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| 1 | Contrasting trends of PM2.5 and surface-ozone concentrations in China from 2013 to 2017显示文摘Although much attention has been paid to investigating and controlling air pollution in China,the trends of air-pollutant concentrations on a national scale have remained unclear.Here,we quantitatively investigated the variation of air pollutants in China using long-term comprehensive data sets from 2013 to 2017,during which Chinese government made major efforts to reduce anthropogenic emission in polluted regions.Our results show a significant decreasing trend in the PM2.5 concentration in heavily polluted regions of eastern China,with an annual decrease of〜7%compared with measurements in 2013.The measured decreased concentrations of SO2>NO2 and CO(a proxy for anthropogenic volatile organic compounds)could explain a large fraction of the decreased PM2.5 concentrations in different regions.As a consequence;the heavily polluted days decreased significantly in corresponding regions.Concentrations of organic aerosol;nitrate;sulfate,ammonium and chloride measured in urban Beijing revealed a remarkable reduction from 2013 to 2017;connecting the decreases in aerosol precursors with corresponding chemical components closely.However;surface-ozone concentrations showed increasing trends in most urban stations from 2013 to 2017;which indicates stronger photochemical pollution.The boundary-layer height in capital c让ies of eastern China showed no significant trends over the Beijing-Tianjin-Hebei,Yangtze River Delta and Pearl River Delta regions from 2013 to 2017;which confirmed the reduction in anthropogenic emissions.Our results demonstrated that the Chinese government was successful in the reduction of particulate matter in urban areas from 2013 to 2017,although the ozone concentration has increased significantly;suggesting a more complex mechanism of improving Chinese air quality in the future. | Yonghong Wang Wenkang Gao Shuai Wang Tao Song Zhengyu Gong Dongsheng Ji Lili Wang Zirui Liu Guiqian Tang Yanfeng Huo Shili Tian Jiayun Li Mingge Li Yuan Yang Biwu Chu Tuukka Petaja Veli-Matti Kerminen Hong He Jiming Hao Markku Kulmala Yuesi Wang Yuanhang Zhang | 2020 | National Science Review2020，7，8： | 51 |
| 2 | Role of ammonia in forming secondary aerosols from gasoline vehicle exhaust显示文摘Ammonia(NH3) plays vital roles in new particle formation and atmospheric chemistry. Although previous studies have revealed that it also influences the formation of secondary organic aerosols(SOA) from ozonolysis of biogenic and anthropogenic volatile organic compounds(VOCs), the influence of NH3 on particle formation from complex mixtures such as vehicle exhausts is still poorly understood. Here we directly introduced gasoline vehicles exhausts(GVE) into a smog chamber with NH3 absorbed by denuders to examine the role of NH3 in particle formation from GVE. We found that removing NH3 from GVE would greatly suppress the formation and growth of particles. Adding NH3 into the reactor after 3 h photo-oxidation of GVE, the particle number concentration and mass concentrations jumped explosively to much higher levels, indicating that the numbers and mass of particles might be enhanced when aged vehicle exhausts are transported to rural areas and mixed with NH3-rich plumes. We also found that the presence of NH3 had no significant influence on SOA formation from GVE. Very similar oxygen to carbon(O:C) and hydrogen to carbon(H:C) ratios resolved by aerosol mass spectrometer with and without NH3 indicated that the presence of NH3 also had no impact on the average carbon oxidation state of SOA from GVE. | Tengyu Liu Xinming Wang Wei Deng Yanli Zhang Biwu Chu Xiang Ding Qihou Hu Hong He Jiming Hao | 2015 | Science China Chemistry2015，58，9： | 7 |
| 3 | Hygroscopicity of particles generated from photooxidation of α-pinene under diferent oxidation conditions in the presence of sulfate seed aerosols显示文摘Smog chamber experiments were conducted to investigate the hygroscopicity of particles generated from photooxidation of α-pinene/NOx with diferent sulfate seed aerosols or oxidation conditions. Hygroscopicity of particles was measured by a tandem diferential 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. | Biwu Chu Kun Wang Hideto Takekawa Junhua Li Wei Zhou Jingkun Jiang Qinxing Ma Hong He Jiming Hao | 2014 | Journal of Environmental Sciences2014，26，1： | 6 |
| 4 | Distinct potential aerosol masses under different scenarios of transport at a suburban site of Beijing显示文摘In order to evaluate the secondary aerosol formation potential at a suburban site of Beijing,in situ perturbation experiments in a potential aerosol mass(PAM) reactor were carried out in the winter of 2014.The variations of secondary aerosol formation as a function of time,OH exposure,and the concentrations of gas phase pollutants and particles were reported in this study.Two periods with distinct secondary aerosol formation potentials,marked as Period Ⅰ and Period Ⅱ,were identified during the observation.In Period Ⅰ,the secondary aerosol formation potential was high,and correlated well to the air pollutants,i.e.,SO_2,NO_2,and CO.The maximal secondary aerosol formation was observed with an aging time equivalent to about 3 days of atmospheric oxidation.In period Ⅱ,the secondary aerosol formation potential was low,with no obvious correlation with the air pollutants.Meanwhile,the aerosol mass decreased,instead of showing a peak,with increasing aging time.Backward trajectory analysis during the two periods confirmed that the air mass in Period Ⅰwas mainly from local sources,while it was attributed mostly to long distance transport in Period Ⅱ.The air lost its reactivity during the long transport and the particles became highly aged,resulting in a low secondary aerosol formation potential.Our experimental results indicated that the in situ measurement of the secondary aerosol formation potential could provide important information for evaluating the contributions of local emission and long distance transport to the aerosol pollution. | Biwu Chu Yongchun Liu Qingxin Ma Jinzhu Ma Hong He Gang Wang Shuiyuan Cheng Xinming Wang | 2016 | Journal of Environmental Sciences2016，28，1： | 5 |
| 5 | Differences of the oxidation process and secondary organic aerosol formation at low and high precursor concentrations显示文摘Current atmospheric quality models usually underestimate the level of ambient secondary organic aerosol(SOA), one of the possible reasons is that the precursors at different concentrations may undergo different oxidation processes and further affect SOA formation. Therefore, there is a need to perform more chamber studies to disclose the influence. In this work, SOA formation over a wide range of initial precursor concentrations(tens of ppb to hundreds of ppb levels) was investigated in a 30 m3 indoor smog chamber,and mainly through the analysis of multiple generations of VOCs detected from HR-To FPTRMS to expound the difference in the oxidation process between low and high precursor concentrations. Compared to high initial concentrations, gas-phase intermediates formed at low concentrations had a higher intensity by about one order of magnitude, and the lowvolatility compounds also had a higher formation potential due to the competition between semi-volatile intermediates and precursors with oxidants. In addition, the formed SOA was more oxidized with higher f44 value(0.14 ± 0.02) and more relevant to real atmosphere than that formed at high concentrations. This work should help to deeply understand SOA formation and improve the performance of air quality models for SOA simulation. | Tianzeng Chen Yongchun Liu Biwu Chu Changgeng Liu Jun Liu Yanli Ge Qingxin Ma Jinzhu Ma Hong He | 2019 | Journal of Environmental Sciences2019，31，5： | 4 |
| 6 | Continuous and comprehensive atmospheric observations in Beijing:a station to understand the complex urban atmospheric environment显示文摘Due to profound impact on climate and human health,air quality has attracted attention from all levels of the civil society.The key step in the provision of required tools for the society to tackle the complex air quality problem is to characterize it in a comprehensive manner with a long-term perspective.Here,we describe a continuous and comprehensive observation station and its accompanying state-ofthe-art instrumentation that was established to investigate the complex urban atmospheric environment in a rapidly developing Chinese Megacity.The station,located in downtown Beijing,aims to study air quality by identifying the major atmospheric pollutants and key processes determining their formation and loss mechanisms.A few hundreds of parameters are continuously measured with the state-of-the-art instruments,including trace gas concentrations,aerosol particle size distributions,and mass concentrations,covering aerosol particle chemical composition from molecules to micrometer-sized aerosol particles.This produced long-term,comprehensive big data with around 1�10^(11)bytes per year.In this paper,we provide an overview on the facilities of the station,the instrumentation used,the workflow of continuous observations and examples of results from 2018 to 2019 and a basis for establishing a modern long-term,comprehensive atmospheric urban observation station in other megacities. | Yongchun Liu Chao Yan Zemin Feng Feixue Zheng Xiaolong Fan Yusheng Zhang Chang Li Ying Zhou Zhuohui Lin Yishou Guo Ying Zhang Li Ma Wenshuo Zhou Zhikun Liu Lubna Dada Kaspar Dallenbach Jenni Kontkanen Runlong Cai Tommy Chan Biwu Chu Wei Du Lei Yao Yonghong Wang Jing Cai Juha Kangasluoma Tom Kokkonen Joni Kujansuu Anton Rusanen Chenjuan Deng Yueyun Fu Rujing Yin Xiaoxiao Li Yiqun Lu Yiliang Liu Chaofan Lian Dongsen Yang Weigang Wang Maofa Ge Yuesi Wang Douglas R.Worsnop Heikki Junninen Hong He Veli-Matti Kerminen Jun Zheng Lin Wang Jingkun Jiang Tuukka Petaja Federico Bianchi Markku Kulmala | 2020 | Big Earth Data2020，4，3： | 3 |
| 7 | Comparisons of measured nitrous acid(HONO) concentrations in a pollution period at urban and suburban Beijing, in autumn of 2014显示文摘To study the HONO formation mechanisms during a pollution period, a continuous measurement was performed in both urban and suburban aeras of Beijing. During this period, the PM2.5 concentrations increased to 201 and 137 ?g/m3 in urban and suburban areas, respectively. The concentrations of HONO, CO, SO2, O3, NO, NO2, NOx were 1.45 ppbv, 0.61 ppmv, 8.7 ppbv, 4.3 ppbv, 44.4 ppbv, 37.4 ppbv, 79.4 ppbv and 0.72 ppbv, 1.00 ppmv, 1.2 ppbv, 7.9 ppbv, 3.7 ppbv, 8.2 ppbv, 11.9 ppbv, in urban and suburban areas, respectively. To compare possible pathways of HONO formation in both sites, the contributions of direct emissions, heterogeneous formations, and homogeneous productions were studied. HONO/NO2 ratios in the two sites indicated that heterogeneous reactions of NO2 were more efficient in suburban areas. And in both urban and suburban areas, the increase of PM2.5 concentrations and RH would promote the conversion efficiency in RH that ranged from 0% to 85%. However, when RH was above 85%, the HONO formation slowed down. Moreover, the study of direct emissions and homogeneous reactions showed that they contributed to a majority of HONO increase in urban areas than the 20% contributions in suburban areas. It implied that the high NOx concentrations and NO concentrations in urban areas or in pollution periods would make direct emissions and homogeneous reactions become dominant in HONO formations. | Shengrui Tong Siqi Hou Ying Zhang Biwu Chu Yongchun Liu Hong He Pusheng Zhao Maofa Ge | 2015 | Science China Chemistry2015，58，9： | 3 |
| 8 | Secondary aerosol formation and oxidation capacity in photooxidation in the presence of Al_2O_3 seed particles and SO_2显示文摘To investigate the sensitivity of secondary aerosol formation and oxidation capacity to NOx in homogeneous and heterogeneous reactions, a series of irradiated toluene/NOx/air and ?-pinene/NOx/air experiments were conducted in smog chambers in the absence or presence of Al2O3 seed particles. Various concentrations of NOx and volatile organic compounds(VOCs) were designed to simulate secondary aerosol formation under different scenarios for NOx. Under 'VOC-limited' conditions, the increasing NOx concentration suppressed secondary aerosol formation, while the increasing toluene concentration not only contributed to the increase in secondary aerosol formation, but also led to the elevated oxidation degree for the organic aerosol. Sulfate formation was suppressed with the increasing NOx due to a decreased oxidation capacity of the photooxidation system. Secondary organic aerosol(SOA) formation also decreased with the presence of high concentration of NOx, because organo-peroxy radicals(RO2) react with NOx instead of with peroxy radicals(RO2 or HO2), resulting in the formation of volatile organic products. The increasing concentration of NOx enhanced the formation of sulfate, nitrate and SOA under 'NOx-limited' conditions, in which the heterogeneous reactions played an important role. In the presence of Al2O3 seed particles, a synergetic promoting effect of mineral dust and NOx on secondary aerosol formation in heterogeneous reactions was observed in the photooxidation. This synergetic effect strengthened the positive relationship between NOx and secondary aerosol formation under 'NOx-limited' conditions but weakened or even overturned the negative relationship between NOx and secondary aerosol formation under 'VOC-limited' conditions. Sensitivity of secondary aerosol formation to NOx seemed different in homogeneous and heterogeneous reactions, and should be both taken into account in the sensitivity study. The sensitivity of secondary aerosol formation to NOx was further investigated under 'winter-like' and NH3-rich conditions. No obvious difference for the sensitivity of secondary aerosol formation except nitrate to NOx was observed. | Biwu Chu Tengyu Liu Xiao Zhang Yongchun Liu Qingxin Ma Jinzhu Ma Hong He Xinming Wang Junhua Li Jiming Hao | 2015 | Science China Chemistry2015，58，9： | 3 |
| 9 | Effect of aluminium dust on secondary organic aerosol formation in m-xylene/NO_x photo-oxidation显示文摘As an important anthropogenic volatile organic compound(VOC), m-xylene has attracted numerous attentions due to its potential in secondary organic aerosol(SOA) formation. In this study, effects of aluminium dust seeds(boehmite and alumina) on SOA yield and aerosol size in m-xylene/NOx photo-oxidation were investigated in a 2 m3 smog chamber at 30°C and 50% relative humidity. Compared to the seed-free system, the presence of aluminium seeds resulted in an increase in the SOA yield, and also enhanced the O3 concentration in the chamber. The photolysis of O3 is a major source of OH radical, which is the most important oxidant of m-xylene. The increase in O3 concentration could result in the generation of more OH radicals, and finally contribute to the SOA formation. Seed particles influence the SOA size mainly by acting as condensation nuclei. Semi-volatile organic compounds(SVOCs) were condensed onto these nuclei, resulting in the increase in SOA size. However, when aluminium seeds with high concentrations were introduced into the system, SVOCs that had been condensed onto each particle were dispersed by these seeds, leading to the reduction in aerosol size. | LIU Chang MA QingXin CHU BiWu LIU YongChun HE Hong ZHANG XiaoYe LI JunHua HAO JiMing | 2015 | Science China Earth Sciences2015，58，2： | 2 |
| 10 | Effects of two transition metal sulfate salts on secondary organic aerosol formation in toluene/NOx photooxidation显示文摘Aerosol phase reactions play a very important role on secondary organic aerosol (SOA) formation, and metal-containing aerosols are important components in the atmosphere. In this study, we tested the effects of two transition metal sulfate salts, manganese sulfate (MnSO4) and zinc sulfate (ZnSO4), on the photochemical reactions of a toluene/NOx photooxidation system in a 2 m3 smog chamber. By comparing photochemical reaction products of experiments with and without transition metal sulfate seed aerosols, we evaluated the effects of transition metal sulfate seed aerosols on toluene consumption, NOx conversion and the formation of ozone and SOA. MnSO4 and ZnSO4 seed aerosols were found to have similar effects on photochemical reactions, both enhance the SOA production, while showing negligible effects on the gas phase compounds. These observations are consistent when varying metal sulfate aerosol concentrations. This is attributed to the catalytic effects of MnSO4 and ZnSO4 seed aerosols which may enhance the formation of condensable semivolatile compounds. Their subsequent partitioning into the aerosol phase leads to the observed SOA formation enhancement. | Biwu CHU Jiming HAO Junhua LI Hideto TAKEKAWA Kun WANG Jingkun JIANG | 2013 | Frontiers of Environmental Science & Engineering2013，7，1： | 2 |
| 11 | Coordinated Control of Fine-Particle and Ozone Pollution by the Substantial Reduction of Nitrogen Oxides显示文摘1.Introduction In recent years,the air quality in China has improved significantly.In many cities,however,the concentration of fine particulate matter(PM_(2.5))remains higher than the secondary-level national ambient air quality standard(NAAQS level-2,35μg·m^(-3),GB3095-2012[1])and much higher than the first-level NAAQS(15μg·m^(-3),GB3095-2012[1])and the World Health Organization(WHO)air quality guidelines(5μg·m^(-3)). | Biwu Chu Yan Ding Xiang Gao Junhua Li Tingyu Zhu Yunbo Yu Hong He | 2022 | Engineering2022，8，8： | 1 |
| 12 | Application of smog chambers in atmospheric process studies显示文摘Smog chamber experimental systems,which have been widely used in laboratory simulation for studying atmospheric processes,are comprehensively reviewed in this paper.The components,development history,main research topics and main achievements of smog chambers are introduced.Typical smog chambers in the world,including their volumes,wall materials,light sources and features,are summarized and compared.Key factors of smog chambers and their influences on the simulation of the atmospheric environment are discussed,including wall loss,wall emission and background pollutants.The features of next-generation smog chambers and their application prospect in future studies of the atmospheric environment are also outlined in this paper. | Biwu Chu Tianzeng Chen Yongchun Liu Qingxin Ma Yujing Mu Yonghong Wang Jinzhu Ma Peng Zhang Jun Liu Chunshan Liu Huaqiao Gui Renzhi Hu Bo Hu Xinming Wang Yuesi Wang Jianguo Liu Pinhua Xie Jianmin Chen Qian Liu Jingkun Jiang Junhua Li Kebin He Wenqing Liu Guibin Jiang Jiming Hao Hong He | 2022 | National Science Review2022，9，2： | 1 |
| 13 | Homogeneous and heterogeneous photolysis of nitrate in the atmosphere:state of the science,current research needs,and future prospects显示文摘Nitrate is an important component of atmospheric particulate matter and affects air quality,climate,human health,and the ecosystem.Nitrate was previously considered a permanent sink for nitrogen oxides(NO_(x)).However,this viewpoint has been challenged in recent years because growing research evidence has shown the transformation of nitrate into NO_(x)(i.e.,renoxification).The photolysis of nitrate/HNO3,especially in the particulate phase or adsorbed on particles,can be a significant renoxification process in the atmosphere.The formation and photolysis of nitrate in aerosol not only change the diurnal variation of NO_(x),but also provide long-distance transport of NO_(x)in the form of nitrate,which affects local and regional atmospheric chemistry and air quality.This review summarizes recent advances in the fundamental understanding of the photolysis of nitrate/HNO3 under various atmospheric conditions,with a focus on mechanisms and key factors affecting the process.The atmospheric implications are discussed and future research is recommended. | Yiqun Cao Qingxin Ma Biwu Chu Hong He | 2023 | Frontiers of Environmental Science & Engineering2023，17，4： | 1 |
| 14 | Effects of seed particles Al2O3, Al2(SO4)3 and H2SO4 on secondary organic aerosol显示文摘 | Xiao Zhang Biwu Chu Junhua Li Chaozhi Zhang | 2017 | Frontiers of Environmental Science & Engineering2017，11，4： | 0 |
| 15 | Atmospheric heterogeneous reactions on soot:A review显示文摘Soot particles,composed of elemental carbon and organic compounds,have attracted widespread attention in recent years due to their significant impacts on climate,the environment and human health.Soot has been found to be chemically and physically active in atmospheric aging processes,which leads to alterations in its composition,morphology,hygroscopicity and optical properties and thus changes its environmental and health effects.The heterogeneous reactions on soot also have a significant impact on the transformation of gaseous pollutants into secondary aerosols.Therefore,the interactions between soot and atmospheric substances have been widely investigated to better understand the environmental behaviors of soot.In this review,we systematically summarize the progress and developments in the heterogeneous chemistry on soot over the past_(3)0 years.Atmospheric trace constituents such as NO_(2),O_(3),SO_(2),N_(2)O_(5),HNO_(3),H_(2)SO_(4),OH radical,HO_(2)radical,peroxyacetyl nitrate etc.,are presented in detail from the aspect of their heterogeneous reactions on soot.The possible mechanisms and the effects of environmental conditions on these heterogeneous reactions are also addressed.Further,the impacts of the heterogeneous reactions of soot on the atmospheric environment are discussed,and some aspects of soot-related research which require further investigation are proposed as well. | Yuan Liu Guangzhi He Biwu Chu Qingxin Ma Hong He | 2023 | Fundamental Research2023，3，4： | 0 |
| 16 | Mechanism for the promotional formation of NH_(4)^(+) by SO_(2) on different mineral dust surfaces显示文摘Ammonium is an important atmospheric particulate component that dictates many environmental processes.The promotion of the heterogeneous conversion of NH_(3) to NH_(4)^(+) by SO_(2) on different mineral dust surfaces displays remarkable discrepancies,especially on MgO and α-Fe2O3 surfaces,however,the underlying mechanisms are not well known.Here,using periodic density functional theory(DFT)calculation and Born-Oppenheimer molecular dynamics(BOMD)simulation,we explored the hetero-geneous adsorption of NH_(3) on MgO(110)and α--Fe2O3(001)surfaces in the presence and absence of SO_(2).The results show that on MgO(110)surface,hydrogen-bonding interactions of NH_(3) on both adsorbed hydroxyl or bisulfite/bisulfate sites are observed no matter whether SO_(2) is present or not.While,on theα-Fe2O3(001)surface,significant conversion of NH_(3) to NH_(4)^(+)occurs with the coexistence of SO_(2),which is due to the hydrogen transfer reaction from surface HSO4 to N in NH_(3).The fundamental reason may be that the stronger electron affinity of Fe3+than Mg2+results in adsorbed bisulfate and/or bisulfite with greater acidity on α-Fe2O3 surface than MgO surface.Our results give a molecular-level explanation for the heterogeneous conversion of NH_(3) to NH_(4)^(+)on different mineral dust surfaces under complex air pollution conditions.Considering the fact that ammonium is abundant in secondary particulates,this work would help in understanding the rapid conversion of ammonia to ammonium and in developing classification governance policies for the key precursor pollutants in China. | Hao Li Qingxin Ma Biwu Chu Hong He | 2023 | Particuology2023，，4： | 0 |
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