[Ozone Pollution Characteristics and Sensitivity During the Ozone Pollution Days in Summer 2021 of Xinxiang City].

This study was based on the observation of volatile organic compounds (VOCs), conventional gaseous air pollutants, and meteorological parameters observed at the Xinxiang Municipal Party School site from June to August 2021. The ozone (O3) characteristics and sensitivity of O3 pollution days and the control strategy of its precursors were studied using an observation-based model (OBM). It was found that the meteorological conditions were characterized by high temperature, low humidity, and low pressure in O3-pollution days. The concentrations of O3 and its precursors all increased in the O3 pollution days. Oxygenated volatile organic compounds (OVOCs) and alkanes were the highest-concentration components of VOCs on O3 pollution days in Xinxiang, and OVOCs had the highest ozone formation potential (OFP) and hydroxyl (·OH) reactivity. According to the relative incremental reactivity (RIR) analysis, during the O3 pollution days in Xinxiang, O3sensitivity was in the VOCs-limited regime in June and in the transitional regime in July and August. Ozone production was more sensitive to alkenes and OVOCs. The RIR values of the precursors in June changed throughout the day, but O3 sensitivity remained the VOCs-limited regime. In July and August, O3 sensitivity was the VOCs-limited regime in the morning, transitional regime at noon, transitional and NOx-limited regime, respectively in the afternoon. By simulating different precursor-reduction scenarios, the results showed that the reduction of VOCs was always beneficial to the control of O3, whereas the reduction of NOx had little effect on the control of O3 and a risk of increasing O3.

Characteristics and sources of volatile organic compounds (VOCs) in Xinxiang, China, during the 2021 summer ozone pollution control.

Real-time monitoring of volatile organic compounds (VOCs) was conducted in Xinxiang, China, during the implementation of Xinxiang's ozone pollution control period (CP) in June 2021. To evaluate the effectiveness of the control measures, three study periods were determined by combining meteorological conditions and the implementation time of the control measures: before, during, and after the CP of ozone pollution (BCP, CP, and ACP, respectively). The average concentrations of VOCs during the three periods were 41.20 ± 4.99 ppbv, 33.64 ± 5.65 ppbv, and 37.42 ± 2.59 ppbv, respectively, with the same top three components, namely oxygenated VOCs (OVOCs), alkanes, and halogenated hydrocarbons (XVOCs). However, the concentrations of these three components decreased substantially during the CP (by 19 %, 18 %, and 11 %, respectively). The ozone formation potential (OFP) during the BCP was 144.47 ppbv, which was 1.2 times and 1.3 times higher than those during the ACP and CP periods, respectively. During the CP, the proportion of alkenes that contributed to the OFP decreased significantly by 24 %. Five types of VOCs sources were determined by positive matrix factorization (PMF): (1) solvent use, (2) biogenic, (3) secondary formation, (4) industrial process, and (5) vehicle exhaust and fuel evaporation sources. The VOCs emissions from industrial processes decreased by 54 % during the CP, whereas those from vehicle exhaust and fuel evaporation sources decreased by 36 %, indicating the effectiveness of emission control measures and the importance of these two sources for VOCs control in Xinxiang. In terms of regional transport, the results of the spatial analysis revealed that Hebi and Anyang in the northeast and Zhengzhou and Pingdingshan in the southwest, affected significantly the VOCs of Xinxiang. These results highlight the importance of controlling VOCs emissions in Xinxiang. Furthermore, attention should be paid to controlling the regional transport of surrounding cities.

[Characteristics of Industrial Volatile Organic Compounds(VOCs) Emission in China from 2011 to 2019].

In order to better understand the industrial volatile organic compounds(VOCs) emissions in China in recent years, an industrial VOCs emission inventory was developed from 2011 to 2019, based on the dynamic emission factors method and the comprehensive source classification system. The results showed that VOCs emissions increased first from 11122.7 kt in 2011 to 13397.9 kt in 2017, and then decreased to 13247.0 kt in 2019. The emission structure of the four source categories changed. The contribution from basic organic chemical industries, gasoline storage and transportation, manufacturing(i.e., coatings, inks, pigments, and similar products), and industrial protective coatings continued to increase. On the contrary, the contributions of oil and natural gas processing, automobile, and container manufacturing industries declined over the study period. Among the industrial emissions in China in 2019, industrial coating, printing, and basic organic chemical industries emitted large amounts of VOCs(accounting for 39.2% of the total emission), and because their contribution became increasingly prominent since 2011, these sectors will be the key emission sources in the future. With respect to the spatial distribution in 2019, East China and South China had the largest VOCs emissions. Shandong, Guangdong, Jiangsu, and Zhejiang were the four provinces that contributed the most, accounting for 40.6% of the total VOCs emissions.

[Coating-derived VOCs Emission Characteristics and Environmental Impacts from the Furniture Industry in Guangdong Province].

To determine the differences in emissions among different types of coatings, such as solvent-based, water-based, solvent-based ultra-violet(UV), water-based UV, and powder coatings, representative furniture manufacturing companies were selected for analysis. The emission concentrations and compositional characteristics of volatile organic compounds(VOCs) in different types of coatings were compared and studied. The ozone formation potential(OFP) and secondary organic aerosol formation potential(SOAFP) of the different types of coatings were also analyzed. Solvent-based coatings has higher TVOC concentrations, OFPs, and SOAFPs than water-based, solvent-based UV, water-based UV, and powder coatings. The concentrations and composition of VOCs emitted from the different types of coatings were also different. The main VOC groups of the solvent-based and solvent-based UV coatings were aromatic hydrocarbons and oxygenated volatile organic compounds(OVOCs). Specifically, the proportions of aromatic hydrocarbons are 41.91%-60.67% and 42.51%-43.00%, respectively, and the proportions of OVOCs were 24.75%-41.29% and 41.34%-43.21%, respectively. OVOCs accounted for the highest proportion of VOCs in the water-based, water-based UV, and powder coatings, at 54.02%-62.10%, 55.23%-64.81%, and 42.98%-46.45%, respectively. The major VOC compound of the solvent-based coatings was styrene(14.68%), and the main component of the water-based coatings was methylal(14.61%). The main species of VOCs from the solvent-based UV and water-based UV coatings were butyl acetate(15.36% and 20.56%, respectively). The most abundant species from the powder coatings was ethyl 3-ethoxy propionate(20.19%). Aromatic hydrocarbons were the most important contributor to the OFP of the solvent-based and solvent-based UV coatings, accounting for 79.84% and 80.32%, respectively. Aromatic hydrocarbons(51.48% and 36.71%) and OVOCs(42.30% and 41.03%) were the major contributors to the OFP of the water-based and water-based UV coatings, respectively. Aromatic hydrocarbons(43.46%), OVOCs(28.06%), and olefins(25.24%) were the main factors affecting the OFP of the powder coatings. Aromatic hydrocarbons dominate the SOAFP of solvent-based, water-based, solvent-based UV, water-based UV, and powder coatings, accounting for more than 99%.

[Sources and Control Area Division of Ozone Pollution in Cities at Prefecture Level and Above in China].

Based on the ground-level ozone concentration monitoring data in 2018, the ozone concentrations in 338 cities at the prefecture level and above were analyzed, and the TCEQ method was utilized to calculate the amount of locally generated ozone and regionally transported ozone in each city to divide the national ozone pollution control area and develop appropriate ozone pollution control measures. Correlation analysis was conducted between the amount of locally generated ozone and the daily maximum 8 h average ozone in each city to determine the main source of ozone pollution by determination coefficient (R2). The results show that 121 cities (35.8%) in China exceeded the standard in O3 concentration in 2018. The local generation of O3 in 104 cities has a great impact on the local O3 pollution, and is its main cause. In the other 234 cities, the main source of O3 pollution is regionally transported O3. Cities are classified into four categories based on their ozone concentration levels and pollution sources:cities with a nonattainment ozone situation and mainly locally generated ozone (N-L), cities with a nonattainment ozone situation and mainly regionally transported ozone (N-T), cities with a standard ozone situation and mainly locally generated ozone (S-L), and cities with a standard ozone situation and mainly regionally transported ozone (S-T). Finally, according to the proportion of four city types in each province, the whole country is divided into three types of control areas:severe, moderate, and general. N-L cities in the severe control area account for the largest proportion (20.3%) of the three types of control areas and the pollution is the highest; the proportion of the four categories of cities in the moderate control area are all medium; the general control area mainly includes S-T cities (65.4%), and the pollution is the lowest.

Magnetic microbubble-mediated ultrasound-MRI registration based on robust optical flow model.

BACKGROUND: As a dual-modality contrast agent, magnetic microbubbles (MMBs) can not only improve contrast of ultrasound (US) image, but can also serve as a contrast agent of magnetic resonance image (MRI). With the help of MMBs, a new registration method between US image and MRI is presented. METHODS: In this method, MMBs were used in both ultrasound and magnetic resonance imaging process to enhance the most important information of interest. In order to reduce the influence of the speckle noise to registration, semi-automatic segmentations of US image and MRI were carried out by using active contour model. After that, a robust optical flow model between US image segmentation (floating image) and MRI segmentation (reference image) was built, and the vector flow field was estimated by using the Coarse-to-fine Gaussian pyramid and graduated non-convexity (GNC) schemes. RESULTS: Qualitative and quantitative analyses of multiple group comparison experiments showed that registration results using all methods tested in this paper without MMBs were unsatisfactory. On the contrary, the proposed method combined with MMBs led to the best registration results. CONCLUSION: The proposed algorithm combined with MMBs contends with larger deformation and performs well not only for local deformation but also for global deformation. The comparison experiments also demonstrated that ultrasound-MRI registration using the above-mentioned method might be a promising method for obtaining more accurate image information.