[Audit Indicators and Suggested Ranges for Data Validation of Chemical Components in Ambient PM2.5: A Case Study of the Yangtze River Delta].

Diagnostic indicators for the validation of PM2.5 compositional data were calculated, based on the monitoring results of approximately 2100 ambient samples collected in the Yangzi River Delta from 2014 to 2017. According to the results of a correlation analysis, we propose that the audit indexes of the monitoring data of PM2.5 components in ambient air should include:equivalent ratios of anion-cation charge balance(A/C), the consistency between sum of all measured components(∑species) and weighed PM2.5, the consistency between mass reconstructed PM2.5(PM2.5, reconstructed) and weighed PM2.5, the chemical consistency between elemental S and water-soluble SO42-, elemental K and water-soluble K+, and the chemical consistency of theoretical and tested NH4+. The double-sided 95% reference ranges of anion-cation equivalent balance (A/C), ∑species/PM2.5, PM2.5, reconstructed/PM2.5, S/SO42-, and K/K+ ratios were determined in terms of P2.5 and P97.5 as follows:(0.82, 1.35), (0.63, 0.94), (0.62, 1.00), (0.28, 0.50), and (0.66, 2.31). These diagnostic indicators were helpful for judging the errors of chemical component analysis and retain seasonal variation stability. In most cases, NH4+ existed in the form of NH4NO3 and (NH4)2SO4 in spring and summer. With the approach of autumn and winter, it transformed to NH4NO3, (NH4)2SO4, and NH4Cl. The results of literature verification showed the pass rate of A/C was 87.1% and the rate of other indexes was 100%, indicating that the above audit indexes we propose could be applied to not only the Yangzi River Delta but the entire country. Furthermore, there were certain conditions in applying the diagnostic indicators. The S/SO42- ratio worked well with PM2.5 ≥ 40 µg·m-3 in summer and with 60 µg·m-3 ≤ PM2.5 ≤ 140 µg·m-3 in spring, autumn, and winter. Other audit indexes were available universally in all weathers under the condition of PM2.5 ≥ 60 µg·m-3.

[Observation of Aerosol Optical Properties and New Particle Formation in the Yangtze River Delta].

In a recent field campaign focused on air quality study, aerosol optical properties, particle number concentration, and PM2.5 components were monitored in Changzhou, Jiangsu Province, from May 27 to June 27, 2019. An array of instruments were deployed that included scanning mobility particle size spectrometer (SMPS), aethalometer (AE33), cavity attenuation phase shift single albedo monitor (CAPS-ALB), monitor for aerosols and gases in ambient air (MARGA) and RT-4 organic carbon/elemental carbon (OC/EC) carbon analyzer to study the ① changes in chemical composition and optical parameters of the new particles generated during the campaign period. ② comparison of the aerosol extinction coefficient recorded by these instruments and measured value in the reconstruction of IMPROVE (interagency monitoring of protected visual environment) and the calculated coefficient using MIE theory model were carried out. During the entire campaign, two new particle generation events were observed and also found that the particle size continued to increase from 4 nm to 64 nm. It was monitored that in the initial stage of new particle generation, sulfate contributed greatly. The measured average aerosol extinction coefficient during the period of particle generation, using these instruments was 95.40 Mm-1, while the average aerosol extinction reconstruction using the IMPROVE model was observed to be 140.20 Mm-1. The theoretical calculations based on Mie theory model yielded an average extinction coefficient of 93.54 Mm-1. It was found that the average aerosol extinction in Changzhou is lower than the average value of the urban aerosol extinction coefficient, which is measured to be 300 Mm-1 in China, during this period. The deployment of multiple instruments in a single campaign is more desirable because the combination of all observations helped in better characterization of the physicochemical properties of ambient aerosols from various aspects, including particle size spectrum and chemical composition.

[Treatment Status and Emission Characteristics of Volatile Organic Compounds from Typical Industrial Sources].

The status of treatment equipment, the emission characteristics, and the ozone formation potential (OFP) of volatile organic compounds (VOCs) for 11 typical enterprises, which were categorized into the 8 major VOC emission industries identified by the emission inventory of a typical city in the Yangtze River Delta, are discussed in this paper. There was a large difference in the removal efficiency of non-methane hydrocarbon (NMHC) between different treatment techniques, and even an increase in concentration occurred after some of the treatments. The current treatment equipment for VOCs needs further optimization. The emissions of NMHC, benzene, toluene, and xylene in most of the surveyed enterprises exceeded their corresponding standards, with toluene the worst offender. The most abundant compounds in the eight emission industries were aromatic hydrocarbons and oxygenated VOCs, whereas aromatic hydrocarbons contributed the most to ozone formation potential. There were large differences in emission characteristics of VOCs from different industries. Priority should be placed on the industries that have large OFP when control strategies of VOCs are considered.

[Estimation of Fine Particle (PM2.5) Emission Inventory from Cooking: Case Study for Shanghai].

Cooking is one of important emission sources of fine particles (PM2.5). This study using the catering enterprises of Shanghai as an example, presents a method to estimate the PM2.5 emission inventory from cooking according to the number of stoves, cooking time, and number of customers. Based on in situ measurements, the concentrations of PM2.5 emissions ranged from 0.1 mg ·m-3 to 1.8 mg ·m-3, which exceeded the limit (1.0 mg ·m-3 for lampblack) in the national standard. Organic carbon dominated the PM2.5 emitted from cooking, accounting for more than 50%. Extremely high ratios of organic carbon to elemental carbon were observed, ranging from 58.8 to 752.3, which could be used as an indicator of cooking emissions. The emission factors of PM2.5 in the catering industry are closely related to the scale of the catering enterprises. The emission factors of large-and medium-sized enterprises are obviously higher than those of small and micro enterprises. The PM2.5 emissions of catering enterprises are mainly attributed to high emission loads of large enterprises and those for a large number of small and medium enterprises. The PM2.5 emission inventory of cooking in Shanghai was calculated according to the three emission factors above, and the results were very close. Therefore, the method for estimating the PM2.5 emission inventory for cooking presented in this study is helpful for other Chinese cities to calculate their PM2.5 emission inventory from cooking.

[Chemical Characterization, Spatial Distribution, and Source Identification of Organic Matter in PM2.5 in summertime Shanghai, China].

Particulate organic matter (POM) has attracted increasing attention recently due to its great contribution to fine particles (PM2.5) and complex components and sources. In the present study, 78 particulate organic compounds in PM2.5 were quantified at three sites in Shanghai during summer; these sites were located in urban (Xuhui), suburban (Qingpu), and coastal (Lin'gang) areas of the city. Accordingly, the chemical composition and spatial distribution were investigated and sources were explored based on the indicators and diagnostic ratios combined with backward trajectory. The results showed that during the period of observation, the quantified organic matter in the suburban area is about 319 ng ·m-3, close to the urban area but much higher than that of the coastal areas. Fatty acids were the largest contributors, followed by levoglucosan, polycyclic aromatic hydrocarbons (PAHs), n-alkanes, and hopanes. Source analysis based on tracer methods indicates that gasoline vehicle emissions were the main source of POM in Shanghai. Biomass burning from the northeast impacted somewhat on the urban area and western suburbs during the observation period. Terrestrial plant emissions played an important role in the source of fatty acids at Qingpu and Lin'gang, and emissions of marine phytoplankton and microorganisms were also important for fatty acids at Lin'gang. Coal combustion and motor vehicle exhaust made an important contribution to PAHs according to an analysis of diagnostic ratios. This study presented the characteristics and sources of POM in summertime Shanghai, which facilitates the development of an effective control strategy on PM2.5 pollution.

[Physiochemical Properties of the Aerosol Particles and Their Impacts on Secondary Aerosol Formation at the Background Site of the Yangtze River Delta].

The study of the sources, compositions, and formation mechanisms of pollutants at the background site is crucial for the understanding of episodic events in the Yangtze River Delta (YRD). Secondary species are major components of PM2.5 particles. In this work, the compositions and concentrations of organic matter and secondary organic aerosol (SOA) at a background site of the YRD region were determined. The acidity and liquid water content of aerosol particles were modeled to investigate the impact of the physicochemical properties of aerosol particles on the formation of secondary species. The annual mean PM2.5 concentration in Chunan is 33 µg·m-3, with major contributions from inorganic sulfate (19%), nitrate (15%), ammonium (12%), and organic matter (19%). Nitrate is mainly locally formed, while sulfate is more affected by regional transport, except in winter. We found that the particles at the background site of the YRD have a high acidity and no seasonal variation was observed. The SOA formation at the background site of the YRD is enhanced by the liquid water content of the aerosol in spring, while it is more affected by the concentration of the oxidant, that is, O3, in summer. The contribution of SOA to PM2.5 in summer is as high as 40%.

[Air Pollutant Emission Inventory of Non-road Machineries in Typical Cities in Eastern China].

Based on site investigation of non-road vehicles in Shanghai and Hangzhou located in east China, non-road vehicle emission inventory in 2014 was established in these cities as well as its emission inventory technology. Characteristics of non-road vehicle were also analyzed, including classification, type of fuel, power and emission standard. The results showed that diesel consumed by non-road vehicles was 6.1×105 t in Shanghai and 3.2×105 t in Hangzhou; NOx emission was 3.09×104 t in Shanghai and 1.72×104 t in Hangzhou; PM2.5 emission was 1.41×103 t in Shanghai and 8.1×102 t in Hangzhou, 2014. Emissions from excavators and other construction equipment contributed the most in non-road vehicle emission inventory. Non-road vehicle has become one of the important sources of urban air pollution, whose NOx emissions accounted for 11.1% of all urban sources in Shanghai and 16.1% in Hangzhou, and accounted for 18.5% of mobile sources in Shanghai and 32.2% in Hangzhou.

[Chemical Characteristics of Particulate Matters and Trajectory Influence on Air Quality in Shanghai During the Heavy Haze Episode in December, 2013].

Intensive haze shrouded central and eastern parts of China in Dec. 2013. In this study, the mass concentrations of gaseous and particulate pollutants, and also the chemical compositions of fine particulate matters were obtained based on in-situ measurement in Shanghai urban area. The characteristics of PM2.5 were investigated during different pollution episodes, including dust, haze, fog-haze and long-rang transport episodes. The results showed that pollution was most serious during the fog-haze episode, during which the maximum daily mass concentrations of PM10 and PM2.5 reached 536 microg x m(-3) and 411 microg x m(-3), respectively. During the fog-haze episode, the ratio of PM2.5 to PM10 was over 76.7%, suggesting that high humidity enhanced the secondary formation of NO3-, SO4(2-) and NH4+ in PM2.5. Highest concentration of Ca2+ in PM2.5 occurred during the dust episode and the proportion of primary components in PM2.5 increased obviously. Highest concentration of SO2- was observed in PM25 during the long-range transport episode, with a fast growth rate. Meanwhile, the trajectories reaching Shanghai urban area and cluster analysis during different pollution episodes were simulated by HYSPLIT model. Combined with observation data of PM2.5 in Shanghai urban area, chemical characteristics of PM2.5 in different clusters and potential source apportionment of various pollution episodes were also studied in this study. The result revealed that the air trajectories could be grouped into six clusters based on their spatial similarities. Among these clusters, cluster6 which moved fast was associated with clean air. Cluster2 and cluster3 originating from Mongolia region had strong correlations to dust pollution, along with low PM2.5/PM10 ratio and high concentration of Ca2+ in PM2.5. Compared with other clusters, cluster5 and cluster4 with slow moving speed were more favorable for reactions between particulate species and formation of secondary pollutants during transport. Additionally, the stagnant weather condition under these two clusters with high water vapor when passing over the East China Sea further led to the aggravation of atmospheric pollution in Shanghai.

[Ozone source apportionment at urban area during a typical photochemical pollution episode in the summer of 2013 in the Yangtze River Delta].

With the fast development of urbanization, industrialization and mobilization, the air pollutant emissions with photochemical reactivity become more obvious, causing a severe photochemical pollution with the characteristics of high ozone concentration. However, the ozone source identification is very complicated due to the high non linearity between ozone and its precursors. Thus, ways to reduce ozone is still not clear. A high ozone pollution episode occurred during July, 2013, which lasted for a long period, with large influence area and high intensity. In this paper, we selected this episode to do a case study with the application of ozone source apportionment technology(OSAT) coupled within the CAMx air quality model. In this study, 4 source regions(including Shanghai, north Zhejiang, South Jiangsu and long range transport), 7 source categories (including power plants, industrial process, industrial boilers and kilns, residential, mobile source, volatile source and biogenic emissions) are analyzed to study their contributions to surface O3 in Shanghai, Suzhou and Zhejiang. Results indicate that long range transport contribution to the surface ozone in the YRD is around 20 x 10(-9) - 40 x 10(-9) (volume fraction). The O3 concentrations can increased to 40 x 10(-9) - 100 x 10(-9) (volume fraction) due to precursors emissions in Shanghai, Jiangsu and Zhejiang. As for the regional contribution to 8 hour ozone, long range transport constitutes 42.79% +/- 10.17%, 48.57% +/- 9.97% and 60.13% +/- 7.11% of the surface ozone in Shanghai, Suzhou and Hangzhou, respectively. Regarding the high O3 in Shanghai, local contribution is 28.94% +/- 8.49%, north Zhejiang constitutes 19.83% +/- 10.55%. As for surface O3 in Suzhou, the contribution from south Jiangsu is 26.41% +/- 6.80%. Regarding the surface O3 in Hangzhou, the major regional contributor is north Zhejiang (29.56% +/- 8.33%). Contributions from the long range transport to the daily maximum O3 concentrations are slightly lower than those to the 8-hourly O3, with the contribution of 35.35%-58.04%, while local contributions increase. As for the contributions from source sectors, it is found that the major source contributors include industrial boilers and kilns (18.4%-21.11%), industrial process (19.85%-28.46%), mobile source (21.30%-23.51%), biogenic (13.01%-17.07%) and power plants (7.08%-9.75%). Thus, industrial combustion, industrial processes, and mobile source are major anthropogenic sources of high ozone pollution in summer in the YRD region.