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Development of an automatic measurement system using atmospheric pressure photoionization ultrahigh-resolution mass spectrometry and application for on-line analysis of particulate matter

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Journal of environmental Sciences 2024年第4期138卷 516-530页

作者： Yayuan Dong Ranran Liu Ling Xie Xiaole Pan Yele Sun Lin Wu ZifaWang State Key Laboratory of atmospheric Boundary Layer Physics and atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Center for Excellence in Regional Atmospheric Environment Chinese Academy of SciencesInstitute of Urban EnvironmentXiamen 361021China

On-line chemical characterization of atmospheric particulate matter(PM)with soft ionization technique and ultrahigh-resolution Mass Spectrometry(UHRMS)provides molecular information of organic constituents in real time.Here we describe the development and application of an automatic measurement system that incorporates PM_(2.5)sampling,thermal desorption,atmospheric pressure photoionization,and UHRMS analysis.Molecular formulas of detected organic compounds were deducted from the accurate(±10 ppm)molecular weights obtained at a mass resolution of 100,000,allowing the identification of small organic compounds in PM_(2.5).Detection efficiencies of 28 standard compounds were determined and we found a high sensitivity and selectivity towards organic amines with limits of detection below 10 pg.As a proof of principle,PM_(2.5)samples collected off-line in winter in the urban area of Beijing were analyzed using the Ionization Module and HRMS of the system.The automatic system was then applied to conduct on-line measurements during the summer time at a time resolution of 2 hr.The detected organic compounds comprised mainly CHON and CHN compounds below 350 m/z.Pronounced seasonal variations in elemental composition were observed with shorter carbon backbones and higher O/C ratios in summer than that in winter.This result is consistent with stronger photochemical reactions and thus a higher oxidation state of organics in summer.Diurnal variation in signal intensity of each formula provides crucial information to reveal its source and formation pathway.In summary,the automatic measurement system serves as an important tool for the on-line characterization and identification of organic species in PM_(2.5).

关键词： PM_(2.5) Chemical composition On-line measurement technique High resolution mass spectrometry

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Development and evaluation of an online monitoring single-particle optical particle counter with polarization detection

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Journal of environmental Sciences 2024年第4期138卷 585-596页

作者： Weijie Yao Xiaole Pan Yu Tian Hang Liu Yuting Zhang Shandong Lei Junbo Zhang Yinzhou Zhang LinWu Yele Sun Zifa Wang State Key Laboratory of atmospheric Boundary Layer Physics and atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China

We developed a single-particle optical particle counter with polarization detection(SOPC)for the real-time measurement of the optical size and depolarization ratio(defined as the ratio of the vertical component to the parallel component of backward scattering)of atmospheric particles,the polarization ratio(DR)value can reflect the irregularity of the particles.The SOPC can detect aerosol particles with size larger than 500 nm and the maximum particle count rate reaches~1.8×10^(5)particles per liter.The SOPC uses a modulated polarization laser to measure the optical size of particles according to forward scattering signal and the DR value of the particles by backward S and P signal components.The sampling rate of the SOPC was 106#/(sec·channel),and all the raw data were processed online.The calibration curve was obtained by polystyrene latex spheres with sizes of 0.5-10μm,and the average relative deviation of measurement was 3.96% for sub 3μm particles.T-matrix method calculations showed that the DR value of backscatter light at 120°could describe the variations in the aspect ratio of particles in the above size range.We performed insitu observations for the evaluation of the SOPC,the mass concentration constructed by the SOPC showed good agreement with the PM_(2.5)measurements in a nearby state-controlled monitoring site.This instrument could provide useful data for source appointment and regulations against air pollution.

关键词： Instrument development Single particle detection Measurement uncertainty Optical simulation Mass concentration

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The Impact of the Numbers of Monitoring Stations on the National and regional Air Quality Assessment in China During 2013-18

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Advances in atmospheric Sciences 2022年第10期39卷 1709-1720页

作者： Hongyan LUO Xiao TANG Huangjian WU Lei KONG Qian WU Kai CAO Yating SONG Xuechun LUO Yao WANG Jiang ZHU Zifa WANG LAPC&ICCES Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China

China national air quality monitoring network has become the core data source for air quality assessment and management in China.However,during network construction,the significant change in numbers of monitoring sites with time is easily ignored,which brings uncertainty to air quality assessments.This study aims to analyze the impact of change in numbers of stations on national and regional air quality assessments in China during 2013-18.The results indicate that the change in numbers of stations has different impacts on fine particulate matter(PM_(2.5))and ozone concentration assessments.The increasing number of sites makes the estimated national and regional PM_(2.5) concentration slightly lower by 0.6−2.2μg m^(−3) and 1.4−6.0μg m^(−3) respectively from 2013 to 2018.The main reason is that over time,the monitoring network expands from the urban centers to the suburban areas with low population densities and pollutant emissions.For ozone,the increasing number of stations affects the long-term trends of the estimated concentration,especially the national trends,which changed from a slight upward trend to a downward trend in 2014−15.Besides,the impact of the increasing number of sites on ozone assessment exhibits a seasonal difference at the 0.05 significance level in that the added sites make the estimated concentration higher in winter and lower in summer.These results suggest that the change in numbers of monitoring sites is an important uncertainty factor in national and regional air quality assessments,that needs to be considered in long-term concentration assessment,trend analysis,and trend driving force analysis.

关键词： monitoring network newly added sites PM_(2.5) ozone

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An intercomparison of ozone taken from the Copernicus atmosphere monitoring service and the second Modern-Era retrospective analysis for research and applications over China during 2018 and 2019

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Journal of environmental Sciences 2022年第4期34卷 514-525页

作者： Yujing Zhang Jie Li Jianjun Li Xiaole Pan Wei Wang Lili Zhu Zixi Wang Xueshun Chen Wenyi Yang Zifa Wang The State Key Laboratory of atmospheric Boundary Layer Physics and atmospheric Chemistry Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China China National environmental Monitoring center Beijing 100012China

Spatiotemporal variations of ozone(O_(3))taken from the Copernicus Atmosphere Monitoring Service(CAMS)and the second Modern-Era Retrospective Analysis for Research and Applications(MERRA-2)were intercompared and evaluated with ground and ozone-sonde observations over China in 2018 and 2019.Intercomparison of the surface ozone from CAMS and MERRA-2 reanalysis showed significant negative bias(CAMS minus MERRA-2,same below)at Tibetan Plateau of up to 80μg/m^(3),and the average R^(2)was about 0.6 across China.Evaluated with the ground observations from China National environmental Monitoring center(CNEMC),we found that CAMS and MERRA-2 reanalysis were capable of capturing the key patterns of monthly and diurnal variations of surface ozone over China except for the western region,and MERRA-2 overestimated the observations compared to CAMS.Vertically,the CAMS profiles overestimated the ozone-sonde from the World Ozone and Ultraviolet Radiation Data center(WOUDC)above 200 h Pa with the magnitude reaching up to 150μg/m3,while little bias was found between the reanalysis and observations below 200 h Pa.Intercomparison drawn from the vertical distribution between CAMS and MERRA-2 reanalysis showed that the negative bias appeared throughout the troposphere over China,while the positive bias emerged in the upper troposphere and lower stratosphere(UTLS)with high order of magnitude exceeding 100μg/m^(3),indicating large uncertainties at higher altitudes.In summary,we concluded that CAMS reanalysis showed better agreement with the observations in contrast to MERRA-2,and the large discrepancy especially at higher altitudes between these two reanalysis datasets could not be ignored.

关键词： CAMS MERRA-2 Ozone Intercomparison

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Mechanism for the promotional formation of NH_(4)^(+) by SO_(2) on different mineral dust surfaces

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Particuology 2023年第4期75卷 109-118页

作者： Hao Li Qingxin Ma Biwu Chu Hong He State Key Joint Laboratory of environment Simulation and Pollution Control Research Center for Eco-environmental SciencesChinese Academy of SciencesBeijing100085China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen361021China Institute of atmospheric Physics Chinese Academy of SciencesBeijing100029China

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.

关键词： Mineral dust Heterogeneous reaction Theoretical calculation Ammonium SO_(2)

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Shape dependence of support for NO_x storage and reduction catalysts

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Journal of environmental Sciences 2019年第1期31卷 396-407页

作者： Wen Xie Yunbo Yu Hong He State Key Joint Laboratory of environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of Sciences University of Chinese Academy of Sciences Center for Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences

Pt/BaO/Al_2O_3 catalysts with different BaO loadings prepared from Al_2O_3 nanorods(Pt/BaO/Al_2O_3-nr) and irregular Al_2O_3 nanoparticles(Pt/BaO/Al_2O_3-np) were investigated for NOx storage and reduction(NSR). The Pt/BaO/Al_2O_3 materials derived from Al_2O_3 nanorods always exhibited much higher NOx storage capacity(NSC) over the whole temperature range of 100–400°C than the corresponding Pt/BaO/Al_2O_3-np samples containing the same BaO loading, giving the maximum NSC value of 966.9 μmol/gcatat 400°C, 1.4 times higher than that of Pt/BaO/Al_2O_3-np. Higher catalytic performance of nanorod-supported NSR samples was also observed during lean-rich cyclic conditions(90 sec vs. 5 sec), giving more than 98% NOx conversion at 300–450°C over the Pt/BaO/Al_2O_3-nr sample with 15% BaO loading. To reveal this dependence on the shape of the support during the NSR process, a series of characterization techniques including the Brunauer–Emmett–Teller(BET) method,X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), H_2 temperature programmed reduction(H2-TPR), and in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) were also conducted. It was found that intimate contact of Ba–Al and Ba–Pt sites was achieved over the Pt/BaO/Al_2O_3 surface when using Al_2O_3-nr as a support.This strong interaction among the multi-components of Pt/BaO/Al_2O_3-nr thus triggered the formation of surface nitrite and nitrate during the lean period, and also accelerated the reverse spillover of ad-NOxspecies onto the Pt surface, enhancing their reduction and leading to high NSR performance.

关键词： NOx storage and reduction Pt/BaO/Al2O3 Nanorod Morphology effect Strong interaction

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The balance of acidity and redox capability over modified CeO_2 catalyst for the selective catalytic reduction of NO with NH_3

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Journal of environmental Sciences 2019年第5期31卷 273-279页

作者： Zhihua Lian Wenpo Shan Meng Wang Hong He Qingcai Feng Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion Institute of Urban Environment Chinese Academy of Sciences Research center for Eco-environmental Sciences Chinese Academy of Sciences University of Chinese Academy of Sciences

The effect of acidity and redox capability over sulfuric acid-modified CeO_2 catalysts were studied for the selective catalytic reduction of NO_x with NH_3(NH_3-SCR). The deposition of sulfate significantly enhanced the catalytic performance over CeO_2. NO_x conversion over4H_2SO_4/CeO_2 at 230–440 °C was higher than 90%. The strong redox capability of CeO_2 could result in unselective NH_3 oxidation and decrease high temperatures catalytic activity and N_2 selectivity. The deposition of sulfate increased the acidity and weakened the redox capability, and then increased the high temperature NO_x conversion and N_2 selectivity. An appropriate level of acidity also promoted the activity at 190–250 °C over ceria-based catalysts, and with further increase in the acidity, the SCR activity decreased slightly. Weak redox capability lowered the low-temperature catalytic activity. Excellent SCR activity requires a balance of acidity and redox capability on the catalysts.

关键词： NH3-SCR CeO2 Acidity Redox capability H2SO4

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Adsorptive interaction between typical VOCs and various topological zeolites:Mixture effect and mechanism

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Journal of environmental Sciences 2024年第2期136卷 626-636页

作者： Bo Yu Hua Deng Yuqin Lu Tingting Pan Wenpo Shan Hong He Center for Excellence in Regional Atmospheric Environment and Key Laboratory of Urban Pollutant Conversion Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China State Key Joint Laboratory of environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

Adsorption is one of the most feasible and effective methods to alleviate the volatile organic compounds(VOCs)pollution.However,the mixture effect and mechanism for competitive adsorption of VOCs on zeolites are barely addressed.In this study,toluene,acetone,and ethyl acetate as prevalent VOCs species were removed by four potential zeolites(13X,USY,Beta,ZSM-5)in both single-and multi-component systems.The structure-property relationship between adsorbate-adsorbent pairs was revealed by X-ray diffraction,scanning electron microscopy,energy dispersive spectrometer,X-ray fluorescence,N_(2) adsorption and density function theory calculation.The molecular polarity and volatility of VOCs species played key roles in adsorption and the dynamic uptakes were generally listed as follows:ethyl acetate>toluene>acetone.As for the above VOCs mixtures,13X zeolite selectively adsorbed oxygenated VOCs rather than toluene.In contrast,USY exhibited a preference to trap toluene.Ethyl acetate could be readily enriched by ZSM-5 and Beta selectively.The possible explanations and implications are discussed based on the subtle change in electron density.The results obtained are vital for understanding the mixture effect of VOCs adsorption and may guide the selection of proper adsorbent for real applications.

关键词： Adsorption Zeolites VOCs Mixture effect DFT

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Sources appointment and health risks of PM_(2.5)-bound trace elements in a coastal city of southeastern China

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Journal of environmental Sciences 2024年第4期138卷 561-571页

作者： Ziyi Lin Xiaolong Fan Gaojie Chen Youwei Hong Mengren Li Lingling Xu Baoye Hu Chen Yang Yanting Chen Zhiqian Shao Jinsheng Chen Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Key Lab of Urban environment and Health Institute of Urban EnvironmentChinese Academy ofSciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China Minnan Normal University Zhangzhou 363000China

To gain a comprehensive understanding of sources and health risks of trace elements in an area of China with high population densities and low PM_(2.5)concentrations,15 trace elements(Al,K,Ca,Ti,V,Cr,Mn,Fe,Ni,Cu,Zn,As,Sn,Ba,Pb)in PM_(2.5)were monitored from December 2020 to November 2021 in a representative city,Xiamen.The concentrations of trace elements in Xiamen displayed an obvious seasonal variation and were dominated by K,Fe,Al,Ca and Zn.Based on Positive Matrix Factorization analysis,source appointment revealed that the major sources of trace elements in Xiamen were traffic,dust,biomass and firework combustion,industrial manufacture and shipping emission.According to health risk assessment combined with the source appointment results,it indicated that the average noncarcinogenic risk was below the threshold and cancer risk of four hazardous metals(Cr,Ni,As,Pb)exceeded the threshold(10^(-6)).Traffic-related source had almost half amount of contribution to the health risk induced by PM_(2.5)-bound trace elements.During the dust transport period or Spring Festival period,the health risks exceeded an acceptable threshold even an order of magnitude higher,suggesting that the serious health risks still existed in low PM_(2.5)environment at certain times.Health risk assessment reminded that the health risk reduction in PM_(2.5)at southeastern China should prioritize traffic-related hazardous trace elements and highlighted the importance of controlling vehicles emissions in the future.

关键词： PM_(2.5)-bound trace elements Seasonal variations Source appointment Health risks Traffic-related source

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Robust prediction of hourly PM2.5 from meteorological data using LightGBM

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National Science Review 2021年第10期8卷 115-126页

作者： Junting Zhong Xiaoye Zhang Ke Gui Yaqiang Wang Huizheng Che Xiaojing Shen Lei Zhang Yangmei Zhang Junying Sun Wenjie Zhang State Key Laboratory of Severe Weather and Key Laboratory of atmospheric Chemistry of China Meteorological Administration Chinese Academy of Meteorological Sciences School of Earth and Planetary Sciences University of Chinese Academy of Sciences Center for Excellence in Regional Atmospheric Environment Institute of Urban Environment Chinese Academy of Sciences

Retrieving historical fine particulate matter(PM2.5) data is key for evaluating the long-term impacts of PM2.5on the environment, human health and climate change. Satellite-based aerosol optical depth has been used to estimate PM2.5, but estimations have largely been undermined by massive missing values, low sampling frequency and weak predictive capability. Here, using a novel feature engineering approach to incorporate spatial effects from meteorological data, we developed a robust Light GBM model that predicts PM2.5at an unprecedented predictive capacity on hourly(R~2= 0.75), daily(R~2= 0.84), monthly(R~2= 0.88) and annual(R~2= 0.87) timescales. By taking advantage of spatial features, our model can also construct hourly gridded networks of PM2.5. This capability would be further enhanced if meteorological observations from regional stations were incorporated. Our results show that this model has great potential in reconstructing historical PM2.5datasets and real-time gridded networks at high spatial-temporal resolutions. The resulting datasets can be assimilated into models to produce long-term re-analysis that incorporates interactions between aerosols and physical processes.

关键词： PM2.5 spatial features hourly prediction high accuracy gridded networks

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