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

2016 ◽  
Vol 16 (15) ◽  
pp. 10097-10109 ◽  
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.

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

2016 ◽  
Author(s):  
Pengfei Liu ◽  
Chenglong Zhang ◽  
Yujing Mu ◽  
Chengtang Liu ◽  
Chaoyang Xue ◽  
...  
Keyword(s):  
Mineral Dust ◽  
Water Soluble ◽  
Effective Control ◽  
Pollution Level ◽  
Summer Maize ◽  
Soluble Ions ◽  
Water Soluble Ions ◽  
Variation Characteristics ◽  
Oxidation Ratio ◽  
Haze Days

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.

Size-resolved aerosol water-soluble ions at a regional background station of Beijing, Tianjin, and Hebei, North China

2017 ◽  
Vol 55 ◽  
pp. 146-156 ◽  
Author(s):  
Yongjie Yang ◽  
Rui Zhou ◽  
Yue Yu ◽  
Yan Yan ◽  
Yan Liu ◽  
...  
Keyword(s):  
North China ◽  
Water Soluble ◽  
Regional Background ◽  
Soluble Ions ◽  
Water Soluble Ions

scholarly journals 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 ◽  
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.

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

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 397 ◽  
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.

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

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.

scholarly journals Observation of atmospheric peroxides during Wangdu Campaign 2014 at a rural site in the North China Plain

2016 ◽  
Vol 16 (17) ◽  
pp. 10985-11000 ◽  
Author(s):  
Yin Wang ◽  
Zhongming Chen ◽  
Qinqin Wu ◽  
Hao Liang ◽  
Liubin Huang ◽  
...  
Keyword(s):  
Biomass Burning ◽  
North China Plain ◽  
North China ◽  
Chemical Mechanism ◽  
Rural Site ◽  
Direct Production ◽  
The North ◽  
The North China Plain ◽  
The Impact ◽  
Haze Days

Abstract. Measurements of atmospheric peroxides were made during Wangdu Campaign 2014 at Wangdu, a rural site in the North China Plain (NCP) in summer 2014. The predominant peroxides were detected to be hydrogen peroxide (H2O2), methyl hydroperoxide (MHP) and peroxyacetic acid (PAA). The observed H2O2 reached up to 11.3 ppbv, which was the highest value compared with previous observations in China at summer time. A box model simulation based on the Master Chemical Mechanism and constrained by the simultaneous observations of physical parameters and chemical species was performed to explore the chemical budget of atmospheric peroxides. Photochemical oxidation of alkenes was found to be the major secondary formation pathway of atmospheric peroxides, while contributions from alkanes and aromatics were of minor importance. The comparison of modeled and measured peroxide concentrations revealed an underestimation during biomass burning events and an overestimation on haze days, which were ascribed to the direct production of peroxides from biomass burning and the heterogeneous uptake of peroxides by aerosols, respectively. The strengths of the primary emissions from biomass burning were on the same order of the known secondary production rates of atmospheric peroxides during the biomass burning events. The heterogeneous process on aerosol particles was suggested to be the predominant sink for atmospheric peroxides. The atmospheric lifetime of peroxides on haze days in summer in the NCP was about 2–3 h, which is in good agreement with the laboratory studies. Further comprehensive investigations are necessary to better understand the impact of biomass burning and heterogeneous uptake on the concentration of peroxides in the atmosphere.

scholarly journals Seasonal prediction of winter haze days in the north central North China Plain

2016 ◽  
Vol 16 (23) ◽  
pp. 14843-14852 ◽  
Author(s):  
Zhicong Yin ◽  
Huijun Wang
Keyword(s):  
Prediction Model ◽  
North China Plain ◽  
North China ◽  
Additive Model ◽  
Continuous Increase ◽  
North Central ◽  
The North ◽  
Predictive Skill ◽  
Haze Pollution ◽  
Haze Days

Abstract. Recently, the winter (December–February) haze pollution over the north central North China Plain (NCP) has become severe. By treating the year-to-year increment as the predictand, two new statistical schemes were established using the multiple linear regression (MLR) and the generalized additive model (GAM). By analyzing the associated increment of atmospheric circulation, seven leading predictors were selected to predict the upcoming winter haze days over the NCP (WHDNCP). After cross validation, the root mean square error and explained variance of the MLR (GAM) prediction model was 3.39 (3.38) and 53 % (54 %), respectively. For the final predicted WHDNCP, both of these models could capture the interannual and interdecadal trends and the extremums successfully. Independent prediction tests for 2014 and 2015 also confirmed the good predictive skill of the new schemes. The predicted bias of the MLR (GAM) prediction model in 2014 and 2015 was 0.09 (−0.07) and −3.33 (−1.01), respectively. Compared to the MLR model, the GAM model had a higher predictive skill in reproducing the rapid and continuous increase of WHDNCP after 2010.

scholarly journals High abundances of water-soluble dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls in the mountaintop aerosols over the North China Plain during wheat burning season

2013 ◽  
Vol 13 (16) ◽  
pp. 8285-8302 ◽  
Author(s):  
K. Kawamura ◽  
E. Tachibana ◽  
K. Okuzawa ◽  
S. G. Aggarwal ◽  
Y. Kanaya ◽  
...  
Keyword(s):  
Wheat Straw ◽  
North China Plain ◽  
North China ◽  
Dicarboxylic Acids ◽  
Agricultural Wastes ◽  
Water Soluble ◽  
The North ◽  
The North China Plain ◽  
Volatile Organic ◽  
Field Burning

Abstract. Aerosol (TSP) samples were collected at the summit of Mount Tai (elevation: 1534 m a.s.l., 36.25° N, 117.10° E) located in the North China Plain using a high-volume air sampler and pre-combusted quartz filters. Sampling was conducted on day/night or 3 h basis in the period from 29 May to 28 June 2006 during the field burning of wheat straw residue and the post-burning season. The filter samples were analyzed for low-molecular-weight dicarboxylic acids, ketoacids and α-dicarbonyls using capillary gas chromatography (GC) and GC-MS employing water extraction and butyl ester derivatization. Molecular distributions of dicarboxylic acids (C2-C11, 220–6070 ng m−3) were characterized by a predominance of oxalic (C2) acid (105–3920 ng m−3) followed by succinic (C4) or malonic (C3) acid. Unsaturated aliphatic diacids, including maleic (M), isomaleic (iM) and fumaric (F) acids, were also detected together with aromatic diacids (phthalic, isophthalic and terephthalic acids). ω-oxocarboxylic acids (C2-C9, 24–610 ng m−3) were detected as the second most abundant compound class with the predominance of glyoxylic acid (11–360 ng m−3), followed by α-ketoacid (pyruvic acid, 3–140 ng m−3) and α-dicarbonyls (glyoxal, 1–230 ng m−3 and methylglyoxal, 2–120 ng m−3). We found that these levels (>6000 ng m−3 for diacids) are several times higher than those reported in Chinese megacities at ground levels. The concentrations of diacids increased from late May to early June, showing a maximum on 7 June, and then significantly decreased during the period 8–11 June, when the wind direction shifted from southerly to northerly. Similar temporal trends were found for ketocarboxylic acids and α-dicarbonyls as well as total carbon (TC) and water-soluble organic carbon (WSOC). The temporal variations of water-soluble organics were interpreted by the direct emission from the field burning of agricultural wastes (wheat straw) in the North China Plain and the subsequent photochemical oxidation of volatile and semi-volatile organic precursors emitted from field burning as well as dark ozonolysis of volatile organic compounds and other organics, accretion reactions and oxidation of nonvolatile organics such as unsaturated fatty acids. This study demonstrates that the field burning of agricultural wastes in early summer strongly influenced the air quality of the free troposphere over the North China Plain.

scholarly journals Haze pollution in winter and summer in Zibo, a heavily industrialized city neighboring the Jin-Jin-Ji area of China: source, formation, and implications

2018 ◽  
Author(s):  
Hui Li ◽  
Fengkui Duan ◽  
Yongliang Ma ◽  
Kebin He ◽  
Lidan Zhu ◽  
...  
Keyword(s):  
North China ◽  
Control Policy ◽  
Photochemical Activity ◽  
Heterogeneous Reactions ◽  
Air Pollution Control ◽  
The North ◽  
Haze Pollution ◽  
High Concentrations ◽  
Pollution Control Policy ◽  
Haze Days

Abstract. Continuous field observations of haze pollution were conducted in winter and summer during 2015 in Zibo, a highly industrialized city in the North China Plain that is adjacent to the Jing-Jin-Ji area. PM2.5 concentration averaged 146.7 ± 85.8 and 82.2 ± 44.3 μg m−3 in winter and summer, respectively. The chemical component contributions to PM2.5 showed obvious seasonal variation. Organics were high in winter, but secondary inorganic aerosols (SIA) were high in summer. From non-haze to haze days, the concentration of SIA increased, implying an important role of secondary processes in the evolution process of the pollution. The diurnal behavior of several pollutants during haze days appeared to fluctuate more, but during non-haze days, it was much more stable, suggesting that complex mechanisms are involved. Specifically, gaseous precursors, mixed layer height (MLH), photochemical activity, and relative humidity (RH) also played important roles in the diurnal variation of the pollutants. Normally, larger gaseous precursor concentrations, photochemical activity, and RH, and lower MLH favored high concentrations. In winter, the formation of sulfate was mainly influenced by RH, indicating the importance of heterogeneous reactions in its formation. In contrast, in summer, photochemistry and SO2 concentration had the largest impact on the sulfate level. We found that Zibo was an ammonia-rich city, especially in winter, meaning that the formation of nitrate was through homogeneous reactions between HNO3 and NH3 in the gas phase, followed by partitioning into the particle phase. The RH, NO2, and Excess NH4+ were the main influencing factors for nitrate in winter, whereas Excess NH4+, RH, and temperature were the key factors in summer. The secondary organic carbon (SOC) level depended on the MLH and photochemistry. In winter, the effect of the MLH was stronger than that of photochemistry, but a reversed situation occurred in summer because of the intensive photochemistry. Our work suggested that the inter-transport between Zibo, one of the most polluted cities in north China, and its adjacent areas should be taken into account when formulating air pollution control policy.

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