annual mean burdens of sulfate, nitrate, black carbon （BC）, primary organic aerosol （POA）, secondary organic aerosol （SOA）, and ozone were 0.79, 0.35, 0.05, 0.49, 0.34, and 269 Tg, respectively, in the year 1850, and 1.90, 0.90, 0.11, 0.71, 0.32, and 377 Tg, respectively, in the year 2000. The estimated annual mean top of the atmosphere （TOA） direct radiative forcing of all anthropogenic aerosols based on the AR5 emissions inventories is -0.60 W m^-2 on a global mean basis from 1850 to 2000. However, this is -2.40 W m-2 when forcing values are averaged over eastern China （18-45°N and 95-125°E）. The value for tropospheric ozone is 0.17 W m^-1 on a global mean basis and 0.24 W m^-2 over eastern China. Forcing values indicate that the climatic effect of aerosols over eastern China is much more significant than the globally averaged effect.展开更多
Smog chamber experiments were conducted to investigate the hygroscopicity of particles generated from photooxidation of α-pinene/NOx with different sulfate seed aerosols or oxidation conditions. Hygroscopicity of par...Smog chamber experiments were conducted to investigate the hygroscopicity of particles generated from photooxidation of α-pinene/NOx with different sulfate seed aerosols or oxidation conditions. Hygroscopicity of particles was measured by a tandem differential mobility analyzer （TDMA） in terms of hygroscopic growth factor （Gf）, with a relative humidity of 85%. With sulfate seed aerosols present, Gf of the aerosols decreased very fast before notable secondary organic aerosols （SOA） formation was observed, indicating a heterogeneous process between inorganic seeds and organic products might take place as soon as oxidation begins, rather than only happening after gas-aerosol partition of organic products starts. The final SOA-coated sulfate particles had similar or lower Gf than seed-free SOA. The hygroscopicity of the final particles was not dependent on the thickness but on the hygroscopicity properties of the SOA, which were influenced by the initial sulfate seed particles. In the two designed aging processes, Gf of the particles increased more significantly with introduction of OH radical than with ozone. However, the hygroscopicity of SOA was very low even after a long time of aging, implying that either SOA aging in the chamber was very slow or the Gf of SOA did not change significantly in aging. Using an aerosol composition speciation monitor （ACSM） and matrix factorization （PMF） method, two factors for the components of SOA were identified, but the correlation between SOA hygroscopicity and the proportion of the more highly oxidized factor could be either positive or negative depending on the speciation of seed aerosols present.展开更多
A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60...A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60% of the time during the whole campaign, were characterized by increases of SNA（sulfate, nitrate, and ammonium） and SOA（secondary organic aerosol） concentrations. The average values with standard deviation of SO2-＋4, NO-3, NH4 and SOA were 49.8（± 31.6）, 31.4（±22.3）, 25.8（±16.6） and 8.9（±4.1） μg/m3, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO2-4,NO-3, NH＋4, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR（sulfur oxidation ratio） and NOR（nitrogen oxidation ratio） increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO2-4and NO2 to NO-3, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.展开更多
基金supported by the Basic Research Cultivation Support Plan of Southwest Jiaotong University(No.2682023ZTPY016)the Natural Science Foundation of Sichuan Province(No.2022NSFSC0982)the National Natural Science Foundation of China(Nos.U23A2030,42205100,and 41805095).
文摘To investigate the seasonal characteristics in air pollution in Chengdu,a single particle aerosol mass spectrometry was used to continuously observe atmospheric fine particulate matter during one-month periods in summer and winter,respectively.The results showed that,apart from O_(3),the concentrations of other pollutants(CO,NO_(2),SO_(2),PM_(2.5)and PM_(10))were significantly higher in winter than in summer.All single particle aerosols were divided into seven categories:biomass burning(BB),coal combustion(CC),Dust,vehicle emission(VE),K mixedwith nitrate(K-NO_(3)),Kmixed with sulfate and nitrate(K-SN),and K mixedwith sulfate(K-SO_(4))particles.The highest contributions in both seasons were VE particles(24%).The higher contributions of K-SO_(4)(16%)and K-NO_(3)(10%)particles occurred in summer and winter,respectively,as a result of their different formation mechanisms.S-containing(KSO_(4)and K-SN),VE,and BB particles caused the evolution of pollution in both seasons,and they can be considered as targets for future pollution reduction.The mixing of primary sources particles(VE,Dust,CC,and BB)with secondary components was stronger in winter than in summer.In summer,as pollution worsens,the mixing of primary sources particles with 62[NO_(3)]−weakened,but themixing with 97[HSO_(4)]−increased.However,in winter,the mixing state of particles did not exhibit an obvious evolution rules.The potential source areas in summer were mainly distributed in the southern region of Sichuan,while in winter,besides the southern region,the contribution of the western region cannot be ignored.
基金supported by the National Natural Science Foundation of China (Nos.42077193 and 21976034)the National Key R&D Program (Nos.2022YFC3702600 and 2022YFC3702601)the Shanghai Natural Science Foundation (23ZR1479700).
文摘Ultrasonic humidifiers are commonly used in households to maintain indoor humidity and generate a large number of droplets or spray aerosols.However,there have been various health concerns associated with humidifier use,largely due to aerosols generated during operation.Here,we investigated the size distribution,chemical composition,and charged fraction of aerosol particles emitted from commercial ultrasonic humidifiers.Heavy metals in water used for humidifiers were found to be highly enriched in the ultrasonic humidifier aerosols(UHA),with the enrichment factors ranging from 102 to 107.This enrichment may pose health concerns for the building occupants,as UHA concentrations of up to 106 particles/cm^(3) or 3 mg/m^(3) were observed.Furthermore,approximately 90%of UHA were observed to be electrically charged,for the first time according to our knowledge.Based on this discovery,we proposed and tested a newmethod to remove UHA by using a simple electrical field.The designed electrical field in this work can efficiently remove 81.4%of UHA.Therefore,applying this electrical field could be an effective method to significantly reduce the health risks by UHA.
基金supported by the National Key Research and Development Program of China(No.2022YFC3701000)the National Natural Science Foundation of China(Nos.42130606 and 41931287)+1 种基金the Beijing National Laboratory for Molecular Sciences(BNLMS-CXXM-202011)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y2021013).
文摘With the rapid development of the world economy,complex air pollution has increasingly become a serious threat;for example,with haze events occurring frequently in various regions of the globe.Recent evidence has indicated that secondary aerosols play an important role in haze formation,and that heterogeneous processes are among the main forces driving their explosive growth.In this regard,this paper reviews recent advances in the understanding of the impact of heterogeneous processes on haze chemistry,including the impact on NO_(2)chemistry,marine aerosols,and the hygroscopicity and optical properties of atmospheric aerosols.It is distinguished from past reviews on this topic by focusing mainly on new insights from the past five years.We summarize the main findings of the impacts of heterogeneous processes on NO_(2)chemistry,marine aerosols,and the physicochemical properties of atmospheric aerosols,and propose several future research directions.
基金supported by the State Key Program of the National Natural Science Foundation of China(Grant Nos.42230701,91644215)the National Natural ScienceFoundation of China(Grant Nos.42122062 and 42307137)+3 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010852)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(Grant No.23hytd002)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2023SP218)L.M.acknowledges the Zhuhai Science and Technology Plan Project(Grant No.ZH22036201210115PWC).
文摘The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the influence of continental and marine air masses over the Pearl River Estuary(PRE)region in winter 2021.The sum concentration of SOA tracers was 6.2–132.8 ng m^(−3),with SOAM and SOAI as the main components in both continental(scenarios A1 and A2)and marine air masses(scenario A3),as well as their combination(scenario A4).The highest and lowest levels of SOAM were observed in A1 and A3,respectively,which were mainly related to the variations in meteorological conditions,precursor concentrations,and the degree of photochemical processes.Higher MBTCA/HGA(3-methyl-1,2,3-butanetricarboxylic acid/3-hydroxyglutaric acid)ratios suggested a less significant contribution fromα-pinene to SOAM.The variations of SOAI in the different scenarios were associated with differences in relative humidity,particle acidity,and isoprene/NOx ratios.The respective highest and lowest concentrations of aromatics SOA tracers in A1 and A3 revealed the influence of anthropogenic precursors from upwind continental areas,which was confirmed by the correlation among biogenic and anthropogenic precursors.The results of the tracer-based-method suggested dominant contributions of SOAs from aromatics and monoterpenes,with the highest concentrations in A1.A WRF-Chem simulation revealed that the SOAs from the above precursors only contributed 12%–25%to the total SOA at DWS,while the spatial distributions of SOAs further highlighted that the abundance of SOAs over the PRE region in winter is highly associated with air masses transported from upwind continental areas.
基金supported by the National Natural Science Foundation of China(Grant No.42230601).
文摘The impact of aerosols on clouds,which remains one of the largest aspects of uncertainty in current weather forecasting and climate change research,can be influenced by various factors,such as the underlying surface type,cloud type,cloud phase,and aerosol type.To explore the impact of different underlying surfaces on the effect of aerosols on cloud development,this study focused on the Yangtze River Delta(YRD)and its offshore regions(YRD sea)for a comparative analysis based on multi-source satellite data,while also considering the variations in cloud type and cloud phase.The results show lower cloud-top height and depth of single-layer clouds over the ocean than land,and higher liquid cloud in spring over the ocean.Aerosols are found to enhance the cumulus cloud depth through microphysical effects,which is particularly evident over the ocean.Aerosols are also found to decrease the cloud droplet effective radius in the ocean region and during the mature stage of cloud development in the land region,while opposite results are found during the early stage of cloud development in the land region.The quantitative results indicate that the indirect effect is positive(0.05)in the land region at relatively high cloud water path,which is smaller than that in the ocean region(0.11).The findings deepen our understanding of the influence aerosols on cloud development and the mechanisms involved,which could then be applied to improve the ability to simulate cloud-associated weather processes.
基金supported by the National Natural Science Foundation of China(Nos.42076205 and 42376195).
文摘We conducted a comprehensive analysis of seasonal and long-term variations in organic carbon(OC),elemental carbon(EC),primary organic carbon(POC),and secondary organic carbon(SOC)among total suspended particles on Huaniao Island,China,from 2011 to 2020.The highest OC and EC concentrations were observed in 2014(OC,4.13μg/m^(3))and 2013(EC,1.21μg/m^(3)),respectively;for both,the lowest concentrations occurred in 2017(OC,1.56μg/m^(3);EC,0.69μg/m^(3)).OC and EC exhibited seasonal variations,such that the highest and lowest values for both occurred in winter and summer,respectively;particularly high concentrations were observed in the winter of 2014 on Huaniao Island.By 2020,winter OC and EC concentrations had decreased by 43%and 36%,whereas autumn OC and EC concentrations increased by 38%and 160%compared with 2014.In terms of carbon components,the proportions of OC4 and EC1 significantly declined,whereas the proportions of OC3 and OC2 increased,during the study period.Higher POC and SOC concentrations were mainly observed during the autumn–winter and winter–spring transition periods.POC was most strongly correlated with OC2,followed by OC4 and EC1.SOC was strongly correlated with OC3,especially in winter.These findings highlight the characteristics of temporal variations in individual carbon components,as well as possible associations with POC and SOC.
文摘Carbon dioxide(CO_(2))is often monitored as a convenient yardstick for indoor air safety,yet its ability to stand in for pathogen-laden aerosols has never been settled.To probe the question,we reproduced an open-plan office at full scale(7.2m×5.2m×2.8m)and introduced a breathing plume that carried 4% CO_(2),together with a polydisperse aerosol spanning 0.5–10μm(1320 particles s^(−1)).Inlet air was supplied at 0.7,1.4,and 2.1 m s^(−1),and the resulting fields were simulated with a Realisable k–εRANS model coupled to Lagrangian particle tracking.Nine strategically placed probes provided validation;the calibrated solution deviated fromthe experiment by 58 ppm for CO_(2)(8.1%RMSE)and 0.008 m s^(−1)for velocity(15.7%RMSE).Despite this agreement,gas and particles behaved in sharply different ways.Room-averaged CO_(2)varied by<15%,whereas the aerosol mass rose to almost three-fold the background within slowmoving corner vortices.Sub-micron particles stayed aloft along streamlines,while those≥5μmpeeled away and settled on nearby surfaces.The divergence shows that neither the CO_(2)level nor themeanageof air,taken in isolation,delineates all high-exposure zones.We therefore recommend that ventilation design be informed by a composite diagnosis that couples gas data,size-resolved particle measurements,and rapid CFD appraisal.
文摘Researchers from the National Institute for Occupational Safety and Health(NIOSH)conducted a study in an isolated zone of an underground mine to characterize aerosols generated by:(1)a diesel-powered personnel carrier vehicle operated over a simulated light-duty cycle and(2)the simulated repair of existing equipment using manual metal arc welding(MMAW).Both the diesel-powered vehicle and MMAW process contributed to concentrations of nano and ultrafine aerosols in the mine air.The welding process also contributed to aerosols with electrical mobility and aerodynamic mobility count median diameters of approximately 140 and 480 nm,respectively.The welding particles collected on the filters contained carbon,iron,manganese,calcium,and aluminum.
基金supported by the National Natrual Science Foundation of China (No. 20677036, 20877051)the Shanghai Leading Academic Disciplines (No. S30109)+1 种基金the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministrysupported by the Graduate Innovative Fund from Shanghai University
文摘PM2.5 aerosols were collected in forests along north latitude in boreal-temperate, temperate, subtropical and tropical climatic zones in eastern China, i.e., Changbai Mountain Nature Reserve （CB）, Dongping National Forest Park in Chongming Island （CM）, Dinghu Mountain Nature Reserve （DH）, Jianfengling Nature Reserve in Hainan Island （HN）. The mass concentrations of PM2.5, organic carbon （OC）, elemental carbon （EC）, water soluble organic carbon （WSOC） as well as concentrations of ten inorganic ions （F？, Cl？, NO3？, SO42？, C2O42？, NH4＋, Na＋, K＋, Ca2＋, Mg2＋） were determined. Aerosol chemical mass closures were achieved. The 24-hr average concentrations of PM2.5 were 38.8, 89.2, 30.4, 18 μg/m3 at CB, CM, DH and HN, respectively. Organic matter and EC accounted for 21%–33% and 1.3%–2.3% of PM2.5 mass, respectively. The sum of three dominant secondary ions （SO42-, NO3-, NH4＋） accounted for 44%, 50%, 45% and 16% of local PM2.5 mass at CB, CM, DH and HN, respectively. WSOC comprised 35%–65% of OC. The sources of PM2.5 include especially important regional anthropogenic pollutions at Chinese forest areas.
基金This research was sponsored by the National Key Program for Developing Basic Sciences of China(No.G1999043400)the National Natural Science Foundation of China(Grant Nos.40205016 and 40165001).
文摘As part of the development work of the Chinese new regional climate model (RIEMS), the radiative process of black carbon (BC) aerosols has been introduced into the original radiative procedures of RIEMS, and the transport model of BC aerosols has also been established and combined with the RIEMS model. Using the new model system, the distribution of black carbon aerosols and their radiative effect over the China region are investigated. The influences of BC aerosole on the atmospheric radiative transfer and on the air temperature, land surface temperature, and total rainfall are analyzed. It is found that BC aerosols induce a positive radiative forcing at the top of the atmosphere (TOA), which is dominated by shortwave radiative forcing. The maximum radiative forcing occurs in North China in July and in South China in April. At the same time, negative radiative forcing is observed on the surface. Based on the radiative forcing comparison between clear sky and cloudy sky, it is found that cloud can enforce the TOA positive radiative forcing and decrease the negative surface radiative forcing. The responses of the climate system in July to the radiative forcing due to BC aerosols are the decrease in the air temperature in the middle and lower reaches of the Changjiang River and Huaihe area and most areas of South China, and the weak increase or decrease in air temperature over North China. The total rainfall in the middle and lower reaches of the Changjiang River area is increased, but it decreased in North China in July.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX2-EW-QN208)the National Basic Research Program of China (Grant No. 2010CB428502)+3 种基金the open fund of the State Key Laboratory of Remote Sensing Science (Grant No. OFSLRSS201113)the CAS Strategic Priority Research Program (Grant No. XDA05110103)the R&D Special Fund for Public Welfare Industry (meteorology) by the Ministry of Financethe Ministry of Science and Technology (Grant No. GYHY20100601404)
文摘Using observed daily precipitation data to classify five levels of rainy days by strength in South China （SC）,with an emphasis on the Pearl River Delta （PRD） region,the spatiotemporal variation of different grades of precipitation during the period 1960-2010 was analyzed and the possible link with anthropogenic aerosols examined.Statistical analysis showed that drizzle and small precipitation has significantly decreased,whereas medium to heavy precipitation has increased slightly over the past 50 years （although not statistically significant）.Further data analysis suggested that the decline in drizzle and small precipitation probably has a strong link to increased concentrations of anthropogenic aerosols produced by large-scale human activities related to the rapid socioeconomic development of the PRD region.These aerosols may also have led to the obvious decreasing trend in horizontal visibility and sunshine duration in SC,which is statistically significant according to the t-test.
基金supported by the National Key R&D Program of China (No. 2017YFC0210000)the Beijing Municipal Science and Technology Project (No. ZL171100000617002)+2 种基金the Scientific Research Project of the Beijing Education Commission (No. KM201510028007)LAC/CMA (2017A01)the National Natural Science Foundation of China (Nos.41471306, 41505133, 41705113, 41877312)
文摘Secondary organic aerosols(SOAs) are an important component of particulates, but whether biogenic SOAs(BSOAs) or anthropogenic SOAs(ASOAs) are the dominant contributors to haze pollution remains poorly characterized. In this study, particulate samples were collected from September 2014 to August 2015 at an urban site in Jinan, which is the capital of Shandong Province and a typical city in the North China Plain. The PM2.5 samples were analyzed for BSOA(isoprene(SOAI) and monoterpenes(SOAM)) and ASOA(aromatic(SOAA)) tracers. The concentrations of the SOAAtracer(1.1 ± 1.0 ng/m3) were lowest, and those of SOAItracers(41.8 ± 86.2 ng/m3) were highest, with the concentrations of SOAMtracers(19.4 ± 9.9 ng/m3) being intermediate. The SOAItracers were more abundant in the summer and less abundant in the winter. Both SOAIand SOAMincreased with increasing ozone level but decreased with increasing NOx level. Correlation analysis revealed a good correlation between 2,3-dihydroxy-4-oxopentanoic acid and levoglucosan levels in three seasons. These results suggested that biomass burning activities occurring in the NCP can enhance the emissions of aromatics and should be controlled, especially in the autumn and winter. SOA tracers were classified according to pollution degree, and the results showed that as pollution increases, the contributions of SOAAincrease. These results indicate that reducing anthropogenic emissions is necessary to prevent SOA pollution, especially during heavy pollution episodes.
基金supported by the China National Natural Science Fund for Distinguished Young Scholars (No. 41325014)the National Key R&D Plan (Quantitative Relationship and Regulation Principle between Regional Oxidation Capacity of Atmospheric and Air Quality) (No. 2017YFC0210000)+1 种基金the program from National Nature Science Foundation of China (No. 41773117) (No. 41405122, 91543116)the West Light Foundation of Chinese Academy of Sciences
文摘Size-resolved biogenic secondary organic aerosols （BSOA） derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau （a continental background site） and five cities of China were measured using gas chromatography/mass spectrometry （GC/MS）. Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations （R^2 = 0.44-0.90） between BSOA and sulfate were found at the six sites, suggesting that anthropogenic pollution （i.e., sulfate） could enhance SOA formation, because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. Size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode （〈3.3 μm） except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse （〉3.3 μm） modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.
文摘A simple, sensitive and convenient ion chromatography(IC) method was established for the simultaneous determination of twelve water-soluble inorganic anions(F -, Cl -, NO - 2, NO - 3, SO 2- 3, SO 2- 4, PO 3- 4), and fifteen water-soluble organic ions(formate, acetate, MSA, oxalate, malonate, succinate, phthalates, etc.) in atmospheric aerosols. The linear concentrations ranged from 0.005 μg/m 3 to 500 μg/m 3(r = 0.999—0.9999). The relative standard deviation(RSD) were 0.43%—2.00% and the detection limits were from 2.7 ng/m 3 to 88 ng/m 3. The proposed method was successfully applied to the simultaneous determination of those inorganic ions and organic ions in PM 2.5 of Beijing.
基金supported by the National Natural Science Foundation of China (Nos.42075082,41875147,42090031)the S&T Development Fund of CAMS (No.2020KJ001),Basic Research Fund of CAMS (No.2020Z002)the Innovation and Development Program of CMA (No.CXFZ2021Z089)
文摘A hygroscopic tandem differentialmobility analyser(H-TDMA)was used to observe the sizeresolved hygroscopic characteristics of submicron particles in January and April 2018 in urban Beijing.The probability distribution of the hygroscopic growth factor(HGF-PDF)in winter and spring usually showed a bimodal pattern,with more hygroscopic mode(MH)being more dominant.The seasonal variation in particle hygroscopicity was related to the origin of air mass,which received polluted southerly air masses in spring and clean northwesterly air masses in winter.Particles showed stronger hygroscopic behaviour during heavy pollution episodes(HPEs)with elevated concentrations of secondary aerosols,especially higher mass fraction of nitrate,which were indicated using the PM2.5(particulate matter with diameter below 2.5μm)mass concentration normalised by CO mass concentration.The hygroscopic parameter(κ)values were calculated using H-TDMA(κhtdma)and chemical composition(κchem).The closure study showed thatκchem was overestimated in winter afternoon when compared withκhtdma,because the organic particle hygroscopic parameter(κorg)was overestimated in the calculations.It was influenced by the presence of a high concentration of hydrocarbon-like organic aerosol(HOA)with a weak water uptake ability.A positive relationship was observed betweenκorg and the ratio of oxygenated organic aerosol(OOA)and HOA,thereby indicating that the strong oxidation state enhanced the hygroscopicity of the particles.This study revealed the effect of local emission sources and secondary aerosol formation processes on particle hygroscopicity,which is of great significance for understanding the pollution formation mechanism in the North China Plain.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No.KZCX2-YW-Q11-03)the"Strategic Priority Research Program"of the Chinese Academy of Sciences(Grant No. XDA05100502)+1 种基金the National Basic Research Program of China (Grant No.2010CB950804)100 Talents Program of the Chinese Academy of Sciences
文摘The direct climatic effect of aerosols for the 1980-2000 period over East Asia was numerically investigated by a regional scale coupled climate-chemistry/ aerosol model, which includes major anthropogenic aerosols （sulfate, black carbon, and organic carbon） and natural aerosols （soil dust and sea salt）. Anthropogenic emissions used in model simulation are from a global emission inventory prepared for the Intergovernmental Panel on Climate Change Fifth Assessment Report （IPCC AR5）, whereas natural aerosols are calculated online in the model. The simulated 20-year average direct solar radiative effect due to aerosols at the surface was estimated to be in a range of-9- -33 W m-2 over most areas of China, with maxima over the Gobi desert of West China, and-12 W m-2 to -24 W m-2 over the Sichuan Basin, the middle and lower reaches of the Yellow River and the Yangtze River. Aerosols caused surface cooling in most areas of East Asia, with maxima of-0.8℃ to -1.6℃ over the deserts of West China, the Sichuan Basin, portions of central China, and the middle reaches of the Yangtze River. Aerosols induced a precipitation decrease over almost the entire East China, with maxima of-90 mm/year to -150 mm/year over the Sichuan Basin, the middle reaches of the Yangtze River and the lower reaches of the Yellow River. Interdecadal variation of the climate response to the aerosol direct radiative effect is evident, indicating larger decrease in surface air temperature and stronger per- turbation to precipitation in the 1990s than that in the 1980s, which could be due to the interdecadal variation of anthropogenic emissions.
基金supported by the National Natural Science Foundation of China(Nos.51978010,52022005).
文摘Continuous aggravated surface O_(3) over North China Plain(NCP)has attracted widely public concern.Herein,we evaluated the effects of changes in aerosols,precursor emissions,and meteorology on O_(3) in summer(June)of 2015–2019 over NCP via 8 scenarios with WRF-Chem model.The simulated mean MDA8 O_(3) in urban areas of 13 major cities in NCP increased by 17.1%∼34.8%,which matched well with the observations(10.8%∼33.1%).Meanwhile,the model could faithfully reproduce the changes in aerosol loads,precursors,and meteorological conditions.A relatively-even O_(3) increase(+1.2%∼+3.9%for 24-h O_(3) and+1.0%∼+3.8%for MDA8 O_(3))was induced by PM_(2.5) dropping,which was consistent with the geographic distribution of regional PM_(2.5) reduction.Meanwhile,the NO_(2) reduction coupled with a nearconstant VOCs led to the elevated VOCs/NOx ratios,and then caused O_(3) rising in the areas under VOCs-limited regimes.Therein,the pronounced increases occurred in Handan,Xingtai,Shijiazhuang,Tangshan,and Langfang(+10.7%∼+13.6%for 24-h O_(3) and+10.2%∼+12.2%forMDA8 O_(3));while the increases in other citieswere 5.7%∼10.5%for 24-h O_(3) and 4.9%∼9.2%for MDA8 O_(3).Besides,the meteorological fluctuations brought about the more noticeable O_(3) increases in northern parts(+12.5%∼+13.5%for 24-h O_(3) and+11.2%∼+12.4%for MDA8 O_(3))than those in southern and central parts(+3.2%∼+9.3%for 24-h O_(3) and+3.7%∼+8.8%for MDA8 O_(3)).The sum of the impacts of the three drivers reached 16.7%∼21.9%,which were comparable to the changes of the observed O_(3).Therefore,exploring reasonable emissionsreduction strategies is essential for the ozone pollution mitigation over this region.
基金supported by the National Natural Science Foundation of China (Grant Nos.90711004 and40825016)the Chinese Academy of Sciences (Grant Nos.KZCX2-YW-Q1 and KZCX2-YW-Q11-03)
文摘This study estimates direct radiative forcing by tropospheric ozone and all aerosols between the years 1850 and 2000, using the new IPCC AR5 （the Intergovernmental Panel on Climate Change Fifth Assessment Report） emissions inventories and a fully coupled chemistry-aerosol general circulation model. As compared to the previous Global Emissions Inventory Activity （GEIA） data, that have been commonly used for forcing estimates since 1990, the IPCC AR5 emissions inventories report lower anthropogenic emissions of organic carbon and black carbon aerosols and higher sulfur and NOx emissions. The simulated global and annual mean burdens of sulfate, nitrate, black carbon （BC）, primary organic aerosol （POA）, secondary organic aerosol （SOA）, and ozone were 0.79, 0.35, 0.05, 0.49, 0.34, and 269 Tg, respectively, in the year 1850, and 1.90, 0.90, 0.11, 0.71, 0.32, and 377 Tg, respectively, in the year 2000. The estimated annual mean top of the atmosphere （TOA） direct radiative forcing of all anthropogenic aerosols based on the AR5 emissions inventories is -0.60 W m^-2 on a global mean basis from 1850 to 2000. However, this is -2.40 W m-2 when forcing values are averaged over eastern China （18-45°N and 95-125°E）. The value for tropospheric ozone is 0.17 W m^-1 on a global mean basis and 0.24 W m^-2 over eastern China. Forcing values indicate that the climatic effect of aerosols over eastern China is much more significant than the globally averaged effect.
基金supported by the National Natural Science Foundation of China(No.20937004,21107060,21190054)the"Strategic Priority Research Program"of the Chinese Academy of Sciences(No.XDB05010102)supported by Toyota Motor Corporation and Toyota Central Research and Development Laboratories Inc
文摘Smog chamber experiments were conducted to investigate the hygroscopicity of particles generated from photooxidation of α-pinene/NOx with different sulfate seed aerosols or oxidation conditions. Hygroscopicity of particles was measured by a tandem differential mobility analyzer （TDMA） in terms of hygroscopic growth factor （Gf）, with a relative humidity of 85%. With sulfate seed aerosols present, Gf of the aerosols decreased very fast before notable secondary organic aerosols （SOA） formation was observed, indicating a heterogeneous process between inorganic seeds and organic products might take place as soon as oxidation begins, rather than only happening after gas-aerosol partition of organic products starts. The final SOA-coated sulfate particles had similar or lower Gf than seed-free SOA. The hygroscopicity of the final particles was not dependent on the thickness but on the hygroscopicity properties of the SOA, which were influenced by the initial sulfate seed particles. In the two designed aging processes, Gf of the particles increased more significantly with introduction of OH radical than with ozone. However, the hygroscopicity of SOA was very low even after a long time of aging, implying that either SOA aging in the chamber was very slow or the Gf of SOA did not change significantly in aging. Using an aerosol composition speciation monitor （ACSM） and matrix factorization （PMF） method, two factors for the components of SOA were identified, but the correlation between SOA hygroscopicity and the proportion of the more highly oxidized factor could be either positive or negative depending on the speciation of seed aerosols present.
基金supported by the National Natural Science Foundation of China (Nos. 41475113, 41175018)the CAS Strategic Priority Research Program (No. XDB05010500)
文摘A field experiment from 18 August to 8 September 2006 in Beijing, China, was carried out. A hazy day was defined as visibility 〈 10 km and RH（relative humidity） 〈 90%. Four haze episodes, which accounted for ～ 60% of the time during the whole campaign, were characterized by increases of SNA（sulfate, nitrate, and ammonium） and SOA（secondary organic aerosol） concentrations. The average values with standard deviation of SO2-＋4, NO-3, NH4 and SOA were 49.8（± 31.6）, 31.4（±22.3）, 25.8（±16.6） and 8.9（±4.1） μg/m3, respectively, during the haze episodes, which were 4.3, 3.4, 4.1, and 1.7 times those in the non-haze days. The SO2-4,NO-3, NH＋4, and SOA accounted for 15.8%, 8.8%, 7.3%, and 6.0% of the total mass concentration of PM10 during the non-haze days. The respective contributions of SNA species to PM10 rose to about27.2%, 15.9%, and 13.9% during the haze days, while the contributions of SOA maintained the same level with a slight decrease to about 4.9%. The observed mass concentrations of SNA and SOA increased with the increase of PM10 mass concentration, however, the rate of increase of SNA was much faster than that of the SOA. The SOR（sulfur oxidation ratio） and NOR（nitrogen oxidation ratio） increased from non-haze days to hazy days, and increased with the increase of RH. High concentrations of aerosols and water vapor favored the conversion of SO2 to SO2-4and NO2 to NO-3, which accelerated the accumulation of the aerosols and resulted in the formation of haze in Beijing.
