Dry deposition of particulate matter at an urban forest, wetland and lake surface in Beijing

Liu, Jiakai; Zhu, Lijuan; Wang, Huihui; Yang, Yilian; Liu, Jiatong; Qiu, Dongdong; Wörns, MA; Zhang, Zhenming; Liu, Jinglan

doi:10.1016/j.atmosenv.2015.11.023

Cited by 79 publications

(51 citation statements)

References 46 publications

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“…Although the anthropogenic emissions may be significantly reduced during nighttime, the boundary layer height at night is typically low and the wind speed is low (Table 2), which limits the diffusion of air pollutants and leads to a rise in the concentrations. Moreover, the stagnant meteorological conditions during nighttime are unfavorable to the dry deposition of fine particles, especially those in accumulation mode [47]. As a result, the concentration of primary EC during nighttime was 1.5 times what it was during daytime.…”

Section: Day-night Differencesmentioning

confidence: 82%

Chemical and Light Extinction Characteristics of Atmospheric Aerosols in Suburban Nanjing, China

Zhang

et al. 2017

Atmosphere

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This work reports the chemical and light extinction characteristics of the atmospheric particles collected from January to November 2014 in suburban Nanjing. Size-segregated measurement results showed that more than 80% of the major aerosol components were concentrated in PM 2.5 . The concentration of PM 2.5 was highest in winter and lowest in autumn. Specifically, K + concentration peaked in late spring indicating heavy influences from straw burning, while sulfate concentration was highest in summer and its daytime concentration was also higher than its nighttime concentration, both reflecting a significant role of photochemical production. Nevertheless, except for sulfate, all other components had higher concentrations during nighttime, signifying the role of unfavorable meteorological conditions in exacerbating the air pollution. The IMPROVE formula was employed, which can reconstruct the PM 2.5 mass and light extinction well. The light extinction was mainly contributed by (NH 4 ) 2 SO 4 and NH 4 NO 3 (together 58.3%). Mass concentrations of all PM 2.5 components increased significantly with the increase of pollution levels, but nitrate increased most rapidly; correspondingly, the contribution of nitrate to light extinction also increased quickly when pollution became heavy. Such results were different from those observed in Beijing-Tianjin-Hebei where sulfate increased most quickly. Our results thus highlight that reduction of vehicular NO 2 is likely a priority for air quality improvement in Nanjing. Back trajectory analysis showed the dominance of the local air mass and the one from Huanghai, yet the air mass originated from Bohai, and passed though Shandong and north of Jiangsu province could deliver highly-polluted air to Nanjing, as well.

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Section: Day-night Differencesmentioning

confidence: 82%

Chemical and Light Extinction Characteristics of Atmospheric Aerosols in Suburban Nanjing, China

Zhang

et al. 2017

Atmosphere

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“…On the one hand, PM 2.5 was significantly affected by natural factors such as climate, topography, and surface vegetation [42,43,44] besides socio-economic drivers. C year is a combined effect of these factors.…”

Section: Discussionmentioning

confidence: 99%

Socioeconomic Drivers of PM2.5 in the Accumulation Phase of Air Pollution Episodes in the Yangtze River Delta of China

Cai-rong

Liu

et al. 2016

IJERPH

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Recent studies in PM2.5 sources show that anthropogenic emissions are the main contributors to haze pollution. Due to their essential roles in establishing policies for improving air quality, socioeconomic drivers of PM2.5 levels have attracted increasing attention. Unlike previous studies focusing on the annual PM2.5 concentration (Cyear), this paper focuses on the accumulation phase of PM2.5 during the pollution episode (PMAE) in the Yangtze River Delta in China. This paper mainly explores the spatial variations of PMAE and its links to the socioeconomic factors using a geographical detector and simple linear regression. The results indicated that PM2.5 was more likely to accumulate in more developed cities, such as Nanjing and Shanghai. Compared with Cyear, PMAE was more sensitive to socioeconomic impacts. Among the twelve indicators chosen for this study, population density was an especially critical factor that could affect the accumulation of PM2.5 dramatically and accounted for the regional difference. A 1% increase in population density could cause a 0.167% rise in the maximal increment and a 0.214% rise in the daily increase rate of PM2.5. Additionally, industry, energy consumption, and vehicles were also significantly associated with PM2.5 accumulation. These conclusions could serve to remediate the severe PM2.5 pollution in China.

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“…in which U(z) (m·s −1 ) is the average wind velocity; u* (m·s −1 ) is friction velocity which can be directly measured; k is the von Karman constant (0.41); d (m) is displacement height; Z 0 is roughness length, which is used to model the horizontal mean wind speed near the ground and is equivalent to the height at which the wind speed theoretically becomes zero [19], according to Zhang et al (2001) [20], Z 0 was determined by considering different seasons and land use categories-in our study, Z 0 was 0.75 at Olympic Forest Park and 0.8 at Jiufeng National Forest Park. The value of d can be calculated by iterative method [18] as:…”

Section: Calculation Of Deposition Velocitymentioning

confidence: 99%

Deposition of PM2.5 Sulfate in the Spring on Urban Forests in Beijing, China

Zhao

Lun

et al. 2017

Atmosphere

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Water-soluble ions such as sulfate may have great impacts on atmospheric pollution. To determine the deposition effect of PM 2.5 sulfates, the major PM 2.5 constituents, in the forest canopy in Beijing, China, an investigation was carried out in an urban forest, Olympic Forest Park, and a suburban forest, Jiufeng National Forest Park. We measured the vertical distributions of sulfate by using monitoring towers in the two forests at the same times in March and May 2013. Sulfate (SO 4 2− )was predominant in all PM 2.5 water-soluble inorganic ions, with a proportion >40%. The vertical concentration of SO 4 2− increased with height, and the average sulfate concentration in Olympic ForestPark was higher than that in Jiufeng National Forest Park. Results also revealed that meteorological conditions had significant impacts on both the sulfate concentration and the deposition velocity. In winter, the deposition of SO 4 2− through the canopy was not obvious in the two forest parks, which was quite the opposite in spring. The deposition velocity in the daytime was higher than that in the nighttime in both Olympic Forest Park (0.9 ± 1.0 cm/s vs. 0.4 ± 0.3 cm/s) and Jiufeng National Forest Park (1.3 ± 1.2 cm/s vs. 0.8 ± 0.8 cm/s). While Jiufeng National Forest Park turned out to have a higher average sulfate deposition velocity than Olympic Forest Park.

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Dry deposition of particulate matter at an urban forest, wetland and lake surface in Beijing

Cited by 79 publications

References 46 publications

Chemical and Light Extinction Characteristics of Atmospheric Aerosols in Suburban Nanjing, China

Chemical and Light Extinction Characteristics of Atmospheric Aerosols in Suburban Nanjing, China

Socioeconomic Drivers of PM2.5 in the Accumulation Phase of Air Pollution Episodes in the Yangtze River Delta of China

Deposition of PM2.5 Sulfate in the Spring on Urban Forests in Beijing, China

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