Average Mass Concentrations Of PM2 Research Articles

Chemical fractionation of heavy metals in fine particulate matter and their health risk assessment through inhalation exposure pathway.

Samples of PM2.5 were collected from an urban area close to a national highway in Agra, India and sequentially extracted into four different fractions: water soluble (F1), reducible (F2), oxidizable (F3) and residual fraction (F4) for chemical fractionation of arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni) and lead (Pb). The metals were analyzed by inductively coupled plasma optical emission spectroscopy in each fraction. The average mass concentration of PM2.5 was 93 ± 24μgm-3.The total concentrations of Cr, Pb, Ni, Co, As and Cd in fine particle were 192 ± 54, 128 ± 25, 108 ± 34, 36 ± 6, 35 ± 5 and 8 ± 2ngm-3, respectively. Results indicated that Cd and Co had the most bioavailability indexes. Risk Assessment Code and contamination factors were calculated to assess the environmental risk. The present study evaluated the potential Pb hazard to young children using the Integrated Exposure Uptake Biokinetic Model. From the model, the probability density of PbB (blood lead level) revealed that at the prevailing atmospheric concentration, 0.302 children are expected to have PbB concentrations exceeding 10μg dL-1 and an estimated IQ (intelligence quotient) loss of 1.8 points. The predicted blood Pb levels belong to Group 3 (PbB < 5μg dL-1). Based on the bioavailable fractions, carcinogenic and non-carcinogenic risks via inhalation exposure were assessed for infants, toddlers, children, males and females. The hazard index for potential toxic metals was 2.50, which was higher than the safe limit (1). However, the combined carcinogenic risk for infants, toddlers, children, males and females was marginally higher than the precautionary criterion (10-6).

Responses of healthy young males to fine-particle exposure are modified by exercise habits: a panel study

BackgroundAerobic exercise benefits health but increases inhalation of fine particles (PM2.5) in ambient air. Acute cardiopulmonary responses to PM2.5 exposure in individuals with different exercise habits, especially in areas with severe air pollution, are not well understood.MethodsTo examine acute cardiopulmonary responses to PM2.5 exposure modified by exercise habits, a panel of 20 healthy non-smoking male subjects, recruited in Beijing, China, completed seven visits. The exercise frequency per week and preferred exercise place were recorded using a baseline questionnaire to describe exercise habits. Fractional exhaled nitric oxide (FeNO), cytokines in exhaled breath condensate, blood pressure, and pulse-wave analysis (PWA) indices were measured during each visit as biomarkers of acute cardiopulmonary responses. The hourly average mass concentration of PM2.5 and black carbon (BC), and the number concentrations of ultrafine particles (UFP) and accumulation mode particles (AMP) were monitored throughout the follow-up period at an outdoor fixed monitoring station beginning 14 days prior to each visit. Linear mixed-effects models were used to evaluate the associations between acute changes in biomarker levels and exposure to PM2.5 and its constituents. The primary aim was to assess the modification of long-term exercise habits on these associations.ResultsFeNO concentration, systolic blood pressure, ejection duration, aortic augmentation pressure, and aortic pressure index were positively associated with exposure to PM2.5 and its constituents. However, no associations with cytokine levels or diastolic blood pressure were observed. In a stratified analysis, we found that acute cardiopulmonary responses were modified by exercise habit. Specifically, the interquartile ranges (IQR) of increases in the 6–12-h moving average (MA) PM2.5 and AMP exposure were associated with 19–21% and 24–26% increases in FeNO, respectively, in subjects with high exercise frequency; these associations were significantly stronger than those in subjects with low exercise frequency. An IQR increase in 3–11-d MA AMP exposure was associated with a 10–26% increase in aortic augmentation pressure in subjects with low exercise frequency; this association was significantly stronger than that in subjects with high exercise frequency. An IQR increase in 9–13-d MA UFP exposure was associated with a 13–17% increase in aortic augmentation pressure in subjects who preferred outdoor exercise; this association was stronger than that in subjects who preferred indoor exercise.ConclusionsIn highly polluted areas, frequent exercise might protect against PM2.5-associated arterial stiffness but exacerbate airway inflammation.

Chemical Characteristics and Sources of Submicron Particles in a City with Heavy Pollution in China

Submicron particle (PM1) pollution has received increased attention in recent years; however, few studies have focused on such pollution in the city of Shijiazhuang (SJZ), which is one of the most polluted cities in the world. In this study, we conducted an intensive simultaneous sampling of PM1 and PM2.5 in autumn 2016, in order to explore pollution characteristics and sources in SJZ. The results showed that the average mass concentrations of PM1 and PM2.5 were 70.51 μg/m3 and 91.68 μg/m3, respectively, and the average ratio of PM1/PM2.5 was 0.75. Secondary inorganic aerosol (SIA) was the dominant component in PM1 (35.9%) and PM2.5 (32.3%). An analysis of haze episodes found that SIA had a significant influence on PM1 pollution, NH4+ promoted the formation of pollution, and SO42− and NO3− presented different chemical mechanisms. Additionally, the results of source apportionment implied that secondary source, biomass burning and coal combustion, traffic, industry, and dust were the major pollution sources for SJZ, accounting for 45.4%, 18.9%, 15.7%, 10.3%, and 9.8% of PM1, respectively, and for 42.4%, 18.8%, 12.2%, 10.2%, and 16.4% of PM2.5, respectively. Southern Hebei, mid-eastern Shanxi, and northern Henan were the major contribution regions during the study period. Three transport pathways of pollutants were put forward, including airflows from Shanxi with secondary source, airflows from the central Beijng–Tianjin–Hebei region with fossil fuel burning source, and airflows from the southern North China Plain with biomass burning source. The systematic analysis of PM1 could provide scientific support for the creation of an air pollution mitigation policy in SJZ and similar regions.

Deposition modeling of ambient aerosols in human respiratory system: Health implication of fine particles penetration into pulmonary region

In this study, we have monitored 1-h (afternoon) ambient concentrations of size-segregated particles by means of 12 channels aerosol spectrometer (PALAS; welas® 2000) over 130 days in one year (2015/2016) from a highly polluted and populated region (Kanpur) in central Indo-Gangetic Plain (IGP). Average mass concentrations of PM2.5 (fine) and PM10-2.5 (coarse) varied from ∼40–160 and 30–67 μg m−3, respectively. PM mass size distribution analysis revealed multi-modal peaks in monsoon (tri-modal: < 0.5; 1.4–1.8; 7.8 μm), post monsoon (tetra-modal: < 0.5; 1.4–1.8; 3.2; 7.8 μm), winter (tri-modal: < 0.5; 1.4–1.8; 5.8 μm) and summer (tetra-modal: < 0.5; 1.4–1.8; 3.2; 7.8 μm). The MMAD ± GSD were found to be 2.1 μm ± 3.0 (monsoon), 1.0 ± 3.0 μm (post monsoon), 1.1 μm ± 2.7 (winter) and 2.4 μm ± 2.9 (summer). A computational model (Multiple Path Particle Dosimetry: MPPD, v 2.11) analysis revealed total PM mass deposition in human respiratory airways (test subject: male adult) was 34.1 μg in monsoon, 64.5 μg in post monsoon, 40.6 μg in winter and 34.4 μg in summer. Coarse particles exhibited higher mass deposition fraction (84%) in HEAD (extrathoracic), whereas fine particles deposited significantly (33%) in PUL (pulmonary region). Intensification of biomass and biofuel burning emissions during post-monsoon and wintertime have implications to deeper penetration and higher mass deposition fraction of fine-particles in the PUL region. High PM concentration and its significant deposition in PUL region calls for immediate measures to be taken to improve regional air quality to reduce health hazards and disease burden for exposed population.

Characteristics of PM2.5 Chemical Compositions and Their Effect on Atmospheric Visibility in Urban Beijing, China during the Heating Season.

Beijing, which is the capital of China, suffers from severe Fine Particles (PM2.5) pollution during the heating season. In order to take measures to control the PM2.5 pollution and improve the atmospheric environmental quality, daily PM2.5 samples were collected at an urban site from 15 November to 31 December 2016, characteristics of PM2.5 chemical compositions and their effect on atmospheric visibility were analyzed. It was found that the daily average mass concentrations of PM2.5 ranged from 7.64 to 383.00 μg m−3, with an average concentration of 114.17 μg m−3. On average, the Organic Carbon (OC) and Elemental Carbon (EC) contributed 21.39% and 5.21% to PM2.5, respectively. Secondary inorganic ions (SNA: SO42− + NO3− + NH4+) dominated the Water-Soluble Inorganic Ions (WSIIs) and they accounted for 47.09% of PM2.5. The mass concentrations of NH4+, NO3− and SO42− during the highly polluted period were 8.08, 8.88 and 6.85 times greater, respectively, than during the clean period, which contributed most to the serious PM2.5 pollution through the secondary transformation of NO2, SO2 and NH3. During the highly polluted period, NH4NO3 contributed most to the reconstruction extinction coefficient (b′ext), accounting for 35.7%, followed by (NH4)2SO4 (34.44%) and Organic Matter (OM: 15.24%). The acidity of PM2.5 in Beijing was weakly acid. Acidity of PM2.5 and relatively high humidity could aggravate PM2.5 pollution and visibility impairment by promoting the generation of secondary aerosol. Local motor vehicles contributed the most to NO3−, OC, and visibility impairment in urban Beijing. Other sources of pollution in the area surrounding urban Beijing, including coal burning, agricultural sources, and industrial sources in the Hebei, Shandong, and Henan provinces, released large amounts of SO2, NH3, and NO2. These, which were transformed into SO42−, NH4+, and NO3− during the transmission process, respectively, and had a great impact on atmospheric visibility impairment.

Analysis of Compositional Variation and Source Characteristics of Water-Soluble Ions in PM2.5 during Several Winter-Haze Pollution Episodes in Shenyang, China

From 18 February to 13 March 2014 and from 17 December 2016 to 27 January 2017, an online analyzer for monitoring aerosols and gases (MARGA) and an online single particle aerosol mass spectrometer (SPAMS) were used to measure and analyze the concentrations and sources of water-soluble (WS) ions in PM10, PM2.5, and gases (NH3, HNO3, HCl), in Shenyang City, China. During the field campaign, nine haze episodes (or smog episodes, total 582 h) were identified, with 960 identified as non-haze periods. The average mass concentrations of PM2.5 and total water-soluble ions (TWSIs) in PM2.5 during haze episodes were 131 μg·m−3 and 77.2 μg·m−3, 2.3 times and 1.9 times the values in non-haze periods, respectively. The average mass concentration of TWSIs in PM2.5 was 55.9 μg·m−3 (accounting for 55.9% of PM2.5 mass loading), 37.6% of which was sulfate, 31.7% nitrate, 20.0% ammonium, 6.6% chloride, 1.9% potassium, 1.4% calcium, and 0.8% magnesium throughout the campaign. Concentrations of sulfate, nitrate, and ammonium (SNA) secondary pollution ions increased rapidly during haze episodes to as much as 2.2 times, 3.0 times, and 2.4 times higher than during non-haze periods, respectively. Diurnal variations during non-haze periods were significant, while complex pollution was insignificant. Based on changes in the backward trajectories and concentrations of WS ions, the hazy episodes were divided into three types: complex, coal-burning, and automobile exhaust pollution. All complex episodes had high concentrations and greater contributions of ammonium nitrate from complex and automobile exhaust pollution, while the contribution of ammonium sulfate from coal-burning pollution was greater than that of ammonium nitrate. The correlation coefficients among SNA species were very high in complex pollution, with nitrate and sulfate the main forms present. The results of principal component analysis (PCA) were related to emissions from burning coal for heating and from long-range transmission in winter. In the case of exhaust pollution, NO3− accounted for the highest percentage of PM2.5, and NH4+ was more closely related to NO3− than to SO42−. Coal-burning pollution was the most common type of pollution in Shenyang. The contribution of sulfate was higher than that of nitrate. Based on PCA, the contribution of coal-burning emissions varied from 36.7% to 53.6% due to industry, soil sources, and other factors.

Aerosol optical absorption coefficients at a rural site in Northwest China: The great contribution of dust particles

An intensive measurement campaign was conducted at a rural site in Northwest China to investigate aerosol optical absorption properties, using the ground-based mobile facility of the Semi-Arid Climate and Environment Observatory of Lanzhou University (SACOL). The average mass concentration of PM2.5 was 103 ± 4 μg m−3 during the 20-day campaign in April 2014. Black carbon (BC) only accounted for ∼0.4% of the PM2.5 on average, with the mean concentration of 443 ± 12 ng m−3 measured using a single particle soot photometer (SP2). The aerosol absorption coefficient (σap) was 5.69 ± 0.01 Mm−1 on average, recorded by a multi-angle absorption photometer (MAAP) at the wavelength of 637 nm. It showed a linear relationship with BC mass concentration during non-dust periods, especially at their diurnal peaks of 07:00–09:00 a.m. (local standard time), deriving a bulk mass absorption efficiency (MAE) for BC of 8.5 ± 1.1 m2 g−1. The σap increased sharply during the dust storm, while the BC remained at a lower concentration than other moments, implying that the dust particles had a considerable contribution to light absorption. On average, dust particles accounted for 26.7% of the aerosol absorption and increased to 71.6% during the dust storm. The MAE of dust was calculated to be 0.014 ± 0.00028 m2 g−1, which was comparable to that measured in the downwind regions in East Asia. Based on the Mie theory for spherical particles, the refractive index (m) of natural mineral dust particles was estimated to be 1.50–0.0007i in Northwest China.

Analysis of the Characteristics and Sources of Carbonaceous Aerosols in PM2.5 in the Beijing, Tianjin, and Langfang Region, China.

PM2.5 samples from Beijing, Tianjin, and Langfang were simultaneously collected from 20 November 2016 to 25 December 2016, and the organic carbon (OC) and elemental carbon (EC) content in the samples were measured and analyzed. The pollution characteristics and sources of OC and EC in atmospheric PM2.5 for three adjacent cities were discussed. The average mass concentrations of OC in PM2.5 in Beijing, Tianjin, and Langfang were 27.93 ± 23.35 μg/m3, 25.27 ± 12.43 μg/m3, and 52.75 ± 37.97 μg/m3, respectively, and the mean mass concentrations of EC were 6.61 ± 5.13 μg/m3, 6.14 ± 2.84 μg/m3, and 12.06 ± 6.81 μg/m3, respectively. The average mass concentration of total carbon (TC) accounted for 30.5%, 24.8%, and 49% of the average mass concentration of PM2.5 in the atmosphere. The total carbonaceous matter (TCA) in Beijing, Tianjin, and Langfang was 51.29, 46.57, and 96.45 μg/m3, respectively. The TCA was the main component of PM2.5 in the region. The correlation between OC and EC in the three cities showed R2 values of 0.882, 0.633, and 0.784 for Beijing, Tianjin, and Langfang, respectively, indicating that the sources of urban carbonaceous aerosols had good consistency and stability. The OC/EC values of the three sampling points were 4.48 ± 1.45, 4.42 ± 1.77, and 4.22 ± 1.29, respectively, considerably greater than 2, indicating that the main sources of pollution were automobile exhaust, and the combustion of coal and biomass. The OC/EC minimum ratio method was used to estimate the secondary organic carbon (SOC) content in Beijing, Tianjin and Langfang. Their values were 10.73, 10.71, and 19.51, respectively, which accounted for 38%, 42%, and 37% of the average OC concentration in each city, respectively. The analysis of the eight carbon components showed that the main sources of pollutants in Beijing, Tianjin, and Langfang were exhaust emissions from gasoline vehicles, but the combustion of coal and biomass was relatively low. The pollution of road dust was more serious in Tianjin than in Beijing and Langfang. The contribution of biomass burning and coal-burning pollution sources to atmospheric carbon aerosols in Langfang was more prominent than that of Beijing and Tianjin.

Characteristics of Key Size Spectrum of PM2.5 Affecting Winter Haze Pollution in Taiyuan

PM2.5 is generally considered as a main pollutant causing the formation of haze. Based on meteorological parameters, aerosol distribution, and PM monitoring data in Taiyuan during November and December 2016, the characteristics of the key size spectrum of PM2.5 affecting haze were discussed. During the observation period, haze was frequent and serious. Heavy haze time accounts for 25.35% of the total haze time. Haze events occurred frequently when the relative humidity was greater than 80% and wind speed was less than 1.5 m·s-1, especially for severe haze. Mild and moderate level haze occurred frequently when the relative humidity was less than 80% and greater than 40% and when wind speed was less than 1.5 m·s-1. Slight haze mainly occurred when the relative humidity was 20%-40% and the wind speed was 1.25-2.55 m·s-1. The average mass concentration of PM2.5 was 209.45 μg·m-3, which was three times the level during non-haze events. With an increase in the haze level, the mass concentration of PM2.5 and the ratio of PM2.5/PM10 increased. PM1 was the key particle size affecting haze in the low humidity environment. PM0.5 was the key particle size that affects slight haze, mild haze, and moderate haze in the high humidity environment, while PM1 was the key particle size that affects heavy haze. The contribution of surface concentration to visibility decreased with high humidity, but the particle size increased by moisture absorption leading to an increase in the extinction efficiency factor, which compensated for the lack of surface concentration. The increase in the particle size parameter was an important factor for PM2.5 affecting the haze pollution with high humidity.

Characterization and Variation of Organic Carbon (OC) and Elemental Carbon (EC) in PM2.5 During the Winter in the Yangtze River Delta Region, China

Two hundred seventy-nine PM2.5 samples were collected from January 9, 2015 to January 31, 2015 in Lin'an, Nanjing, and Suzhou. They were analyzed for organic carbon (OC) and elemental carbon (EC) following the thermal/optical reflection protocol. The pollution characteristics of OC and EC in PM2.5 during the winter in the Yangtze River Delta were discussed in detail.The average mass concentrations of PM2.5 in the three sample sites were (123.56±61.11), (144.77±62.91), and (156.5±68.97) μg·m-3, respectively, which were in excess of the Ambient Air Quality Standard (GB 3095-2012) 24-hr mass-based standard of 75 μg·m-3. The average mass concentration of OC and EC were (21.93±11.69)/(6±3.6), (20.32±10.3)/(5.39±3.07), and (27.08±14.35)/(6.4±4.29) μg·m-3, respectively. Lin'an, which is regarded as the background site for the atmospheric environment in the Yangtze River Delta, is also polluted seriously. The OC was strongly correlated with EC in Lin'an (R2=0.83), Nanjing (R2=0.72), and Suzhou (R2=0.72). This shows that the carbonaceous aerosols have similar sources during the winter in the Yangtze River Delta. All of the samples' OC/EC ratios exceeded 2.0, with the sample OC/EC ratios mainly distributed in the range of 2.5-6.0, indicating that coal combustion and vehicle exhaust are the main sources of OC and EC. The estimated mass concentrations of SOC were (9.23±5.26), (6.82±4.36), and (12.56±7.52) μg·m-3, respectively, which contributed 42%, 34%, and 46% to the OC, indicating that SOC is an important part of OC. Backward-trajectory shows that the mass concentrations of PM2.5, OC, and EC have a good correlation with the transmission path of the main air mass. The mass concentrations of PM2.5, OC, and EC controlled by the air mass from poor air quality areas are 1.14-1.7 times, 1.55-2.1 times, and 1.94-2.47 times higher than that in the air mass from good air quality areas.

Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

Abstract. Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components, and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a thermodenuder aerosol mass spectrometer (TD-AMS) system was deployed to study the volatility of non-refractory submicron particulate matter (PM1) species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7±20.1 µg m−3, with organic aerosol (OA) being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with a mass fraction remaining (MFR) of 0.57 at 50 ∘C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 ∘C), and the volatility had a relatively linear correlation with the TD temperature (from the ambient temperature to 200 ∘C), with an evaporation rate of 0.45 %∘C-1. Five subtypes of OA were resolved from total OA using positive matrix factorization (PMF) for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass-burning OA (BBOA, 8.9 %), and two oxygenated OAs (OOAs): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA factors presented different volatilities, and the volatility sequence of the OA factors at 50 ∘C was HOA (MFR of 0.56) &gt; LO-OOA (0.70) &gt; COA (0.85) ≈ BBOA (0.87) &gt; MO-OOA (0.99), which was not completely consistent with the sequence of their O ∕ C ratios. The high volatility of HOA implied that it had a high potential to be oxidized to secondary species in the gas phase. The aerosol volatility measurement results in this study provide useful parameters for the modeling work of aerosol evolution in China and are also helpful in understanding the formation mechanisms of secondary aerosols.

Temporal variations of fine and coarse particulate matter sources in Jeddah, Saudi Arabia

ABSTRACTThis study provides the first comprehensive analysis of the seasonal variations and weekday/weekend differences in fine (aerodynamic diameter <2.5 μm; PM2.5) and coarse (aerodynamic diameter 2.5–10 μm; PM2.5–10) particulate matter mass concentrations, elemental constituents, and potential source origins in Jeddah, Saudi Arabia. Air quality samples were collected over 1 yr, from June 2011 to May 2012 at a frequency of three times per week, and analyzed. The average mass concentrations of PM2.5 (21.9 μg/m3) and PM10 (107.8 μg/m3) during the sampling period exceeded the recommended annual average levels by the World Health Organization (WHO) for PM2.5 (10 μg/m3) and PM10 (20 μg/m3), respectively. Similar to other Middle Eastern locales, PM2.5–10 is the prevailing mass component of atmospheric particulate matter at Jeddah, accounting for approximately 80% of the PM10 mass. Considerations of enrichment factors, absolute principal component analysis (APCA), concentration roses, and backward trajectories identified the following source categories for both PM2.5 and PM2.5–10: (1) soil/road dust, (2) incineration, and (3) traffic; and for PM2.5 only, (4) residual oil burning. Soil/road dust accounted for a major portion of both the PM2.5 (27%) and PM2.5–10 (77%) mass, and the largest source contributor for PM2.5 was from residual oil burning (63%). Temporal variations of PM2.5–10 and PM2.5 were observed, with the elevated concentration levels observed for mass during the spring (due to increased dust storm frequency) and on weekdays (due to increased traffic). The predominant role of windblown soil and road dust in both the PM2.5 and PM2.5–10 masses in this city may have implications regarding the toxicity of these particles versus those in the Western world where most PM health assessments have been made in the past. These results support the need for region-specific epidemiological investigations to be conducted and considered in future PM standard setting.Implications: Temporal variations of fine and coarse PM mass, elemental constituents, and sources were examined in Jeddah, Saudi Arabia, for the first time. The main source of PM2.5–10 is natural windblown soil and road dust, whereas the predominant source of PM2.5 is residual oil burning, generated from the port and oil refinery located west of the air sampler, suggesting that targeted emission controls could significantly improve the air quality in the city. The compositional differences point to a need for health effect studies to be conducted in this region, so as to directly assess the applicability of the existing guidelines to the Middle East air pollution.

Aerosol Chemical Characteristics for Different Air Pollution Levels in North Suburban Nanjing

PM2.5samples were collected in a northern suburb of Nanjing during the winter of 2015. Water soluble ions and carbonaceous substances under different air quality levels were analyzed by an 850 professional IC-type ion chromatograph produced by Metrohm and a Model 2001A carbon analyzer. The results show that the average mass concentration of PM2.5, SO42-, NO3-, and NH4+ during heavy pollution days was 4.0, 6.4, 3.1, and 3.9 times higher than on clear days, respectively. Three main secondary ions were all in the form of (NH4)2SO4 and NH4NO3 on all days. Two kinds of acid pollution days were mainly affected by the flow source. The proportion of fixed sources on the heavy pollution days was greater than on the light/moderate pollution days. The highest mass concentrations of organic carbon (OC) and elemental carbon (EC) were 49.8 μg·m-3 and 10.3 μg·m-3, respectively. The average concentration of SOC on clear days was the lowest (4.28 μg·m-3). The proportion of secondary organic carbon (SOC) in the OC on clear days was more than on the other two pollution days (41.14%). Coal combustion and motor vehicle exhaust emissions were the main contributors to carbonaceous substances by abundances of carbonaceous components.

Characteristics and Source Identification of Carbonaceous Aerosols in PM2.5 Measurements During Summer and Fall in Changzhou

To better understand the characterization and sources of carbonaceous components, a total of 60 fine particle (PM2.5) samples were collected in Changzhou during summer (July to August) and fall (October to November) of 2016. The average mass concentrations of PM2.5, organic carbon (OC), and elemental carbon (EC) during this study period were observed to be 73.0, 14.3 and 3.3 μg·m-3 in summer and 84.2, 13.2, and 3.5 μg·m-3 in fall, respectively. The average mass fraction of carbonaceous aerosols (OC+EC) in the PM2.5 measurement was estimated to be 24.3% in summer and 20.7% in fall. Eight carbonaceous fractions, resolved by following the IMPROVE-A thermal/optical reflectance protocol, showed strong correlation (r>0.92) between OC2, OC3, OC4 and EC1 and close correlations between EC2 and EC3 (r>0.65), indicating probable similar contributors. OC and EC were moderately correlated, suggesting complex contributions to carbonaceous aerosol. The water soluble organic carbon (WSOC) to OC ratio (WSOC/OC) in the fall (60.9%) was slightly higher than that in the summer (57.4%), while secondary organic carbon (SOC) to OC ratio (SOC/OC) was lower in the fall (49.0%) compared with the summer (52.5%). The SOC/OC ratio was lower than the WSOC/OC for both seasons, suggesting that part of WSOC component originates from primary emissions. The significant correlation of WSOC and SOC confirms that most SOC is water soluble. Relationships between each carbonaceous species and the principal component analysis indicate that vehicle emissions and coal combustion are the two main emission sources of carbonaceous aerosols from the observation period. Back trajectory analysis was used to indicate that carbonaceous components at sampling site are mainly affected by local emission sources and short distance transport, whereas the contribution of long-distance transmission is small.

Characteristics and Sources of Water Soluble Inorganic Ions in Fine Particulate Matter During Winter in Xuzhou

A total of 32 daily PM2.5 samples were collected from December 2016 to February 2017 in the urban area of Xuzhou city. Water-soluble inorganic ions (WSⅡs), including F-, Cl-, NO3-, SO42-, Na+, Mg2+, NH4+, K+ and Ca2+, were determined by ion chromatography. The average mass concentration of PM2.5 was (164.8±77.3) μg·m-3 and the average total mass concentration of the nine ions was (67.5±36.1) μg·m-3, the contribution of the WSⅡs to the PM2.5 was more than 40.9%. The order of the concentrations of individual ions was NO3- > SO42- > NH4+ > Cl- > Ca2+ > K+ > Na+ > Mg2+ > F-. NH4+, NO3-, and SO42- (SNA) were the major components of the water-soluble ions in the PM2.5 measurement. The average mass concentration of WSⅡs in clean air, mild haze, and severe haze was (12.8±8.8), (59.0±22.8) and (86.3±36.0) μg·m-3, respectively. The contribution of SNA to WSⅡs was 86.4%, 82.8%, and 78.9%, respectively. The correlation between each component of SNA with each other was significant. NH4+, NO3-, and SO42- were in the form of (NH4)2SO4 and NH4NO3. Secondary formation, biomass burning, fossil fuel combustion, and dust were the major sources of the water-soluble ions in PM2.5.

Characterization of metal(loid)s in indoor and outdoor PM2.5 of an office in winter period

ABSTRACTThe characterization of indoor (a naturally ventilated office) and outdoor (adjacent courtyard) metals in PM2.5 during a winter period in Xi'an, China were carried out. The results indicated that the average mass concentrations of PM2.5 in indoor and outdoor environments all exceeded the daily average limit of 75 µg m–3 set by the Chinese government. The dominant metals in PM2.5 were Ca, Al, Zn, Mg, Fe, and Pb in both indoor and outdoor air. Concentration of As was much higher than the standard of 6 ng m–3 issued by the government. Enrichment factor analysis showed that anthropogenic emissions might be the primary sources of As, Cd, Pb, and Zn, while crust was the main origin of Co. A majority of indoor-to-outdoor concentration ratios of metal were lower than 1 indicating mostly the contribution of outdoor sources rather than indoor ones. As and Cr in both indoor and outdoor air posed the highest noncarcinogenic and carcinogenic risks, respectively. The noncarcinogenic and carcinogenic risks were 2.74 and 2.54 × 10−4 indoor and 4.04 and 3.87 × 10−4 outdoor, which suggested that possible adverse health effects should be of concern.

Chemical partitioning of fine particle-bound As, Cd, Cr, Ni, Co, Pb and assessment of associated cancer risk due to inhalation, ingestion and dermal exposure

The bioavailability and human health risks of As, Pb, Ni, Co, Cr and Cd in fine particulate matter (PM2.5) at an urban site on a National highway in Agra, India were investigated. Inductively coupled plasma-optical emission spectrometer was used for metal analysis in sequentially extracted samples to ascertain the highly mobile, reducible, bioavailable and immobile fractions of the metals. Cancer risk resulting from inhalation, dermal and ingestion exposure to each metal in these fractions was calculated according to US EPA models. The average mass concentration of PM2.5 was 87.16 ± 62.51 μg/m3. Cr, Ni and Pb were the most abundant metals. The results showed that Pb and Cr were higher in the mobile fraction. Cd and Co had high bioavailability. Ingestion is the major exposure pathway for all heavy metals except Cr to infants, children and adults followed by inhalation and dermal contact. The cumulative risk for Cr(VI) due to dermal and inhalation routes exceed the maximum acceptable limit for children of age 1–7 years, 8–15 years and adults when total concentration is considered, but the estimated risks are within the acceptable limit when the bioavailable, water soluble and mobile fraction are taken into account. Hence the study shows that children and adults living in the vicinity of this site are more susceptible, hence more attention should be paid to protect them from pollution hazards. The study indicates the importance of metal speciation in assessing associated human health risks.

Seasonal variations in high time-resolved chemical compositions, sources, and evolution of atmospheric submicron aerosols in the megacity Beijing

Abstract. A severe regional haze problem in the megacity Beijing and surrounding areas, caused by fast formation and growth of fine particles, has attracted much attention in recent years. In order to investigate the secondary formation and aging process of urban aerosols, four intensive campaigns were conducted in four seasons between March 2012 and March 2013 at an urban site in Beijing (116.31° E, 37.99° N). An Aerodyne high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS) was deployed to measure non-refractory chemical components of submicron particulate matter (NR-PM1). The average mass concentrations of PM1 (NR-PM1+black carbon) were 45.1 ± 45.8, 37.5 ± 31.0, 41.3 ± 42.7, and 81.7 ± 72.4 µg m−3 in spring, summer, autumn, and winter, respectively. Organic aerosol (OA) was the most abundant component in PM1, accounting for 31, 33, 44, and 36 % seasonally, and secondary inorganic aerosol (SNA, sum of sulfate, nitrate, and ammonium) accounted for 59, 57, 43, and 55 % of PM1 correspondingly. Based on the application of positive matrix factorization (PMF), the sources of OA were obtained, including the primary ones of hydrocarbon-like (HOA), cooking (COA), biomass burning OA (BBOA) and coal combustion OA (CCOA), and secondary component oxygenated OA (OOA). OOA, which can be split into more-oxidized (MO-OOA) and less-oxidized OOA (LO-OOA), accounted for 49, 69, 47, and 50 % in four seasons, respectively. Totally, the fraction of secondary components (OOA+SNA) contributed about 60–80 % to PM1, suggesting that secondary formation played an important role in the PM pollution in Beijing, and primary sources were also non-negligible. The evolution process of OA in different seasons was investigated with multiple metrics and tools. The average carbon oxidation states and other metrics show that the oxidation state of OA was the highest in summer, probably due to both strong photochemical and aqueous-phase oxidations. It was indicated by the good correlations (r = 0.53–0.75, p &lt; 0.01) between LO-OOA and odd oxygen (Ox = O3 + NO2), and between MO-OOA and liquid water content in aerosols. BBOA was resolved in spring and autumn, influenced by agricultural biomass burning (e.g., field preparation burnings, straw burning after the harvest). CCOA was only identified in winter due to domestic heating. These results signified that the comprehensive management for biomass burning and coal combustion emissions is needed. High concentrations of chemical components in PM1 in Beijing, especially in winter or in adverse meteorological conditions, suggest that further strengthening the regional emission control of primary particulate and precursors of secondary species is expected.

Concentrations of metallic elements in long-range-transported aerosols measured simultaneously at three coastal sites in China and Japan

To determine the effects of long-range transport of aerosols from an upwind area in East Asia to a downwind area in Japan, we chemically analyzed aerosols collected simultaneously on Tuoji Island (Shandong Province, China), Fukue Island (Nagasaki Prefecture, Japan), and Cape Hedo (Okinawa Prefecture, Japan). We focused on changes in the metallic composition of PM2.5 aerosols during long-range transport. The average mass concentrations of PM2.5 at the three sites decreased in the order Tuoji Island > Fukue Island ≈ Cape Hedo (48.3 ± 4.5, 13.9 ± 1.5, and 13.2 ± 0.9 μg/m3, respectively). The fraction of coarse particles in total suspended particles estimated by (1–PM2.5/TSP) was highest on Cape Hedo, indicating that the contribution of sea salts was increased by long-range transport of the aerosols over the ocean. Enrichment factor analysis revealed that at all three sites, Al, K, Ca, Mn, Fe, Co, Sr, and Ba originated from soil; whereas Cr, Ni, Cu, Zn, As, Mo, Ag, Cd, Sn, Sb, Tl, and P appeared to be of anthropogenic origin. Na was the most abundant element on Cape Hedo, indicating the addition of sea salts during aerosol transport. The V concentration was highest at Fukue Island, which was ascribed to V emission from ships. Sixty-one percent of the V on Fukue Island and 62% of the V on Cape Hedo were determined to have originated from ships, implicating of data obtained on dates during which backward trajectory analysis indicated that the same air mass passed over Tuoji Island, Fukue Island, and Cape Hedo in that order.

Chemical composition of fine mode particulate matter (PM2.5) in an urban area of Delhi, India and its source apportionment

In this paper, the chemical constitutes of PM2.5 mass [organic carbon (OC), elemental carbon (EC), water soluble inorganic ionic components (WSIC), and trace elements] was estimated for its chemical characteristics and source apportionment study at Delhi, India during January 2013 to May 2014. In the present case, the average mass concentration of PM2.5 was recorded as 125.5±77.2μg m−3 (range: 31.1–429.5μg m−3). The average concentration of major and trace elements (Na, Mg, Al, P, S, Cl, K, Ca, Cr, Ti, AS, Br, Pb, Fe, Zn and Mn) was accounted for ~22% of PM2.5 mass. Strong seasonal variation was observed in PM2.5 mass concentration and its chemical composition with maxima during winter and minima during monsoon seasons. The chemical composition of the PM2.5 was reconstructed using IMPROVE equation from the analyzed elemental composition of PM2.5 mass. In reconstructed PM2.5 mass, the highest contribution accounted from particulate organic matter (27.5%) to other components e.g., soil/crustal matter (16.1%), ammonium sulphate (16.1%), ammonium nitrate (13.1%), sea salt (17.1%) and light absorbing carbon (10.2%). In the present study, Positive Matrix Factorization (PMF) was used for identifying the PM2.5 sources at the observational site of Delhi. The major source of PM2.5 was identified as secondary aerosols (23.2%), soil dust (22.5%), vehicle emissions (18.5%), fossil fuel burning (13.1%), biomass burning (12.3%), industrial emissions (6.3%) and sea salts (4.1%) at Delhi.