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The Comprehensive Air-quality Model with extensions (CAMx) was used to explore the sensitivity of PM 2.5 and O 3 concentrations to four selected meteorological factors: wind speed, temperature, water vapor mixing ratio (Q), and planetary boundary layer height (PBLH) during two pollution episodes over the North China Plain (NCP). We also investigated the impact pathways of different meteorological factors on the formation of PM 2.5 and O 3. It is found that PM 2.5 was more sensitive to the selected meteorological factors in the southeastern NCP, where high anthropogenic emissions and severe air pollution occur. Large variations were observed along the Taihang Mountains, where the height of the terrain changes dramatically. The sensitivity of O 3 to wind speed, PBLH, temperature, and Q was mainly determined by the inhibition effects of PM 2.5 in winter, while in summer, the complex chemical reactions were dominant. Significant diurnal variations of process analysis (PA) results were observed under various meteorological conditions. Higher temperature generally enhance heterogeneous chemistry and transport of NO 3 - through the top boundary layer during night-time in winter, however, in summer, the heterogeneous chemistry of NO 3 - and NH 4 + during daytime were the major pathways to the increased PM 2.5 due to increased temperature. Moreover, temperature alter PM 2.5 concentrations through affecting vertical diffusivity and relative humidity, and alter O 3 concentrations by affecting the gas phase chemistry and mass fluxes through the top boundary layer. Q mainly affects the rate of chemical reactions of PM 2.5 and O 3 . The different impact pathways suggest that it is essential to consider variations in meteorological factors, in addition to the direct impacts of wind speed and PBLH, more attention should be paid to the complex impacts of temperature and Q, when developing emission control strategies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Light-absorbing organic carbon (OC), also referred to as "brown carbon" (BrC), has been intensively investigated in atmospheres impacted by biomass burning. However, other BrC sources (e.g., secondary formation in the atmosphere) are rarely studied in ambient aerosols. In the current work, forty-five PM 2.5 filter samples were collected in Research Triangle Park (RTP), NC, USA from June 1st to July 15th, 2013. The bulk carbonaceous components, including OC, elemental carbon (EC), water soluble OC (WSOC), and an array of organic molecular markers were measured; an ultraviolet/visible spectrometer was used to measure the light absorption of methanol extractable OC and WSOC. The average light absorption per OC and WSOC mass of PM 2.5 samples in summer RTP are 0.36 ± 0.16 m 2 gC -1 and 0.29 ± 0.13 m 2 gC -1 , respectively, lower than the ambient aerosol samples impacted by biomass burning and/or fossil fuel combustion (0.7-1.6 m 2 gC -1 ) from other places. Less than 1% of the aqueous extracts absorption is attributed to the light-absorbing chromophores (nitroaromatic compounds) identified in this work. To identify the major sources of BrC absorption in RTP in the summer, Positive Matrix Factorization (PMF) was applied to a dataset containing optical properties and chemical compositions of carbonaceous components in PM 2.5 . The results suggest that the formation of biogenic secondary organic aerosol (SOA) containing organosulfates is an important BrC source, contributing up to half of the BrC absorption in RTP during the summertime., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Polar organic compounds and elements were quantified in PM(10) aerosols collected in urban and rural areas of Baoji, an inland city of China, during winter and spring 2008. Concentrations of biomass burning markers and high molecular weight n-alkanoic acids (HMW, >C(22:0)) were heavily increased in winter. In contrast, sugars presented in higher levels in the spring, among which sucrose was the most abundant with an average of 219ngm(-3) in winter and 473ngm(-3) in spring respectively. This suggests enhanced biotic activity in the warm season, whereas no obvious trend was observed for sugar alcohols, concentrations of the three sugar alcohols in spring were only 0.94-2.3 times as those in winter, indicating a second pathway of their formation other than fungal spores in cold season. Major crustal elements (i.e., Fe, K, Mn and Ti) in PM(10) aerosols were also observed in larger concentrations in spring samples than those in winter due to an enhancement of coarse particles from soil minerals. By using principal component analysis (PCA) and positive matrix factorization (PMF), sources and their contributions to the PM components were also investigated in this study. Four factors were extracted with both models, and the sources represented by different factors were based on the highest loaded marker species as follows: factor 1, soil and road dust (Fe, Sr and Ti); factor 2, biomass burning (levoglucosan, galactosan and syringic acid); factor 3, microbial emissions (fructose and sucrose); and factor 4, fossil fuel combustion and fungal spores influence (Pb, Zn, arabitol and mannitol). The high correlation between PM(10) and factor 1 suggested that PM(10) pollution in Baoji was dominated by soil and dust re-suspension., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Air pollution in the developed regions of eastern China has been intensively investigated in the past decade. However, there is a relative dearth of air pollution studies on the northwest of inland China (e.g., Xinjiang). In this work, hourly measurement data of six criteria air pollutants (PM2.5, PM10, CO, NO2, O3, and SO2) for the past five years (2018–2022) from Hami and Turpan cities of eastern Xinjiang were analyzed to reveal air pollution characteristics and the distribution of potential sources. Hami and Turpan had the highest AQI values in winter due to increased coal combustion for domestic heating and unfavorable meteorological conditions. The slight elevations of AQI values in spring were caused by frequent dust storms. PM10 was the most frequent main pollutant in both Hami (63.1%) and Turpan (74.1%), followed by PM2.5 and O3. Except for O3, PM2.5, PM10, SO2, NO2, and CO exhibited a generally decreasing pattern in annual average values. But the annual average concentrations of PM10 in Hami (83.5 μg·m−3) and Turpan (139 μg·m−3) in 2022 were still higher than those in eastern China. Diurnal and monthly variations of the six criteria pollutants were influenced by a combination of emission sources and meteorological conditions. The air masses in eastern Xinjiang mainly originated from the west and north and were affected by both inter-regional and intra-regional transport. Analysis of the distribution of potential sources showed that local emissions strongly impacted particulate matter pollution in winter, while regional transport played a dominant role in other seasons. O3 showed a broad distribution of potential sources across all four seasons. Considering that the trend that O3 pollution increased year by year, eastern Xinjiang might face a similar pollution situation as eastern China, i.e., the combined pollution of particulate matter and O3. [ABSTRACT FROM AUTHOR]

Abstract: Polar organic compounds and elements were quantified in PM10 aerosols collected in urban and rural areas of Baoji, an inland city of China, during winter and spring 2008. Concentrations of biomass burning markers and high molecular weight n-alkanoic acids (HMW, >C22:0) were heavily increased in winter. In contrast, sugars presented in higher levels in the spring, among which sucrose was the most abundant with an average of 219ngm−3 in winter and 473ngm−3 in spring respectively. This suggests enhanced biotic activity in the warm season, whereas no obvious trend was observed for sugar alcohols, concentrations of the three sugar alcohols in spring were only 0.94–2.3 times as those in winter, indicating a second pathway of their formation other than fungal spores in cold season. Major crustal elements (i.e., Fe, K, Mn and Ti) in PM10 aerosols were also observed in larger concentrations in spring samples than those in winter due to an enhancement of coarse particles from soil minerals. By using principal component analysis (PCA) and positive matrix factorization (PMF), sources and their contributions to the PM components were also investigated in this study. Four factors were extracted with both models, and the sources represented by different factors were based on the highest loaded marker species as follows: factor 1, soil and road dust (Fe, Sr and Ti); factor 2, biomass burning (levoglucosan, galactosan and syringic acid); factor 3, microbial emissions (fructose and sucrose); and factor 4, fossil fuel combustion and fungal spores influence (Pb, Zn, arabitol and mannitol). The high correlation between PM10 and factor 1 suggested that PM10 pollution in Baoji was dominated by soil and dust re-suspension. [Copyright &y& Elsevier]

Abstract: Normal alkanes and PAHs in atmospheric PM10 aerosols collected during 2008 winter and spring in Baoji, a mid-scale inland city of China, were determined on a molecular level. Concentrations of n-alkanes ranged from 232 to 3583 ng/m3 with an average of 1733 ng/m3 in winter and from 124 to 1160 ng/m3 with an average of 449 ng/m3 in spring, while PAHs in the PM10 samples were 594±405 and 128±82 ng/m3 in the two seasons. Molecular compositions showed that CPI (odd/even) values of n-alkanes were close to unity for all the samples especially in winter, and diagnostic ratios of PAHs (e.g., Phe/(Phe+Ant), CPAH/ΣPAHs and IcdP/(IcdP+BghiP)) were found similar to those in coal burning smoke with a strong linear relationship (R 2 ≥0.85) between PAHs and fossil fuel derived n-alkanes, demonstrating that coal burning is the main source of n-alkanes and PAHs in the city, especially in winter due to house heating. Concentrations of the determined compounds in Baoji are much higher than those in Chinese mega-cities, suggesting that air pollution in small cities in the country is more serious and need more attention. [Copyright &y& Elsevier]

Abstract: Molecular compositions and size distributions of water-soluble organic compounds (WSOC, i.e., sugars, sugar-alcohols and carboxylic acids) in particles from urban air of Nanjing, China during a severe haze event caused by field burning of wheat straw were characterized and compared with those in the summer and autumn non-haze periods. During the haze event levoglucosan (4030 ng m−3) was the most abundant compound among the measured WSOC, followed by succinic acid, malic acid, glycerol, arabitol and glucose, being different from those in the non-haze samples, in which sucrose or azelaic acid showed a second highest concentration, although levoglucosan was the highest. The measured WSOC in the haze event were 2–20 times more than those in the non-hazy days. Size distribution results showed that there was no significant change in the compound peaks in coarse mode (>2.1 μm) with respect to the haze and non-haze samples, but a large difference in the fine fraction (<2.1 μm) was found with a sharp increase during the hazy days mostly due to the increased emissions of wheat straw burning. Molecular compositions of organic compounds in the fresh smoke particles from wheat straw burning demonstrate that sharply increased concentrations of glycerol and succinic and malic acids in the fine particles during the haze event were mainly derived from the field burning of wheat straw, although the sources of glucose and related sugar-alcohols whose concentrations significantly increased in the fine haze samples are unclear. Compared to that in the fresh smoke particles of wheat straw burning an increase in relative abundance of succinic acid to levoglucosan during the haze event suggests a significant production of secondary organic aerosols during transport of the smoke plumes. [Copyright &y& Elsevier]

The influence of atmosphere pollution on human health is receiving more and more concerns as strengthened anthropogenic activity had brought excessive pollutant into the atmosphere. To date, the quantitative estimation about the contribution of atmosphere on the accumulation of heavy metal in the edible cereal parts induced by anthropogenic forcing is scarce. Taking the Yangtze River Delta area, China as an example, this study estimates quantitatively the influence of atmosphere on the concentration of heavy metal in the aboveground wheat tissues induced by anthropogenic industrial activity at the regional scale. The results show that the aboveground wheat tissues in the southern Yangtze River Delta area accumulated much more heavy metals than that in the northern area, although there is no significant difference in the geological and climate conditions, soil types, agricultural manages, wheat cultivar and soil heavy metals concentrations (even heavy metals concentrations in wheat root) between the southern area and northern area. The mean concentrations of Pb, Zn, Cu and Cd in wheat grain in southern area have exceeded the thresholds of contamination levels. The present study suggests that the influence of atmosphere on the accumulation of Hg, Cd, Pb, Zn, Cu, Ni and Cr in the aboveground wheat tissues is greatly significant when high amounts of pollutant are measured in the atmosphere. Based on translocation coefficient of the element, it is estimated that atmospheric pollution induced by anthropogenic forcing might lead to the concentration of heavy metals in wheat straw and grain increase by approximately 100% and 354% (Hg), 64% and 293% (Pb), 122% and 160% (Cr), 50% and 38% (Cd) and 14% and 41% (Cu), respectively. • Contribution of atmosphere on heavy metal in wheat is estimated quantitatively. • Excessive heavy metal in wheat was found in south of Yangtze River Delta, China. • Anthropogenic air pollution greatly enhances heavy metal accumulation in wheat. • Anthropogenic forcing can increase Hg concentration in wheat grain by about 3 times. [ABSTRACT FROM AUTHOR]