Formation and Evolution of Secondary Particulate Matter During Heavy Haze Pollution Episodes in Northeast China in Winter

Abstract Based on the simultaneous observation of fine particulate matter (PM2.5) and its chemical components in four heavy haze pollution episodes at 14 sampling sites in northeast China from 2017 to 2019, the formation and existence of sulfate (SO42-) and nitrate (NO3-) secondary contaminants under different stages of the pollution episodes, and different meteorological and emission conditions were compared. The results yielded three main findings. (1) Organic carbon (OC) was the most important component of PM2.5, followed by NO3-,SO42-,and ammonium (NH4+). Nitrate surpassed sulfate as the most important secondary inorganic component over the study period. (2) The significant increase in atmospheric OC, SO42-, and NO3-concentrations was an important reason for haze formation. Meteorological factors such as wind direction, wind speed, temperature (T), relative humidity (RH), and atmospheric oxidability played an important role in secondary pollutant formation. (3) There were two potential SO42- formation mechanisms. The first was the gas-phase reaction of the hydroxyl radical(OH·) leading to the oxidation of nitrogen dioxide (NO2) and sulfur dioxide (SO2),and high ozone (O3) concentrations. A high atmospheric oxidability and high winter Ts were very important for SO42- formation. The second mechanism occurred under neutral or weakly alkaline conditions when large amounts of SO2 could enter aerosol droplets, and NO2 was more likely to react in the aqueous phase with SO2 to increase the output of SO42-. Nitrate formation was may be mainly due to the homogeneous gas-phase reaction of OH· with NO2, SO2, and ammonia(NH3). The highest NO3 concentration was observed under mild winter Ts, high RH, high atmospheric oxidability (O3 and nitrous acid (HONO)), high NH3 concentrations, and suitable light conditions. The differences in SO42- formation between northeast China and other regions were mainly a result of the suppression of the aqueous reaction of SO42- due to the low T in winter and low-sulfur coal emissions, which resulted in the gas-phase oxidation process with the highest SO42- production capacity becoming an important process. However, the aqueous reaction process was the most common mechanism of SO42- production in northeast China.

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Formation mechanisms of atmospheric nitrate and sulfate during the winter haze pollution periods in Beijing: gas-phase, heterogeneous and aqueous-phase chemistry

10.5194/acp-2019-994 ◽

2019 ◽

Author(s):

Pengfei Liu ◽

Can Ye ◽

Chaoyang Xue ◽

Chenglong Zhang ◽

Yujing Mu ◽

...

Keyword(s):

Gas Phase ◽

Aqueous Phase ◽

Sampling Period ◽

Convincing Evidence ◽

Formation Mechanisms ◽

Phase Reaction ◽

So2 Oxidation ◽

Mean Values ◽

Sulfate Production ◽

Haze Pollution

Abstract. A vast area in China is currently going through severe haze episodes with drastically elevated concentrations of PM2.5 in winter. Nitrate and sulfate are main constituents of PM2.5 but their formations via NO2 and SO2 oxidation are still not comprehensively understood, especially under different pollution or atmospheric relative humidity (RH) conditions. To elucidate formation pathways of nitrate and sulfate in different polluted cases, hourly samples of PM2.5 were collected continuously in Beijing during the wintertime of 2016. Three serious pollution cases were identified reasonably during the sampling period and the secondary formations of nitrate and sulfate were found to make a dominant contribution to atmospheric PM2.5 under the relatively high RH condition. The significant correlation between NOR and NO2 × O3 during the nighttime under the RH ≥ 60 % condition indicated that the heterogeneous hydrolysis of N2O5 involving aerosol liquid water was responsible for the nocturnal formation of nitrate at the extremely high RH levels. The more coincident trend of NOR and HONO × DR (direct radiation) × NO2 than Dust × NO2 during the daytime under the 30 % < RH < 60 % condition provided convincing evidence that the gas-phase reaction of NO2 with OH played a pivotal role in the diurnal formation of nitrate at moderate RH levels. The extremely high mean values of SOR during the whole day under the RH ≥ 60 % condition could be ascribed to the evident contribution of SO2 aqueous-phase oxidation to the formation of sulfate during the severe pollution episodes. Based on the parameters measured in this study and the known sulfate production rate calculation method, the oxidation pathway of H2O2 rather than NO2 was found to contribute greatly to the aqueous-phase formation of sulfate.

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Formation mechanisms of atmospheric nitrate and sulfate during the winter haze pollution periods in Beijing: gas-phase, heterogeneous and aqueous-phase chemistry

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-4153-2020 ◽

2020 ◽

Vol 20 (7) ◽

pp. 4153-4165 ◽

Cited By ~ 8

Author(s):

Pengfei Liu ◽

Can Ye ◽

Chaoyang Xue ◽

Chenglong Zhang ◽

Yujing Mu ◽

...

Keyword(s):

Gas Phase ◽

Aqueous Phase ◽

Sampling Period ◽

Convincing Evidence ◽

Formation Mechanisms ◽

Phase Reaction ◽

So2 Oxidation ◽

Mean Values ◽

Sulfate Production ◽

Haze Pollution

Abstract. A vast area in China is currently going through severe haze episodes with drastically elevated concentrations of PM2.5 in winter. Nitrate and sulfate are the main constituents of PM2.5, but their formations via NO2 and SO2 oxidation are still not comprehensively understood, especially under different pollution or atmospheric relative humidity (RH) conditions. To elucidate formation pathways of nitrate and sulfate in different polluted cases, hourly samples of PM2.5 were collected continuously in Beijing during the wintertime of 2016. Three serious pollution cases were identified reasonably during the sampling period, and the secondary formations of nitrate and sulfate were found to make a dominant contribution to atmospheric PM2.5 under the relatively high RH condition. The significant correlation between NOR, NOR = NO3-/(NO3-+NO2), and [NO2]2 × [O3] during the nighttime under the RH≥60 % condition indicated that the heterogeneous hydrolysis of N2O5 involving aerosol liquid water was responsible for the nocturnal formation of nitrate at the extremely high RH levels. The more often coincident trend of NOR and [HONO] × [DR] (direct radiation) × [NO2] compared to its occurrence with [Dust] × [NO2] during the daytime under the 30 % < RH < 60 % condition provided convincing evidence that the gas-phase reaction of NO2 with OH played a pivotal role in the diurnal formation of nitrate at moderate RH levels. The extremely high mean values of SOR, SOR = SO42-/(SO42-+SO2), during the whole day under the RH≥60 % condition could be ascribed to the evident contribution of SO2 aqueous-phase oxidation to the formation of sulfate during the severe pollution episodes. Based on the parameters measured in this study and the known sulfate production rate calculation method, the oxidation pathway of H2O2 rather than NO2 was found to contribute greatly to the aqueous-phase formation of sulfate.

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Prediction of Alkanolamine pKa Values by Combined Molecular Dynamics Free Energy Simulations and ab initio Calculations

10.26434/chemrxiv.11215025 ◽

2019 ◽

Author(s):

Javad Noroozi ◽

William Smith

Keyword(s):

Molecular Dynamics ◽

Free Energy ◽

Ab Initio Calculations ◽

Gas Phase ◽

Quantum Chemical ◽

Phase Reaction ◽

Pka Values ◽

Gas Phase Reaction ◽

Reaction Free Energy ◽

Energy Simulations

We use molecular dynamics free energy simulations in conjunction with quantum chemical calculations of gas phase reaction free energy to predict alkanolamines pka values. <br>

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Metabolic alteration of Methylococcus capsulatus str. Bath during a microbial gas-phase reaction

Bioresource Technology ◽

10.1016/j.biortech.2021.125002 ◽

2021 ◽

Vol 330 ◽

pp. 125002

Author(s):

Yan-Yu Chen ◽

Yuki Soma ◽

Masahito Ishikawa ◽

Masatomo Takahashi ◽

Yoshihiro Izumi ◽

...

Keyword(s):

Gas Phase ◽

Phase Reaction ◽

Methylococcus Capsulatus ◽

Gas Phase Reaction ◽

Metabolic Alteration

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Influence of Water on the Gas-Phase Reaction of Dimethyl Sulfide with BrO in the Marine Boundary Layer

ACS Omega ◽

10.1021/acsomega.0c05945 ◽

2021 ◽

Vol 6 (3) ◽

pp. 2410-2419

Author(s):

Junyao Li ◽

Narcisse T. Tsona ◽

Shanshan Tang ◽

Xiuhui Zhang ◽

Lin Du

Keyword(s):

Boundary Layer ◽

Gas Phase ◽

Dimethyl Sulfide ◽

Marine Boundary Layer ◽

Phase Reaction ◽

Gas Phase Reaction ◽

Influence Of Water

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Effect of Different Pollution Parameters and Chemical Components of PM2.5 on Health of Residents of Xinxiang City, China

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18136821 ◽

2021 ◽

Vol 18 (13) ◽

pp. 6821

Author(s):

Shuang Wang ◽

Mandeep Kaur ◽

Tengfei Li ◽

Feng Pan

Keyword(s):

Particulate Matter ◽

Carcinogenic Risk ◽

Water Soluble ◽

Chemical Components ◽

Maximum Effect ◽

Exposure Concentration ◽

Soluble Ions ◽

Haze Pollution ◽

Water Soluble Ions ◽

Blood Routine

The present study was planned to explore the pollution characteristics, health risks, and influence of atmospheric fine particulate matter (PM2.5) and its components on blood routine parameters in a typical industrial city (Xinxiang City) in China. In this study, 102 effective samples 28 (April–May), 19 (July–August), 27 (September–October), 28 (December–January) of PM2.5 were collected during different seasons from 2017 to 2018. The water-soluble ions and metal elements in PM2.5 were analyzed via ion chromatography and inductively coupled plasma–mass spectrometry. The blood routine physical examination parameters under different polluted weather conditions from January to December 2017 and 2018, the corresponding PM2.5 concentration, temperature, and relative humidity during the same period were collected from Second People’s Hospital of Xinxiang during 2017–2018. Risk assessment was carried out using the generalized additive time series model (GAM). It was used to analyze the influence of PM2.5 concentration and its components on blood routine indicators of the physical examination population. The “mgcv” package in R.3.5.3 statistical software was used for modeling and analysis and used to perform nonparametric smoothing on meteorological indicators such as temperature and humidity. When Akaike’s information criterion (AIC) value is the smallest, the goodness of fit of the model is the highest. Additionally, the US EPA exposure model was used to evaluate the health risks caused by different heavy metals in PM2.5 to the human body through the respiratory pathway, including carcinogenic risk and non-carcinogenic risk. The result showed that the air particulate matter and its chemical components in Xinxiang City were higher in winter as compared to other seasons with an overall trend of winter > spring > autumn > summer. The content of nitrate (NO3−) and sulfate (SO42−) ions in the atmosphere were higher in winter, which, together with ammonium, constitute the main components of water-soluble ions in PM2.5 in Xinxiang City. Source analysis reported that mobile pollution sources (coal combustion emissions, automobile exhaust emissions, and industrial emissions) in Xinxiang City during the winter season contributed more to atmospheric pollution as compared to fixed sources. The results of the risk assessment showed that the non-carcinogenic health risk of heavy metals in fine particulate matter is acceptable to the human body, while among the carcinogenic elements, the order of lifetime carcinogenic risk is arsenic (As) > chromium(Cr) > cadmium (Cd) > cobalt(Co) > nickel (Ni). During periods of haze pollution, the exposure concentration of PM2.5 has a certain lag effect on blood routine parameters. On the day when haze pollution occurs, when the daily average concentration of PM2.5 rises by 10 μg·m−3, hemoglobin (HGB) and platelet count (PLT) increase, respectively, by 9.923% (95% CI, 8.741–11.264) and 0.068% (95% CI, 0.067–0.069). GAM model analysis predicted the maximum effect of PM2.5 exposure concentration on red blood cell count (RBC) and PLT was reached when the hysteresis accumulates for 1d (Lag0). The maximum effect of exposure concentration ofPM2.5 on MONO is reached when the lag accumulation is 3d (Lag2). When the hysteresis accumulates for 6d (Lag5), the exposure concentration of PM2.5 has the greatest effect on HGB. The maximum cumulative effect of PM2.5 on neutrophil count (NEUT) and lymphocyte (LMY) was strongest when the lag was 2d (Lag1). During periods of moderate to severe pollution, the concentration of water-soluble ions and heavy metal elements in PM2.5 increases significantly and has a significant correlation with some blood routine indicators.

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