O3 Formation Research Articles

VOCs sources and roles in O3 formation in the central Yangtze River Delta region of China

Surface ozone (O3) pollution has become a prominent air quality problem in the Yangtze River Delta (YRD) region of China in recent years. Since O3 is non-linearly related to its precursors (volatile organic compounds (VOCs), nitrogen oxides (NOx)), identifying the characteristics of VOCs is significant for the control of O3 pollution. In this study, online observation of ambient VOCs from August to October 2018 was conducted at 2 sites in Changzhou, an industrial city located in the central YRD region, to investigate the O3 pollution characteristics, sources of VOCs, and their roles in O3 formation. The average concentration of VOCs in Changzhou during the observational period was 39.52 ± 23.14 ppb. Alkanes, oxygenated VOCs (OVOCs), and halocarbons were the main contributors to the total VOCs concentration, with the average relative contributions of 39.4%, 23.1%, and 16.1%, respectively. An observation-based model (OBM) was used to investigate the sensitivity of O3 formation to VOCs and NOx. Results of relative incremental reactivity (RIR) of individual VOC and empirical kinetics modeling approach (EKMA) showed that the O3 formation in Changzhou was within the VOCs-limited regime. Anthropogenic VOCs with the largest RIR values were xylenes and propene, respectively. The positive matrix factorization (PMF) model was applied to quantitatively identify the sources of VOCs. Six factors were resolved, including vehicle exhaust, gasoline evaporation, paint and solvent usage, electronic manufacturing, petrochemical industry, and biogenic source & secondary formation. The average relative contribution of traffic-related emissions to the total VOCs mass concentration was about 49.5%, followed by electronic manufacturing (22.9%), paint and solvent usage (14.7%), and petrochemical industry (7.1%). The average relative contributions of individual sources for xylenes and propene were further compared. Xylenes were mainly emitted from paint and solvent usage (60%), electronic manufacturing (17%), and vehicle exhaust (16%). Petrochemical industry (67%) and vehicle exhaust (30%) were the major sources of propene. Therefore, VOCs from industrial emissions and traffic-related emissions should be given priority for the control of O3 pollution in the central YRD region.

Heterogeneous catalytic reaction of NO2 to HONO on hematite

The heterogenous catalytic reactions of NO2 on mineral dusts represent one of the important sources of HONO that promote the formation of O3 and other air pollutants, but the mechanism is poorly understood. First principles calculations, including a Hubbard-like +U correction and a dispersion correction, were employed to investigate the heterogeneous interaction of NO2 on the hematite (0001) surface. The competitive adsorption between the most common gas molecules in polluted air (NO2, CO, SO2, O3, H2O, O2, and N2) were also investigated. Under dry conditions, the (NO3δ−)(NOδ+) intermediate species can transform into surface NO3 and gaseous NO. Under wet conditions, the simulations predicted the production of HONO and HNO3 through the hydrolysis of NO2 via (NO3δ−)(NOδ+). Adsorption energies show that the surface Fe site provides strong interactions. Charge transfer occurs from the Fe atom to the adsorbate molecules. This study may facilitate the understanding of the transformations of the atmospheric gas pollutants on naturally occurring mineral dust aerosols. The heterogenous reaction may impact on global atmospheric chemistry.

Ozone Formation at a Suburban Site in the Pearl River Delta Region, China: Role of Biogenic Volatile Organic Compounds

Ozone (O3) is becoming an increasingly concerning air quality problem in China, and previous O3 control strategies focused primarily on reducing anthropogenic volatile organic compounds (AVOCs), while neglecting the role of biogenic VOCs (BVOCs) in O3 formation. In this study, a field campaign was conducted at a suburban site in the Pearl River Delta region of China with high BVOC emissions from 29 August to 3 September 2020. An empirical kinetic modelling approach (EKMA) showed that VOC-limited was the dominant feature for O3 formation at the site. The relative incremental reactivity (RIR) values calculated by the box model (AtChem2-MCM) revealed that isoprene, formaldehyde, methylglyoxal and acetaldehyde had the highest RIRs. Simulation results from the box model also showed that isoprene played a substantial role in the formation of secondary carbonyls, especially contributing 32–92% to the formaldehyde production rate. Box model simulations further showed that during the O3 pollution period with high BVOC emissions, only near zero AVOC emissions could prevent O3 if the levels of nitrogen oxides (NOx) remained unchanged. The results suggest that the presence of high BVOC emissions can greatly impact efforts to control O3 by reducing AVOCs, particularly in regions with relatively high NOx levels (up to 51 ppbv in this study). In the long term, it may be essential to control NOx and choose low BVOC-emitting tree species in urban planning to address this issue, particularly as BVOC emissions are projected to become a more significant source of reactive VOCs with enhanced control of AVOCs.

Biogenic emissions-related ozone enhancement in two major city clusters during a typical typhoon process

Typhoons could influence air quality via multiple chemical and physical process and has attracted much scientific attention. A typical typhoon, In-Fa, passed through Yangtze River Delta (YRD) and Jing-Jin-Ji (JJJ) after it made a landfall in China. Under such influences, two city clusters both experienced high ozone (O3) concentrations, with JJJ about 5 days earlier than YRD. Data from several environmental monitoring sites and three regional sites indicated that cross-regional transport and biogenic emissions both played an important role in O3 formation. During the typhoon process, O3 precursors were first transported from YRD and its surrounding areas to JJJ due to the summer monsoon. After that, air masses from northern China returned to YRD due to the peripheral winds of the typhoon. High O3 was concentrated in downwind regions, causing fast secondary formation. The peripheral winds and downdrafts of typhoon led to high temperature and stagnant weather, favorable for biogenic emissions. Observed isoprene concentration was doubled. The ratio of isoprene to VOCs also increased by around 5%. The modeling results showed the contribution of BVOCs to O3 could reach 10 ppb in JJJ when the typhoon made its landfall in YRD. When the typhoon moved to JJJ, the cross-transport of air masses from northern China to YRD contributed half of biogenic-emission-related O3. Our research extends the knowledge into the importance of biogenic emissions to O3 and cross-regional transport during a typhoon process.

Identification of the roles of urban plume and local chemical production in ozone episodes observed in Long Island Sound during LISTOS 2018: Implications for ozone control strategies

Long Island Sound (LIS) frequently experiences ozone (O3) exceedance events that surpass national ambient air quality standards (NAAQS) due to complex driving factors. The underlying mechanisms governing summertime O3 pollution are investigated through collaborative observations from lidar remote sensing and ground samplers during the 2018 LIS Tropospheric O3 Study (LISTOS). Regional transport and local chemical reactions are identified as the two key driving factors behind the observed O3 episodes in LIS. An enhanced laminar structure is observed in the O3 vertical structure in the atmospheric boundary layer (i.e., 0–2 km layer) for the case dominated by regional transport. An O3 formation regime shift is found in ozone-precursor sensitivity (OPS) for the O3 exceedance event dominated by regional transport with NOx-enriched air mass transport from the New York City (NYC) urban area to LIS. Furthermore, the Integrated Process Rate (IPR) analysis demonstrates that transport from the NYC urban area contributed 40% and 27.1% of surface O3 enhancement to the cases dominated by regional transport and local production, respectively. This study provides scientific evidence to uncovers two key processes that govern summertime O3 pollution over LIS and can help to improve emission control strategies to meet the attainment standards for ambient O3 levels over LIS and other similar coastal areas.

Determination of the apparent effective ionization coefficient in mixtures of He and O2 using steady-state Townsend discharge: effect of penning ionization and attachment

He:O2 gas mixtures are popular in many non-thermal plasma applications because of the good thermal conductivity of He and high production of reactive oxygen species. The applications utilizing reactive oxygen species, in particular, applications in biomedicine require accurate knowledge of the fundamental ionization parameters of gases such as the ionization coefficient. This study was focused on experimental determination of the reduced apparent effective ionization coefficient α ea /N in He:O2 mixtures. Experiments were conducted in the absolute pressure range of 10–800 Torr and reduced electric field E/N range of 40–1000 Td utilizing a steady-state non-self-sustaining Townsend discharge. Experimental results were compared with a theoretical model which was based on BOLSIG + calculation of ionization and attachment coefficients and additionally considered the ion conversion of O− to O2 −, detachment from O2 − and formation of O3 − and Penning ionization by He metastable species. The measurements agreed reasonably well with model calculations. Comparison with model suggest that He metastable species affect net ionization in He:O2 mixtures with O2 concentrations up to 10% often encountered in the applications and thus should be included in models of atmospheric pressure plasmas. The attachment of electrons became important at O2 concentrations above 10% and is therefore less important in most applications.

Hydrogen-Rich Pyrolysis from Ni-Fe Heterometallic Schiff Base Centrosymmetric Cluster Facilitates NiFe Alloy for Efficient OER Electrocatalysts.

Binary metal nickel-iron alloys have been proven to have great potential in oxygen evolution reaction (OER) electrocatalysis, but there are still certain challenges in how to construct more efficient nickel-iron alloy electrocatalysts and maximize their own advantages. In this work, a heterometallic nickel-iron cluster (L=C64 H66 Fe4 N8 Ni2 O19 ) of Schiff base (LH3 =2-amino-1,3-propanediol salicylaldehyde) is designed as a precursor to explore its behavior in the pyrolysis process under inert atmosphere. The combination of TG-MS, morphology, and X-ray characterization techniques shows that the Schiff base ligands in the heterometallic clusters produces a strong reductive atmosphere during pyrolysis, which enable the two 3d metals Ni and Fe to form NiFe alloys. Moreover, Fe2 O3 /Fe0.64 Ni0.36 @Cs carbon nanomaterials are formed, in which Fe2 O3 /Fe0.64 Ni0.36 is the potential active material for OER. It is also found that the centrosymmetric structure of the heterometallic Schiff base precursor is potentially related to the formation of the Fe2 O3 /Fe0.64 Ni0.36 alloy@carbon structures. The Fe2 O3 /Fe0.64 Ni0.36 @C-800 provides 274mV overpotential in 1m KOH solution at 10mAcm-2 in OER. This work provides an effective basis for further research on Schiff base bimetallic doping-derived carbon nanomaterials as excellent OER electrocatalysts.

Identifying the airport as a key urban VOC source in the Pearl River Delta, China

Volatile organic compounds (VOCs) are the main precursors of ozone (O3) and secondary organic aerosol (SOA) formation in the atmosphere. The traditional positive matrix factorization (PMF) source apportionment method is mainly based on the time series of VOCs at a single site, and its results cannot indicate the difference spatially. In this study, a refined spatial distribution study was carried out in Shenzhen in the Pearl River Delta (PRD) region, China, with 110 sampling sites covering the city. Ninety-two VOC compounds were quantitatively analyzed and the spatial distribution characteristics of various VOCs were obtained. Based on the PMF source apportionment of multisite samples, five types of sources and their spatial distributions of vehicle exhaust, gasoline leakage, industrial processes, airport-related sources and regional transport were identified. The airport source was resolved for the first time in the VOC source apportionment and was further verified by the measured source spectra in the airport. It is found that the airport-related sources accounted for 19% of the ambient VOC concentrations in Shenzhen and had strong Cl radical reaction activity, indicating that the airport-related sources may have a greater impact on O3 and SOA formation in coastal cities than previously expected.

Weekend-weekday variations, sources, and secondary transformation potential of volatile organic compounds in urban Zhengzhou, China

Periodical changes of human activities cause weekend-weekday differences of volatile organic compounds (VOCs) and nitrogen oxides (NO + NO2 = NOx) emissions, which induce urban ozone (O3) pollution and secondary organic aerosol (SOA) in fine particulate (with aerodynamic diameters ≤2.5 μm; PM2.5). However, influences of weekend-weekday differences in primary emissions on the production of secondary pollutants remain unknown. The TROPOspheric Monitoring Instrument and surface observations are carried to simultaneously monitor VOCs, NO2, O3, and PM2.5 concentrations in urban Zhengzhou, China during the weekend and the weekday. Reductions in anthropogenic activities result in atmospheric VOCs and NO2 reductions during the weekend. The ratios of formaldehyde columns to NO2 columns during the weekend afternoon and the weekday afternoon (0.53 and 0.39, respectively) are less than 2.30, indicating the O3 formation under the VOC-limited regime. Lower total VOCs (TVOCs) mixing ratios but higher ratios of TVOCs mixing ratios to NO2 mixing ratios during the weekend afternoon perform faster photochemical O3 production. In contrast, higher TVOCs mixing ratios are responsible for higher SOA formation during the weekday. Based on the positive matrix factorization model and VOCs reactivities, solvent usage, vehicle exhaust, and industrial sources are majorly responsible for SOA (80.1%) and O3 (79.9%) formation potential. To reduce O3 concentrations during the weekend and SOA concentrations during the weekday collaboratively, solvent, vehicle, and industrial activities should be transformed from weekday to weekend.

Emission characteristics, environmental impact assessment and priority control strategies derived from VOCs speciation sourcely through measurement for wooden furniture-manufacturing industry in China

Volatile organic compounds (VOCs) from wooden furniture-manufacturing industry is an important emission source. The VOC content levels, source profiles, emission factors and inventories, O3 and SOA formation, and priority control strategies were investigated from the source. One hundred sixty-eight representative woodenware coatings were sampled, and VOC species and contents were determined. The VOC, O3 and SOA emission factors per gram of coatings for three types of woodenware coatings were quantified. The total VOC, O3 and SOA emissions from wooden furniture-manufacturing industry in 2019 were 976,976 t/a, 2,840,282 t/a, 24,970 t/a, and solvent-based coatings accounted for 98.53 %, 99.17 % and 99.6 % of the total VOC, O3 and SOA emissions, respectively. Aromatics and esters were major organic groups, contributing 49.80 % and 36.03 % to total VOC emissions, respectively. Aromatics contributed 86.14 % and 100 % to total O3 and SOA emissions, respectively. The top 10 species contributing to VOC, O3 and SOA had been identified. Four benzene series, including o-Xylene, m-Xylene, toluene and ethylbenzene, were ranked as the first-class priority control species, accounting for 85.90 % and 99.89 % of the total O3 and SOA, respectively. Priority should be given to solvent-based coatings, aromatics and four benzene series for future O3 and SOA reduction for wooden furniture-manufacturing industry.

Integrating ambient carbonyl compounds provides insight into the constrained ozone formation chemistry in Zibo city of the North China Plain

Quantifying the impact of carbonyl compounds (carbonyls) on ozone (O3) photochemical formation is crucial to formulating targeted O3 mitigation strategies. To investigate the emission source of ambient carbonyls and their integrated observational constraint on the impact of O3 formation chemistry, a field campaign was conducted in an industrial city (Zibo) of the North China Plain from August to September 2020. The site-to-site variations of OH reactivity for carbonyls were in accordance with the sequence of Beijiao (BJ, urban, 4.4 s−1) > Xindian (XD, suburban, 4.2 s−1) > Tianzhen (TZ, suburban, 1.6 s−1). A 0-D box model (MCMv3.3.1) was applied to assess the O3-precursor relationship influenced by measured carbonyls. It was found that without carbonyls constraint, the O3 photochemical production of the three sites was underestimated to varying degrees, and the biases of overestimating the VOC-limited degree were also identified through a sensitivity test to NOx emission changes, which may be associated with the reactivity of carbonyls. In addition, the results of the positive matrix factorization (PMF) model indicated that the main source of aldehydes and ketones was secondary formation and background (81.6% for aldehydes, 76.8% for ketones), followed by traffic emission (11.0% for aldehydes, 14.0% for ketones). Incorporated with the box model, we found that biogenic emission contributed the most to the O3 production at the three sites, followed by traffic emission as well as industry and solvent usage. Meanwhile, the relative incremental reactivity (RIR) values of O3 precursor groups from diverse VOC emission sources featured consistencies and differences at the three sites, which further highlights the importance of the synergetic mitigation of target O3 precursors at regional and local scales. This study will help to provide targeted policy-guiding O3 control strategies for other regions.

Impacts of Agricultural Soil NOx Emissions on O3 Over Mainland China

AbstractRegional ozone (O3) pollution has currently become an urgent air pollution problem in China. Nitrogen oxides (NOX) are key precursor pollutants for O3 formation. However, pollution control policies have generally neglected or simplified the impacts of soil NOX emissions in rural regions. This study aims to evaluate the effect of soil NOX emissions on O3 in agricultural areas of China based on high‐resolution soil NOX emission inventory and the WRF‐Chem air quality model. We first validate the simulation result of the O3 concentration with surface O3 observations over China using the selected optimal physicochemical scheme. After that, four scenarios are designed to simulate and analyze the regional sensitivity of O3 to soil NOX emissions and to quantify the effect of soil NOX emissions on O3 concentration. The results indicate that as soil NOX emissions increase, the overall spatial pattern does not change notably over mainland China, but the O3 concentration increases remarkably in the northwest and northeast of China. Additionally, we discover that changes of O3 concentration across mainland China differ substantially among regions. Our results highlight the effect of soil NOX emissions on air quality in agricultural areas. The control of O3 pollution in China should take into account the comprehensive consequences of various emission sources, as well as their regional differences.

Significant impact of VOCs emission from coking and coal/biomass combustion on O3 and SOA formation in taiyuan, China

Volatile organic compounds (VOCs) are the significant precursors of ozone (O3) and secondary organic aerosols (SOA) in fine particles (PM2.5). To effectively control O3 and PM2.5 pollution, VOCs were measured in Taiyuan during the prevailing seasons of pollution: summer (July 16 to 29), autumn (October 21 to November 5), and winter (December 26, 2021, to January 4, 2022). The highest total VOC (TVOC) concentrations were observed in winter (30.62 ± 14.81 ppbv), followed by autumn (25.98 ± 12.83 ppbv) and summer (11.43 ± 8.01 ppbv). Alkanes and alkenes were the dominant species, which together accounted for 78.35%–85.35% of TVOC concentration during the observation period. The ozone formation potential (OFP) and secondary organic aerosol production potential (SOAP) were used to estimate the contribution of VOC species and sources to O3 and SOA production. Alkenes were the dominant contributor to OFP, accounting for 71.88%–80.82%, while aromatics were the primary contributor to SOAP, accounting for 92.66%–96.14%. Based on the positive matrix factorization (PMF) model results, coking sources (21.89%) and coal/biomass combustion (22.86%) were not only the major VOC sources during the observation, but also contributed significantly to OFP (64.16%–81.38%) and SOAP (57.09%–75.28%), respectively. According to the potential source area of TVOC, and the VOCs, OFP and SOAP concentration of each source under different trajectories, VOC contributions were increasingly coming from the coking sources and coal/biomass combustion in local and southwest of Taiyuan. Consequently, it is essential to control the VOC emissions from coking sources and coal/biomass combustion in local and southwest regions to alleviate PM2.5 and O3 pollution in Taiyuan.

Quantitative evidence from VOCs source apportionment reveals O3 control strategies in northern and southern China

Ground-level ozone (O3) pollution has received widespread attention because its rising trend and adverse ecological impacts. However, the extremely strong photochemical reactions of its precursor volatile organic compounds (VOCs) increase the difficulty of reducing VOCs emissions to alleviate O3. Here, we carried out a one-year comprehensive observation in two representative cities, Tianjin (TJ, Northern China) and Guangzhou (GZ, Southern China). By revealing the concentration characteristics of three different types of VOCs, i.e., initial VOCs without photochemical reaction (In-VOCs), consumed VOCs (C-VOCs), and measured VOCs after the reaction (M-VOCs), we elucidated the important role of C-VOCs in the formation of O3. Although the overall trends were similar in both cities, the average concentration level of VOCs in GZ was 8.2 ppbv higher than that in TJ, and the photochemical loss of VOCs was greater by 2.2 ppbv. In addition, various drivers affecting O3 generation from C-VOCs were specifically explored, and it was found that most alkenes of TJ were key substances for rapid O3 formation compared to aromatics of GZ. Meanwhile, favorable meteorological conditions such as high temperature (T > 31 °C in TJ, and T > 33 °C in GZ), low relative humidity (56% in TJ and 45% in GZ), and stable atmospheric environment (proper pressure and gentle wind speed) also contribute to the generation of O3. More importantly, we combined chemical kinetics and receptor model to quantify the three-type VOCs source contributions and assess the potential impact of C-VOCs sources on O3 production, thus proposing environmental abatement technologies corresponding to the three types of VOCs. The differences in the comparison results of the three-type VOCs highlight the need to reduce O3 pollution from C-VOCs sources, which provides insights for future clean air policies development.

Decadal Application of WRF/Chem under Future Climate and Emission Scenarios: Impacts of Technology-Driven Climate and Emission Changes on Regional Meteorology and Air Quality

This work presents new climate and emissions scenarios to investigate changes on future meteorology and air quality in the U.S. Here, we employ a dynamically downscaled Weather Research and Forecasting model coupled with chemistry (WRF/Chem) simulations that use two Intergovernmental Panel on Climate Change scenarios (i.e., A1B and B2) integrated with explicitly projected emissions from a novel Technology Driver Model (TDM). The projected 2046–2055 emissions show widespread reductions in most gas and aerosol species under both TDM/A1B and TDM/B2 scenarios over the U.S. The WRF/Chem simulations show that under the combined effects of the TDM/A1B climate and emission changes, the maximum daily average 8-h ozone (MDA8 h O3) increases by ~3 ppb across the U.S. mainly due to widespread increases in near-surface temperature and background methane concentrations, with some contributions from localized TDM emission changes near urban centers. For the TDM/B2 climate and emission changes, however, the MDA8 h O3 is widely decreased, except near urban centers where the relative TDM emission changes and O3 formation regimes leads to increased O3. The number of O3 exceedance days (i.e., MDA8 h O3 > 70 ppb) for the entire domain is significantly reduced by a grid cell maximum of up to 43 days (domain average ~0.5 days) and 62 days (domain average ~2 days) for the TDM/A1B and TDM/B2 scenarios, respectively, while in the western U.S., larger O3 increases lead to increases in nonattainment areas, especially for the TDM/A1B scenario. The combined effects of climate and emissions (for both A1B and B2 scenarios) will lead to widespread decreases in the daily 24-h average (DA24 h) PM2.5 concentrations, especially in the eastern U.S. (max decrease up to 93 µg m−3). The PM2.5 changes are dominated by decreases in anthropogenic emissions for both the TDM/A1B and TDM/B2 scenarios, with secondary effects on decreasing PM2.5 from climate change. The number of PM2.5 exceedance days (i.e., DA24 h PM2.5 > 35 µg m−3) is significantly reduced over the eastern U.S. under both TDM/A1B and B2 scenarios, which suggests that both climate and emission changes may synergistically lead to decreases in PM2.5 nonattainment areas in the future.

Classification of ozone pollution and analysis of meteorological factors in the Yangtze River Delta

ABSTRACT Serious regional ozone (O3) pollution often plagues the Yangtze River Delta (YRD). The formation mechanism of these regional pollution events, including the meteorological and emission factors leading to these pollution events and how to affect the distribution of O3, still needs further research and exploration. In this study, we first define the standard of O3 regional pollution in the YRD, and then select 248 regional pollution cases from 2015 to 2020 according to the defined standard. For the pollution cases in pollution months (May and June), PCT (principal component analysis in T-mode) classification method is used to classify the ozone concentration distribution in YRD area. The regional distribution of the O3 concentrations in the YRD is divided into five types, and the overall type (Type 1) accounts for 15%, which is related to the control of YRD area by high-pressure center. Under the control of high pressure, the weather is sunny with the high temperature, and this weather condition is favorable for ozone generation and intercity transmission, causing extensive pollution. The double center type (Type 2) accounts for 8%. This type of YRD is controlled by the front of the high pressure (the high-pressure center is located in North China), and the weather in the middle and north is conducive to the generation and transmission of O3. Inland type (Type 3) accounts for 24%. The main body of this type of high pressure is located in Mongolia. The easterly wind in YRD area is conducive to the inland transmission of O3 precursors. The northern coastal type (Type 4) accounts for 44%. This type of YRD area is mainly controlled by the weak pressure field. The weather in the northern coastal area is sunny and the solar radiation for a long time is conducive to the formation of O3. The southern coastal type (Type 5) accounts for 10%, the solar radiation is strong in the southern region mainly under the influence of the post-offshore high pressure. This study provides new insights into the relationship between O3 pollution distribution types and atmospheric circulation in YRD area, and reveals the difference of potential meteorological impacts of different O3 pollution distribution types.

A new NMVOC speciated inventory for a reactivity-based approach to support ozone control strategies in Spain

Ozone (O3) pollution is a persistent problem in many regions of Spain, so understanding O3 precursor emissions and trends is essential to design effective control strategies. We estimated the impact of Non-Methane Volatile Organic Compounds (NMVOC) species upon O3 formation potential (OFP) using the maximum incremental reactivity approach. For this, we developed a speciated NMVOC emission inventory for Spain from 2010 to 2019 combining national reported emissions with state-of-the-art speciation profiles, which resulted in a database of emissions for over 900 individual NMVOC species and 153 individual sectors. Additionally, we analysed 2030 emission projections to quantify the expected impact of planned measures on future OFP levels. Overall, the main activities contributing to OFP in Spain are paint manufacturing and applications (20 %), manure management (16 %), and domestic solvent use (6 %). These activities contribute unevenly across regions. The more urbanised areas report a larger contribution from the solvent sector (64 % in Madrid), while in rural areas, manure management and agricultural waste burning gain importance (24 % in Extremadura), indicating that local control measures should be implemented. The top 10 NMVOC species contributing to OFP are ethanol, ethene, xylenes, propene, toluene, formaldehyde, 1,3-butadiene, styrene, n-butane, and cyclopentane, which together are responsible for 54 % of the total OFP. Our trend analysis indicates a reduction of NMVOC emissions and OFP of −5 % and −10 % between 2010 and 2019, respectively. The larger decrease in OFP is driven by a bigger reduction in xylenes (−29 %) and toluene (−28 %) from paint application industries and the road transport sector. By 2030 a significant increase (+37 %) in the OFP from the public electricity sector is expected due to the planned increase in biomass use for power generation. Our results indicate that policies should focus on paint reformulation, limiting aerosol products, and implementing NMVOC control devices in future biomass power plants.

Anthropogenic VOCs in the Long Island Sound, NY Airshed and their role in ozone production

Cities like New York and areas downwind have poor air quality due to pollution generated by human activity. Ozone (O3), a harmful pollutant, is produced in the atmosphere from photochemical reactions involving volatile organic compounds (VOCs) and nitrogen oxides (NOx). Aircraft measurements of VOCs obtained during an O3 event in May 2017 over the New York City metropolitan area, Long Island Sound, and Connecticut show concentrations of O3 exceeding 100 ppb between ∼200 and 500 m above the surface. During this campaign, 35 whole air canisters were collected, and 50 VOC species were measured. Biogenic isoprene often dominates VOC reactivity in summer months, but analysis of the chemistry in the middle of the Planetary Boundary Layer (PBL) indicates that primary anthropogenic VOCs such as propylene and isopentane played a major, possibly dominant role in this Spring 2017 O3 event and are suitable targets for control.The most important measured anthropogenic VOCs ranked by OH reactivity were propylene and isopentane, with n-butane and 1-pentene also playing a substantial role. The most important anthropogenic VOCs ranked by Ozone Formation Potential (OFP) were again propylene and isopentane, but aromatic species like toluene were also large contributors. Isoprene ranked tenth in importance for OFP. For VOC species with short lifetimes, like isoprene and propylene, mixing of air parcels throughout the PBL means air above the surface may quickly become depleted of these VOCs, allowing longer-lived, anthropogenic VOCs to have a proportionally greater impact on photochemical O3 production aloft. Our observations indicate that VOC reactivity was much larger in the morning than in the afternoon, suggesting controls of propylene, isopentane, and aromatics overnight may be useful for reducing morning concentrations of VOCs and therefore possibly reduce maximum concentrations of O3 observed in the afternoon. Finally, because formaldehyde (HCHO) was not measured during these flights, and since oxygenates also contribute to O3 formation, we estimate the relative contribution of isoprene and propylene to HCHO formation using a box model. Propylene produces ∼25% and isoprene produces ∼4% of HCHO within the box model.

New insight into formation mechanism, source and control strategy of severe O3 pollution: The case from photochemical simulation in the Wuhan Metropolitan Area, Central China

The Wuhan Metropolitan Area, located in Central China, has experienced severe O3 pollution in recent years; thus urging to diagnose formation regime and propose reasonable control strategies. Multi-source data of air pollutants and meteorological factors in 4 cities during August 2019 when severe regional O3 pollution occurred were obtained; then, in-situ O3 formation mechanism, the O3-precursors sensitivity, the sources and control strategies of O3 were evaluated based on the combination of the 0-D photochemical observation-based model and the positive matrix factorization model through the analysis of local ozone budget, the relative incremental reactivity, an empirical kinetic model approach and source apportionment. The results indicated the P(O3) (net O3 production rate) was 25 ppbv h−1 in Ezhou and 11–13 ppbv h−1 in other 3 cities. The dominated photochemical production of O3 was NO + HO2 reaction (62–71%), whereas the main pathway to destroy O3 during daytime was NO2 + OH (>70%) and nocturnal loss of O3 with alkenes even reached up to 39–46%. Generally, O3 formation was sensitive to AVOC (Anthropogenic Volatile Organic Compounds), in which reactive aromatics, OVOCs (Oxygenated VOCs), and alkenes (xylenes, ethylene, isoprene, methyl vinyl ketone, hexanal, toluene and methacrolein, specifically) as well as abundant i-pentane should be targeted to alleviate O3 pollution. The highly reactive VOCs sources for O3 formation in this region were vehicular exhaust (28–41%), industrial emissions (20–29% except Ezhou), and solvent use (17–29% except Huangshi). Co-reduction of O3 precursors in aforementioned reactive emissions according to optimal ratios of AVOC to NO2, i.e., 5:1 (Wuhan and Huanggang), 4:1 (Ezhou), and 6:1 (Huangshi), could achieve local O3 effective mitigation. Surprisingly, P(O3) could reduce by 38% and 48% under 40% AVOC cut accompanied by NO2 in more contaminated cities (Wuhan and Ezhou). Overall, our study provides new insight to future collaborative O3 alleviation strategies formulation in Central China, which quantified O3 formation at different precursors levels in different cities suffering from regional O3 pollution, concluded best precursors control ratios and confirmed validity of O3 mitigation through precursors-oriented emission reduction in vital sources.

城市植物挥发性有机化合物排放与臭氧相互作用及其机制

PDF HTML阅读 XML下载 导出引用 引用提醒 城市植物挥发性有机化合物排放与臭氧相互作用及其机制 DOI: 10.5846/stxb202202240431 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 长株潭城乡融合发展的生态环境效应与耦合机制项目（U21A2010） The interactions and mechanisms between biogenic volatile organic compounds emissions and ozone concentrations in urban areas: A review Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:近地面臭氧（O3）已成为继PM2.5后影响我国空气质量的一种重要二次污染物。随着氮氧化物浓度的持续下降和气候变暖的加剧，城市O3的形成对挥发性有机化合物的浓度更加敏感。近年来城市绿色空间显著增长，植物源挥发性有机化合物（BVOCs）排放和浓度逐年增加。针对BVOCs与近地面O3之间复杂的交互作用，从植物BVOCs的特性与作用出发，综述了不同因素尤其是O3浓度增加对树木生理状态及BVOCs排放速率的影响，定量分析了已有研究中O3对不同植物异戊二烯和单萜烯排放速率的影响，以及BVOCs对O3形成的贡献，总结了BVOCs与O3相互作用研究领域存在的不足。未来亟需加强的研究包括：（1）城市树种BVOCs排放因子的实测，建立物种的排放速率数据库，优化模型参数，提升精细尺度BVOCs排放量估算模型精度；（2）多种环境因子，比如污染物浓度、温湿度等对城市植物BVOCs排放的交互作用和综合影响的研究；（3）植物BVOCs对O3形成贡献的定量研究，及其对植物抗污染能力的影响，为城市建设中的树种选择及减轻城市O3污染提供理论依据和借鉴。 Abstract:In China, surface ozone (O3) has become a major secondary pollutant as the fine particulate pollution problem was largely addressed. As nitrogen oxide concentrations continue to decline and climate warming intensifies, urban ozone formation becomes more sensitive to VOC emissions. With the continuous increase of urban green space in recent years, the emissions of Biogenic Volatile Organic Compounds (BVOCs) have also increased, and thus played an increased role in ozone formation. This paper presented a comprehensive review of the interactions and mechanisms between BVOCs emissions and ozone concentrations in urban areas. We first reviewed the current states and trends in the response of plant physiological state and BVOCs emission rate to environmental stress, especially the elevated O3 concentration, with a particular emphasis on previous studies that focused on the effects of O3 on isoprene and monoterpene emission rates of various plans. We then summarized the role of BVOCs plays in O3 formation. Based on the review of the existing studies, we found a few knowledge gaps and identified several priorities for future research:(1) studies on quantifying the BVOCs emission rate of different urban tree species to build a more comprehensive database for BVOCs emission rate that can be used to optimize the parameters of BVOCs emissions models, and thereby to improve the precision of the fine-scale BVOCs emission estimation; (2) Exploring the interaction and comprehensive influence of various environmental factors on BVOCs emissions from urban plants, such as pollutant concentration, temperature, and humidity; (3) Quantifying the contribution of plant BVOCs to O3 formation and its effect on plant resistance to air pollution, which aims to provide a theoretical basis and reference for the selection of tree species for urban greening and the reduction of urban O3 pollution. 参考文献 相似文献 引证文献