Research on the ozone formation sensitivity indicator of four urban agglomerations of China using Ozone Monitoring Instrument (OMI) satellite data and ground-based measurements.

Near surface ozone is a typical secondary pollutant, and is mostly generated by a series of complex photochemical reactions of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the air under sunlight. At present, a large number of studies have applied FNR (a ratio of formaldehyde (HCHO) to nitrogen dioxide (NO2) retrieved by satellite) indicator to study the ozone formation sensitivity (OFS). OFS analysis is critical for taking targeted ozone pollution prevention and control measures. Regional OFS can be more accurately diagnosed by utilizing localized FNR threshold. In this study, localized FNR thresholds were established for four severe ozone polluted urban agglomerations in China (Beijing-Tianjin-Hebei (BTH) region, Yangtze River Delta (YRD) region, Pearl River Delta (PRD) region, and Chengdu-Chongqing (CY) region), based on the statistical analysis between FNR (obtained from OMI observation, with daily transit time of approximately 13:45 local standard time) and ΔO3/ΔNO2 (the ratio of ozone change to nitrogen dioxide change between two consecutive months, obtained from ground measurements) from 2014 to 2016. And these thresholds were verified by the statistical analysis between FNR and ΔO3/O3 (ozone change rate between two consecutive months), and between FNR and O3 concentration during the OFS significant shift months. Furthermore, the results were also compared and verified with the method proposed by previous studies. The results indicate that there are significant regional dependences in the FNR threshold, and the lower-upper limits for the four urban agglomerations are as follows: 0.65-1.21 for BTH, 0.64-1.48 for the YRD, 1.25-2.39 for the PRD, and 1.44-3.69 for CY (FNR < lower limit indicates VOCs-limited regime; lower limit < FNR < upper limit indicates transitional regime; FNR > upper limit indicates NOx-limited regime). This method eliminates the problems associated with the undifferentiated use of FNR thresholds in different regions and significantly reduces the deviations for OFS.

[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%.

Relationships of ozone formation sensitivity with precursors emissions, meteorology and land use types, in Guangdong-Hong Kong-Macao Greater Bay Area, China.

Due to the influences of precursors emissions, meteorology, geography and other factors, ozone formation sensitivity (OFS) is generally spatially and temporally heterogeneous. This study characterized detailed spatial and temporal variations of OFS in Guangdong-Hong Kong-Macao Greater Bay Area (GBA) from 2012 to 2016 based on OMI satellite data, and analyzed the relationships of OFS with precursors emissions, meteorology and land use types (LUTs). From 2012 to 2016, the OFS tended to be NOx-limited in GBA, with the value of FNR (HCHO/NO2) increasing from 2.04 to 2.22. According to the total annual emission statistics of precursors, NOx emissions decreased by 33.1% and VOCs emissions increased by 35.2% from 2012 to 2016, directly resulting in OFS tending to be NOx-limited. The Grey Relation Analysis results show that total column water (TCW), surface net solar radiation (SSR), air temperature at 2 m (T2) and surface pressure (SP) are the top four meteorological factors with the greatest influences on OFS. There are significant positive correlations between FNR and T2, SSR, TCW, and significant negative correlations between FNR and SP. In GBA, the OFS tends to be NOx-limited regime in wet season (higher T2, SSR, TCW and lower SP) and VOCs-limited regime in dry season (lower T2, SSR, TCW and higher SP). The FNR displays obvious gradient variations on different LUTs, with the highest in "Rural areas", second in "Suburban areas" and lowest in "Urban areas".

[Volatile Organic Compound Emission Characteristics of Furniture Manufacturing Enterprises and the Influence on the Atmospheric Environment].

The furniture manufacturing industry is a typical industry with high pollution, low added value, relatively outdated technology and low levels of pollution control. The process of furniture manufacturing uses a large number of paints and adhesives, which emit a great quantity of volatile organic compounds (VOCs). The furniture manufacturing industry is a key industry for the control of VOCs in China. The VOCs emission characteristics and environmental impact of the furniture manufacturing industry has been studied in this work, which could be helpful for the Chinese government when formulating VOCs pollution control policy for this industry. In this study, a typical furniture manufacturing enterprise was chosen as the object. The emission concentration level and source profile of VOCs in a typical enterprise was obtained, and an assessment of the environmental impact of furniture manufacturing was developed. The results showed that the concentration of VOCs in the workshop ranged from 9.18 to 181.58 mg·m-3, the concentration of VOCs in the stack was 30.64-155.94 mg·m-3, and the treatment efficiency was 7.43%-67.14%. The main species of VOCs in the workshop were aromatic hydrocarbons, esters, and aldehydes and ketones; the main species of VOCs in the stack are esters and aromatic hydrocarbons, followed by alkanes, and the main VOCs in the industry are sec-butyl acetate, toluene, m-xylene, methylal and ethylbenzene. The average ozone generation potential (OFP) of workshop and stack VOCs was 258.01 and 289.14 mg·m-3, respectively, and the average secondary organic aerosol generation potential (SOAFP) of workshop and stack VOCs was 148.66 and 165.31 mg·m-3, respectively. The most important contribution to the OFP and SOAFP in each emission sector is aromatic hydrocarbons. The OFP and SOAFP in the edge-sealing workshop are large and the VOCs should be controlled. The main malodorous substances at the shop boundary are sec-butyl acetate, m-xylene, butyl acetate, p-xylene, ethylbenzene, 1-ethyl-3-methylbenzene, o-xylene, and toluene; the VOCs at the factory boundary produce almost no odor pollution. Targeted enhanced control of aromatic hydrocarbons and esters should be adopted to achieve effective emission reduction of VOCs in furniture manufacturing.