Diurnal, weekly and monthly spatial variations of air pollutants and air quality of Beijing

Chen, Wei; Tang, Haoyu; Zhao, Hongwei

doi:10.1016/j.atmosenv.2015.08.040

Cited by 138 publications

(87 citation statements)

References 16 publications

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“…Since 2006, the API has been declining steadily, which is not consistent with the results in Figure 1 because the AOD has not shown a comparable decline. Moreover, the API is greatest in the winter or spring seasons, while summer has the lowest API [61], as shown in Figure 13. The median or average seasonal APIs have declined since 2001.…”

Section: Discussionmentioning

confidence: 87%

Analysis of Aerosol Properties in Beijing Based on Ground-Based Sun Photometer and Air Quality Monitoring Observations from 2005 to 2014

et al. 2016

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Aerosol particles are the major contributor to the deterioration of air quality in China's capital, Beijing. Using ground-based sun photometer observations from 2005 to 2014, the long-term variations in optical properties and microphysical properties of aerosol in and around Beijing were investigated in this study. The results indicated little inter-annual variations in aerosol optic depth (AOD) but an increase in the fine mode AODs both in and outside Beijing. Furthermore, the single scattering albedo in urban Beijing is larger, while observations at the site that is southeast of Beijing suggested that the aerosol there has become more absorbing. The intra-annual aspects were as follow: The largest AOD and high amount of fine mode aerosols are observed in the summer. However, the result of air pollution index (API) that mainly affected by the dry density of near-surface aerosol indicated that the air quality has been improving since 2006. Winter and spring were the most polluted seasons considering only the API values. The inconsistency between AOD and API suggested that fine aerosol particles may have a more important role in the deterioration of air quality and that neglecting particulate matter with aerodynamic diameter less than 2.5 µm (PM 2.5 ) in the calculation of API might not be appropriate in air quality evaluation. Through analysis of the aerosol properties in high API days, the results suggested that the fine mode aerosol, especially PM 2.5 has become a major contributor to the aerosol pollution in Beijing.

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Section: Discussionmentioning

confidence: 87%

Analysis of Aerosol Properties in Beijing Based on Ground-Based Sun Photometer and Air Quality Monitoring Observations from 2005 to 2014

et al. 2016

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“…d via a municipal website [13]. These 35 stations can be divided into four groups accordin eographical locations: urban stations, suburban stations, background stations, and tr s. These 35 stations are unevenly and sparsely distributed across the city (Figure 1).…”

Section: Air Quality Monitoring Datamentioning

confidence: 99%

“…The correlation between measured data and validated data must be larger than 0.93 [31]. The municipal government has publicized real-time monitoring data for all six pollutants in Beijing collected every hour at the aforementioned 12 state-controlled stations and another 23 municipal stations, with the latter data released via a municipal website [13]. These 35 stations can be divided into four groups according to their geographical locations: urban stations, suburban stations, background stations, and traffic stations.…”

Section: Air Quality Monitoring Datamentioning

confidence: 99%

Analysis of Aerosol Radiative Forcing over Beijing under Different Air Quality Conditions Using Ground-Based Sun-Photometers between 2013 and 2015

et al. 2016

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Aerosol particles can strongly affect both air quality and the radiation budget of the atmosphere. Above Beijing, the capital city of China, large amounts of aerosols within the atmospheric column have caused the deterioration of local air quality and have influenced radiative forcings at both the top and the bottom of the atmosphere (BOA and TOA). Observations of aerosol radiative forcing and its efficiency have been made using two sun-photometers in urban Beijing between 2013 and 2015, and have been analyzed alongside two air quality monitoring stations' data by dividing air quality conditions into unpolluted, moderately polluted, and heavily polluted days. Daily average PM 2.5 concentrations varied greatly in urban Beijing (5.5-485.0 µg/m 3 ) and more than one-third of the analyzed period is classified as being polluted according to the national ambient air quality standards of China. The heavily polluted days had the largest bottom of atmosphere (BOA) and top of atmosphere (TOA) radiative forcings, but the smallest radiative forcing efficiencies, while the unpolluted days showed the opposite characteristics. On heavily polluted days, the averaged BOA aerosol radiative forcing occasionally exceeded´150 W/m 2 , which represents a value about three-times greater than that for unpolluted days. BOA aerosol radiative forcing was around two-to-three times as large as TOA aerosol radiative forcing under various air quality conditions, although both were mostly negative, suggesting that aerosols had different magnitudes of cooling effects at both the surface and the top of the atmosphere. Unpolluted days had the largest average values of aerosol radiative forcing efficiencies at BOA (and TOA) levels, which exceeded 190 W/m 2 (´70 W/m 2 ), compared with the lowest average values in heavily polluted days of around´120 W/m 2 (´55 W/m 2 ). These results suggest that the high concentrations of particulate matter pollution in the urban Beijing area had a strong cooling effect at both BOA and TOA levels.

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“…In Changping site, downwind of Beijing city, the monthly average of peak O 3 concentrations reaches 100 ppb in July, while the AOT40 (accumulated hourly O 3 concentration over a threshold of 40 ppb during daytime) from June to August is 29 ppm h in 2014 (Feng et al, 2015b;Yuan et al, 2015). The yearly average of daily peak O 3 concentration reaches 60 ppb at some of 35 monitoring stations in Beijing during May 2014 to April 2015 (Chen et al, 2015), and short-term projected emissions suggest that O 3 concentration will further increase (Yamaji et al, 2008). Therefore, O 3 concentrations in Beijing frequently exceed the threshold value of 40 ppb and AOT40 critical level of 5 ppm h, which have been established in Europe to protect sensitive tree species against O 3 (LRTAP, 2010).…”

Section: Introductionmentioning

confidence: 99%

Effects of elevated ozone on physiological, anatomical and ultrastructural characteristics of four common urban tree species in China

Gao

Calatayud

García‐Breijo

et al. 2016

Ecological Indicators

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a b s t r a c tFast urbanization has led to ozone (O 3 ) being the main pollutant in summer in most of China. To assess future ground-level O 3 effects on the service of urban greening species and clarify the underlying mechanism of O 3 damage, four common urban greening species, Ailanthus altissima (AA), Fraxinus chinensis (FC), Platanus orientalis (PO) and Robinia pseudoacacia (RP) were exposed to non-filtered air (NF) and to elevated O 3 (E-O 3 ) in open-top chambers. E-O 3 induced visible injury in all species as well as microscopic alterations such as collapse of the palisade parenchyma cells, callose accumulation, or chloroplast and mitochondrial accelerated senescence. E-O 3 significantly reduced light-saturated CO 2 assimilation (A sat ), the maximum activity of Rubisco (Vc max ), the maximum electron transport rate (J max ), and fluorescence parameters such as the quantum yield of noncyclic electron transport ( PSII ), and the quenching of photochemical efficiency of PSII (qP). It also increased total antioxidant capacity, phenolics and ascorbate contents. No significant interaction between O 3 and species was found in photosynthetic performance and antioxidant systems, suggesting that the four species selected were sensitive to O 3 . Of all four species, AA was the most sensitive species due to a combination of earlier injury onset, anatomical features, lower antioxidant responses and higher stomatal conductance. The sensitivity of tree species to O 3 is a factor to be considered for urban greening. Ozone may affect important urban forest ecosystem services by reducing CO 2 assimilation.

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Diurnal, weekly and monthly spatial variations of air pollutants and air quality of Beijing

Cited by 138 publications

References 16 publications

Analysis of Aerosol Properties in Beijing Based on Ground-Based Sun Photometer and Air Quality Monitoring Observations from 2005 to 2014

Analysis of Aerosol Properties in Beijing Based on Ground-Based Sun Photometer and Air Quality Monitoring Observations from 2005 to 2014

Analysis of Aerosol Radiative Forcing over Beijing under Different Air Quality Conditions Using Ground-Based Sun-Photometers between 2013 and 2015

Effects of elevated ozone on physiological, anatomical and ultrastructural characteristics of four common urban tree species in China

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