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Jun Zheng - One of the best experts on this subject based on the ideXlab platform.

  • contribution of nitrous acid to the atmospheric oxidation capacity in an Industrial Zone in the yangtze river delta region of china
    Atmospheric Chemistry and Physics, 2020
    Co-Authors: Jun Zheng, Yiwei Diao, Weiwei Wang, Xiaowen Shi, Xinrong Ren, Halim Jabbour, Yuchan Zhang, Wenhui Zhu
    Abstract:

    Abstract. A suite of instruments was deployed to simultaneously measure nitrous acid (HONO), nitrogen oxides ( NOx = NO + NO2 ), carbon monoxide (CO), oZone ( O3 ), volatile organic compounds (VOCs – including formaldehyde, HCHO) and meteorological parameters near a typical Industrial Zone in Nanjing in the Yangtze River Delta (YRD) region of China from 1 to 31 December 2015. High levels of HONO were detected using a wet-chemistry-based method. HONO ranged from 0.03 to 7.04 ppbv with an average of 1.32±0.92  ppbv. Elevated daytime HONO was frequently observed with a minimum of several hundred parts per trillion by volume (pptv) on average, which cannot be explained by the homogeneous OH + NO reaction ( POH+NO ) and primary emissions ( Pemission ), especially during periods with high particulate matter (PM 2.5 ) loadings. HONO chemistry and its impact on the atmospheric oxidation capacity in the study area were further investigated using a Master Chemical Mechanism (MCM) box model. The results show that the average hydroxyl radical (OH) production rate was dominated by the photolysis of HONO ( 7.13×106  molec. cm −3  s −1 ), followed by the ozonolysis of alkenes ( 3.94×106  molec. cm −3  s −1 ), the photolysis of O3 ( 2.46×106  molec. cm −3  s −1 ) and the photolysis of HCHO ( 1.60×106  molec. cm −3  s −1 ) during the campaign period, especially within plumes that originated from the Industrial Zone. Model simulations indicated that heterogeneous chemistry played an important role in HONO formation. The average nighttime NO2 to HONO conversion rate was determined to be ∼0.8  % h −1 . A good correlation between nocturnal HONO∕NO2 and the product of particle surface area density ( S∕V ) and relative humidity (RH), S / V ⋅ RH , supports the heterogeneous NO2∕H2O reaction mechanism. The other HONO source, designated as Punknonwn , was about twice as high as POH+NO on average and displayed a diurnal profile with an evidently photo-enhanced feature, i.e., photosensitized reactions of NO2 may be an important daytime HONO source. Nevertheless, our results suggest that daytime HONO formation was mostly due to the light-induced conversion of NO2 on aerosol surfaces, whereas heterogeneous NO2 reactions on the ground surface dominated nocturnal HONO production. Our study indicated that an elevated PM 2.5 level during haze events can promote the conversion of NO2 to HONO by providing more heterogeneous reaction sites, thereby increasing the atmospheric oxidation capacity, which may further promote the formation of secondary air pollutants. Highlights: High levels of HONO, with an average of 1.32±0.92  ppbv, were observed near one of the largest Industrial Zones in the YRD region of China. HONO photolysis and alkene ozonolyses contributed the most to OH production and, hence, the atmospheric oxidation capacity. High loading of PM 2.5 provided additional reaction surfaces for HONO formation. Heterogeneous formation mechanisms were the most important daytime HONO sources and were further enhanced by sunlight.

  • on line measurement of fluorescent aerosols near an Industrial Zone in the yangtze river delta region using a wideband integrated bioaerosol spectrometer
    Science of The Total Environment, 2019
    Co-Authors: Zhibin Wang, Yiwei Diao, Weiwei Wang, Dongsen Yang, Wenhui Zhu, Hongliang Zhang, Jun Zheng
    Abstract:

    Abstract In this work, we present on-line fluorescent aerosol measurements by the wideband integrated bioaerosol spectrometer (WIBS-4A) near an Industrial Zone in Nanjing, a megacity in the Yangtze-River-Delta (YRD) region. The fieldwork was conducted from April 1 to May 8, 2014. A TSI. 3321 aerosol-particle-sizer (APS) was simultaneously deployed to measure the total number size distribution of aerosol with diameter from 0.8–20 μm. Both WIBS-4A and APS reported similar number concentration and temporal profiles (R2 = 0.72). However, the daily average number of potential bioaerosols was only 0.5 ± 0.2% of the total particles detected by the WIBS-4A and displayed a completely different diurnal profile from that of APS. In addition, WIBS-4A can only provide integrated fluorescent signals, which strongly limited the potential to specifically identify the bioaerosols. Accordingly, hierarchical-agglomerative-cluster-analysis (HACA) was utilized to identify and speciate the potential bioaerosols from the WIBS-4A dataset. By maximizing the total distances among all potential cluster centers, a 12-cluster solution was accepted as the optimum result. These clusters were further identified according to their fluorescent signatures, size, and morphology, i.e., non-bioaerosols, bacteria, and fungal spores and/or pollen fragments. Bacteria were the dominant bioaerosol species detected in this work. The diurnal profiles of bioaerosols correlated very well with relatively humidity (RH), reaching daily maxima around 3 AM~6 AM, indicating the presence of humidity controlled bioaerosol emission mechanism, i.e., bacteria may flourish under moderate ambient temperature, RH, and the absence of UV radiation. The size- and AF-distributions of bioaerosols indicated that bioaerosols normally varied substantially in size and assumed a rather irregular shape. Although the number concentration of bioaerosols was relatively small, most bioaerosols can efficiently serve as ice nuclei by providing rough and irregular surfaces, verified by the observation results. Therefore, WIBS-4A measurements can still be informative for investigations of bioaerosols in the atmosphere, especially when HACA method was incorporated into the data processing.

  • Quantification of the Influence of Industrial Emissions on Volatile Organic Compounds (VOCs) Using PMF Model: A Case Study of Jiangbei Industrial Zone in Nanjing
    Huan jing ke xue= Huanjing kexue, 2018
    Co-Authors: Hu Kun, Ming Wang, Jun Zheng, Hong-li Wang, Lu Xingdong, Sheng-ao Jing, Chao Chen
    Abstract:

    Volatile organic compounds(VOCs)are important precursors of oZone and secondary organic aerosol. The effect of Industrial emissions on ambient VOC concentrations in the Jiangbei Industrial Zone in Nanjing was evaluated using the ambient VOCs measurements taken at Nanjing University of Information Science and Technology (NUIST) during March 2017. The monitoring data showed that the sum of 92 measured VOCs (TVOCs) ranged from 10.3×10-9 to 200.5×10-9. Some VOC species, such as ethylene, propene, benzene, styrene, and dichloromethane had abnormally high values. Positive matrix factorization model (PMF) was used to identify the main sources of VOCs. The results showed that Industrial emissions on average accounted for 50.0% of TVOCs, while petrochemical industry, chemical industry, and paints & solvents use accounted for 14.9%, 19.3% and 15.8%, respectively. During a VOC pollution episode, the contribution of Industrial emissions reached 74.9%. The direction of Industrial sources was determined by combining the wind speed and wind direction data.

  • detection of formaldehyde emissions from an Industrial Zone in the yangtze river delta region of china using a proton transfer reaction ion drift chemical ionization mass spectrometer
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Yiwei Diao, Bingjie Zhang, Weiwei Wang, Dongsen Yang, Ming Wang, Jun Zheng
    Abstract:

    Abstract. A proton transfer reaction ion-drift chemical ionization mass spectrometer (PTR-ID-CIMS) equipped with a hydronium (H3+O) ion source was developed and deployed near an Industrial Zone in the Yangtze River Delta (YRD) region of China in spring 2015 to investigate industry-related emissions of volatile organic compounds (VOCs). Air pollutants including formaldehyde (HCHO), aromatics, and other trace gases (O3 and CO) were simultaneously measured. Humidity effects on the sensitivity of the PTR-ID-CIMS for HCHO detection were investigated and quantified. The performances of the PTR-ID-CIMS were also validated by intercomparing with offline HCHO measurement technique using 2,4-dinitrophenylhydraZone (DNPH) cartridges and the results showed fairly good agreement (slope  =  0.81, R2  =  0.80). The PTR-ID-CIMS detection limit of HCHO (10 s, three-duty-cycle averages) was determined to be 0.9–2.4 (RH  =  1–81.5 %) parts per billion by volume (ppbv) based on 3 times the standard deviations of the background signals. During the field study, observed HCHO concentrations ranged between 1.8 and 12.8 ppbv with a campaign average of 4.1 ± 1.6 ppbv, which was comparable with previous HCHO observations in other similar locations of China. However, HCHO diurnal profiles showed few features of secondary formation. In addition, time series of both HCHO and aromatic VOCs indicated strong influence from local emissions. Using a multiple linear regression fit model, on average the observed HCHO can be attributed to secondary formation (13.8 %), background level (27.0 %), and industry-related emissions, i.e., combustion sources (43.2 %) and chemical productions (16.0 %). Moreover, within the plumes the industry-related emissions can account for up to 69.2 % of the observed HCHO. This work has provided direct evidence of strong primary emissions of HCHO from industry-related activities. These primary HCHO sources can potentially have a strong impact on local and regional air pollution formation in this area of China. Given the fact that the YRD is the largest economic Zone in China and is dense with petrochemical industries, primary Industrial HCHO emissions should be strictly monitored and regulated.

Yiwei Diao - One of the best experts on this subject based on the ideXlab platform.

  • contribution of nitrous acid to the atmospheric oxidation capacity in an Industrial Zone in the yangtze river delta region of china
    Atmospheric Chemistry and Physics, 2020
    Co-Authors: Jun Zheng, Yiwei Diao, Weiwei Wang, Xiaowen Shi, Xinrong Ren, Halim Jabbour, Yuchan Zhang, Wenhui Zhu
    Abstract:

    Abstract. A suite of instruments was deployed to simultaneously measure nitrous acid (HONO), nitrogen oxides ( NOx = NO + NO2 ), carbon monoxide (CO), oZone ( O3 ), volatile organic compounds (VOCs – including formaldehyde, HCHO) and meteorological parameters near a typical Industrial Zone in Nanjing in the Yangtze River Delta (YRD) region of China from 1 to 31 December 2015. High levels of HONO were detected using a wet-chemistry-based method. HONO ranged from 0.03 to 7.04 ppbv with an average of 1.32±0.92  ppbv. Elevated daytime HONO was frequently observed with a minimum of several hundred parts per trillion by volume (pptv) on average, which cannot be explained by the homogeneous OH + NO reaction ( POH+NO ) and primary emissions ( Pemission ), especially during periods with high particulate matter (PM 2.5 ) loadings. HONO chemistry and its impact on the atmospheric oxidation capacity in the study area were further investigated using a Master Chemical Mechanism (MCM) box model. The results show that the average hydroxyl radical (OH) production rate was dominated by the photolysis of HONO ( 7.13×106  molec. cm −3  s −1 ), followed by the ozonolysis of alkenes ( 3.94×106  molec. cm −3  s −1 ), the photolysis of O3 ( 2.46×106  molec. cm −3  s −1 ) and the photolysis of HCHO ( 1.60×106  molec. cm −3  s −1 ) during the campaign period, especially within plumes that originated from the Industrial Zone. Model simulations indicated that heterogeneous chemistry played an important role in HONO formation. The average nighttime NO2 to HONO conversion rate was determined to be ∼0.8  % h −1 . A good correlation between nocturnal HONO∕NO2 and the product of particle surface area density ( S∕V ) and relative humidity (RH), S / V ⋅ RH , supports the heterogeneous NO2∕H2O reaction mechanism. The other HONO source, designated as Punknonwn , was about twice as high as POH+NO on average and displayed a diurnal profile with an evidently photo-enhanced feature, i.e., photosensitized reactions of NO2 may be an important daytime HONO source. Nevertheless, our results suggest that daytime HONO formation was mostly due to the light-induced conversion of NO2 on aerosol surfaces, whereas heterogeneous NO2 reactions on the ground surface dominated nocturnal HONO production. Our study indicated that an elevated PM 2.5 level during haze events can promote the conversion of NO2 to HONO by providing more heterogeneous reaction sites, thereby increasing the atmospheric oxidation capacity, which may further promote the formation of secondary air pollutants. Highlights: High levels of HONO, with an average of 1.32±0.92  ppbv, were observed near one of the largest Industrial Zones in the YRD region of China. HONO photolysis and alkene ozonolyses contributed the most to OH production and, hence, the atmospheric oxidation capacity. High loading of PM 2.5 provided additional reaction surfaces for HONO formation. Heterogeneous formation mechanisms were the most important daytime HONO sources and were further enhanced by sunlight.

  • on line measurement of fluorescent aerosols near an Industrial Zone in the yangtze river delta region using a wideband integrated bioaerosol spectrometer
    Science of The Total Environment, 2019
    Co-Authors: Zhibin Wang, Yiwei Diao, Weiwei Wang, Dongsen Yang, Wenhui Zhu, Hongliang Zhang, Jun Zheng
    Abstract:

    Abstract In this work, we present on-line fluorescent aerosol measurements by the wideband integrated bioaerosol spectrometer (WIBS-4A) near an Industrial Zone in Nanjing, a megacity in the Yangtze-River-Delta (YRD) region. The fieldwork was conducted from April 1 to May 8, 2014. A TSI. 3321 aerosol-particle-sizer (APS) was simultaneously deployed to measure the total number size distribution of aerosol with diameter from 0.8–20 μm. Both WIBS-4A and APS reported similar number concentration and temporal profiles (R2 = 0.72). However, the daily average number of potential bioaerosols was only 0.5 ± 0.2% of the total particles detected by the WIBS-4A and displayed a completely different diurnal profile from that of APS. In addition, WIBS-4A can only provide integrated fluorescent signals, which strongly limited the potential to specifically identify the bioaerosols. Accordingly, hierarchical-agglomerative-cluster-analysis (HACA) was utilized to identify and speciate the potential bioaerosols from the WIBS-4A dataset. By maximizing the total distances among all potential cluster centers, a 12-cluster solution was accepted as the optimum result. These clusters were further identified according to their fluorescent signatures, size, and morphology, i.e., non-bioaerosols, bacteria, and fungal spores and/or pollen fragments. Bacteria were the dominant bioaerosol species detected in this work. The diurnal profiles of bioaerosols correlated very well with relatively humidity (RH), reaching daily maxima around 3 AM~6 AM, indicating the presence of humidity controlled bioaerosol emission mechanism, i.e., bacteria may flourish under moderate ambient temperature, RH, and the absence of UV radiation. The size- and AF-distributions of bioaerosols indicated that bioaerosols normally varied substantially in size and assumed a rather irregular shape. Although the number concentration of bioaerosols was relatively small, most bioaerosols can efficiently serve as ice nuclei by providing rough and irregular surfaces, verified by the observation results. Therefore, WIBS-4A measurements can still be informative for investigations of bioaerosols in the atmosphere, especially when HACA method was incorporated into the data processing.

  • detection of formaldehyde emissions from an Industrial Zone in the yangtze river delta region of china using a proton transfer reaction ion drift chemical ionization mass spectrometer
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Yiwei Diao, Bingjie Zhang, Weiwei Wang, Dongsen Yang, Ming Wang, Jun Zheng
    Abstract:

    Abstract. A proton transfer reaction ion-drift chemical ionization mass spectrometer (PTR-ID-CIMS) equipped with a hydronium (H3+O) ion source was developed and deployed near an Industrial Zone in the Yangtze River Delta (YRD) region of China in spring 2015 to investigate industry-related emissions of volatile organic compounds (VOCs). Air pollutants including formaldehyde (HCHO), aromatics, and other trace gases (O3 and CO) were simultaneously measured. Humidity effects on the sensitivity of the PTR-ID-CIMS for HCHO detection were investigated and quantified. The performances of the PTR-ID-CIMS were also validated by intercomparing with offline HCHO measurement technique using 2,4-dinitrophenylhydraZone (DNPH) cartridges and the results showed fairly good agreement (slope  =  0.81, R2  =  0.80). The PTR-ID-CIMS detection limit of HCHO (10 s, three-duty-cycle averages) was determined to be 0.9–2.4 (RH  =  1–81.5 %) parts per billion by volume (ppbv) based on 3 times the standard deviations of the background signals. During the field study, observed HCHO concentrations ranged between 1.8 and 12.8 ppbv with a campaign average of 4.1 ± 1.6 ppbv, which was comparable with previous HCHO observations in other similar locations of China. However, HCHO diurnal profiles showed few features of secondary formation. In addition, time series of both HCHO and aromatic VOCs indicated strong influence from local emissions. Using a multiple linear regression fit model, on average the observed HCHO can be attributed to secondary formation (13.8 %), background level (27.0 %), and industry-related emissions, i.e., combustion sources (43.2 %) and chemical productions (16.0 %). Moreover, within the plumes the industry-related emissions can account for up to 69.2 % of the observed HCHO. This work has provided direct evidence of strong primary emissions of HCHO from industry-related activities. These primary HCHO sources can potentially have a strong impact on local and regional air pollution formation in this area of China. Given the fact that the YRD is the largest economic Zone in China and is dense with petrochemical industries, primary Industrial HCHO emissions should be strictly monitored and regulated.

Weiwei Wang - One of the best experts on this subject based on the ideXlab platform.

  • contribution of nitrous acid to the atmospheric oxidation capacity in an Industrial Zone in the yangtze river delta region of china
    Atmospheric Chemistry and Physics, 2020
    Co-Authors: Jun Zheng, Yiwei Diao, Weiwei Wang, Xiaowen Shi, Xinrong Ren, Halim Jabbour, Yuchan Zhang, Wenhui Zhu
    Abstract:

    Abstract. A suite of instruments was deployed to simultaneously measure nitrous acid (HONO), nitrogen oxides ( NOx = NO + NO2 ), carbon monoxide (CO), oZone ( O3 ), volatile organic compounds (VOCs – including formaldehyde, HCHO) and meteorological parameters near a typical Industrial Zone in Nanjing in the Yangtze River Delta (YRD) region of China from 1 to 31 December 2015. High levels of HONO were detected using a wet-chemistry-based method. HONO ranged from 0.03 to 7.04 ppbv with an average of 1.32±0.92  ppbv. Elevated daytime HONO was frequently observed with a minimum of several hundred parts per trillion by volume (pptv) on average, which cannot be explained by the homogeneous OH + NO reaction ( POH+NO ) and primary emissions ( Pemission ), especially during periods with high particulate matter (PM 2.5 ) loadings. HONO chemistry and its impact on the atmospheric oxidation capacity in the study area were further investigated using a Master Chemical Mechanism (MCM) box model. The results show that the average hydroxyl radical (OH) production rate was dominated by the photolysis of HONO ( 7.13×106  molec. cm −3  s −1 ), followed by the ozonolysis of alkenes ( 3.94×106  molec. cm −3  s −1 ), the photolysis of O3 ( 2.46×106  molec. cm −3  s −1 ) and the photolysis of HCHO ( 1.60×106  molec. cm −3  s −1 ) during the campaign period, especially within plumes that originated from the Industrial Zone. Model simulations indicated that heterogeneous chemistry played an important role in HONO formation. The average nighttime NO2 to HONO conversion rate was determined to be ∼0.8  % h −1 . A good correlation between nocturnal HONO∕NO2 and the product of particle surface area density ( S∕V ) and relative humidity (RH), S / V ⋅ RH , supports the heterogeneous NO2∕H2O reaction mechanism. The other HONO source, designated as Punknonwn , was about twice as high as POH+NO on average and displayed a diurnal profile with an evidently photo-enhanced feature, i.e., photosensitized reactions of NO2 may be an important daytime HONO source. Nevertheless, our results suggest that daytime HONO formation was mostly due to the light-induced conversion of NO2 on aerosol surfaces, whereas heterogeneous NO2 reactions on the ground surface dominated nocturnal HONO production. Our study indicated that an elevated PM 2.5 level during haze events can promote the conversion of NO2 to HONO by providing more heterogeneous reaction sites, thereby increasing the atmospheric oxidation capacity, which may further promote the formation of secondary air pollutants. Highlights: High levels of HONO, with an average of 1.32±0.92  ppbv, were observed near one of the largest Industrial Zones in the YRD region of China. HONO photolysis and alkene ozonolyses contributed the most to OH production and, hence, the atmospheric oxidation capacity. High loading of PM 2.5 provided additional reaction surfaces for HONO formation. Heterogeneous formation mechanisms were the most important daytime HONO sources and were further enhanced by sunlight.

  • on line measurement of fluorescent aerosols near an Industrial Zone in the yangtze river delta region using a wideband integrated bioaerosol spectrometer
    Science of The Total Environment, 2019
    Co-Authors: Zhibin Wang, Yiwei Diao, Weiwei Wang, Dongsen Yang, Wenhui Zhu, Hongliang Zhang, Jun Zheng
    Abstract:

    Abstract In this work, we present on-line fluorescent aerosol measurements by the wideband integrated bioaerosol spectrometer (WIBS-4A) near an Industrial Zone in Nanjing, a megacity in the Yangtze-River-Delta (YRD) region. The fieldwork was conducted from April 1 to May 8, 2014. A TSI. 3321 aerosol-particle-sizer (APS) was simultaneously deployed to measure the total number size distribution of aerosol with diameter from 0.8–20 μm. Both WIBS-4A and APS reported similar number concentration and temporal profiles (R2 = 0.72). However, the daily average number of potential bioaerosols was only 0.5 ± 0.2% of the total particles detected by the WIBS-4A and displayed a completely different diurnal profile from that of APS. In addition, WIBS-4A can only provide integrated fluorescent signals, which strongly limited the potential to specifically identify the bioaerosols. Accordingly, hierarchical-agglomerative-cluster-analysis (HACA) was utilized to identify and speciate the potential bioaerosols from the WIBS-4A dataset. By maximizing the total distances among all potential cluster centers, a 12-cluster solution was accepted as the optimum result. These clusters were further identified according to their fluorescent signatures, size, and morphology, i.e., non-bioaerosols, bacteria, and fungal spores and/or pollen fragments. Bacteria were the dominant bioaerosol species detected in this work. The diurnal profiles of bioaerosols correlated very well with relatively humidity (RH), reaching daily maxima around 3 AM~6 AM, indicating the presence of humidity controlled bioaerosol emission mechanism, i.e., bacteria may flourish under moderate ambient temperature, RH, and the absence of UV radiation. The size- and AF-distributions of bioaerosols indicated that bioaerosols normally varied substantially in size and assumed a rather irregular shape. Although the number concentration of bioaerosols was relatively small, most bioaerosols can efficiently serve as ice nuclei by providing rough and irregular surfaces, verified by the observation results. Therefore, WIBS-4A measurements can still be informative for investigations of bioaerosols in the atmosphere, especially when HACA method was incorporated into the data processing.

  • detection of formaldehyde emissions from an Industrial Zone in the yangtze river delta region of china using a proton transfer reaction ion drift chemical ionization mass spectrometer
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Yiwei Diao, Bingjie Zhang, Weiwei Wang, Dongsen Yang, Ming Wang, Jun Zheng
    Abstract:

    Abstract. A proton transfer reaction ion-drift chemical ionization mass spectrometer (PTR-ID-CIMS) equipped with a hydronium (H3+O) ion source was developed and deployed near an Industrial Zone in the Yangtze River Delta (YRD) region of China in spring 2015 to investigate industry-related emissions of volatile organic compounds (VOCs). Air pollutants including formaldehyde (HCHO), aromatics, and other trace gases (O3 and CO) were simultaneously measured. Humidity effects on the sensitivity of the PTR-ID-CIMS for HCHO detection were investigated and quantified. The performances of the PTR-ID-CIMS were also validated by intercomparing with offline HCHO measurement technique using 2,4-dinitrophenylhydraZone (DNPH) cartridges and the results showed fairly good agreement (slope  =  0.81, R2  =  0.80). The PTR-ID-CIMS detection limit of HCHO (10 s, three-duty-cycle averages) was determined to be 0.9–2.4 (RH  =  1–81.5 %) parts per billion by volume (ppbv) based on 3 times the standard deviations of the background signals. During the field study, observed HCHO concentrations ranged between 1.8 and 12.8 ppbv with a campaign average of 4.1 ± 1.6 ppbv, which was comparable with previous HCHO observations in other similar locations of China. However, HCHO diurnal profiles showed few features of secondary formation. In addition, time series of both HCHO and aromatic VOCs indicated strong influence from local emissions. Using a multiple linear regression fit model, on average the observed HCHO can be attributed to secondary formation (13.8 %), background level (27.0 %), and industry-related emissions, i.e., combustion sources (43.2 %) and chemical productions (16.0 %). Moreover, within the plumes the industry-related emissions can account for up to 69.2 % of the observed HCHO. This work has provided direct evidence of strong primary emissions of HCHO from industry-related activities. These primary HCHO sources can potentially have a strong impact on local and regional air pollution formation in this area of China. Given the fact that the YRD is the largest economic Zone in China and is dense with petrochemical industries, primary Industrial HCHO emissions should be strictly monitored and regulated.

Wenhui Zhu - One of the best experts on this subject based on the ideXlab platform.

  • contribution of nitrous acid to the atmospheric oxidation capacity in an Industrial Zone in the yangtze river delta region of china
    Atmospheric Chemistry and Physics, 2020
    Co-Authors: Jun Zheng, Yiwei Diao, Weiwei Wang, Xiaowen Shi, Xinrong Ren, Halim Jabbour, Yuchan Zhang, Wenhui Zhu
    Abstract:

    Abstract. A suite of instruments was deployed to simultaneously measure nitrous acid (HONO), nitrogen oxides ( NOx = NO + NO2 ), carbon monoxide (CO), oZone ( O3 ), volatile organic compounds (VOCs – including formaldehyde, HCHO) and meteorological parameters near a typical Industrial Zone in Nanjing in the Yangtze River Delta (YRD) region of China from 1 to 31 December 2015. High levels of HONO were detected using a wet-chemistry-based method. HONO ranged from 0.03 to 7.04 ppbv with an average of 1.32±0.92  ppbv. Elevated daytime HONO was frequently observed with a minimum of several hundred parts per trillion by volume (pptv) on average, which cannot be explained by the homogeneous OH + NO reaction ( POH+NO ) and primary emissions ( Pemission ), especially during periods with high particulate matter (PM 2.5 ) loadings. HONO chemistry and its impact on the atmospheric oxidation capacity in the study area were further investigated using a Master Chemical Mechanism (MCM) box model. The results show that the average hydroxyl radical (OH) production rate was dominated by the photolysis of HONO ( 7.13×106  molec. cm −3  s −1 ), followed by the ozonolysis of alkenes ( 3.94×106  molec. cm −3  s −1 ), the photolysis of O3 ( 2.46×106  molec. cm −3  s −1 ) and the photolysis of HCHO ( 1.60×106  molec. cm −3  s −1 ) during the campaign period, especially within plumes that originated from the Industrial Zone. Model simulations indicated that heterogeneous chemistry played an important role in HONO formation. The average nighttime NO2 to HONO conversion rate was determined to be ∼0.8  % h −1 . A good correlation between nocturnal HONO∕NO2 and the product of particle surface area density ( S∕V ) and relative humidity (RH), S / V ⋅ RH , supports the heterogeneous NO2∕H2O reaction mechanism. The other HONO source, designated as Punknonwn , was about twice as high as POH+NO on average and displayed a diurnal profile with an evidently photo-enhanced feature, i.e., photosensitized reactions of NO2 may be an important daytime HONO source. Nevertheless, our results suggest that daytime HONO formation was mostly due to the light-induced conversion of NO2 on aerosol surfaces, whereas heterogeneous NO2 reactions on the ground surface dominated nocturnal HONO production. Our study indicated that an elevated PM 2.5 level during haze events can promote the conversion of NO2 to HONO by providing more heterogeneous reaction sites, thereby increasing the atmospheric oxidation capacity, which may further promote the formation of secondary air pollutants. Highlights: High levels of HONO, with an average of 1.32±0.92  ppbv, were observed near one of the largest Industrial Zones in the YRD region of China. HONO photolysis and alkene ozonolyses contributed the most to OH production and, hence, the atmospheric oxidation capacity. High loading of PM 2.5 provided additional reaction surfaces for HONO formation. Heterogeneous formation mechanisms were the most important daytime HONO sources and were further enhanced by sunlight.

  • on line measurement of fluorescent aerosols near an Industrial Zone in the yangtze river delta region using a wideband integrated bioaerosol spectrometer
    Science of The Total Environment, 2019
    Co-Authors: Zhibin Wang, Yiwei Diao, Weiwei Wang, Dongsen Yang, Wenhui Zhu, Hongliang Zhang, Jun Zheng
    Abstract:

    Abstract In this work, we present on-line fluorescent aerosol measurements by the wideband integrated bioaerosol spectrometer (WIBS-4A) near an Industrial Zone in Nanjing, a megacity in the Yangtze-River-Delta (YRD) region. The fieldwork was conducted from April 1 to May 8, 2014. A TSI. 3321 aerosol-particle-sizer (APS) was simultaneously deployed to measure the total number size distribution of aerosol with diameter from 0.8–20 μm. Both WIBS-4A and APS reported similar number concentration and temporal profiles (R2 = 0.72). However, the daily average number of potential bioaerosols was only 0.5 ± 0.2% of the total particles detected by the WIBS-4A and displayed a completely different diurnal profile from that of APS. In addition, WIBS-4A can only provide integrated fluorescent signals, which strongly limited the potential to specifically identify the bioaerosols. Accordingly, hierarchical-agglomerative-cluster-analysis (HACA) was utilized to identify and speciate the potential bioaerosols from the WIBS-4A dataset. By maximizing the total distances among all potential cluster centers, a 12-cluster solution was accepted as the optimum result. These clusters were further identified according to their fluorescent signatures, size, and morphology, i.e., non-bioaerosols, bacteria, and fungal spores and/or pollen fragments. Bacteria were the dominant bioaerosol species detected in this work. The diurnal profiles of bioaerosols correlated very well with relatively humidity (RH), reaching daily maxima around 3 AM~6 AM, indicating the presence of humidity controlled bioaerosol emission mechanism, i.e., bacteria may flourish under moderate ambient temperature, RH, and the absence of UV radiation. The size- and AF-distributions of bioaerosols indicated that bioaerosols normally varied substantially in size and assumed a rather irregular shape. Although the number concentration of bioaerosols was relatively small, most bioaerosols can efficiently serve as ice nuclei by providing rough and irregular surfaces, verified by the observation results. Therefore, WIBS-4A measurements can still be informative for investigations of bioaerosols in the atmosphere, especially when HACA method was incorporated into the data processing.

Dongsen Yang - One of the best experts on this subject based on the ideXlab platform.

  • on line measurement of fluorescent aerosols near an Industrial Zone in the yangtze river delta region using a wideband integrated bioaerosol spectrometer
    Science of The Total Environment, 2019
    Co-Authors: Zhibin Wang, Yiwei Diao, Weiwei Wang, Dongsen Yang, Wenhui Zhu, Hongliang Zhang, Jun Zheng
    Abstract:

    Abstract In this work, we present on-line fluorescent aerosol measurements by the wideband integrated bioaerosol spectrometer (WIBS-4A) near an Industrial Zone in Nanjing, a megacity in the Yangtze-River-Delta (YRD) region. The fieldwork was conducted from April 1 to May 8, 2014. A TSI. 3321 aerosol-particle-sizer (APS) was simultaneously deployed to measure the total number size distribution of aerosol with diameter from 0.8–20 μm. Both WIBS-4A and APS reported similar number concentration and temporal profiles (R2 = 0.72). However, the daily average number of potential bioaerosols was only 0.5 ± 0.2% of the total particles detected by the WIBS-4A and displayed a completely different diurnal profile from that of APS. In addition, WIBS-4A can only provide integrated fluorescent signals, which strongly limited the potential to specifically identify the bioaerosols. Accordingly, hierarchical-agglomerative-cluster-analysis (HACA) was utilized to identify and speciate the potential bioaerosols from the WIBS-4A dataset. By maximizing the total distances among all potential cluster centers, a 12-cluster solution was accepted as the optimum result. These clusters were further identified according to their fluorescent signatures, size, and morphology, i.e., non-bioaerosols, bacteria, and fungal spores and/or pollen fragments. Bacteria were the dominant bioaerosol species detected in this work. The diurnal profiles of bioaerosols correlated very well with relatively humidity (RH), reaching daily maxima around 3 AM~6 AM, indicating the presence of humidity controlled bioaerosol emission mechanism, i.e., bacteria may flourish under moderate ambient temperature, RH, and the absence of UV radiation. The size- and AF-distributions of bioaerosols indicated that bioaerosols normally varied substantially in size and assumed a rather irregular shape. Although the number concentration of bioaerosols was relatively small, most bioaerosols can efficiently serve as ice nuclei by providing rough and irregular surfaces, verified by the observation results. Therefore, WIBS-4A measurements can still be informative for investigations of bioaerosols in the atmosphere, especially when HACA method was incorporated into the data processing.

  • detection of formaldehyde emissions from an Industrial Zone in the yangtze river delta region of china using a proton transfer reaction ion drift chemical ionization mass spectrometer
    Atmospheric Measurement Techniques, 2016
    Co-Authors: Yiwei Diao, Bingjie Zhang, Weiwei Wang, Dongsen Yang, Ming Wang, Jun Zheng
    Abstract:

    Abstract. A proton transfer reaction ion-drift chemical ionization mass spectrometer (PTR-ID-CIMS) equipped with a hydronium (H3+O) ion source was developed and deployed near an Industrial Zone in the Yangtze River Delta (YRD) region of China in spring 2015 to investigate industry-related emissions of volatile organic compounds (VOCs). Air pollutants including formaldehyde (HCHO), aromatics, and other trace gases (O3 and CO) were simultaneously measured. Humidity effects on the sensitivity of the PTR-ID-CIMS for HCHO detection were investigated and quantified. The performances of the PTR-ID-CIMS were also validated by intercomparing with offline HCHO measurement technique using 2,4-dinitrophenylhydraZone (DNPH) cartridges and the results showed fairly good agreement (slope  =  0.81, R2  =  0.80). The PTR-ID-CIMS detection limit of HCHO (10 s, three-duty-cycle averages) was determined to be 0.9–2.4 (RH  =  1–81.5 %) parts per billion by volume (ppbv) based on 3 times the standard deviations of the background signals. During the field study, observed HCHO concentrations ranged between 1.8 and 12.8 ppbv with a campaign average of 4.1 ± 1.6 ppbv, which was comparable with previous HCHO observations in other similar locations of China. However, HCHO diurnal profiles showed few features of secondary formation. In addition, time series of both HCHO and aromatic VOCs indicated strong influence from local emissions. Using a multiple linear regression fit model, on average the observed HCHO can be attributed to secondary formation (13.8 %), background level (27.0 %), and industry-related emissions, i.e., combustion sources (43.2 %) and chemical productions (16.0 %). Moreover, within the plumes the industry-related emissions can account for up to 69.2 % of the observed HCHO. This work has provided direct evidence of strong primary emissions of HCHO from industry-related activities. These primary HCHO sources can potentially have a strong impact on local and regional air pollution formation in this area of China. Given the fact that the YRD is the largest economic Zone in China and is dense with petrochemical industries, primary Industrial HCHO emissions should be strictly monitored and regulated.