Analysis of a winter regional haze event and its formation mechanism in the North China Plain

Zhao, Xueyan; Zhao, Pusheng; Xu, Jing; Wang, Meng; Pu, Wenyuan; Dong, Fan; He, Di; Shi, Qingfeng

doi:10.5194/acp-13-5685-2013

Cited by 591 publications

(323 citation statements)

References 37 publications

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“…However, urban area only takes up approximately 5% area in China while cropland is the dominant surface type also featuring dense population and high PM2.5 exposure (Liu, 2005;Xu et al, 2011). Frequent regional-scale haze pollution and cropland-dominant land cover in China make 15 it necessary to figure out this interaction over rural area Zhao et al, 2013b). The differences in surface parameters between cities and rural area are listed in Table 2.…”

Section: A Comparison Of the Dome Effect Over Urban And Rural Areasmentioning

confidence: 99%

Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

Wang¹,

Huang²,

Ding³

2017

Preprint

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Black carbon (BC) has been identified to play a critical role in aerosol-planet boundary layer (PBL) interaction and further deterioration of near-surface air pollution in megacities, which has been named as its "dome effect". However, the impacts of key factors that influence this effect, such as the vertical distribution and aging processes of BC, and also the underlying land surface, have not been quantitatively explored yet. Here, based on available in-situ measurements of meteorology and 15 atmospheric aerosols together with the meteorology-chemistry online coupled model, WRF-Chem, we conduct a set of parallel simulations to quantify the roles of these factors in influencing the BC's dome effect and surface haze pollution, and discuss the main implications of the results to air pollution mitigation in China. We found that the impact of BC on PBL is very sensitive to the altitude of aerosol layer. The upper level BC, especially those near the capping inversion, is more essential in suppressing the PBL height and weakening the turbulence mixing. The dome effect of BC tends to be significantly intensified 20 as BC aerosol mixed with scattering aerosols during winter haze events, resulting in a decrease of PBL height by more than 25%. In addition, the dome effect is more substantial (up to 15%) in rural areas than that in the urban areas with the same BC loading, indicating an unexpected regional impact of such kind of effect to air quality in countryside. This study suggests that China's regional air pollution would greatly benefit from BC emission reductions, especially those from the elevated sources from the chimneys and also the domestic combustions in rural areas, through weakening the aerosol-boundary layer 25 interactions that triggered by BC.

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Section: A Comparison Of the Dome Effect Over Urban And Rural Areasmentioning

confidence: 99%

Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

Wang¹,

Huang²,

Ding³

2017

Preprint

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“…Due to particle precipitation and wall loss, the concentration of particles inside the chamber dropped gradually. Simultaneous measurements with the sensors, the SidePak, and the SMPS started when the mass concentration given by the SidePak was below 1 mg/m 3 , which is slightly above the typical PM concentrations in highly polluted cities (Tiwari et al 2013;Zhao et al 2013;Guo et al 2014). The whole process took approximately 2.5 h (Figure 2b), which was close to the gravitational precipitation time for a 1 mm (aerodynamic size) particle to drop from the top to the bottom of the chamber (»2.4 h).…”

Section: Chamber For Particle Measurementmentioning

confidence: 99%

“…indicated by the R 2 values calculated by the least-square regression (Figures 4a, b, d, e, g, and h). Given the low cost of these particle sensors, it will be worthwhile to apply these sensors to obtain local and real-time PM concentrations in polluted cities, where the daily upper limit of particle concentrations is around 600 mg/m 3 , and the hourly upper limit of particle concentrations is higher than 1 mg/m 3 (Tiwari et al 2013;Zhao et al 2013;Guo et al 2014). Among the three sensors, the GP2Y sensor gave the highest linearity with an R 2 value of 0.9838 for sensors of the same type on four sides of the chamber wall in one measurement, and 0.9831 for the same sensor on one side of the chamber wall in several measurements.…”

Section: Linearity Of Responsementioning

confidence: 99%

Laboratory Evaluation and Calibration of Three Low-Cost Particle Sensors for Particulate Matter Measurement

Wang

et al. 2015

Aerosol Science and Technology

365

290

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Particle sensors offer significant advantages of compact size and low cost, and have recently drawn great attention for usage as portable monitors measuring particulate matter mass concentrations. However, most sensor systems have not been thoroughly evaluated with standardized calibration protocols, and their data quality is not well documented. In this work, three low-cost particle sensors based on light scattering (Shinyei PPD42NS, Samyoung DSM501A, and Sharp GP2Y1010AU0F) were evaluated by calibration methods adapted from the US EPA 2013 Air Sensor Workshop recommendations. With a SidePak (TSI Inc., St. Paul, MN, USA), a scanning mobility particle sizer (TSI Inc.), and an AirAssure TM PM 2.5 Indoor Air Quality Monitor (TSI Inc.), which itself relies on a GP2Y1010AU0F sensor as reference instruments, six performance aspects were examined: linearity of response, precision of measurement, limit of detection, dependence on particle composition, dependence on particle size, and relative humidity and temperature influences. This work found that: (a) all three sensors demonstrated high linearity against SidePak measured concentrations, with R 2 values higher than 0.8914 in the particle concentration range of 0-1000 mg/m 3 , and the linearity depended on the studied range of particle concentrations; (b) the standard deviations of the sensors varied from 15 to 90 mg/m 3 for a concentration range of 0-1000 mg/m 3 ; (c) the outputs of all three sensors depended highly on particle composition and size, resulting in as high as 10 times difference in the sensor outputs; and (d) humidity affected the sensor response. This article provides further recommendations for applications of the three tested sensors.

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“…Sulfate formation in aqueous solution is generated by the uptake of SO 2 onto wet, pre-existing particles or cloud droplets followed by oxidation by O 3 , H 2 O 2, NO 2 or O 2 catalyzed by Fe(III) and Mn(II) (Seinfeld and Pandis, 2006;Wang et al, 2012). Previous studies found that sulfate is produced mainly by heterogeneous reactions by oxidizing SO 2 on wet, pre-existing particles or cloud droplets under high relative humidity (RH) conditions in haze episode in winter Li et al, 2011;Wang et al, 2012;Zhao et al, 2013). Both laboratory experiments and in situ observations suggest that the aqueous oxidation of SO 2 is attributed to catalysis by metals, such as iron and manganese (Turšič et al, 2003;Li et al, 2011;Wang et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Secondary Formation of Sulfate and Nitrate during a Haze Episode in Megacity Beijing, China

Liu

Sun

et al. 2015

Aerosol Air Qual. Res.

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A heavy haze episode that occurred in Beijing from 20 September to 27 September, 2011 was observed to explore the secondary processes of the haze episode. During the haze episode, the relatively stable synoptic conditions and regional transport from polluted areas in the south and southwest of Beijing favored the formation of haze. Significant increases of PM 2.5 /PM 10 ratio was observed during haze period, which implied that the haze was caused by fine particles. Additionally, the presence of secondary inorganic pollutants (SO 4 2-, NO 3 -and NH 4 + ) sharply increased during the haze episode, which indicated that secondary processes significantly strengthened the haze episode. The sulfur oxidation ratio (SOR) sharply increased from a non-haze episode with a highest value of 0.11 to a haze episode with a highest value of 0.62. Low correlations between SOR and O 3 and the temperature were found, whereas a high correlation between SOR and RH was found during the haze episode, which implied that sulfate was mainly produced by the aqueous-phase oxidation of SO 2 rather than the gas-phase conversion of SO 2 to sulfate in haze episode in Beijing. Furthermore, a fine linear relationship between SOR and the surface area (dS) of particles smaller than 1 µm confirmed the heterogeneous processes of sulfate formation in haze episode. The nitrogen oxidation ratio (NOR) also sharply increased from a non-haze episode with a highest value of 0.03 to a haze episode with a highest value of 0.26, which indicated more intense secondary formation of nitrate in haze episode. Nitrate was found to be mainly produced by a homogenous reaction under ammonium-rich conditions. Higher RH in haze episode reduced the thermodynamic equilibrium constant Ke', and favored the thermodynamic equilibrium reaction of HNO 3 (g) + NH 3 (g) ↔ NH 4 NO 3 (s, aq) to formed nitrate, which might help explain the enhanced homogenous production of nitrate in haze episode. In addition, a good empirical fit (R 2 = 0.70) between NOR and dS was found, which indicated that the particle surface area significantly contributed to the intense homogeneous production of nitrate in haze episode.

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Analysis of a winter regional haze event and its formation mechanism in the North China Plain

Cited by 591 publications

References 37 publications

Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

Dome effect of black carbon and its key influencing factors: A one-dimensional modelling study

Laboratory Evaluation and Calibration of Three Low-Cost Particle Sensors for Particulate Matter Measurement

Secondary Formation of Sulfate and Nitrate during a Haze Episode in Megacity Beijing, China

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