Research

545 KiB

Open AccessArticle

A Case Study of Chemical Characteristics of Daytime and Nighttime Ambient Particles in Shanghai, China

by Chongshu Zhu, Junji Cao, Jiamao Zhou, Suixin Liu, Wenting Dai, Ting Zhang, Zhuzi Zhao, Zhenxing Shen, Hua Li and Ping Wang

Atmosphere 2015, 6(8), 1141-1153; https://doi.org/10.3390/atmos6081141 - 07 Aug 2015

Cited by 9 | Viewed by 5071

Abstract

Ambient daytime and nighttime PM_2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) and TSP (the total suspended particulates) samples were collected at two sites (named Pudong and Jinshan) in Shanghai. The concentrations of PM_2.5 and TSP were lower at [...] Read more.

Ambient daytime and nighttime PM_2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) and TSP (the total suspended particulates) samples were collected at two sites (named Pudong and Jinshan) in Shanghai. The concentrations of PM_2.5 and TSP were lower at Pudong than at Jinshan. Higher PM_2.5 and TSP concentrations were observed during daytime than nighttime for both sites. Carbonaceous aerosol and secondary sulfate were the most abundant components. Larger enrichment factor (EFs) of Zn, Pb, Cl, and S for Jinshan nighttime were observed than for other sampling periods. PM_2.5 showed higher relative spatial uniformity (the coefficients of divergence, COD = 0.18) than TSP (COD = 0.23) during the sampling period. The variations of chemical components and the species ratios showed that the contributions of primary particulate emissions in Jinshan (industrial zone) were more significant than in Pudong (residential zone). Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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2132 KiB

Open AccessArticle

In-Situ Aircraft Measurements of the Vertical Distribution of Black Carbon in the Lower Troposphere of Beijing, China, in the Spring and Summer Time

by Delong Zhao, Xuexi Tie, Yang Gao, Qiang Zhang, Haijun Tian, Kai Bi, Yongli Jin and Pengfei Chen

Atmosphere 2015, 6(5), 713-731; https://doi.org/10.3390/atmos6050713 - 20 May 2015

Cited by 26 | Viewed by 6451

Abstract

Due to rapid economic development in recent years, China has become a major global source of refractory black carbon (rBC) particles. However, surface rBC measurements have been limited, and the lower troposphere suffers from a complete lack of measurements, especially in heavily rBC-polluted [...] Read more.

Due to rapid economic development in recent years, China has become a major global source of refractory black carbon (rBC) particles. However, surface rBC measurements have been limited, and the lower troposphere suffers from a complete lack of measurements, especially in heavily rBC-polluted regions such as China’s capital, Beijing (BJ). In this study, we present the first concentration measurements using an airborne Single Particle Soot Photometer (SP2) instrument, including vertical distributions, size distributions, and the mixing state of rBC particles in the lower troposphere in BJ and its surrounding areas. The measurements were conducted from April to June 2012 during 11 flights. The results show that the vertical rBC distributions had noticeable differences between different air masses. When an air mass originated from the south of BJ (polluted region), the rBC particles were strongly compressed in the planetary boundary layer (PBL), and showed a large vertical gradient at the top of the PBL. In contrast, when an air mass originated from the north of BJ (clean region), there was a small vertical gradient. This analysis suggests that there was significant regional transport of rBC particles that enhanced the air pollution in BJ, and the transport not only occurred near the surface but also in the middle levels of the PBL (around 0.5 to 1 km). The measured size distributions show that about 80% of the rBC particles were between the diameters of 70 and 400 nm, and the mean diameter of the peak rBC concentrations was about 180–210 nm. This suggests that the rBC particles were relatively small particles. The mixing state of the rBC particles was analyzed to study the coating processes that occurred on the surface of these particles. The results indicate that the air mass strongly affected the number fraction (NF) of the coated particles. As for a southern air mass, the local air pollution was high, which was coupled with a lower PBL height and higher humidity. Consequently, hygroscopic growth occurred rapidly, producing a high NF value (~65%) of coated rBC particles. The correlation coefficient between the NF and the local relative humidity (RH) was 0.88, suggesting that the rBC particles were quickly converted from hydrophobic to hydrophilic particles. This rapid conversion is very important because it suggests a shorter lifetime of rBC particles under heavily polluted conditions. In contrast, under a northern air mass, there was no clear correlation between the NF and the local humidity. This suggests that the coating process occurred during the regional transport in the upwind region. In this case, the lifetime was longer than the southern air mass condition. Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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870 KiB

Open AccessArticle

Characteristics of Carbonaceous Species in PM2.5 in Wanzhou in the Hinterland of the Three Gorges Reservior of Northeast Chongqing, China

by Liuyi Zhang, Yimin Huang, Yuan Liu, Fumo Yang, Guoxin Lan, Chuan Fu and Jun Wang

Atmosphere 2015, 6(4), 534-546; https://doi.org/10.3390/atmos6040534 - 13 Apr 2015

Cited by 20 | Viewed by 5776

Abstract

Daily PM2.5 samples were collected in the four consecutive seasons in 2013 in Wanzhou, the second largest city in Chongqing Municipality of China and in the hinterland of the Three Gorges Reservior on Yangtze River and analyzed for the mass concentrations and carbonaceous [...] Read more.

Daily PM2.5 samples were collected in the four consecutive seasons in 2013 in Wanzhou, the second largest city in Chongqing Municipality of China and in the hinterland of the Three Gorges Reservior on Yangtze River and analyzed for the mass concentrations and carbonaceous species of PM2.5 to investigate the abundance and seasonal characteristics of PM2.5, and organic carbon (OC) and elemental carbon (EC). The annual average PM2.5 concentrations were 125.3 μg·m⁻³, while OC and EC were 23.6 μg·m⁻³ and 8.7 μg·m⁻³, respectively. The total carbonaceous aerosol (TCA) accounted for 32.6% of the PM2.5 mass. On seasonal average, the OC and EC concentrations ranked in the order of winter > fall > spring > summer, which could be attributed to the combined effects of changes in local emissions and seasonal meteorological conditions. Strong OC-EC correlations were found in the winter and fall, suggesting the contributions of similar sources. The lowest OC-EC correlation occurred in the summer, probably due to the increases in biogenic emission and formation of secondary organic aerosol (SOA) through photochemical activity. Average secondary organic carbon (SOC) concentration was 9.0 μg·m⁻³, accounting for 32.3% of the total OC. The average ratios of SOA/PM2.5 of 3.8%~15.7% indicated that SOA was a minor fraction in fine particles of Wanzhou. Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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857 KiB

Open AccessArticle

Evaluation of Policy Influence on Long-Term Indoor Air Quality in Emperor Qin’s Terra-Cotta Museum, China

by Hua Li, Tafeng Hu, Wenting Jia, Junji Cao, Suixin Liu, Rujin Huang, Tao Ma and Na Xi

Atmosphere 2015, 6(4), 474-489; https://doi.org/10.3390/atmos6040474 - 03 Apr 2015

Cited by 3 | Viewed by 5490

Abstract

Long-term measurement results of indoor air quality (IAQ) from 1989 to 2013 inside Pit No. 1, the largest display hall in Emperor Qin’s Terra-cotta Museum (QTM), were used to evaluate the effectiveness of measures for conservation environment improvement of antiques. By comparing the [...] Read more.

Long-term measurement results of indoor air quality (IAQ) from 1989 to 2013 inside Pit No. 1, the largest display hall in Emperor Qin’s Terra-cotta Museum (QTM), were used to evaluate the effectiveness of measures for conservation environment improvement of antiques. By comparing the results of sampling campaigns in 2013 with databases in 1989, 2004–2005, 2006–2007 and 2011, seasonal and inter-annual variation in microclimate, aerosol chemical compositions and gaseous pollutant concentrations were incorporated in estimating the probable influences of the management of the surroundings, tourist flow, excavation and restoration tasks and renovation and/or new construction work on IAQ in the QTM. After the implementation of the environmental policies in 1990s, a significant decrease of indoor particulate matter mass for the QTM was quantified. The mass concentrations of summer TSP decreased from 540.0 μg∙m⁻³ in 1994 to 172.4 μg∙m⁻³ in 2004, as well as the winter TSP decreased from 380.0 μg∙m⁻³ in 1994 to 312.5 μg∙m⁻³ in 2005. The mass concentrations of summer PM_2.5 decreased from 108.4 μg∙m⁻³ in 2004 to 65.7 μg∙m⁻³ in 2013, as well as the winter PM_2.5 decreased from 242.3 μg∙m⁻³ in 2005 to 98.6 μg∙m⁻³ in 2013. However, it is noted that potential hazards due to the fluctuant microclimate conditions, gaseous and secondary particulate acidic species in indoor air should still be considered to ensure the long-term preservation and conservation of the museum’s artifact collection. Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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946 KiB

Open AccessArticle

Characteristics of Organic and Elemental Carbon in PM_2.5 and PM_0.25 in Indoor and Outdoor Environments of a Middle School: Secondary Formation of Organic Carbon and Sources Identification

by Hongmei Xu, Benjamin Guinot, Zhenxing Shen, Kin Fai Ho, Xinyi Niu, Shun Xiao, Ru-Jin Huang and Junji Cao

Atmosphere 2015, 6(3), 361-379; https://doi.org/10.3390/atmos6030361 - 17 Mar 2015

Cited by 24 | Viewed by 7703

Abstract

Secondary organic carbon (SOC) formation and its effects on human health require better understanding in Chinese megacities characterized by a severe particulate pollution and robust economic reform. This study investigated organic carbon (OC) and elemental carbon (EC) in PM_2.5 and PM_0.25 [...] Read more.

Secondary organic carbon (SOC) formation and its effects on human health require better understanding in Chinese megacities characterized by a severe particulate pollution and robust economic reform. This study investigated organic carbon (OC) and elemental carbon (EC) in PM_2.5 and PM_0.25 collected 8–20 March 2012. Samples were collected inside and outside a classroom in a middle school at Xi’an. On average, OC and EC accounted for 20%–30% of the particulate matter (PM) mass concentration. By applying the EC-tracer method, SOC’s contribution to OC in both PM size fractions was demonstrated. The observed changes in SOC:OC ratios can be attributed to variations in the primary production processes, the photochemical reactions, the intensity of free radicals, and the meteorological conditions. Total carbon (TC) source apportionment by formula derivation showed that coal combustion, motor vehicle exhaust, and secondary formation were the major sources of carbonaceous aerosol. Coal combustion appeared to be the largest contributor to TC (50%), followed by motor vehicle exhaust (25%) and SOC (18%) in both size fractions. Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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2127 KiB

Open AccessArticle

Characteristics of Black Carbon Aerosol during the Chinese Lunar Year and Weekdays in Xi’an, China

by Qiyuan Wang, Suixin Liu, Yaqing Zhou, Junji Cao, Yongming Han, Haiyan Ni, Ningning Zhang and Rujin Huang

Atmosphere 2015, 6(2), 195-208; https://doi.org/10.3390/atmos6020195 - 05 Feb 2015

Cited by 12 | Viewed by 6892

Abstract

Black carbon (BC) aerosol plays an important role in climate forcing. The net radiative effect is strongly dependent on the physical properties of BC particles. A single particle soot photometer and a carbon monoxide analyser were deployed during the Chinese Lunar Year (CLY) [...] Read more.

Black carbon (BC) aerosol plays an important role in climate forcing. The net radiative effect is strongly dependent on the physical properties of BC particles. A single particle soot photometer and a carbon monoxide analyser were deployed during the Chinese Lunar Year (CLY) and on weekdays at Xi’an, China, to investigate the characteristics of refractory black carbon aerosol (rBC). The rBC mass on weekdays (8.4 μg·m⁻³) exceeds that during the CLY (1.9 μg·m⁻³), presumably due to the lower anthropogenic emissions during the latter. The mass size distribution of rBC shows a primary mode peak at ~205 nm and a small secondary mode peak at ~102-nm volume-equivalent diameter assuming 2 g·cm⁻³ in void-free density in both sets of samples. More than half of the rBC cores are thickly coated during the CLY (f_BC = 57.5%); the percentage is slightly lower (f_BC = 48.3%) on weekdays. Diurnal patterns in rBC mass and mixing state differ for the two sampling periods, which are attributed to the distinct anthropogenic activities. The rBC mass and CO mixing ratios are strongly correlated with slopes of 0.0070 and 0.0016 μg·m⁻³·ppbv⁻¹ for weekdays and the CLY, respectively. Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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826 KiB

Open AccessArticle

PM_2.5 Chemical Compositions and Aerosol Optical Properties in Beijing during the Late Fall

by Huanbo Wang, Xinghua Li, Guangming Shi, Junji Cao, Chengcai Li, Fumo Yang, Yongliang Ma and Kebin He

Atmosphere 2015, 6(2), 164-182; https://doi.org/10.3390/atmos6020164 - 26 Jan 2015

Cited by 18 | Viewed by 6636

Abstract

Daily PM_2.5 mass concentrations and chemical compositions together with the aerosol optical properties were measured from 8–28 November 2011 in Beijing. PM_2.5 mass concentration varied from 15.6–237.5 μg∙m⁻³ and showed a mean value of 111.2 ± 73.4 μg∙m⁻³. [...] Read more.

Daily PM_2.5 mass concentrations and chemical compositions together with the aerosol optical properties were measured from 8–28 November 2011 in Beijing. PM_2.5 mass concentration varied from 15.6–237.5 μg∙m⁻³ and showed a mean value of 111.2 ± 73.4 μg∙m⁻³. Organic matter, NH₄NO₃ and (NH₄)₂SO₄ were the major constituents of PM_2.5, accounting for 39.4%, 15.4%, and 14.9% of the total mass, respectively, while fine soil, chloride salt, and elemental carbon together accounted for 27.7%. Daily scattering and absorption coefficients (σ_sc and σ_ap) were in the range of 31.1–667 Mm⁻¹ and 8.24–158.0 Mm⁻¹, with mean values of 270 ± 200 Mm⁻¹ and 74.3 ± 43.4 Mm⁻¹. Significant increases in σ_sc and σ_ap were observed during the pollution accumulation episodes. The revised IMPROVE algorithm was applied to estimate the extinction coefficient (b_ext). On average, organic matter was the largest contributor, accounting for 44.6% of b_ext, while (NH₄)₂SO₄, NH₄NO₃, elemental carbon, and fine soil accounted for 16.3% 18.0%, 18.6%, and 2.34% of b_ext, respectively. Nevertheless, the contributions of (NH₄)₂SO₄ and NH₄NO₃ were significantly higher during the heavy pollution periods than those on clean days. Typical pollution episodes were also explored, and it has been characterized that secondary formation of inorganic compounds is more important than carbonaceous pollution for visibility impairment in Beijing. Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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773 KiB

Open AccessArticle

Variations in PM₁₀, PM_2.5 and PM_1.0 in an Urban Area of the Sichuan Basin and Their Relation to Meteorological Factors

by Yang Li, Quanliang Chen, Hujia Zhao, Lin Wang and Ran Tao

Atmosphere 2015, 6(1), 150-163; https://doi.org/10.3390/atmos6010150 - 09 Jan 2015

Cited by 218 | Viewed by 14798

Abstract

Daily average monitoring data for PM₁₀, PM_2.5 and PM_1.0 and meteorological parameters at Chengdu from 2009 to 2011 are analyzed using statistical methods to replicate the effect of urban air pollution in Chengdu metropolitan region of the Sichuan Basin. [...] Read more.

Daily average monitoring data for PM₁₀, PM_2.5 and PM_1.0 and meteorological parameters at Chengdu from 2009 to 2011 are analyzed using statistical methods to replicate the effect of urban air pollution in Chengdu metropolitan region of the Sichuan Basin. The temporal distribution of, and correlation between, PM₁₀, PM_2.5 and PM_1.0 particles are analyzed. Additionally, the relationships between particulate matter (PM) and certain meteorological parameters are studied. The results show that variations in the average mass concentrations of PM₁₀, PM_2.5 and PM_1.0 generally have the same V-shaped distributions (except for April), with peak/trough values for PM average mass concentrations appearing in January/September, respectively. From 2009 to 2011, the inter-annual average mass concentrations of PM₁₀, PM_2.5 and PM_1.0 fall year on year. The correlation coefficients of daily concentrations of PM₁₀ with PM_2.5, PM₁₀ with PM_1.0, and PM_2.5 with PM_1.0 were high, reaching 0.91, 0.83 and 0.98, respectively. In addition, the average ratios of PM_2.5/PM₁₀, PM_1.0/PM₁₀ and PM_1.0/PM_2.5 were 85%, 78% and 92%, respectively. From this, fine PM is determined to be the principal pollutant in the Chengdu region. Except for averaged air pressure values, negative correlations exist between other meteorological parameters and PM. Temperature and air pressure influenced the transport and accumulation of PM by affecting convection. Winds promoted PM dispersion. Precipitation not only accelerated the deposition of wet PM, but also inhibited surface dust transport. There was an obvious correlation between PM and visibility; the most important cause of visibility degradation was due to the light extinction of aerosol particles. Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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