scholarly journals Formation of condensable organic vapors from anthropogenic and biogenic VOCs is strongly perturbed by NO<sub>x</sub> in eastern China

2021 ◽  
Author(s):  
Yuliang Liu ◽  
Wei Nie ◽  
Yuanyuan Li ◽  
Dafeng Ge ◽  
Chong Liu ◽  
...  
Keyword(s):  
Eastern China ◽  
Carbon Number ◽  
Decisive Role ◽  
Urban Atmosphere ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Peroxy Radicals ◽  
Related Factors ◽  
Organic Vapors ◽  
Nighttime Chemistry

Abstract. Oxygenated organic molecules (OOMs) are the crucial intermediates linking volatile organic compounds (VOCs) to secondary organic aerosol (SOA) in the atmosphere, but understandings on the characteristics of OOMs and their formations from VOCs are very limited. Ambient observations of OOMs using recently developed mass spectrometry techniques are still limited, especially in polluted urban atmosphere where VOCs and oxidants are extremely variable and complex. Here, we investigate OOMs, measured by a nitrate-ion-based chemical ionization mass spectrometer at Nanjing in eastern China, through performing positive matrix factorization on binned mass spectra (binPMF). The binPMF analysis reveals three factors about anthropogenic VOCs (AVOCs) daytime chemistry, three isoprene-related factors, three factors about biogenic VOCs (BVOCs) nighttime chemistry, and three factors about nitrated phenols. All factors are influenced by NOx in different ways and to different extents. Over 1000 non-nitro molecules have been identified and then reconstructed from the selected solution of binPMF, and about 72 % of the total signals are contributed by nitrogen-containing OOMs, mostly regarded as organic nitrates formed through peroxy radicals terminated by nitric oxide or nitrate-radical-initiated oxidations. Moreover, multi-nitrates account for about 24 % of the total signals, indicating the significant presence of multiple generations, especially for isoprene (e.g., C5H10O8N2 and C5H9O10N3). Additionally, the distribution of OOMs concentration on carbon number confirm their precursors driven by AVOCs mixed with enhanced BVOCs during summer. Our results highlight the decisive role of NOx on OOMs formation in densely populated areas, and encourage more studies on the dramatic interactions between anthropogenic and biogenic emissions.

scholarly journals Formation of condensable organic vapors from anthropogenic and biogenic volatile organic compounds (VOCs) is strongly perturbed by NO<sub><i>x</i></sub> in eastern China

2021 ◽  
Vol 21 (19) ◽  
pp. 14789-14814
Author(s):  
Yuliang Liu ◽  
Wei Nie ◽  
Yuanyuan Li ◽  
Dafeng Ge ◽  
Chong Liu ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Eastern China ◽  
Carbon Number ◽  
Decisive Role ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Peroxy Radicals ◽  
Related Factors ◽  
Volatile Organic

Abstract. Oxygenated organic molecules (OOMs) are the crucial intermediates linking volatile organic compounds (VOCs) to secondary organic aerosols (SOAs) in the atmosphere, but comprehensive understanding of the characteristics of OOMs and their formation from VOCs is still missing. Ambient observations of OOMs using recently developed mass spectrometry techniques are still limited, especially in polluted urban atmospheres where VOCs and oxidants are extremely variable and complex. Here, we investigate OOMs, measured by a nitrate-ion-based chemical ionization mass spectrometer at Nanjing in eastern China, through performing positive matrix factorization on binned mass spectra (binPMF). The binPMF analysis reveals three factors about anthropogenic VOC (AVOC) daytime chemistry, three isoprene-related factors, three factors about biogenic VOC (BVOC) nighttime chemistry, and three factors about nitrated phenols. All factors are influenced by NOx in different ways and to different extents. Over 1000 non-nitro molecules have been identified and then reconstructed from the selected solution of binPMF, and about 72 % of the total signals are contributed by nitrogen-containing OOMs, mostly regarded as organic nitrates formed through peroxy radicals terminated by nitric oxide or nitrate-radical-initiated oxidations. Moreover, multi-nitrates account for about 24 % of the total signals, indicating the significant presence of multiple generations, especially for isoprene (e.g., C5H10O8N2 and C5H9O10N3). Additionally, the distribution of OOM concentration on the carbon number confirms their precursors are driven by AVOCs mixed with enhanced BVOCs during summer. Our results highlight the decisive role of NOx in OOM formation in densely populated areas, and we encourage more studies on the dramatic interactions between anthropogenic and biogenic emissions.

Composition of ultrafine particles in urban Beijing: Measurement using a thermal desorption chemical ionization mass spectrometer

2021 ◽  
Author(s):  
Xiaoxiao Li ◽  
Yuyang Li ◽  
Michael Lawler ◽  
Jiming Hao ◽  
James Smith ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Thermal Desorption ◽  
Ultrafine Particles ◽  
Chemical Ionization ◽  
Urban Atmosphere ◽  
Ionization Mass ◽  
Radioactive Materials ◽  
Desorption Chemical Ionization ◽  
Wide Range ◽  
Primary Emissions

&lt;p&gt;Ultrafine particles (UFPs) dominate the particle number population in the urban atmosphere and revealing their chemical composition is important. The thermal desorption chemical ionization mass spectrometer (TDCIMS) can semi-continuously measure UFP composition at the molecular level. We modified a TDCIMS and deployed it in urban Beijing. Radioactive materials in the TDCIMS for aerosol charging and chemical ionization were replaced by soft X-ray ionizers so that it can be operated in countries with tight regulations on radioactive materials. Protonated N-methyl-2-pyrrolidone ions were used as the positive reagent ion, which selectively detects ammonia and low-molecular weight-aliphatic amines and amides vaporized from the particle phase. With superoxide as the negative reagent ion, a wide range of inorganic and organic compounds were observed, including nitrate, sulfate, aliphatic acids with carbon numbers up to 18, and highly oxygenated CHO, CHON, and CHOS compounds. The latter two can be attributed to parent ions or the decomposition products of organonitrates and organosulfates/organosulfonates, respectively. Components from both primary emissions and secondary formation of UFPs were identified. Compared to the UFPs measured at forest and marine sites, those in urban Beijing contain more nitrogen-containing and sulfur-containing compounds. These observations illustrate unique features of the UFPs in this polluted urban environment and provide insights into their origins.&lt;/p&gt;

Photooxidation and ozonolysis of Δ3-carene and its oxidation product caronaldehyde in the atmospheric simulation chamber SAPHIR

2021 ◽  
Author(s):  
Luisa Hantschke ◽  
Anna Novelli ◽  
Birger Bohn ◽  
Changmin Cho ◽  
David Reimer ◽  
...  
Keyword(s):  
Oxidation Product ◽  
Boreal Forests ◽  
Oxidation Products ◽  
Organic Nitrate ◽  
Organic Nitrates ◽  
Peroxy Radicals ◽  
Atmospheric Conditions ◽  
Oxidation Reactions ◽  
Reaction Rate Constants ◽  
Simulation Chamber

&lt;p&gt;Of the total global annual monoterpene emissions, &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene contributes 4.5 %, making it the 7&lt;sup&gt;th&lt;/sup&gt; most abundant monoterpene worldwide. As it is primarily emitted by pine trees, &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene can regionally gain in importance, for example in boreal forests and Mediterranean regions.&amp;#160; Oxidation products of monoterpenes such as organic nitrates and aldehydes are known to impact the formation of secondary pollutants such as ozone and particles, so understanding their atmospheric formation and fate is crucial.&lt;/p&gt;&lt;p&gt;The photooxidation and ozonolysis of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene and the photooxidation and photolysis of its main daytime photooxidation product caronaldehyde were investigated in the atmospheric simulation chamber SAPHIR. Oxidation reactions were studied under atmospheric conditions with high (&gt; 8 ppbv) and low (&lt; 2 ppbv) NOx concentrations. Reaction rate constants of the reaction of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene with OH and O&lt;sub&gt;3&lt;/sub&gt;, and of the reaction of caronaldehyde with OH as well as photolysis frequencies of caronaldehyde were determined. Production and destruction rates of the sum of hydroxyl and peroxy radicals (ROx = OH+HO2+RO2) were analysed to determine if there were unaccounted production and loss processes of radicals in the oxidation of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene. The yield of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene&amp;#8217;s oxidation product caronaldehyde was determined from measured timeseries from OH photooxidation and ozonolysis experiments. Additionally, the OH yield from ozonolysis of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene was determined.&lt;/p&gt;&lt;p&gt;Organic nitrate (RONO&lt;sub&gt;2&lt;/sub&gt;) yields of the reaction of RO&lt;sub&gt;2&lt;/sub&gt; + NO, from RO&lt;sub&gt;2&lt;/sub&gt; produced from the reactions of &amp;#916;&lt;sup&gt;3&lt;/sup&gt;-carene and caronaldehyde with OH were determined by analyzing the reactive nitrogen species (NOy) in the chamber.&lt;/p&gt;

Unexpected Fast Monoterpene Oxidation In Eastern China

2021 ◽  
Author(s):  
Haichao Wang
Keyword(s):  
Eastern China ◽  
Field Measurements ◽  
Ozone Production ◽  
Nitrate Radical ◽  
Peroxy Radicals ◽  
Ozone Pollution ◽  
Volatile Organic ◽  
Secondary Aerosols ◽  
Photochemical Ozone

&lt;p&gt;Monoterpene plays an important role in the formation of secondary aerosols and ozone in the troposphere. However, the field characterization of monoterpene chemistry in ozone pollution is still very sparse. Here we report fast daytime oxidation of monoterpene by hydroxyl radical, nitrate radical and ozone based on field measurements in Eastern China. We find fast monoterpene oxidation produces peroxy radicals efficiently and enhances the photochemical ozone production largely with an additional 8.6 ppb of ozone production per day on average (14%), whose effect was even more important than that of isoprene chemistry in the analyzed dataset. We propose that the reduction of anthropogenic volatile organic compounds should be much more stringent in the presence of high monoterpenes to alleviating ozone pollution.&lt;/p&gt;

n-Alkanes and compound carbon isotope records from Lake Yiheshariwusu in the Hulun Buir sandy land, northeastern China

The Holocene ◽  
2020 ◽  
Vol 30 (10) ◽  
pp. 1451-1461
Author(s):  
Manman Xie ◽  
Qing Sun ◽  
Haowei Dong ◽  
Siwen Liu ◽  
Wenyu Shang ◽  
...  
Keyword(s):  
Time Series ◽  
Carbon Isotope ◽  
Summer Monsoon ◽  
Monsoon Rainfall ◽  
Eastern China ◽  
Carbon Number ◽  
C3 Plants ◽  
Sandy Land ◽  
The Holocene ◽  
Effective Precipitation

The Hulun Buir sandy land in northern China is located at the northern limit region of the East Asian summer monsoon (EASM) and is therefore sensitive to the extension of the front of the rainfall belt. Here we report an n-alkane and compound-specific carbon isotope record from the Holocene sediments of Lake Yiheshariwusu in the middle of the Hulun Buir sandy land. The sediments contain a suite of n-alkanes with a strong odd over even carbon number predominance, with the maximum contribution from nC31, which is a typical distribution in grassland regions. The low temperatures in this cold region greatly limit the growth of C4 plants and thus the long-chain n-alkanes in lake sediments are mainly derived from leaf wax lipids of C3 plants growing within the sandy land. In this C3-vegetation-dominated region, the δ13C27–33 value (weighted carbon isotope values of nC27– nC33) are regulated mainly by the physiological and biochemical responses of plants to water stress and are therefore interpreted as a proxy of effective precipitation or humidity. The δ13C27–33 time series shows a trend of gradually decreasing values that suggests an increase in effective precipitation since 8.5 ka (1 ka = 1000 cal yr BP). Relative droughts occurred during the intervals of 6.3–5.5, 4.1–3.6 ka, and during the last 200 years. In addition, the δ13C27–33 time series and comparable paleoenvironmental records from neighboring sites suggest opposite trends of summer monsoon rainfall between northeastern and southeastern China. We suggest that a coupled process between low and high latitudes (the western Pacific Subtropical High and the Okhotsk High) may have played a fundamental role in regulating the shift of the frontal rainfall belt and monsoon rainfall distribution in eastern China during the Holocene.

scholarly journals Characterization of nighttime formation of particulate organic nitrates based on high-resolution aerosol mass spectrometry in an urban atmosphere in China

2018 ◽  
Author(s):  
Kuangyou Yu ◽  
Qiao Zhu ◽  
Ke Du ◽  
Xiao-Feng Huang
Keyword(s):  
High Resolution ◽  
Factorization Method ◽  
Urban Atmosphere ◽  
Ozone Production ◽  
Urban Site ◽  
High Time Resolution ◽  
Organic Nitrates ◽  
Aerosol Mass ◽  
Polluted Atmosphere

Abstract. Organic nitrates are important atmospheric species that significantly affect the cycling of NOx and ozone production. However, characterization of particulate organic nitrates and their sources in inorganic nitrate-abundant particles in polluted atmosphere is a big challenge, and has been little performed in the literature. In this study, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site in South China from 2015 to 2016 to characterize particulate organic nitrates with high time resolution. Based on two different data processing methods, 13–21 % of the total measured nitrates was identified to be organic nitrates in spring, 41–64 % in summer and 16%–25 % in autumn; however, in winter, most measured nitrates were inorganic. The good correlation between organic nitrates and fresh secondary organic aerosol identified by the positive matrix factorization method at night rather than in the daytime indicated a potentially important role of nighttime secondary formation. Therefore, we theoretically estimated nighttime NO3 radical concentrations and SOA formation using the various VOCs measured simultaneously. Consequently, the calculated products of monoterpene reacting with NO3 agreed well with the organic nitrates in terms of both concentration and variation, suggesting that the biogenic VOC reactions with NO3 at night are the dominant formation pathway for particulate organic nitrates in polluted atmosphere, despite of much higher abundance of anthropogenic VOCs.

scholarly journals Determination of Semivolatile Organic Nitrates in Ambient Atmosphere by Gas Chromatography/Electron Ionization–Mass Spectrometry

Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 88 ◽  
Author(s):  
Rui Li ◽  
Xiaotong Jiang ◽  
Xinfeng Wang ◽  
Tianshu Chen ◽  
Lin Du ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Analytical Techniques ◽  
Electron Ionization ◽  
Electron Ionization Mass Spectrometry ◽  
Ionization Mass Spectrometry ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Ambient Atmosphere ◽  
Characteristic Fragment

Semivolatile organic nitrates (SVONs) contribute a large proportion of total organic nitrates and play an important role in the tropospheric chemistry. However, the composition and concentrations of SVONs in the atmosphere remain unclear due to the lack of reliable analytical techniques for specific organic nitrates. In this study, a method based on gas chromatography and electron ionization–mass spectrometry was developed to detect ambient SVONs that were collected via polyurethane foam disk enrichment. Three SVONs were identified in the semivolatile samples from urban Jinan during spring based on the characteristic fragment ions of [NO2]+ and [CH2NO3]+ and the characteristic fragment loss of NO2 and NO3: 1-pentyl nitrate (molecular weight [MW] = 133), 4-hydroxy-isoprene nitrate (MW = 147), and (3,4)-di-hydroxy-isoprene nitrate (MW = 163). The latter two isoprene nitrates were rarely detected in the real atmosphere in previous studies. The contents of 1-pentyl nitrate, 4-hydroxy-isoprene nitrate, and (3,4)-di-hydroxy-isoprene nitrate were roughly quantified based on the standard of 1-pentyl nitrate, with a detection limit of 50 μg L−1. In addition, Fourier transform infrared spectrometry was used to determine the total SVONs content. The average concentrations of 1-pentyl nitrate, 4-hydroxy-isoprene nitrate, (3,4)-di-hydroxy-isoprene nitrate, and total SVONs in Jinan during spring were 20.2 ± 7.2, 13.2 ± 7.2, 36.5 ± 8.4, and 380.0 ± 190.8 ng m−3, respectively. The three identified SVONs contributed only 20.2 ± 5.5% to the total SVONs, which suggests that some unidentified SVONs are present in the ambient atmosphere and that studies with improved or advanced analytical techniques will be required to identify them.

scholarly journals Prevalence and Related Factors for Myopia in School-Aged Children in Qingdao

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Jin Tao Sun ◽  
Meng An ◽  
Xiao Bo Yan ◽  
Guo Hua Li ◽  
Da Bo Wang
Keyword(s):  
Technological Development ◽  
Eastern China ◽  
Outdoor Activity ◽  
Related Factors ◽  
Development Zone ◽  
Logistic Regression Models ◽  
Adolescent Students ◽  
School Aged Children ◽  
Eye Examination ◽  
Near Work

Purpose. To investigate the prevalence and related factors for myopia in school-aged children in the Economic and Technological Development Zone of Qingdao, Eastern China. Methods. A total of 4890 (aged 10 to 15 years) students were initially enrolled in this study. 3753 (76.75%) students with completed refractive error and questionnaire data were analyzed. The children underwent a comprehensive eye examination. Multiple logistic regression models were applied to assess possible factors associated with myopia. Results. The prevalence of myopia increased as the children’s grade increased (χ2=560.584, P<0.001). Low myopia was the main form of myopia in adolescent students (30.22%). With the growth of age, students spent significantly more time on near work (P=0.03) and less time on outdoor activity (P<0.001). In multivariate models, only the following variables were significantly associated with myopia: age, two myopic parents, outdoor activity time, and continuous near work without 5 min rest. Conclusions. The prevalence of myopia increased as the grade increased. Age, two myopic parents, and continuous near work time without 5 min rest were risk factors for myopia. Outdoor activities had protective effect for myopia.

scholarly journals Oxygenated products formed from OH-initiated reactions of trimethylbenzene: Autoxidation and accretion

2020 ◽  
Author(s):  
Yuwei Wang ◽  
Archit Mehra ◽  
Jordan E. Krechmer ◽  
Gan Yang ◽  
Xiaoyu Hu ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Mass Spectrometer ◽  
Chemical Ionization ◽  
Flow Reactor ◽  
Time Of Flight ◽  
Oxidation Products ◽  
Urban Atmosphere ◽  
Reaction Pathways ◽  
Peroxy Radicals ◽  
Flight Mass Spectrometer

Abstract. Gas-phase oxidation pathways and products of anthropogenic volatile organic compounds (VOCs), mainly aromatics, are the subject of intensive research with attention paid to their contributions to secondary organic aerosol (SOA) formation and potentially, new particle formation (NPF) in the urban atmosphere. In this study, a series of OH-initiated oxidation experiments of trimethylbenzene (TMB, C9H12) including 1,2,4-TMB, 1,3,5-TMB, 1,2,3-TMB, and 1,2,4-(methyl-D3)-TMBs (C9H9D3) were investigated in an oxidation flow reactor (OFR), in the absence and presence of NOx. Products were measured using a suite of state-of-the-art instruments, i.e., a nitrate-based chemical ionization – atmospheric pressure interface time-of-flight mass spectrometer (Nitrate CI-APi-TOF), an iodide-adduct chemical ionization – time-of-flight mass spectrometer (Iodide CI-TOF) equipped with a Filter Inlet for Gases and AEROsols (FIGAERO), and a Vocus proton-transfer-reaction mass spectrometer (Vocus PTR). A large number of C9 products with 1–11 oxygen atoms and C18 products presumably formed from dimerization of C9 peroxy radicals were observed, hinting the extensive existence of autoxidation and accretion reaction pathways in the OH-initiated oxidation reactions of TMBs. Oxidation products of 1,2,4-(methyl-D3)-TMBs with deuterium atoms in different methyl substituents were then used as a molecular basis to propose potential autoxidation reaction pathways. Accretion of C9 peroxy radicals is the most significant for aromatics with meta-substituents and the least for aromatics with ortho-substituents, if the number and size of substituted groups are identical. The presence of NOx would suppress the formation of C18 highly oxygenated molecules (HOMs) and enhance the formation of organonitrates, and even dinitrate organic compounds. Our results show that the oxidation products of TMB are much more diverse and could be more oxygenated than the current mechanisms predict.

scholarly journals Chinese SO<sub>2</sub> pollution over Europe – Part 1: Airborne trace gas measurements and source identification by particle dispersion model simulations

2009 ◽  
Vol 9 (1) ◽  
pp. 1377-1405 ◽  
Author(s):  
V. Fiedler ◽  
R. Nau ◽  
S. Ludmann ◽  
F. Arnold ◽  
H. Schlager ◽  
...  
Keyword(s):  
Source Identification ◽  
Dispersion Model ◽  
Eastern China ◽  
Particle Dispersion ◽  
Ionization Mass ◽  
Model Simulations ◽  
The North ◽  
Transport Experiment ◽  
Research Aircraft ◽  
Gas Measurements

Abstract. A large SO2-rich pollution plume of Chinese origin was detected by aircraft based CIMS (Chemical Ionization Mass Spectrometry) measurements at 3–7.5 km altitude over the North Atlantic on 3 May 2006 during the INTEX (Intercontinental Chemical Transport Experiment) campaign. Additional trace gases (NO, NOy, CO, H2O) were measured and used for comparison and source identification. All measurements took place aboard the German research aircraft Falcon. The atmospheric SO2 mole fraction was markedly increased inside the plume and reached up to 900 pmol/mol. The measured ratio SO2/NOy of 1.4 suggests combustion of coal or fuel with a very high sulfur content as a source of the excess SO2. Accompanying FLEXPART particle dispersion model simulations indicate that the probed pollution plume originated at low altitudes over densely populated and industrialized areas in eastern China about 8–12 days prior to the measurements.

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