A modelling study of the terrain effects on haze pollution in the Sichuan Basin

Zhang, Lei; Guo, Xiaomei; Zhao, Tianliang; Gong, Sunling; Xu, Xiangde; Li, Yueqing; Luo, Li; Gui, Ke; Wang, Dan; Zheng, Yu; Yin, Xiaohong

doi:10.1016/j.atmosenv.2018.10.007

Cited by 119 publications

(54 citation statements)

References 46 publications

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“…With the accumulation of PM 2.5 concentration, NSA, OC, EC and metal element concentrations have an increasing trend, but their ratio with PM 2.5 gradually decreases, indicating that other compositions have a higher contribution. This result, on the one hand, may be since some chemical compositions such as ions and dust have not been included in the statistics; on the other hand, the unknown component may also have a high contribution characteristic to PM 2.5 (Zhang et al, 2015;Huang et al, 2014). For the contribution characteristics of unknown components of PM 2.5 , studies in some regions of China show that the contribution of higher PM 2.5 concentration is higher than that of lower PM 2.5 concentration (Huang et al, 2014;Li et al, 2017;Geng et al, 2019).…”

Section: Pollution Characteristics Of the Interannual And Entire Obsementioning

confidence: 99%

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Elucidating the pollution characteristics of nitrate, sulfate and ammonium in PM2.5 in Chengdu, southwest China, based on 3-year measurements

et al. 2020

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Abstract. Nitrate, sulfate and ammonium (NSA) are the main secondary inorganic aerosols of PM2.5 and play an important role in air pollution. In this study, a 3-year observational experiment was conducted from 1 January 2015 to 31 December 2017, in Chengdu, southwest China. NSA pollution characteristics, chemical conversion generation, emission reduction control sensitivity and pollutant regional transport characteristics were analyzed. NSA are the most important chemical compositions of particles with aerodynamic equivalent diameter ≤2.5 µm in ambient air (PM2.5), and the contribution of nitrate to the accumulation of PM2.5 concentration is greater than that of sulfate and ammonium. NSA also have obvious characteristics of annual, monthly, seasonal, diurnal and weekly variations. Through observation data and model simulation, it was also found that the existence of an aerosol aqueous environment plays an important role in the formation and existence of NSA. Sensitivity analysis between NSA found that controlling NO3- and SO42- plays an important role in reducing the contribution of NSA to PM2.5, which also implies that the current control of NOx and SO2 is important for improving air pollution. Combined with meteorological conditions and potential source contribution function (PSCF) analysis, local emissions and regional emissions of pollutants are found to have important impacts on Chengdu's atmospheric environment. This research result not only provides an assessment of the current atmospheric emission reduction effect but also provides an important reference for atmospheric pollution control.

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Section: Pollution Characteristics Of the Interannual And Entire Obsementioning

confidence: 99%

“…At night, with the increase in RH (Fig. S8), dissolved ozone, free radicals, hydrogen peroxide and NO 2 can catalyze SO 2 to form secondary aerosols through an aqueous phase reaction (Zhang et al, 2015;An et al, 2019). The seasonal diurnal variation in NSA is shown in Fig.…”

Section: Diurnal and Weekly Variationsmentioning

confidence: 99%

Elucidating the pollution characteristics of nitrate, sulfate and ammonium in PM2.5 in Chengdu, southwest China, based on 3-year measurements

et al. 2020

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“…Anthropogenic activities associated with rapidly developed industrialization and urbanization have been leading to a sustained increase in the amounts of atmospheric pollutants, especially in the fast-developing countries (IPCC, 2013). As one of the largest emission sources of aerosols and their precursors, China has been suffering from serious air pollution for years (Lei et al, 2011;Li et al, 2011), with severe haze events frequently occurring in winter, especially over large urban agglomerations, such as the North China Plain (NCP) (Han et al, 2014;Gao et al, 2015), the Yangtze River Delta area (YRD) (Ding et al, 2016;Wang et al, 2016a), the Pearl River Delta area (PRD) (Fan et al, 2015;Liu et al, 2018b), and the Sichuan Basin (SCB) (Zhao et al, 2018;Zhang et al, 2019). During severe haze events, the observed maximum hourly surface-layer PM 2.5 (fine particulate matter with aerodynamic diameter of 2.5 µm or less) concentration exceeded 1000 µg m -3 (Wang et al, 2013b;Sun et al, 2016;Li et al, 2017a), which could significantly influence visibility (Li et al, 2014), radiation budget (Steiner et al, 2013), atmospheric circulation (Jiang et al, 2017), cloud properties (Unger et al, 2009), and even human health (Guo et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

Assessing the formation and evolution mechanisms of severe haze pollution in Beijing−Tianjin−Hebei region by using process analysis

Chen¹,

Zhu²,

Liu³

et al. 2019

Preprint

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Abstract. Fine&#8211;particle pollution associated with haze threatens human health, especially in the North China Plain, where extremely high PM2.5 concentrations were frequently observed during winter. In this study, the WRF&#8211;Chem model coupled with an improved integrated process analysis scheme was used to investigate the formation and evolution mechanisms of a haze event happened over Beijing&#8211;Tianjin&#8211;Hebei (BTH) in December 2015, including examining the contributions of local emission and outside transport to the absolute PM2.5 concentration in BTH, and the contributions of each detailed physical or chemical process to the variations in the PM2.5 concentration. The influence mechanisms of aerosol radiative forcing (including aerosol direct and indirect effects) were also examined by using the process analysis. During the aerosol accumulation stage (December 20&#8211;22, Stage_1), the average near&#8211;surface PM2.5 concentration in BTH was 250.0&#8201;&#181;g&#8201;m&#8722;3, which was contributed by local emission of 42.3&#8201;% and outside transport of 36.6&#8201;%. During the aerosol dispersion stage (December 23&#8211;27, Stage_2), the average concentration of PM2.5 was 107.9&#8201;&#181;g&#8201;m&#8722;3. The contribution of local emission increased to 50.9&#8201;%, while the contribution of outside transport decreased to 24.3&#8201;%. The 24&#8211;h change (23:00LST minus 00:00LST) in the near&#8211;surface PM2.5 concentration was +50.4&#8201;&#181;g&#8201;m&#8722;3 during Stage_1 and &#8722;41.5&#8201;&#181;g&#8201;m&#8722;3 during Stage_2. Contributions of aerosol chemistry process and vertical mixing process to the 24&#8211;h change were +43.8 (+17.9) &#181;g&#8201;m&#8722;3 and &#8722;161.6 (&#8722;221.6) &#181;g&#8201;m&#8722;3 for Stage_1 (Stage_2), respectively. Small differences in contributions from other processes were found between Stage_1 and Stage_2, such as advection process, cloud chemistry process, and so on. Therefore, the PM2.5 increase over BTH during haze formation stage (Stage_1) was mainly attributed to strong production by aerosol chemistry process and weak removal by vertical mixing process. When aerosol radiative feedback was considered, the 24&#8211;h PM2.5 increase was enhanced by 9.6 &#181;g&#8201;m&#8722;3 during Stage_1, which could be mainly attributed to the contributions of vertical mixing process (+39.8&#8201;&#181;g&#8201;m&#8722;3), advection process (&#8722;38.6&#8201;&#181;g&#8201;m&#8722;3) and aerosol chemistry process (+5.1&#8201;&#181;g&#8201;m&#8722;3). The restrained vertical mixing could be the primary reason for the enhancement in near&#8211;surface PM2.5 increase when aerosol radiative forcing was considered.

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“…Ning et al (2018) studied the impacts of low-pressure systems on air pollution events in northwest Sichuan during winter, and found that a stagnant situation before a low-pressure system benefits the accumulation of pollutants, while, after the low-pressure system, pollutants are likely to be removed by the strengthening wind conditions and the vertical exchange in the atmosphere [30]. Liao et al (2018) also focused on the stagnation effects on southwestern China [31], while Zhang et al (2019) studied Sichuan Basin's terrain effects [32]. Both studies obtain a relationship between pollutants' properties and meteorological factors similar to that obtained by .…”

Section: Discussionmentioning

confidence: 99%

Analysis of a Severe Pollution Episode in December 2017 in Sichuan Province

Zeng

Zheng

2019

Atmosphere

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To analyze a pollution process in Sichuan from 12 December 2017 to 2 January 2018, hourly pollutant data from 90 environmental monitors with surface data and sounding data from 21 meteorological stations were used to determine the sources of pollutants and the correlation between pollution levels and meteorological conditions. The results show that the whole process could be divided into two parts: (1) from 20 December 2017 to 30 December 2017, when, driven by a static stable atmosphere, the Sichuan basin experienced a long-lasting haze episode with an air quality index (AQI) that exceeded 150; and (2) after 30 December 2017, when a Mongolian cyclone developed and brought a large amount of cold air to Sichuan that improved the horizontal and vertical turbulence exchange and removed most of the pollutants. However, the northern part of Sichuan, affected by the cold air that carried dust from Shanxi and Qinghai, suffered an abrupt change in the extent of PM10 that led to an aggravation of this pollution process.

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A modelling study of the terrain effects on haze pollution in the Sichuan Basin

Cited by 119 publications

References 46 publications

Elucidating the pollution characteristics of nitrate, sulfate and ammonium in PM<sub>2.5</sub> in Chengdu, southwest China, based on 3-year measurements

Elucidating the pollution characteristics of nitrate, sulfate and ammonium in PM<sub>2.5</sub> in Chengdu, southwest China, based on 3-year measurements

Assessing the formation and evolution mechanisms of severe haze pollution in Beijing−Tianjin−Hebei region by using process analysis

Analysis of a Severe Pollution Episode in December 2017 in Sichuan Province

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A modelling study of the terrain effects on haze pollution in the Sichuan Basin

Cited by 119 publications

References 46 publications

Elucidating the pollution characteristics of nitrate, sulfate and ammonium in PM&lt;sub&gt;2.5&lt;/sub&gt; in Chengdu, southwest China, based on 3-year measurements

Elucidating the pollution characteristics of nitrate, sulfate and ammonium in PM&lt;sub&gt;2.5&lt;/sub&gt; in Chengdu, southwest China, based on 3-year measurements

Assessing the formation and evolution mechanisms of severe haze pollution in Beijing−Tianjin−Hebei region by using process analysis

Analysis of a Severe Pollution Episode in December 2017 in Sichuan Province

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Elucidating the pollution characteristics of nitrate, sulfate and ammonium in PM<sub>2.5</sub> in Chengdu, southwest China, based on 3-year measurements

Elucidating the pollution characteristics of nitrate, sulfate and ammonium in PM<sub>2.5</sub> in Chengdu, southwest China, based on 3-year measurements