The variation characteristics and possible sources of atmospheric water-soluble ions in Beijing

Abstract. The North China plain (NCP) including Beijing is currently suffering from severe haze events due to high pollution level of atmospheric fine particles called PM2.5. To mitigate the serious pollution status, identification of the sources of PM2.5 is urgently needed for the effective control measures. A total of 235 daily samples of PM2.5 were collected in Beijing through the year of 2014, and the variation characteristics of water-soluble ions (WSIs) in the PM2.5 were comprehensively analyzed for recognizing their possible sources. The results indicated that the periodic emissions from farmers' activities made evident contribution to the atmospheric WSIs in Beijing. The unusually high ratio of Cl− to Na+ in summer could be rationally explained by the prevailing fertilization of NH4Cl for planting summer maize in the vast area of NCP. The remarkable elevation of Cl− in winter was ascribed to coal combustion for heating by farmers. The most serious pollution episodes in autumn were coincident with significant elevation of Ca2+ which was ascribed to be from harvest of the summer maize and tillage for planting the winter wheat. The mineral dust emission from the harvest and tillage not only increased the atmospheric concentrations of the primary pollutants, but also greatly accelerated formation of sulfate and nitrate through heterogeneous reactions of NO2 and SO2 on the mineral dust. The relatively high concentration of K+ in winter and autumn further confirmed that crop straw burning made evident contribution to atmospheric PM2.5 in Beijing. The backward trajectories also indicated that the highest concentrations of WSIs usually occurred in the air parcel from southwest/south regions with high density of farmers. In addition, the values of nitrogen oxidation ratio (NOR) and the sulfur oxidation ratio (SOR) were found to be much higher under haze days than under non-haze days, implying that formation of sulfate and nitrate was greatly accelerated through heterogeneous or multiphase reactions of NO2 and SO2 on PM2.5.

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The possible contribution of the periodic emissions from farmers' activities in the North China Plain to atmospheric water-soluble ions in Beijing

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-10097-2016 ◽

2016 ◽

Vol 16 (15) ◽

pp. 10097-10109 ◽

Cited By ~ 25

Author(s):

Pengfei Liu ◽

Chenglong Zhang ◽

Yujing Mu ◽

Chengtang Liu ◽

Chaoyang Xue ◽

...

Keyword(s):

North China Plain ◽

North China ◽

Mineral Dust ◽

Water Soluble ◽

The North ◽

Soluble Ions ◽

Water Soluble Ions ◽

High Concentrations ◽

Oxidation Ratio ◽

Haze Days

Abstract. The North China Plain (NCP), which includes Beijing, is currently suffering from severe haze events due to a high pollution level of PM2.5. To mitigate the serious pollution problem, identification of the sources of PM2.5 is urgently needed for the effective control measures. Daily samples of PM2.5 were collected in Beijing city and in a rural area in Baoding, Hebei Province through the year of 2014, and the seasonal variation of water-soluble ions (WSIs) in PM2.5 was comprehensively analysed to determine their possible sources. The results indicated that the periodic emissions from farmers' activities made a significant contribution to the atmospheric WSIs in Beijing. The relatively high concentration of K+ in winter and autumn at the two sampling sites confirmed that crop straw burning contributed to atmospheric K+ in Beijing. The remarkable elevation of Cl− at the two sampling sites as well as the evident increase of the Cl− ∕ K+ ratio and the Cl− proportion in WSIs during the winter in Beijing could be ascribed to coal combustion for heating by farmers. The unusually high ratio of Cl− to Na+ in summer, the obviously high concentrations of Cl− in the rural sampling site and the elevation of Cl− proportion in WSIs in Beijing during the maize fertilization could be explained by the use of the prevailing fertilizer of NH4Cl in the vast area of NCP. The abnormally high concentrations of Ca2+ at the two sampling sites and the elevation of Ca2+ proportion during the period of the maize harvest and soil ploughing in Beijing provided convincing evidence that the intensive agricultural activities in autumn contributed to the regional mineral dust. The most serious pollution episodes in autumn were coincident with significant elevation of Ca2+, indicating that the mineral dust emission from the harvest and soil ploughing not only increased the atmospheric concentrations of the primary pollutants, but also greatly accelerated formation of sulfate and nitrate through heterogeneous reactions of NO2 and SO2 on the mineral dust. The backward trajectories also indicated that the highest concentrations of WSIs usually occurred in the air parcel from southwest–south regions, which have a high density of farmers. In addition, the values of nitrogen oxidation ratio (NOR) and the sulfur oxidation ratio (SOR) were found to be much greater under haze days than under non-haze days, implying that formation of sulfate and nitrate was greatly accelerated through heterogeneous or multiphase reactions of NO2 and SO2 on PM2.5.

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Chemical Characteristics of Major Inorganic Ions in PM2.5 Based on Year-Long Observations in Guiyang, Southwest China—Implications for Formation Pathways and the Influences of Regional Transport

Atmosphere ◽

10.3390/atmos11080847 ◽

2020 ◽

Vol 11 (8) ◽

pp. 847

Author(s):

Hao Xiao ◽

Hua-Yun Xiao ◽

Zhong-Yi Zhang ◽

Neng-Jian Zheng ◽

Qin-kai Li ◽

...

Keyword(s):

Chemical Composition ◽

Inorganic Ions ◽

Sulfur Oxidation ◽

Average Concentration ◽

Water Soluble ◽

Soluble Ions ◽

Water Soluble Ions ◽

Transformation Mechanisms ◽

Higher Temperature ◽

Oxidation Ratio

Sulfate, nitrate and ammonium (SNA) are the dominant components of water-soluble ions (WSIs) in PM2.5, which are of great significance for understanding the sources and transformation mechanisms of PM2.5. In this study, daily PM2.5 samples were collected from September 2017 to August 2018 within the Guiyang urban area and the concentrations of the major WSIs in the PM2.5 samples were characterized. The results showed that the average concentration of SNA (SO42−, NO3−, NH4+) was 15.01 ± 9.35 μg m−3, accounting for 81.05% (48.71–93.76%) of the total WSIs and 45.33% (14.25–82.43%) of the PM2.5 and their possible chemical composition in PM2.5 was (NH4)2SO4 and NH4NO3. The highest SOR (sulfur oxidation ratio) was found in summer, which was mainly due to the higher temperature and O3 concentrations, while the lowest NOR (nitrogen oxidation ratio) found in summer may ascribe to the volatilization of nitrates being accelerated at higher temperature. Furthermore, the nitrate formation was more obvious in NH4+-rich environments so reducing NH3 emissions could effectively control the formation of nitrate. The results of the trajectory cluster analysis suggested that air pollutants can be easily enriched over short air mass trajectories from local emission sources, affecting the chemical composition of PM2.5.

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Observation and Source Apportionment of Trace Gases, Water-Soluble Ions and Carbonaceous Aerosol During a Haze Episode in Wuhan

Atmosphere ◽

10.3390/atmos10070397 ◽

2019 ◽

Vol 10 (7) ◽

pp. 397 ◽

Cited By ~ 1

Author(s):

Zhengxu Gao ◽

Xiaoling Wang ◽

Lijuan Shen ◽

Hua Xiang ◽

Honglei Wang

Keyword(s):

Organic Carbon ◽

Air Pollutants ◽

Principal Component ◽

Water Soluble ◽

Vehicle Exhaust ◽

Soluble Ions ◽

Secondary Formation ◽

Water Soluble Ions ◽

Haze Episode ◽

Haze Days

As the new core region of the haze pollution, the terrain effect of sub-basin and water networks over the Twin-Hu Basin (THB) in the Yangtze River Middle-Reach (YRMR) had great impacts on the variations and distributions of air pollutants. In this study, trace gases (NH3, HNO3, and HCl), water-soluble ions (WSIs), organic carbon (OC), and elemental carbon (EC) were measured in PM2.5 from 9 January to 27 January 2018, in Wuhan using monitoring for aerosols and gases (MARGA) and a semi-continuous OC/EC analyzer (Model RT-4). The characteristics of air pollutants during a haze episode were discussed, and the PM2.5 sources were quantitatively analyzed on haze and non-haze days using the principal component analysis/absolute principal component scores (PCA/APCS) model. The average PM2.5 concentration was 122.61 μg·m−3 on haze days, which was 2.20 times greater than it was on non-haze days. The concentrations of secondary water soluble ions (WSIs) including NO3−, SO42−, and NH4+ increased sharply on haze days, which accounted for 91.61% of the total WSIs and were 2.43 times larger than the values on non-haze days. The heterogeneous oxidation reactions of NO2 and SO2 during haze episodes were proven to be the major sources of sulfate and nitrate in PM2.5. On haze days, the concentrations of EC, primary organic carbon (POC), and secondary organic carbon (SOC) were 1.68, 1.69, and 1.34 times larger than those on non-haze days, the CO, HNO3, and NH3 concentrations enhanced and relatively low SO2, O3, and HNO2 levels were observed on haze days. The diurnal variations of different pollutants distinctly varied on haze days. The PM2.5 in Wuhan primarily originated from the secondary formation, combustion, dust, industry, and vehicle exhaust sources. The source contributions of the secondary formation + combustion sources to PM2.5 on haze days were 2.79 times larger than the level on non-haze days. The contribution of the vehicle exhaust + combustion source on haze days were 0.59 times the value on non-haze days. This description is supported by a summary of how pollutant concentrations and patterns vary in the THB compared to the variations in other pollution regions in China, which have been more completely described.

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Seasonal variations of water-soluble ions in PM10 at a WMO/GAW station in the Yangtze River Delta, China

E3S Web of Conferences ◽

10.1051/e3sconf/202019404058 ◽

2020 ◽

Vol 194 ◽

pp. 04058

Author(s):

Dongqing Fang ◽

Junli Jin ◽

Wei Huang ◽

Yong Zhang ◽

Wanqi Sun ◽

...

Keyword(s):

Yangtze River ◽

Inorganic Ions ◽

Yangtze River Delta ◽

Water Soluble ◽

The Yangtze River ◽

Soluble Ions ◽

Water Soluble Ions ◽

Water Soluble Inorganic Ions ◽

Oxidation Ratio ◽

The Yangtze River Delta

In order to understand the seasonal levels, formation mechanism and atmospheric chemical behaviours of water-soluble ions of PM10 in the Yangtze River Delta (YRD) region, aerosol samples were collected from January 2nd to December 28th, 2017 at a WMO/GAW regional background station in Lin’an. The concentrations of PM mass and nine water-soluble inorganic ions were obtained. The annual average concentration of PM10 was 59.9±33.9 μg m−3, lower than those reported in previous studies, indicating air quality of YRD region was improved. Nine water-soluble inorganic ions was accounted for 30.2-45.1% of the total PM mass, while ammonium (NH4+), sulfate (SO42+), as well as nitrate (NO3-) were the major ions which contributed 86.3% to total ions. The NO3- concentration was lowest in summer but highest in winter, suggesting it was likely influenced by thermodynamics. The levels of SO42- in spring and winter were related to photochemical reaction and regional transportation. Except for the SNA, Ca2+ was highest in four seasons likely due to sand storm and road fugitive dust. The annual mean ratio of [NO3-]/[SO42-] was nearly to 1, indicating mobile and stationary sources were equally important in Lin’an. The mean nitrogen oxidation ratio (NOR) and sulfur oxidation ratio (SOR) were 0.22±0.13 and 0.41±0.13, respectively, suggesting secondary formation was significant in the atmosphere at the background station of YRD region.

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The Analysis of Water-Soluble Ions and Inorganic Elements in Atmospheric Particulates, Chancheng, Foshan, China

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.281.215 ◽

2011 ◽

Vol 281 ◽

pp. 215-222 ◽

Cited By ~ 1

Author(s):

Yong Hong Liu ◽

Wu Ying Zhang ◽

Wei Jia Xu ◽

Cheng Wang ◽

Qian Ru Zhu

Keyword(s):

Weather Conditions ◽

Automatic Monitoring ◽

Enrichment Factors ◽

Water Soluble ◽

Pollution Level ◽

Inorganic Elements ◽

Atmospheric Particulate ◽

Atmospheric Particulates ◽

Soluble Ions ◽

Water Soluble Ions

This paper investigated the concentrations of the water-soluble ions (e.g. SO42-, NO3- )and the inorganic elements in the atmospheric particulate, Chancheng, Foshan, China. The samples were collected on the roof of Liangtang Urban Air Automatic Monitoring Station, Chancheng, Foshan, in September and December, 2009. The NO3-/SO42- ratios of the PM10 in September and December are 0.20 and 0.62 respectively, but these of the PM2.5 in September and December are 0.14 and 0.36, respectively. It is clearly that the air pollution in Chancheng, Foshan is mainly from stationary source. The concentrations of the PM2.5 and PM10 in September are great lower than these in December. The concentrations of SO42- in atmospheric particulate, Chancheng, Foshan were nearly same for September and December, but the concentration of NO3- in September is considerable lower than that of December. It probably related to the weather conditions in September e.g. high temperature, high humidity and strong solar radiation, those are conducive to the photochemical reaction of SO2 to form SO42-, also conducive to the volatilization of the NO3-. The percentages of Ca, Al, Fe, K in the inorganic elements of atmospheric particulate ranged from 10 wt% to 20 wt%, so these elements were the major components of the atmospheric particulate. The results showed that the enrichment factors of Cu, Pb, Zn in atmospheric particulates, Chancheng, Foshan were >50, indicating highly enrichment and pollution level V.

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