Seasonal and spatial variations of optical properties of light absorbing carbon and its influencing factors in a typical polluted city in Yangtze River Delta, China

Chen, Dong; Zhao, Yu; Lyu, Ritao; Wu, Rongrong; Dai, Liang; Zhao, Yunhui; Chen, Feng; Zhang, Jie; Yu, Huan; Guan, Miao

doi:10.1016/j.atmosenv.2018.11.022

Cited by 40 publications

(19 citation statements)

References 47 publications

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“…MARGA is a state-of-the-art instrument which monitors near-real-time water-soluble ions in aerosols and their gaseous precursors (Lanciki, 2018), and it was able to capture rapid compositional changes in PM 2.5 (Chen et al, 2017). The site was on the roof of the building of the Jiangsu Provincial Academy of Environmental Science (30 m above the ground) surrounded by residential and commercial buildings and heavy traffic (JSPAES; Li et al, 2015;Chen et al, 2019). The data of October 2014 were applied in this work to evaluate the NH 3 inventories through air quality simulation.…”

Section: Ground-based and Satellite Observationsmentioning

confidence: 99%

Quantification and evaluation of atmospheric ammonia emissions with different methods: a case study for the Yangtze River Delta region, China

et al. 2020

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Abstract. To explore the effects of data and method on emission estimation, two inventories of NH3 emissions of the Yangtze River Delta (YRD) region in eastern China were developed for 2014 based on constant emission factors (E1) and those characterizing agricultural processes (E2). The latter derived the monthly emission factors and activity data integrating the local information of soil, meteorology, and agricultural processes. The total emissions were calculated to be 1765 and 1067 Gg with E1 and E2, respectively, and clear differences existed in seasonal and spatial distributions. Elevated emissions were found in March and September in E2, attributed largely to the increased top dressing fertilization and to the enhanced NH3 volatilization under high temperature, respectively. A relatively large discrepancy between the inventories existed in the northern YRD with abundant croplands. With the estimated emissions 38 % smaller in E2, the average of simulated NH3 concentrations with an air quality model using E2 was 27 % smaller than that using E1 at two ground sites in the YRD. At the suburban site in Pudong, Shanghai (SHPD), the simulated NH3 concentrations with E1 were generally larger than observations, and the modeling performance was improved, indicated by the smaller normalized mean errors (NMEs) when E2 was applied. In contrast, very limited improvement was found at the urban site JSPAES, as E2 failed to improve the emission estimation of transportation and residential activities. Compared to NH3, the modeling performance for inorganic aerosols was better for most cases, and the differences between the simulated concentrations with E1 and E2 were clearly smaller, at 7 %, 3 %, and 12 % (relative to E1) for NH4+, SO42-, and NO3-, respectively. Compared to the satellite-derived NH3 column, application of E2 significantly corrected the overestimation in vertical column density for January and October with E1, but it did not improve the model performance for July. The NH3 emissions might be underestimated with the assumption of linear correlation between NH3 volatilization and soil pH for acidic soil, particularly in warm seasons. Three additional cases, i.e., 40 % abatement of SO2, 40 % abatement of NOx, and 40 % abatement of both species, were applied to test the sensitivity of NH3 and inorganic aerosol concentrations to precursor emissions. Under an NH3-rich condition, estimation of SO2 emissions was detected to be more effective on simulation of secondary inorganic aerosols compared to NH3. Reduced SO2 would restrain the formation of (NH4)2SO4 and thereby enhance the NH3 concentrations. To improve the air quality more effectively and efficiently, NH3 emissions should be substantially controlled along with SO2 and NOx in the future.

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Section: Ground-based and Satellite Observationsmentioning

confidence: 99%

Quantification and evaluation of atmospheric ammonia emissions with different methods: a case study for the Yangtze River Delta region, China

et al. 2020

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“…The campaigns were conducted at three sites in Nanjing, i.e., NJU, PAES and NUIST, representative for the suburban, urban and industrial region, respectively (see the site locations in Figure S1 in the Supplement). NJU (32.07°N, 118.57°E) was on the roof (25 m above the ground) of the School of the Environment building in the Nanjing University campus in eastern suburban Nanjing (Chen et al, 2017;2019). PAES (32.03°N, 118.44°E) was on the roof (30 m above the ground) of the Jiangsu Provincial Academy of Environmental Science building in western urban Nanjing.…”

Section: Site Descriptionmentioning

confidence: 99%

“…protocol. More details on the analyzer operation were described in our previous studies (Chen et al, 2017;2019). Recent studies indicated that methanol soluble organic carbon (MSOC) was a more suitable BrC surrogate than water soluble organic carbon (WSOC) and was thus used in present study (Cheng et al, 2016;Huang et al, 2018;Lei et al, 2018).…”

Section: Three Anions (So 4 2-mentioning

confidence: 99%

Characterization and source apportionment of aerosol light scattering in a typical polluted city in Yangtze River Delta, China

Chen¹,

Yu²,

Zhang³

et al. 2020

Preprint

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Abstract. Through online observation and offline chemistry analysis of samples at suburban, urban and industrial sites (NJU, PAES and NUIST respectively) in Nanjing, a typical polluted city in Yangtze River Delta, we optimized the aerosol light scattering estimation method, identified its influencing factors, and quantified the contributions of emission sources to aerosol scattering. The daily average concentration of PM2.5 during the sampling period (November 2015–March 2017) was 163.1 ± 13.6 μg/m3 for the heavily polluted period, 3.8 and 1.6 times those for the clean (47.9 ± 15.8 μg/m3) and lightly polluted (102.1 ±v16.4 μg/m3) periods, respectively. The largest increase in PM concentration and its major chemical components was found at the size range of 0.56&ndash1.0 μm for the heavily polluted period, and the contributions of nitrate and sulfate were the greatest in the 0.56–1.0 μm fraction (19.4–39.7 % and 18.1–34.7 % respectively) for all the three periods. The results indicated that the large growth of nitrate and sulfate were one of the major reasons for the polluted periods. Based on measurements at the three sites, the US IMPROVE algorithm was optimized to evaluate aerosol scattering in eastern China. The light-absorption capacity OC was estimated to account for over half of the methanol soluble organic carbon (MSOC) at NJU and PAES, whereas the fraction was lower at NUIST. Based on Mie theory, we found that the high relative humidity (RH) could largely enhance the light scattering effect of accumulation particles, but it had few effects on the mixing state of particles. The scattering coefficients of particles within the 0.56–1.0 μm range contributed the most to the total scattering (28–69 %). The mass scattering efficiency (MSE) of sulfate and nitrate increased with the elevated pollution level, whereas a low MSE of organic matter (OM) was found for the heavily polluted period, probably because a proportion of OM had only light-absorption property. A coupled model of positive matrix factorization (PMF) and Mie theory was developed and applied for the source apportionment of aerosol light scattering. Coal burning, industry and vehicles were identified as the major sources of the reduced visibility in Nanjing, with an estimated collective contribution at 64–70 %. The comparison between the clean and polluted period suggested that the increased primary particle emissions from vehicles and industry were the major causes of the visibility degradation in urban and industrial regions, respectively. In addition, secondary aerosols were a great contributor to the reduced visibility.

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“…The formation of sulfate, nitrate and ammonium (SNA) is mainly affected by the emissions of precursors and the atmospheric oxidation capacity. Due to the great use of fossil fuel consumption, the emissions of precursors SO 2 and NO x per unit area in eastern China were estimated to be 2.3 and 3.4 times larger than the national average, respectively (Cheng et al, 2012;Shi et al, 2014). Under high RH, moreover, the SNA formation could significantly be elevated through gas-to-particle heterogeneous reactions for the heavily polluted period (Seinfeld and Pandis, 2006).…”

Section: Mass Concentrations and Size Distributions Of Pm Compositionsmentioning

confidence: 99%

Characterization and source apportionment of aerosol light scattering in a typical polluted city in the Yangtze River Delta, China

et al. 2020

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Abstract. Through online observation and offline chemistry analysis of samples at suburban, urban and industrial sites (NJU, PAES and NUIST, respectively) in Nanjing, a typical polluted city in the Yangtze River Delta, we optimized the aerosol light scattering estimation method, identified its influencing factors and quantified the contributions of emission sources to aerosol scattering. The daily average concentration of PM2.5 during the sampling period (November 2015–March 2017) was 163.1±13.6 µg m−3 for the heavily polluted period, 3.8 and 1.6 times those for the clean (47.9±15.8 µg m−3) and lightly polluted (102.1±16.4 µg m−3) periods, respectively. The largest increase in PM concentration and its major chemical components was found at the size range of 0.56–1.0 µm for the heavily polluted period, and the contributions of nitrate and sulfate were the greatest in the 0.56–1.0 µm fraction (19.4 %–39.7 % and 18.1 %–34.7 %, respectively) for all the three periods. The results indicated that the large growth of nitrate and sulfate was one of the major reasons for the polluted periods. Based on measurements at the three sites, the US Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithm was optimized to evaluate aerosol scattering in eastern China. The light absorption capacity of organic carbon (OC) was estimated to account for over half of the methanol-soluble organic carbon (MSOC) at NJU and PAES, whereas the fraction was lower at NUIST. Based on the Mie theory, we found that the high relative humidity (RH) could largely enhance the light scattering effect of accumulation particles, but it had few effects on the mixing state of particles. The scattering coefficients of particles within the 0.56–1.0 µm range contributed the most to the total scattering (28 %–69 %). The mass scattering efficiency (MSE) of sulfate and nitrate increased with the elevated pollution level, whereas a low MSE of organic matter (OM) was found for the heavily polluted period, probably because a proportion of OM had only a light absorption property. A coupled model of positive matrix factorization (PMF) and the Mie theory was developed and applied for the source apportionment of aerosol light scattering. Coal burning, industry and vehicles were identified as the major sources of the reduced visibility in Nanjing, with an estimated collective contribution at 64 %–70 %. The comparison between the clean and polluted period suggested that the increased primary particle emissions from vehicles and industry were the major causes of the visibility degradation in urban and industrial regions, respectively. In addition, secondary aerosols were a great contributor to the reduced visibility.

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Seasonal and spatial variations of optical properties of light absorbing carbon and its influencing factors in a typical polluted city in Yangtze River Delta, China

Cited by 40 publications

References 47 publications

Quantification and evaluation of atmospheric ammonia emissions with different methods: a case study for the Yangtze River Delta region, China

Quantification and evaluation of atmospheric ammonia emissions with different methods: a case study for the Yangtze River Delta region, China

Characterization and source apportionment of aerosol light scattering in a typical polluted city in Yangtze River Delta, China

Characterization and source apportionment of aerosol light scattering in a typical polluted city in the Yangtze River Delta, China

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