scholarly journals Amplified role of potential HONO sources in O<sub>3</sub> formation in North China Plain during autumn haze aggravating processes

2021 ◽  
Author(s):  
Jingwei Zhang ◽  
Chaofan Lian ◽  
Weigang Wang ◽  
Maofa Ge ◽  
Yitian Guo ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Heterogeneous Reaction ◽  
Ground Surface ◽  
Field Studies ◽  
Daily Maximum ◽  
Pollution Levels ◽  
The North ◽  
Order Of Magnitude ◽  
High Concentrations

Abstract. Co-occurrences of high concentrations of PM2.5 and ozone (O3) have been frequently observed in haze aggravating processes in the North China Plain (NCP) over the past few years, and higher O3 concentrations during hazy days were supposed to be related to nitrous acid (HONO), but the key sources of HONO enhancing O3 during haze aggravating processes remain unclear, and will be explored in this study by using the WRF-Chem model, which is improved to include ground-based (traffic, soil, and indoor emissions, and the NO2 heterogeneous reaction on ground surface (Hetground)) and aerosol-related (the NO2 heterogeneous reaction on aerosol surfaces (Hetaerosol) and nitrate photolysis (Photnitrate)) potential HONO sources. The results indicate that ground-based HONO sources producing HONO enhancements showed a rapid decrease with height, while the NO+OH reaction and aerosol-related HONO sources decreased slowly with height. Photnitrate contributions to HONO concentrations enhanced with aggravated pollution levels, the enhanced HONO due to Photnitrate in hazy days was about one order of magnitude larger than in clean days and Photnitrate dominated HONO sources (~30–70 % when the ratio of the photolysis frequency of nitrate (Jnitrate) to gas nitric acid (JHNO3) equals 30) at higher layers (> 800 m). Compared with that in clean days, the Photnitrate contribution to the enhanced daily maximum 8-h averaged O3 was increased by over one magnitude during the haze aggravating process. Photnitrate contributed only ~5 % of the surface HONO in daytime with a Jnitrate/JHNO3 ratio of 30 but contributed ~30–50 % of the enhanced O3 near the surface in NCP in hazy days. Surface O3 was dominated by volatile organic compounds-sensitive chemistry, while O3 at higher altitude (> 800 m) was dominated by NOx-sensitive chemistry. Photnitrate had a limited impact on nitrate concentrations (< 15 %) even with a Jnitrate/JHNO3 ratio of 120. The above results suggest that more field studies of Jnitrate in the atmosphere are still needed.

scholarly journals Cloud scavenging of abundant anthropogenic refractory particles at a mountain site in North China

2018 ◽  
Author(s):  
Lei Liu ◽  
Jian Zhang ◽  
Liang Xu ◽  
Qi Yuan ◽  
Dao Huang ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Size Composition ◽  
Climate Forcing ◽  
Pollution Levels ◽  
Aerosol Cloud ◽  
The North ◽  
The North China Plain ◽  
Transmission Electron ◽  
Cloud Scavenging

Abstract. Aerosol-cloud interaction remains a major source of uncertainty in climate forcing estimate. Our knowledge about the aerosol-cloud interaction is particularly weak in heavily polluted conditions. In this study, cloud residual (cloud RES) and cloud interstitial (cloud INT) particles were collected during cloud events under different pollution levels from 22 July to 1 August, 2014 at Mt. Tai (1532 m above sea level) located in the North China Plain (NCP). Transmission electron microscopy (TEM) was used to investigate size, composition, and mixing state of individual cloud RES and INT particles. Our results show that S-rich particles were predominant (78 %) during clean periods (PM2.5 

scholarly journals Study on the Change Characteristics of and Population Exposure to Heatwave Events on the North China Plain

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Long-Fei Zhan ◽  
Yanjun Wang ◽  
Hemin Sun ◽  
Jianqing Zhai ◽  
Mingjin Zhan
Keyword(s):  
North China Plain ◽  
North China ◽  
Climatic Factors ◽  
Demographic Data ◽  
Population Exposure ◽  
Central Position ◽  
Daily Maximum ◽  
The North ◽  
The North China Plain ◽  
The Impact

In accordance with the China Meteorological Administration definition, this study considered a weather process with a maximum surface temperature of ≥35°C for more than three consecutive days as a heatwave event. Based on a dataset of daily maximum temperatures from meteorological stations on the North China Plain, including ordinary and national basic/reference surface stations, the intensity-area-duration method was used to analyze the spatiotemporal distribution characteristics of heatwave events on the North China Plain (1961–2017). Moreover, based on demographic data from the Statistical Yearbook and Greenhouse Gas Initiative (GGI) Population Scenario Database of the Austrian Institute for International Applied Systems Analysis (IIASA), population exposure to heatwave events was also studied. The results showed that the frequency, intensity, and area of impact of heatwave events on the North China Plain initially decreased (becoming weaker and less extensive) and then increased (becoming stronger and more extensive). Similarly, the trend of population exposure to heatwave events initially decreased and then increased, and the central position of exposure initially moved southward and then returned northward. Population exposure in the eastern Taihang Mountains was found significantly higher than in the western Taihang Mountains. In relation to the change of population exposure to heatwave events on the North China Plain, the influence of climatic factors was found dominant with an absolute contribution rate of >75%. Except for 2011–2017, increase in population also increased the exposure to heatwaves, particularly in the first half of the study period. Interaction between climatic and population factors generally had less impact on population exposure than either climatic factors or population factors alone. This study demonstrated a method for assessing the impact of heatwave events on population exposure, which could form a scientific basis for the development of government policy regarding adaption to climate change.

Seasonal effects of additional HONO sources and the heterogeneous reactions of N2O5 on nitrate in the North China Plain

2020 ◽  
Author(s):  
Yu Qu ◽  
Junling An
Keyword(s):  
North China Plain ◽  
North China ◽  
Heterogeneous Reaction ◽  
Heterogeneous Reactions ◽  
Seasonal Effects ◽  
Weather Research And Forecasting ◽  
The North ◽  
The North China Plain ◽  
Four Seasons ◽  
Hydrolysis Of

&lt;p&gt;We coupled the heterogeneous hydrolysis of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; into the newly updated Weather Research and Forecasting model with Chemistry (WRF-Chem) to reveal the relative importance of the hydrolysis of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; and additional nitrous acid (HONO) sources for the formation of nitrate during high PM&lt;sub&gt;2.5&lt;/sub&gt; events in the North China Plain (NCP) in four seasons. The results showed that additional HONO sources produced the largest nitrate concentrations in winter and negligible nitrates in summer, leading to a 10% enhancement of a PM&lt;sub&gt;2.5&lt;/sub&gt; peak in southern Beijing and a 15% enhancement in southeastern Hebei in winter. In contrast, the hydrolysis of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; produced high nitrate in summer and low nitrate in winter, with the largest contribution of nearly 20% for a PM&lt;sub&gt;2.5&lt;/sub&gt; peak in southeastern Hebei in summer. During PM&lt;sub&gt;2.5 &lt;/sub&gt;explosive growth events, the additional HONO sources played a key role in nitrate increases in southern Beijing and southwestern Hebei in winter, whereas the hydrolysis of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5 &lt;/sub&gt;contributed the most to a rapid increase in nitrate in other seasons. HONO photolysis produced more hydroxyl radicals, which were greater than 1.5 &amp;#956;g m&lt;sup&gt;-3&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt; in the early explosive stage and led to a rapid nitrate increase at the southwestern Hebei sites in winter, while the heterogeneous reaction of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; contributed greatly to a significant increase in nitrate in summer. The above results suggest that the additional HONO sources and the heterogeneous hydrolysis of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; contributed the most to nitrate formation in NCP in winter and summer, respectively.&lt;/p&gt;

scholarly journals Radical chemistry at a rural site (Wangdu) in the North China Plain: Observation and model calculations of OH, HO<sub>2</sub> and RO<sub>2</sub> radicals

2016 ◽  
Author(s):  
Zhaofeng Tan ◽  
Hendrik Fuchs ◽  
Keding Lu ◽  
Birger Bohn ◽  
Sebastian Broch ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Chemical Mechanism ◽  
Ozone Production ◽  
Rural Site ◽  
Daily Maximum ◽  
Model Calculations ◽  
Mixing Ratios ◽  
The North ◽  
The North China Plain

Abstract. A comprehensive field campaign was carried out in summer 2014 in Wangdu located in the North China Plain. A month of continuous OH, HO2 and RO2 measurements were achieved. Observations of radicals by laser induced fluorescence (LIF) technique gave daily maximum concentrations between (5–15) × 106 cm−3, (3–14) × 108 cm−3 and (3–15) × 108 cm−3 for OH, HO2 and RO2, respectively. Measured OH reactivities (inverse OH lifetimes) were 10 to 20 s−1 during daytime. A chemical box model constrained by trace-gas observations and based on a state-of-the-art chemical mechanism is used to interpret the observed radical concentrations. In general, the model can reasonably well reproduce measured radical concentrations during daytime. Like in previous field campaigns in China, modelled and measured OH concentrations agree for NO mixing ratios higher than 1 ppbv, but systematic discrepancies are observed in the afternoon for NO mixing ratios of less than 300 pptv (the model-measurement ratio is between 1.4 to 2 in this case). If additional OH recycling equivalent to 100 pptv NO is assumed, the model is also capable of reproducing the observed OH concentrations for conditions of high VOC and low NOx concentrations with good agreement in HO2 and RO2. Observed RO2 concentrations are underestimated in the morning hours by a factor of 3 to 5. This indicates that an additional chemical source of RO2 is missing in the model. The OH reactivity is also underpredicted in the early morning. Increasing VOC concentrations to match measured OH reactivity helps to reduce the discrepancy between modelled and measured RO2. The underprediction of RO2 coincides with high NO concentrations and therefore leads to a significant underestimation of the local ozone production rates determined from the peroxy radical (HO2 and RO2) reactions with NO. The underestimation corresponds to a daily integral ozone production of about 20 ppbv per day.

scholarly journals Spatial Characteristics of PM2.5 Pollution among Cities and Policy Implication in the Northern Part of the North China Plain

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 77
Author(s):  
Yangjun Wang ◽  
Hongli Li ◽  
Jin Feng ◽  
Wu Wang ◽  
Ziyi Liu ◽  
...  
Keyword(s):  
Prevention And Control ◽  
North China Plain ◽  
North China ◽  
Recent Decade ◽  
Clustering Coefficient ◽  
Spatial Characteristics ◽  
Pollution Levels ◽  
The North ◽  
The North China Plain ◽  
And Control

In the recent decade, the North China Plain (NCP) has been among the region’s most heavily polluted by PM2.5 in China. For the nonattainment cities in the NCP, joint pollution control with related cities is highly needed in addition to the emission controls in their own cities. However, as the basis of decision-making, the spatial characteristics of PM2.5 among these cities are still insufficiently revealed. In this work, the spatial characteristics among all nonattainment cities in the northern part of the North China Plain (NNCP) region were revealed based on data mining technologies including clustering, coefficient of divergence (COD), network correlation model, and terrain and meteorology analysis. The results indicate that PM2.5 pollution of cities with a distance of less than 180 km exhibits homogeneity in the NCP region. Especially, the sub-region, composed of Xinxiang, Hebi, Kaifeng, Zhengzhou, and Jiaozuo, was strongly homogeneous and a strong correlation exists among them. Compared with spring and summer, much stronger correlations of PM2.5 between cities were found in autumn and winter, indicating a strong need for joint prevention and control during these periods. All nonattainment cities in this region were divided into city-clusters, depending on the seasons and pollution levels to further helping to reduce their PM2.5 concentrations effectively. Air stagnation index (ASI) analysis indicates that the strong correlations between cities in autumn were more attributed to the transport impacts than those in winter, even though there were higher PM2.5 concentrations in winter. These results provided an insight into joint prevention and control of pollution in the NCP region.

scholarly journals Contribution of hydroxymethanesulfonate (HMS) to severe winter haze in the North China Plain

2020 ◽  
Author(s):  
Tao Ma ◽  
Hiroshi Furutani ◽  
Fengkui Duan ◽  
Takashi Kimoto ◽  
Jingkun Jiang ◽  
...  
Keyword(s):  
Ion Chromatography ◽  
North China Plain ◽  
North China ◽  
Molar Ratio ◽  
Formation Mechanisms ◽  
Aerosol Formation ◽  
Severe Winter ◽  
The North ◽  
The North China Plain ◽  
High Concentrations

Abstract. Severe winter hazes accompanied by high concentrations of fine particulate matter (PM2.5) occur frequently in the North China Plain and threaten public health. Organic matter (OM) and sulfate are recognized as major components of PM2.5, while atmospheric models often fail to predict their high concentrations during severe winter hazes due to incomplete understanding of secondary aerosol formation mechanisms. By using a novel combination of single particle mass spectrometer and optimized ion chromatography measurement, here we show that hydroxymethanesulfonate (HMS), formed by the reaction between formaldehyde (HCHO) and dissolved SO2 in aerosol water, is ubiquitous in Beijing winter. The HMS concentration and the molar ratio of HMS to sulfate increased with the deterioration of winter haze. High concentrations of precursors (SO2 and HCHO) coupled with low oxidant levels, low temperature, high relative humidity, and moderately acid pH facilitate the heterogeneous formation of HMS, which could account for up to 15 % of OM in winter haze and lead to 36 % overestimates of sulfate when using traditional ion chromatography measurements. Despite the clean air actions have substantially reduced SO2 emissions, HMS concentration and molar ratio of HMS to sulfate during severe winter hazes increased from 2015 to 2016 with the growth of HCHO concentration. Our findings illustrate the significant contribution of heterogeneous HMS chemistry to severe winter hazes in Beijing, which help to improve the prediction of OM and sulfate, and suggest that the reduction in HCHO can help to mitigate haze pollution.

scholarly journals Efficient N<sub>2</sub>O<sub>5</sub> uptake and NO<sub>3</sub> oxidation in the outflow of urban Beijing

2018 ◽  
Vol 18 (13) ◽  
pp. 9705-9721 ◽  
Author(s):  
Haichao Wang ◽  
Keding Lu ◽  
Song Guo ◽  
Zhijun Wu ◽  
Dongjie Shang ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Field Studies ◽  
Organic Nitrate ◽  
Air Masses ◽  
Dinitrogen Pentoxide ◽  
Nitryl Chloride ◽  
The North ◽  
Heterogeneous Processes ◽  
Volatile Organic

Abstract. Nocturnal reactive nitrogen compounds play an important role in regional air pollution. Here we present the measurements of dinitrogen pentoxide (N2O5) associated with nitryl chloride (ClNO2) and particulate nitrate (pNO3-) at a suburban site of Beijing in the summer of 2016. High levels of N2O5 and ClNO2 were observed in the outflow of the urban Beijing air masses, with 1 min average maxima of 937 and 2900 pptv, respectively. The N2O5 uptake coefficients, γ, and ClNO2 yield, f, were experimentally determined from the observed parameters. The N2O5 uptake coefficient ranged from 0.012 to 0.055, with an average of 0.034 ± 0.018, which is in the upper range of previous field studies reported in North America and Europe but is a moderate value in the North China Plain (NCP), which reflects efficient N2O5 heterogeneous processes in Beijing. The ClNO2 yield exhibited high variability, with a range of 0.50 to unity and an average of 0.73 ± 0.25. The concentration of the nitrate radical (NO3) was calculated assuming that the thermal equilibrium between NO3 and N2O5 was maintained. In NOx-rich air masses, the oxidation of nocturnal biogenic volatile organic compounds (BVOCs) was dominated by NO3 rather than O3. The production rate of organic nitrate (ON) via NO3 + BVOCs was significant, with an average of 0.10 ± 0.07 ppbv h−1. We highlight the importance of NO3 oxidation of VOCs in the formation of ON and subsequent secondary organic aerosols in summer in Beijing.

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