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Although air quality guidelines generally use the atmospheric concentration of fine particulate matter (PM 2.5) as a metric for air pollution evaluation and management, the fact cannot be ignored that different particle toxicities are unequal and significantly related to their sources and chemical compositions. Therefore, judging the most harmful source and identifying the toxic component would be helpful for optimizing air quality standards and prioritizing targeted PM 2.5 control strategies to protect public health more effectively. Since the combustions of fuels, including oil, coal, and biomass, are the main anthropogenic sources of environmental PM 2.5 , their discrepant contributions to health risks of mixed ambient aerosol pollution dominated by the respective emission intensity and unequal toxicity of chemical components need to be identified. In order to quantify the differences between these combustion primary emissions, 10 types of PM 2.5 from each typical source group, i.e., vehicle exhaust, coal combustion, and plant biomass (domestic biofuel) burning, were collected for comparative study with toxicological mechanisms. In total, 30 types of individual combustion samples were intercompared with representative urban ambient air PM 2.5 samples, whose chemical characteristics and biological effects were investigated by component analysis (carbon, metals, soluble ions) and in vitro toxicity assays (cell viability, oxidative stress, inflammatory response) of human lung adenocarcinoma epithelial cells (A549). Carbonaceous fractions were plenteous in automobile exhaust and biomass burning, while heavy metals were more plentiful in PM 2.5 from coal combustion and automobile exhaust. The overall ranking of mass-normalized cytotoxicity for source-specific PM 2.5 was automobile exhaust > coal combustion > domestic plant biomass burning > ambient urban air, possibly with differential toxicity triggers, and showed that the carbonaceous fractions (organic carbon, OC; elemental carbon, EC) and redox-active transition metals (V, Ni, Cr) assisted by water-soluble ions (Ca 2+ , Mg 2+ , F - , Cl -) might play important roles in inducing cellular reactive organic species (ROS) production, causing oxidative stress and inflammation, resulting in cell injury and apoptosis, and thus damaging human health. Coupled with the source apportionment results of typical urban ambient air PM 2.5 in eastern China, reducing toxic PM 2.5 from these anthropogenic combustions will be greatly beneficial to public health. In addition to the air pollution control measures that have been implemented, like strengthening the vehicle emission standards, switching energy from coal to gas and electricity, and controlling the open incineration of agricultural straws, further methods could be considered, especially by preferentially reducing the diesel exhaust, lessening the coal combustion by replacement with low-ash clean coals, and depressing the rural crop straw biomass burning emissions. [ABSTRACT FROM AUTHOR]

Abstract: Trace metals in soils may pose risks to both ecosystem and human health, especially in an urban environment. However, only a fraction of the metal content in soil is mobile and/or available for biota uptake and human ingestion. Various environmental availabilities of trace metals (Cu, Pb and Zn) in topsoil from highly urbanized areas of Hong Kong to plants, organisms, and humans, as well as the leaching potential to groundwater were evaluated in the present study. Forty selected soil samples were extracted with 0.11M acid acetic, 0.01M calcium chloride, 0.005M diethylenetriaminepentaacetic acid, and simplified physiologically based extraction tests (PBET) for the operationally defined mobilizable, effectively bioavailable, potentially bioavailable, and human bioaccessible metal fractions, respectively. The metals were generally in the order of Zn>Cu∼Pb for both mobility (24%, 7.6%, 6.7%) and effective bioavailability (2.8%, 0.9%, 0.6%), Pb (18%)>Cu (13%)>Zn (7.4%) for potential bioavailability, and Pb (59%)∼Cu (58%)>Zn (38%) for human bioaccessibility. Although the variations in the different available concentrations of metals could mostly be explained by total metal concentrations in soil, the regression model predictions were further improved by the incorporation of soil physicochemical properties (pH, OM, EC). The effectively bioavailable Zn and Pb were mostly related to soil pH. Anthropogenic Pb in urban soils tended to be environmentally available as indicated by Pb isotopic composition analysis. Combining various site-specific environmental availabilities might produce a more realistic estimation for the integrated ecological and human health risks of metal contamination in urban soils. [Copyright &y& Elsevier]

Abstract: Contaminants in urban soils can directly pose significant human health risks through oral ingestion, particle inhalation, and dermal contact, especially for children in public parks. Both non-carcinogenic and carcinogenic risks of heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) were characterized in 40 surface soils (exposed lawns) from 14 urban parks in Xiamen, China. Results based on total metal concentrations may overestimate the actual risks in comparison with oral bioaccessibility assessment that were estimated by a simplified physiologically based extraction test (SBET). After considering the soil-specific bioaccessibility (Cd>Cu>Pb>Mn>Zn>Co~Ni>Cr), the non-cancer hazard of Pb to children via oral ingestion should be a consideration though its Hazard Index (HI) was below one. The overall cancer risks to adults still exceeded the target value 10−6, mainly contributed by Cr (93.8%) and Pb (6.19%) via dermal contact (68.3%) and oral ingestion (30.4%). To produce a more realistic estimation for human health risks of metal contamination in urban soils, a framework combining land use type and bioaccessibility is recommended and thereby should be applied for the derivation of risk-based, site-specific soil guidelines. [Copyright &y& Elsevier]

Abstract: The contamination of urban soils can affect the health of people living in urban areas, and the surrounding ecosystems. Urbanization in China has taken place at an unprecedented pace in the last three decades. This paper provides an overview of studies on the quality of urban soils in China with special reference to trace metal contamination. It summarizes the characteristics of accumulation, spatial and temporal distribution, and major sources of various toxic or potentially toxic trace metals in urban soils as reported in recent literature. Levels of pollution in urban soil and road dust were discussed using the concentrations, enrichment factors, pollution indexes, and chemical fractionation of trace metals in major cities of China, and compared with other countries. In future studies, more pollutants in urban environments need to be included in multi-compartmental environmental surveillance for potential risk assessments. In addition to routine urban soil surveys by a harmonized methodology, a comprehensive assessment of soil quality is needed for the control and management of many urban brownfield sites. Taking into consideration pathways of exposure and site characteristics, risk assessment frameworks for major pollutants in urban soils, which integrate land use type and environmental availability, may be developed in the future. [Copyright &y& Elsevier]

Urban soil Pb contamination is a great human health risk. Lead distribution and source in topsoils from 14 parks in Shanghai, China were investigated along an urban–rural gradient. Topsoils were contaminated averagely with 65 mg Pb kg−1, 2.5 times higher than local soil background concentrations. HCl-extracts contained more anthropogenic Pb signatures than total sample digests as revealed by the higher 207/206Pb and 208/206Pb ratios in extracts (0.8613 ± 0.0094 and 2.1085 ± 0.0121 versus total digests 0.8575 ± 0.0098 and 2.0959 ± 0.0116). This suggests a higher sensitivity of HCl-extraction than total digestion in identifying anthropogenic Pb sources. Coal combustion emission was identified as the major anthropogenic Pb source (averagely 47%) while leaded gasoline emission contributed 12% overall. Urbanization effects were observed by total Pb content and anthropogenic Pb contribution. This study suggests that to reduce Pb contamination, Shanghai might have to change its energy composition to clean energy. [Copyright &y& Elsevier]

The concentration and loading distribution of trace metals (Cu, Zn, Pb, Co, Ni, Cr, and Mn) and major elements (Al, Ca, Fe, and Mg) in different particle size fractions (2000–280, 280–100, 100–50, 50–10, 10–2, and <2μm) of surface soils from highly urbanized areas in Hong Kong were studied. The enrichment of Pb, Cu, and Zn in the urban soils was strongly influenced by anthropogenic activities, and Pb accumulated in fine particles was mainly derived from past vehicular emissions as shown by Pb isotopic signatures. Trace metals primarily accumulated in clay, fine silt, and very fine sand fractions, and might pose potential health risks via the inhalation of resuspended soil particles in the air (PM10 or PM2.5), and ingestion of adhered soils through the hand-to-mouth pathway. The mobility, bioavailability, and human bioaccessibility of Pb and Zn in bulk soils correlated significantly with metal concentrations in fine silt and/or very fine sand fractions. [Copyright &y& Elsevier]

PM 2.5 pollution is a widespread environmental and health problem, particularly in China. Besides leading to well-known diseases in the respiratory system, PM 2.5 can also alter immune function to induce or aggravate allergic diseases. To determine whether there are temporal and spatial differences in the allergic responses to PM 2.5 , monthly samples were collected from four regions (urban, industrial, suburban, and rural areas) through a whole year in Nanjing city, China. Inorganic chemical components (metals and water-soluble ions) of PM 2.5 were analyzed, and the rat basophil cells (RBL-2H3) exposed to PM 2.5 were assessed through quantitative measures of degranulation (β-hex and histamine) and pro-inflammation cytokine (IL-4 and TNF-α) expression. The highest levels of β-hex were measured in winter and spring PM 2.5 from urban and industrial areas, or autumn PM 2.5 from suburban and rural areas. With respect to histamine, autumn PM 2.5 samples were most potent irrespective of the location. Autumn and winter PM 2.5 induced higher levels of IL-4 than spring and summer samples. However, spring and autumn PM 2.5 caused higher levels of TNF-α. The concentrations of water-soluble ions (NH 4 +, K+ and Cl−), as well as heavy metals (Pb and Cr), were directly and statistically correlated to the inflammation observed in vitro. In general, the differences between regional and seasonal PM 2.5 in stimulating cell degranulation may depend on endotoxin and airborne allergen content of PM 2.5. The heavy metals and water-soluble ions in PM 2.5 were mostly anthropogenic, which increased the particles' mass-based cellular inflammatory potential, therefore, their health risks, e.g. from vehicular exhaust, coal, and biomass combustion, cannot be ignored. [Display omitted] • PM 2.5 could directly enhance β-hexosaminidase release by basophilic cells. • Degranulation of basophil cells exposed to PM 2.5 show regional and seasonal variations. • PM 2.5 shows the strong pro-inflammation effect on basophilic cells. • Airborne heavy metals and water-soluble ions correlate positively with cell inflammatory response. • PM 2.5 -induced cellular inflammation was driven by anthropogenic sources. [ABSTRACT FROM AUTHOR]

Environmental air pollutants pose significant threats to public health, especially the toxicity and diseases caused by the atmospheric fine particulate matters (PM 2.5). Since the health risks vary with both the concentrations and compositions of PM 2.5 which are determined by aerosol sources, how are their toxic effects relevant to the pollution level becomes an important issue, such as the haze episodes covering clean and polluted days. With the transition from non-pollution to pollution stage, daily PM 2.5 samples were collected from both the urban and industrial areas of Nanjing city, eastern China, covering a typical haze event in autumn-winter. Their unpropitious effects on human lung epithelial cells (A549) were compared by in vitro toxicity assays and chemical component analysis. Both air levels and cytotoxic effects of PM 2.5 varied with the transition of haze event. Although the concentration of PM 2.5 in air is of course the highest in pollution stage driven by local stable meteorological condition, unit mass of them posed higher toxicity (lower cell viability and higher IL-6) but induced lower cell oxidative (evidences of ROS and NQO1 mRNA expression) and inflammatory cytokine TNF-α responses than those particles during non-pollution stage. These patterns were explained by the metals and water-soluble components decreased with the haze development. Non-soluble particulate carbonaceous aerosol compositions might play a significant role in inducing cytotoxicity. Moreover, the regional pattern of episode pollution weakened the spatial variation within a city scale. Since the haze development intensified both the quantity and toxicity of PM 2.5 in air, the health risks of overall aerosol exposure were synthetically amplified during haze weather, so the increased air particles with higher toxic components from fuel combustion sources should be key targets of pollution control. ga1 • Stable atmosphere enables the continuous accumulation of local PM 2.5. • Haze development intensified both quantity and toxicity of PM 2.5 in air. • Regional haze pollution episode weakened the spatial variation within a city. • Trace metals and water-soluble contents in PM 2.5 decreased with haze development. • Non-soluble carbonaceous aerosol compositions might control the haze cytotoxicity. [ABSTRACT FROM AUTHOR]

Dust storm (DS) represent global air pollution and health issues considering the high morbidity and premature death rate every year. This study explores the characteristics, composition, and variations in inhalable particulate matters (PMs) as well as their corresponding in vitro toxicity to human lung epithelial cells (A549) during DS and normal days (ND) in the downtown (DT) and the north suburban (NS) of Nanjing city, eastern China. Results showed that compared to ND, concentrations of heavy metals (i.e., Cr, Cu, Ni, and Pb) bound in PMs were lower during the DS. Furthermore, the relationship of cytotoxicity with Ni and Pb levels in PMs was significant. However, the cytotoxicity difference was insignificant between NS and DT. This may be due to the long-range transport of components from natural sources mixed with local pollutants emitted from anthropogenic sources, offsetting the pollution difference between urban and suburban areas. During both periods, PM 2.5 toxicity was greater than PM 10 , while the potential of PM 10 to induce proinflammatory cytokines was comparable to PM 2.5. Results suggested that inflammation risk will increase significantly during DS due to a substantial increase in ambient air PM 10 concentration. [Display omitted] [ABSTRACT FROM AUTHOR]

Aerosol pollution is a serious environmental issue, especially in China where there has been rapid urbanization. To identify the intra-annual and regional distributions of health risks and potential sources of heavy metals in atmospheric particles with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5), this work collected monthly PM2.5 samples from urban, industrial, suburban, and rural areas in Nanjing city during 2016 and analyzed the heavy metal compositions (Cu, Pb, Cd, Co, V, Sr, Mn, Ti, and Sb). Enrichment factors (EFs) and principal component analysis (PCA) were applied to investigate the sources. The atmospheric PM2.5 pollution level was highest in the industrial area, followed by the urban and suburban areas, and was the lowest in the rural area. Seasonally, the concentrations of PM2.5 and associated heavy metals in spring and winter were higher than those in summer and autumn. Besides natural sources, heavy metal pollution in PM2.5 might come from metallurgical dust in the industrial area, while it mainly comes from automobile exhaust in urban and suburban areas. Health risk assessments revealed that noncancerous hazards of heavy metals in PM2.5 were low, while the lifetime cancer risks obviously exceeded the threshold. The airborne metal pollution in various functional areas of the city impacted human health differently. [ABSTRACT FROM AUTHOR]

Organic pollutants are important harmful components in atmospheric fine particulate matters (PM 2.5), health risks of which varied with temporal and spatial distributions. To clarify the characteristics of atmospheric organic pollution, the concentrations, sources, and human health risks of typical organic compositions in PM 2.5 samples from both industrial and urban areas of Nanjing in eastern China were investigated monthly for a year. Results showed that, the concentrations of PM 2.5 -bound polycyclic aromatic hydrocarbons (PAHs) and n-alkanes were higher in winter and spring than those in summer and autumn. The organic pollution was slightly higher in industrial than urban area, though the PAHs in autumn and the n-alkanes in warm season (summer and autumn) were higher in urban area. With regards to the pollutant sources, the atmospheric PAHs were dominated by motor vehicle exhaust in the urban area, and combined with coal combustion emission in the industrial area. Airborne n-alkanes were mainly from biological source accompanied by fossil fuel combustion in industrial area. The PM 2.5 -bound PAHs indicated higher risks to adults in industrial area than in urban area with the seasonal patterns: winter > spring > autumn > summer. More attention should be paid to the health risks of exposure to organic pollutants accumulated in PM 2.5 during cold season. Controlling vehicle emissions might be the key measure for alleviating atmospheric PAHs and n-alkanes pollution in megacities, while coal purification can be an effective control method in industrial areas. • Organic pollutants are typical harmful components in PM 2.5 • Concentrations, sources, and health risks of PM 2.5 show spatio-temporal patterns. • PAHs and n-alkanes pollution were serious in cold season and industrial area. • Vehicle emission is a key target for alleviating particulate organic pollution. • Coal purification can be an effective pollution control method in industrial area. [ABSTRACT FROM AUTHOR]

Environmental air pollutants pose significant threats to public health, especially the toxicity and diseases caused by the atmospheric fine particulate matters (PM 2.5 ). Since the health risks vary with both the concentrations and compositions of PM 2.5 which are determined by aerosol sources, how are their toxic effects relevant to the pollution level becomes an important issue, such as the haze episodes covering clean and polluted days. With the transition from non-pollution to pollution stage, daily PM 2.5 samples were collected from both the urban and industrial areas of Nanjing city, eastern China, covering a typical haze event in autumn-winter. Their unpropitious effects on human lung epithelial cells (A549) were compared by in vitro toxicity assays and chemical component analysis. Both air levels and cytotoxic effects of PM 2.5 varied with the transition of haze event. Although the concentration of PM 2.5 in air is of course the highest in pollution stage driven by local stable meteorological condition, unit mass of them posed higher toxicity (lower cell viability and higher IL-6) but induced lower cell oxidative (evidences of ROS and NQO1 mRNA expression) and inflammatory cytokine TNF-α responses than those particles during non-pollution stage. These patterns were explained by the metals and water-soluble components decreased with the haze development. Non-soluble particulate carbonaceous aerosol compositions might play a significant role in inducing cytotoxicity. Moreover, the regional pattern of episode pollution weakened the spatial variation within a city scale. Since the haze development intensified both the quantity and toxicity of PM 2.5 in air, the health risks of overall aerosol exposure were synthetically amplified during haze weather, so the increased air particles with higher toxic components from fuel combustion sources should be key targets of pollution control., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Atmospheric fine particulate matter (PM 2.5 ) can harm human health, but the chemical composition and toxicity of PM 2.5 pollution might vary with weather conditions. In order to investigate the impacts of snowfall weather on aerosol characteristics and toxicity by changing particle sources and components, the daily PM 2.5 samples were collected before, during, and after a snowfall event in urban, industrial, suburban, and rural areas of Nanjing city in eastern China, for both chemical composition analysis and cytotoxicity tests. After 24 h exposure to these PM 2.5 , the cell activity, oxidative stress indicators and inflammatory factor expression levels of human lung epithelial cells A549 were measured by ELISA, and DNA damage was determined by comet assay. Although the concentrations of PM 2.5 in the air were reduced during snowfall, they posed stronger cytotoxicity, genetic toxicity and inflammatory responses to A549 cells. Related to the elevated mass concentrations of some components accumulated in PM 2.5 during snowfall, As, Co, Cr, Sr, V, water-soluble Na + and Ca 2+ showed positive correlations with toxicity indicators. Therefore, snowfall will clean air by deposition, but also make the PM 2.5 components remaining in air mostly anthropogenic by covering ground soil/dust, thus increase the particle's mass-based cytotoxicity and their health risks still cannot be ignored, such as the heavy metals and water-soluble ions from automobile exhaust and coal combustion., 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 © 2020 Elsevier B.V. All rights reserved.)

The atmospheric fine particulate matters (PM 2.5 ) induce significant negative effects on human health, such as in the form of oxidative stress and pro-inflammatory response. Organic pollutants are important harmful and toxic compositions in PM 2.5 , risks of which usually show temporal and spatial variations. To investigate the toxic effects of airborne organic pollutants on human lung epithelial cells A549, the PM 2.5 samples were collected monthly from both urban and industrial areas during a whole year in Nanjing, eastern China. After exposure to organic components extracted from these PM 2.5 , the cell viability, lactate dehydrogenase content, oxidative stress index level and inflammatory factor expression level were measured. Supported by the concentrations of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, results showed that, organic components of PM 2.5 from cold season (winter and spring) typically influenced cell membrane, cell oxidation and inflammatory damage, while the urban samples of warm season (summer and autumn) impacted cell viability more prominently. Spatially, the toxicity of samples from industrial sources was generally stronger than that from urban source, but urban samples induced much stronger damage to cell membranes than industrial one. The correlations between the PAHs, n-alkanes contents and toxicity parameters indicated that, the airborne organic components derived from motor vehicle exhaust and coal combustion were possibly the key toxic sources., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Atmospheric fine particulate matters (PM 2.5 ) induce adverse human health effects through inhalation, and the harmful effects of PM 2.5 are determined not only by its air concentrations, but also by the particle components varied temporally. To investigate seasonal differences of the aerosol toxicity effects including cell viability and membrane damage, cell oxidative stress and responses of inflammatory cytokines, the human lung epithelial cells (A549) were exposed to PM 2.5 samples collected in both summer and winter by the in vitro toxicity bioassays. Toxicological results showed that, the PM 2.5 led to the cell viability decrease, cell membrane injury, oxidative stress level increase and inflammatory responses in a dose-dependent manner. Temporally, the cytotoxicity of winter PM 2.5 was higher than summer of this studied industrial area of Nanjing, China. According to the different contents of heavy metals accumulated in PM 2.5 , the transition metals such as Cu might be an important contributor to the aerosol cell toxicity., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Solid/solution partition coefficient (Kd) and speciation of soil heavy metals can be used for predicting their environmental risks. The Kd values and solution speciation of soil Cu, Cd and Zn were analyzed in 40 samples of contaminated agricultural soils around Jiuhua copper mine in eastern Nanjing city, China. The Kd ranges (and mean values) for soil Cu, Cd and Zn are 703-7418 (3453), 37.3-3963 (940) and 319-17965 (7244) L kg-1, respectively, showing a large variability both for metals and soils. The results of differential pulse anodic stripping voltammetry (DPASV) indicates that 95.6% solution Cu is bound to dissolved organic ligands. About half of the dissolved Zn is DPASV-labile at pH<6, while 92.1% solution Zn is in the form of organic complexes at pH>6. DPASV-labile Cd is ranged from 22.6 to 98.7% with the mean value of 56.3%. Multiple linear regressions indicate that Kd, the dissolved and DPASV-labile concentrations of Cd and Zn are mostly influenced by the soil solution pH with R2 of 0.50, 0.59 and 0.63, respectively for Cd, and 0.58, 0.72 and 0.64, respectively for Zn. Considering the second parameter of corresponding soil metal, the linear relationships of Kd with pH were improved with R2 of 0.70 and 0.73 for Cd and Zn, respectively. However, the solubility of soil Cu was insensitive to pH. Only SOC shows a weak relationship to the dissolved Cu with R2 of 0.21. As for its Kd, total soil Cu is the most significant factor. But for DPASV-labile Cu, no soil parameters were found to be good predictors.

To determine the environmental free metal ion activity was a recent hot issue. A method to measure low-level free cupric ion activity in soil solution extracted with 0.01 mol/L KNO3 was developed by using cupric ion-selective electrode (ISE) and calibrating with Cu-buffer solution. Three copper buffers including iminodiacetic acid (IDA), ethylenediamine (EN), and glycine (Gly) were compared for calibrating the Cu-ISE curves in the range of free cupric ions (pCu2+) 7-13. The Cu-EN buffer showed the best electrode response and thus was applied as the calibration buffer. The pCu2+ of 39 contaminated agricultural soils around a copper mine was measured, ranging from 5.03 to 9.20. Most Cu in the soil solutions was found to be complexed with dissolved soil organic matters, averaging 98.1%. The proportion of free Cu2+ ions in the soil solutions decreased with the increasing of solution pH. Soluble Cu and free Cu2+ ions concentrations were analyzed by multiple linear regressions to evaluate the effects of soil properties on metal levels and speciation. The results showed that soil solution pH was the most significant factor influencing pCu2+ (with R2 value of 0.76), while not important for the soluble Cu concentration.