Search

Source contributions and regional transport of maximum daily average 8-h (MDA8) O 3 during a high O 3 month (June 2019) in Henan province in central China are explored using a source-oriented Community Multiscale Air Quality (CMAQ) model. The monthly average MDA8 O 3 exceeds ∼70 ppb in more than half of the areas and shows a clear spatial gradient, with lower O 3 concentrations in the southwest and higher in the northeast. Significant contributions of anthropogenic emissions to monthly average MDA8 O 3 concentrations of more than 20 ppb are predicted in the provincial capital Zhengzhou, mostly due to emissions from the transportation sector (∼50%) and in the areas in the north and northeast regions where industrial and power generation-related emissions are high. Biogenic emissions in the region only contribute to approximately 1-3 ppb of monthly average MDA8 O 3 . In industrial areas north of the province, their contributions reach 5-7 ppb. Two CMAQ-based O 3 -NO x -VOCs sensitivity assessments (the local O 3 sensitivity ratios based on the direct decoupled method and the production ratio of H 2 O 2 to HNO 3 ) and the satellite HCHO to NO 2 column density ratio consistently show that most of the areas in Henan are in NO x -limited regime. In contrast, the high O 3 concentration areas in the north and at the city centers are in the VOC-limited or transition regimes. The results from this study suggest that although reducing NO x emissions to reduce O 3 pollution in the region is desired in most areas, VOC reductions must be applied to urban and industrial regions. Source apportionment simulations with and without Henan anthropogenic emissions show that the benefit of local anthropogenic NO x reduction might be lower than expected from the source apportionment results because the contributions of Henan background O 3 increase in response to the reduced local anthropogenic emissions due to less NO titration. Thus, collaborative O 3 controls in neighboring provinces are needed to reduce O 3 pollution problems in Henan effectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Peroxyacetyl nitrate (PAN) is one of the critical secondary pollutants in photochemical smog. This study investigated the relationship between PAN and PAN precursors with the Regional Atmospheric Chemical Mechanism version 2 model in six episodes recorded in Zhengzhou. In all episodes, peroxyacetyl radical (PA) was primarily produced by acetaldehyde oxidation, with more than 70% contributions. In photochemical episodes and photochemical-haze co-occurring episodes (combined episodes), methylglyoxal secondarily contributes 8.1%-10.6% to PA while in haze pollution, the propagation of other radicals to PA is the second most important source (12.0%-19.1%). Among anthropogenic non-methane hydrocarbons, alkene restricted PAN formation as first-generation precursors, with the relative incremental reactivity of PAN (RIR PAN ) more than 0.6 during three-type episodes. Nitrous acid (HONO) also played important role in PAN formation. Especially during photochemical episodes, RIR PAN (HONO) reached 0.79, which was comparable to the RIR PAN value of alkene. Through sensitivity analysis of the relative formation of PAN to O 3 (the amount of PAN generated when 100 ppb O 3 formed), HONO was identified as the key precursor of PAN in haze pollution by promoting the oxidation of NMHC, while alkene predominated the relative formation of PAN to O 3 in photochemical and combined pollution through producing acetaldehyde. The sensitivity of PAN to HONO is obviously enhanced with higher NOx/VOC ratios during photochemical and combined pollution., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Zhengzhou, the provincial capital of Henan province in Central China and a major hub of the country's transportation network, has been suffering from severe summertime ozone (O 3 ) pollution. Simultaneous field measurements of O 3 and its precursors, including NO x , CO, HONO, and 106 volatile organic compounds (VOCs), were conducted at an urban site (the municipal environmental monitoring station, MEM) in Zhengzhou in July 2019. The Community Multiscale Air Quality (CMAQ) model, which incorporates the Master Chemical Mechanism (MCMv3.3.1), was modified to work as a 0-D observation-based photochemical box model to assess the sources and sinks of HO x radicals and O 3 , and the OH reactivity (K OH ) and ozone formation potential (OFP) of major VOC groups. In addition, the O 3 -NO x -VOC sensitivity was evaluated using the relative incremental reactivity (RIR) and O 3 formation isopleth techniques. The OH radicals were mainly generated from the propagation reaction of HO 2  + NO (91-95%). The daily average mixing ratios of OH and HO 2 radicals were significantly higher during high O 3 days, reaching as high as 4.8 × 10 6 and 7.7 × 10 8 molecules cm -3 , respectively. Photochemical O 3 formation was mostly due to the conversion of NO to NO 2 by HO 2 radicals (52-54%), while the NO 2  + OH reaction was the main contributor to O 3 destruction (70- 76%). Alkenes and aromatics were the main anthropogenic VOC contributors to K OH and OFP. Contributions of biogenic VOCs became much more important on high O 3 days, correlating with the increase in temperature and solar radiation. RIR analysis showed that the O 3 formation was under the VOC-limited on low O 3 days but was in the transition regime during the O 3 pollution buildup and persisting days. These results are generally consistent with those based on the O 3 formation isopleth. This paper provides important corroborative scientific evidence urgently needed by local governments to formulate O 3 pollution control strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Zhengzhou is one of the most haze-polluted cities in Central China with high organic carbon emission, which accounts for 15%-20% of particulate matter (PM 2.5 ) in winter and causes significantly adverse health effects. Volatile organic compounds (VOCs) are the precursors of secondary PM 2.5 and O 3 formation. An investigation of characteristics, sources and health risks assessment of VOCs was carried out at the urban area of Zhengzhou from 1 st to 31 st December, 2019. The mean concentrations of total detected VOCs were 48.8 ± 23.0 ppbv. Alkanes (22.0 ± 10.4 ppbv), halocarbons (8.1 ± 3.9 ppbv) and aromatics (6.5 ± 3.9 ppbv) were the predominant VOC species, followed by alkenes (5.1 ± 3.3 ppbv), oxygenated VOCs (3.6 ± 1.8 ppbv), alkyne (3.5 ± 1.9, ppbv) and sulfide (0.5 ± 0.9 ppbv). The Positive Matrix Factorization model was used to identify and apportion VOCs sources. Five major sources of VOCs were identified as vehicular exhaust, industrial processes, combustion, fuel evaporation, and solvent use. The carcinogenic and non-carcinogenic risk values of species were calculated. The carcinogenic and non-carcinogenic risks of almost all air toxics increased during haze days. The total non-carcinogenic risks exceeded the acceptable ranges. Most VOC species posed no non-carcinogenic risk during three haze events. The carcinogenic risks of chloroform, 1,2-dichloroethane, 1,2-dibromoethane, benzyl chloride, hexachloro-1,3-butadiene, benzene and naphthalene were above the acceptable level (1.0  ×  10 -6 ) but below the tolerable risk level (1.0  ×  10 -4 ). Industrial emission was the major contributor to non-carcinogenic, and solvent use was the major contributor to carcinogenic risks., (Copyright © 2021. Published by Elsevier B.V.)

The Chinese government has developed an ambitious project to promote the application of ethanol gasoline (E10) on a national scale since 2017. Given the difference in fuel properties between E10 and traditional gasoline, it is necessary to evaluate the volatile organic compound (VOC) emissions from E10-fuelled vehicles. In this study, a two-week sampling campaign was conducted in an urban tunnel, in which E10-fuelled vehicles were dominant, to evaluate the characteristics of VOC emissions from the mixed fleet. In total, 105 VOC species were identified, and the ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) were estimated. The results showed that for vehicular VOC concentrations in the tunnel, alkanes, oxygenated VOCs (OVOCs) and alkenes were the most abundant VOC groups, with the average proportion being more than 80% of the total VOCs. The fleet-average VOC emission factor (EF) was 14.8 mg/km/veh, which was much lower than that from traditional gasoline-fuelled vehicle fleets, and alkanes, OVOCs, alkenes and aromatics were the major VOC groups. Because of the large number of E10-fuelled vehicles in the mixed fleet, a high proportion of OVOCs among the vehicular VOC emissions was observed. Ethane, acrolein, ethanol, ethylene and toluene were the top five VOC species with the largest EF in VOC emissions from the fleet. Alkenes were the main contributors with an average contribution of 43.9% of the total OFP, whereas aromatics dominated the total SOAFP by 95.8% on average. These results may provide a reference for the extensive application of ethanol gasoline and the development of vehicular emission models., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Glyburide is a classic antidiabetic drug that is dominant in inflammation regulation, but its specific role in ozone-induced lung inflammation and injury remains unclear. In order to investigate whether glyburide prevents ozone-induced pulmonary inflammation and its mechanism, C57BL/6 mice were intratracheally pre-instilled with glyburide or the vehicle 1 hour before ozone (1 ppm, 3 hours) or filtered air exposure. After 24 hours, the total inflammatory cells and total protein in bronchoalveolar lavage fluid (BALF) were detected. The pathological alternations in lung tissues were evaluated by HE staining. The expression of NLRP3, interleukin-1β (IL-1β), and IL-18 protein in lung tissues was detected by immunohistochemistry. Western blotting was used to examine the levels of caspase-1 p10 and active IL-1β protein. Levels of IL-1β and IL-18 in BALF were measured using ELISA kits. Glyburide treatment decreased the total cells in BALF, the inflammatory score, and the mean linear intercept induced by ozone in lung tissues. In addition, glyburide inhibited the expression of NLRP3, IL-18, and IL-1β protein in lung tissues, and also suppressed NLRP3 inflammasome activation, including caspase-1 p10, active IL-1β protein in lung tissues, IL-1β, and IL-18 in BALF. These results demonstrate that glyburide effectively attenuates ozone-induced pulmonary inflammation and injury via blocking the NLRP3 inflammasome., (© 2020 Wiley Periodicals, Inc.)

On 3rd to May 24, 2018, volatile organic compound (VOC) samples were collected four times a day by using stainless steel canisters at an urban site in Zhengzhou, China. The concentrations, compositions, sources, ozone (O 3 ) formation potential (OFP), and health risk assessment of VOCs were discussed based on the measurements of 103 VOC species. Results show that the average mixing ratio of VOCs was 29.11 ± 15.33 ppbv, and the dominant components comprised oxygenated VOCs (OVOCs) and alkanes, followed by halocarbons, alkenes, aromatics, and a sulfide. Various groups of VOCs had typical diurnal variation characteristics. Alkenes, alkanes, and aromatics contributed most to the OFP. Five sources identified by the positive matrix factorization model revealed solvent utilization as the largest contributor, followed by industrial production, long-lived and secondary species, vehicular emission, and biogenic emission. Solvent utilization and vehicular emission were important sources to OFP. During O 3 episode days, the mixing ratios of alkanes, alkenes, halocarbons, OVOCs, aromatics, and TVOCs decreased to varying degrees; the source contribution of solvent utilization decreased significantly while industrial production showed the opposite trend. VOC species and sources posed no non-carcinogenic risk while five species and all sources except for biogenic emission had carcinogenic risks to exposed population. Industrial emission was the largest contributor to both non-carcinogenic and carcinogenic risks. These results will help to provide some references for O 3 pollution research and prevention and control of pollution sources., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

To investigate the characteristics of ground level ozone (O 3 ) for Henan Province, the ambient air quality monitoring data of 2015 and 2016 were analyzed. The result showed that the 8 h-max-O 3 concentrations displayed a distinct seasonality, where the maximum and minimum values, averaging 140.41, 54.19 μg/m 3 , occurred in summer and winter, respectively. There is a significant correlation between meteorological factors and O 3 concentration. The Voronoi neighborhood averaging analysis indicated that O 3 , temperature, and ultraviolet radiation in Henan province were decreased from northwest to southeast, while relative humidity and precipitation displayed the opposite trend. Besides meteorological factors, the chemical processes play an essential role in ozone formation. Reactions of NO, NO 2 and O 3 form a closed system, and the partitioning point of the OX-component (O 3  + NO 2 ) was at 40 and 80 μg/m 3 for nitrogen oxide (NO X ) in winter and summer, respectively, with NO 2 dominating at higher NOx pollution and O 3 being the major component at lower levels. The relationship between oxidant (OX = O 3 +NO 2 ) and NOx concentrations were evaluated to understand the regional and local contribution of OX. It showed that high regional contribution occurred in the spring, whereas the highest local contribution lead to the summer peak of O 3 observed in Zhengzhou. This present study reveals important environment impacts from the photochemical process and the meteorological conditions in the region with better understanding on the O 3 characterization., (Copyright © 2019. Published by Elsevier B.V.)

Nonmethane volatile organic compounds (NMVOCs) are important precursors of ozone (O3) formation under sufficient nitrogen oxide conditions. Understanding the characteristics and emission sources of NMVOCs, as well as the relationship between NMVOCs and O3 , is of great significance for effective O3 pollution control. In this study, continuous online monitoring of NMVOCs was carried out in Zhengzhou, Henan, from 1–30 June. Furthermore, the study provided recommendations for strategies aimed at reducing O3 formation. During the observation period, the concentration of total NMVOCs (TNMVOCs) varied from 9.9 to 60.3 ppbv, with an average of 22.8 ± 8.3 ppbv. The average concentration of TNMVOCs during O3 pollution events was higher than on clean days. Six major sources of NMVOCs were identified using the positive-matrix-factorization model. Vehicular exhausts (28 %), solvent usage (27 %), and industrial production (22 %) were the main sources. We explore the O3 –precursors relationship and propose observation-oriented O3 control strategies. The results of the relative incremental reactivity (RIR) and the Empirical Kinetics Modeling Approach show that Zhengzhou was under an anthropogenic volatile organic compound (AVOC)-limited regime. NMVOCs had the largest RIR value, while NOx exhibited a negative RIR value. It is noteworthy that the sensitivity of O3 formation to biogenic volatile organic compounds (BVOCs) was greater than that to AVOCs. Considering the reduction effect, it is recommended that the ratio of AVOCs to NOx be maintained at no less than 3:1 to effectively reduce O3 formation. [ABSTRACT FROM AUTHOR]

Peroxyacetyl nitrate (PAN) and ozone (O 3) are two typical indicators of photochemical pollution, which are harmful to human body and environment. In this study, PAN and O 3 were continuously monitored during static management (SM) of the COVID-19 epidemic in Zhengzhou. Briefly, SM refers to control policies in that all except for essential business are closed; work at home; and no people going out and no gathering, etc. During the SM, the temperature suddenly dropped from 26 °C to 14 °C, which provided a good experimental condition for the study of source transformation, accumulation, and consumption of PAN in the atmosphere. The concentrations of PAN were 0.6, 0.8, and 0.5 ppbv in three periods: before, during, and after the SM. During the SM, the lifetime of PAN was increased due to low temperature, and the accumulation time of PAN was longer, resulting in the increase of PAN concentration in daytime faster than the other two periods. During SM, especially after the temperature drops, the average atmospheric lifetime of PAN was 23.8 h, which was higher than 17.6 h before SM and 13.8 h after SM. This indicated that low temperature was more conducive to the accumulation of PAN. The high potential PAN source (CBPF>0.8) mainly came from the northeast of Zhengzhou, and the wind speed range was between 2.5 and 3 m/s. The backward trajectory analysis showed that 83.3% of the air mass from the northeast and northwest had a greater impact on the PAN concentration in Zhengzhou. [Display omitted] • The concentrations of secondary pollutants PAN and O 3 increased during the COVID-19 control period. • PAN is more likely to accumulate at low temperatures. • At high temperatures, PAN is more likely to pyrolysis and release PA radicals. • Northeast and northwest directions are the main source directions of PAN long-distance transmission. [ABSTRACT FROM AUTHOR]

Intensive temporary air pollution control measures were implemented in Zhengzhou (ZZ), a megacity in central China, and six neighboring cities during the 2019 National Games of Ethnic Minorities. The Community Multiscale Air Quality (CMAQ) model and a high-resolution local emission inventory were applied to evaluate the control measures. Reductions of ~35–60% of primary PM (PPM), 45–65% of VOCs, ~5% of NH 3 , 35–45% of NO x , and 30–70% of SO 2 emissions in the central area (i.e., ZZ) and collaborative cities (i.e., the six neighboring cities) lead to significant reductions of daily PM 2.5 by 25–45% in ZZ. Hourly concentrations of PM 2.5 are reduced by as much as 100 μg m−3. Most of the reduction in PM 2.5 is due to primary PM, and NO 3 −, SO 4 2−, and NH 4 + ion concentrations only decrease by 5–6%. Emission reductions in the collaborative cities contribute to 10–30% of the decrease in PM 2.5 and PM 10 in ZZ. Concentrations of daily maximum 8-hr (DM8H) O 3 increase by 2–5% on high O 3 days. Isopleth analysis suggests that the local molar reductions ratio of NO x to VOC needs to be < 0.5 to avoid the increases. More stable meteorology conditions make emission controls in ZZ more effective for PM 2.5 and PM 10 but lead to higher increases in DM8H O 3. These results suggest that control of PPM emissions in ZZ is the most effective in reducing PM 2.5 and PM 10. However, reductions of precursor gaseous in ZZ and the six neighboring cities alone are not effective in reducing the secondary PM components and most likely lead to increases in DM8H O 3. Image 1 • First evaluation of temporary air pollution controls in a megacity in central China. • Most of the reduction in PM 2.5 is mostly due to local primary PM reductions. • Reduction of SO 2 and NO x changes secondary inorganic aerosol (SIA) slightly. • ΔNOx/ΔVOC needs to be < 0.5 to reduce O 3 if only local emissions are controlled. • Coordinated and broader regional controls are needed to further reduce SIA and O 3. [ABSTRACT FROM AUTHOR]