Size distributions and sources of elements in particulate matter at curbside, urban and rural sites in Beijing

Health risks and sources of trace elements and black carbon in PM2.5 from 2019 to 2021 in Beijing

A comprehensive health risk assessment of PM2.5 is meaningful to understand the current status and directions regarding further improving air quality from the perspective of human health. In this study, we evaluated the health risks of PM2.5 as well as highly toxic inorganic components, including heavy metals (HMs) and black carbon (BC) based on long-term observations in Beijing from 2019 to 2021. Our results showed that the relative risks of chronic obstructive pulmonary disease, lung cancer, acute lower respiratory tract infection, ischemic heart disease, and stroke decreased by 4.07%-9.30% in 2020 and 2.12%-6.70% in 2021 compared with 2019. However, they were still at high levels ranging from 1.26 to 1.77, in particular, stroke showed the highest value in 2021. Mn had the highest hazard quotient (HQ, from 2.18 to 2.56) for adults from 2019 to 2021, while Ni, Cr, Pb, As, and BC showed high carcinogenic risks (CR > 1.0×10-6) for adults. The HQ values of Mn and As and the CR values of Pb and As showed constant or slight upwards trends during our observations, which is in contrast to the downward trends of other HMs and PM2.5. Mn, Cr, and BC are crucial toxicants in PM2.5. A significant shrink of southern region sourcesof HMs and BCshrank suggests the increased importance of local sources. Industry, dust, and biomass burning are the major contributors to the non-carcinogenic risks, while traffic emissions and industry are the dominant contributors to the carcinogenic risks in Beijing.

Influence of anthropogenic activities on metals, sugars and PAHs in PM10 in the city of Fez, Morocco: Implications on air quality

Particulate matter (PM) is an important component in the atmosphere, affecting air quality, health, radiation balance, and global climate. To assess regional air quality in the city of Fez, an intensive field campaign was carried out in the autumn of 2019 in the Middle Atlas region of Morocco. Aerosol sampling was performed simultaneously at two urban sites in the city of Fez: (1) Fez University (FU), a sub-urban site, and (2) Fez Parc (FP), an urban site located in the city center of Fez, using PM10 collectors. Various laboratory analyses were carried out, including PM mass, trace metals, inorganic ions, OC/EC, sugar compounds, and PAHs. The results indicate that the PM10 mass (61 ng m-3) was comparable at both sites, with a 37-107 ng m-3 range. Most of the 19 investigated PAHs at the FU site (10.2 ± 6.2 ng m-3) were low-molecular-weight PAHs, while the most abundant PAHs at the FP site (6.9 ± 3.8 ng m-3) were mainly higher-molecular-weight PAHs. A diagnostic ratio analysis at both sites indicated that PAHs originated from fossil fuel combustion and traffic emissions from diesel engines, with Ant/(Ant + Phe) and Flu/(Flu + Pyr) ratios averaging 0.22 and 0.84, respectively. PMF analysis identified traffic emissions as a major source (30%), with secondary inorganic aerosols (20%) and biomass burning (14%). Polar plots highlight the dominance of local anthropogenic activities in PM pollution, with vehicular emissions, industrial activities, and biomass burning. This study shows that local sources and combustion processes significantly contribute to PM10 sources in Morocco, providing insights into air pollution mitigation in North Africa.

Fine particulate matter from brick kilns site and roadside in Lahore, Pakistan: Insight into chemical composition, oxidative potential, and health risk assessment

Background

Human health is seriously threatened by particulate matter (PM) pollution, which is a major environmental problem. A better indicator of biological responses to PM exposure than its mass alone is the PM "oxidative potential (OP)," or ability to oxidize target molecules. When reactive oxygen species (ROS) are generated in the OP in excess of the antioxidant capacity of body due to PM components such metals and organic species, it causes inflammation, deoxyribonucleic acid (DNA), proteins, and lipids damage.

Method

The samples of fine particulate matter (PM2.5) are collected from the brick kiln site and the roadside in Lahore, Pakistan. The organic carbon (OC) and elemental carbon (EC) were estimated by carbon analyzer (DRI 2001A) using the thermal/optical transmittance (TOT) protocol. The water-soluble organic carbon (WSOC) concentration was determined using a total organic carbon analyzer (Shimadzu TOC-L CPN). Ion chromatography (Dionex ICS-900) with a conductivity detector was used to analyze the water-soluble anions (Cl-, NO3-, and SO42-) and cations (NH4+, Na+, K+, Mg2+, and Ca2+). Inductively coupled plasma-mass spectrometry (iCAP TQ ICP-MS, Thermo Scientific) was used to determine the concentrations of metals in the solution. The dithiothreitol (DTT) consumption rate was calculated using a spectrophotometer at a wavelength of 412 nm.

Results

The mean concentrations of PM2.5 at the brick kiln site and roadside reported are 509.3 ± 32.3 μg/m3 and 467.5 ± 24.9 μg/m3, and the average OC/EC ratio is 1.9 ± 0.4 and 2.1 ± 0.1. primary organic carbon (POC) contributed more to OC than secondary organic carbon (SOC), which indicated the dominance of primary combustion sources. The anion equivalent (AE) to cation equivalent (CE) ratio indicated that PM2.5 is acidic at both sites due to the dominance of NO3- and SO42-. The DTT consumption rate normalized by PM2.5 mass (DTTm) and DTT consumption rate normalized by air volume (DTTv) of PM2.5 at the roadside samples are higher than at the brick kiln site due to the higher contribution of ionic species to the mass of PM2.5. Carbonaceous species of PM2.5 at both sampling sites are significantly correlated with DTTv of PM2.5, while metallic species behaved differently. The incremental lifetime cancer risk (ILCR) values (lung cancer) of As and Cr at both sampling sites, while the ILCR value of Cd at the roadside samples is exceeding the permissible limits for adults and children. The lifetime average daily dose (LADD) value for adults is higher than that for children, indicating that children are less vulnerable to metals.

Conclusion

The concentration of PM2.5 at both sampling sites were exceeding the permissible limits of Pakistan' National Environmental Quality Standard (NEQS) and posing risk to the health of the local population. The POC and SOC contribution to OC at the brick kiln site and roadside in Lahore were 84.6%, 15.4% and 84.4%, 15.6%. POC at both sampling sites were the dominant carbon species indicating the dominance of primary combustion sources. The residence of Lahore poses the lung cancer risk due to Cr, As, and Cd at both sampling sites. The results of this study provide important data and evidence for further evaluation of the potential health risks of PM2.5 from brick kiln site and road side in Pakistan and formulation of efficient air-pollution control measures.

Control priority based on source-specific DALYs of PM2.5-bound heavy metals by PMF-PSCF-IsoSource model in urban and suburban Beijing

To determine the priority control sources, an approach was proposed to evaluate the source-specific contribution to health risks from inhaling PM2.5-bound heavy metals (PBHMs). A total of 482 daily PM2.5 samples were collected from urban and suburban areas of Beijing, China, between 2018 and 2019. In addition to the PMF-PSCF model, a Pb isotopic IsoSource model was built for more reliable source apportionment. By using the comprehensive indicator of disability-adjusted life years (DALYs), carcinogenic and noncarcinogenic health risks could be compared on a unified scale. The study found that the annual average concentrations of the total PBHMs were significantly higher in suburban areas than in urban areas, with significantly higher concentrations during the heating season than during the nonheating season. Comprehensive dust accounted for the largest contribution to the concentration of PBHMs, while coal combustion contributed the most to the DALYs associated with PBHMs. These results suggest that prioritizing the control of coal combustion could effectively reduce the disease burden associated with PBHMs, leading to notable public health benefits.

Source identification and health risk assessment of PM2.5 in urban districts of Hanoi using PCA/APCS and UNMIX

Comparing results obtained by different models with different physical assumptions and constraints for source apportionment is important for better understanding the sources of pollutants. Source apportionment of PM2.5 measured at three sites located in inner urban districts of Hanoi was performed using two receptor models, UNMIX and principal component analysis with absolute principle component score (PCA/APCS). A total of 78 daily samples were collected consecutively during the dry and wet seasons in 2019 and 2020. The average PM2.5 concentration (66.26 µg/m3 ± 29.70 µg/m3 with a range from 23.57 to 169.04 µg/m3) observed in Hanoi metropolitan exceeded the National Ambient Air Quality standard QCVN 05:2013/BTNMT (50 µg/m3). Both UNMIX and PCA/APCS expressed comparable ability to reproduce measured PM2.5 concentrations. Additionally, both models identified similar potential sources of PM2.5 including traffic-related emissions, scrap metal recycling villages, crustal mixed with construction sources, coal combustion mixed with industry, and biomass burning. Both UNMIX and PCA/APCS confirmed that traffic-related emission was the most influential PM2.5 with a high percentage contribution of 59% and 55.97%, respectively. All the HQ and Cr values for both children and adults of toxic elements apportioned by both UNMIX and PCA/APCS in every source were within the acceptable range.

Unraveling the complexities of beryllium contamination in agricultural soils: The case of Qingcheng District, Qingyuan City

Metal contamination in agricultural soils has received widespread attention; however, the status of beryllium (Be) contamination in agricultural soils has been inadequately studied. This research was conducted to determine the enrichment level and major sources of Be contamination in the agricultural soil in Qingcheng District, Qingyuan City, and to quantify the potential ecological risk and human health risk (PER and HHR) of Be by integrating geological mineral and remote-sensing image maps. The results of principal component analysis followed by multiple linear regression (PCA-MLR) suggest that Be, Sn, Zn, Pb, As, and Cd are mainly derived from anthropogenic activities; V, Ti, Sc, Cr, and Co are mainly derived from medium acidic granites; Al and Si are mainly derived from geological sources; and K and Na are mainly derived from calcium-alkaline materials. Anthropogenic activities are priority material sources owing to the highest contribution. Be contamination poses a slight PER, and the PER level of agricultural soil was moderate. The HHR caused by Be is negligible. The results of this study can serve as the basis for promoting agricultural soil protection and developing and implementing agricultural policies to reduce environmental pollution in the study area.

Characteristics and health risk assessment of heavy metal pollution in atmospheric particulate matter in different regions of the Yellow River Delta in China

To understand the characteristics, temporal and spatial variation, and health risks of atmospheric heavy metal pollution in different areas of the YRD (Yellow River Delta), atmospheric particles samples were collected in the YRD in China during 2016-2017. A total of 10 monitoring points were chosen in different areas (industrial parks, main urban areas, and rural areas) in the YRD, heavy metals were monitored using atomic fluorescence spectrometry and graphite furnace atomic absorption spectrometry. The results showed that TSP (total suspended particulate), PM₁₀ (particulate matter with an aerodynamic diameter less than 10 μm), and PM_2.5 (particulate matter with an aerodynamic diameter less than 2.5 μm) contents were higher in the Kenli EDZ (economic development zone) and Kenli urban areas than those in other points. The concentration range of heavy metals in atmospheric samples at 10 points was different, with a difference of five orders of magnitude, of which the content of copper (Cu) was the highest, with the highest concentration of 4.375 μg/m³, and the content of particulate mercury (Hg) was the lowest, with the minimum concentration of 0.00001 μg/m³. Among the nine heavy metals, the contents of cadmium (Cd), lead (Pb), and Hg were higher in winter than in summer, and chromium (Cr), nickel (Ni), Cu, and manganese (Mn) were higher in summer than in winter. In addition to Hg, the contents of the other eight heavy metals in particulate matter showed a trend that urban areas and EDZs had higher concentrations than cities and towns and nature reserves, which can be attributed to industrial activities and coal-fired fuel emissions. Health risk assessment was carried out for adults and children, respectively, and the results showed that carcinogens have no obvious carcinogenic risk, but As and Cr have major potential carcinogenic risk. Among the noncarcinogenic substances, Mn has the greatest noncarcinogenic risk, and urban areas and economic development zones have the greatest risk. This study investigated the characteristics and health risk assessment of atmospheric heavy metal pollution in different areas in the YRD to supplement the research contents of atmospheric particulate heavy metals in the YRD in domestics and overseas. It is also critical to study the pollution and migration of heavy metals in China.

Mass, composition, and sources of particulate matter in residential and traffic sites of an urban environment

Present study aims to assess the mass, composition, and sources of PM₁₀ and PM_2.5 (particulate matter having aerodynamic diameter less than or equal to 10 and 2.5 µm aerodynamic diameter, respectively) in Vellore city. Seasonal samples collected in traffic and residential sites were analyzed for ions, elements, organic carbon (OC), and elemental carbon (EC). Source apportionment of PM₁₀ and PM_2.5 is carried out using Chemical Mass Balance, Unmix, Positive Matrix Factorization and Principal Component Analysis receptor models. Results showed that traffic site had higher annual concentration (PM_2.5 = 62 ± 32 and PM₁₀ = 112 ± 23 µg m^-3) when compared to residential site (PM_2.5 = 54 ± 22 and PM₁₀ = 98 ± 20 µg m^-3). Al, Ca, Fe, K, and Mg known to have crustal origin dominated the element composition irrespective of PM size and sampling site. Among ions, SO₄^2- accounted highest in both sites with an average of 70 and 60% to PM_2.5 and PM₁₀ ionic mass. Elemental carbon contribution to PM mass was found highest in traffic site (PM_2.5 = 17 to 23% and PM₁₀ = 8 to 10%) than residential site (PM_2.5 = 9 to 17% and PM₁₀ = 4 to 8%). Elements, ions, OC, and EC accounted 12, 28, 34, and 16% of PM_2.5 mass and 12, 21, 20, and 8% of PM₁₀ mass, respectively. Different sources identified by the receptor models are resuspended road dust, crustal material, secondary aerosol, traffic, non-exhaust vehicular emissions, secondary nitrate, construction, cooking, and biomass burning. Since Vellore is aspiring to be a smart city, this study can help the policymakers in effectively curbing PM.

Health threat of PM2.5-bound trace elements exposure on asthma hospital admission: A time-stratified case-crossover study

Environmental pollution of trace elements has become of main concern due to the adverse effects. To estimate the impact of PM_2.5-bound trace elements on human health, a time-stratified case-crossover study has been designed to examine the short-term associations between 28 elements and asthma hospitalizations from January 2019 to November 2021 in Xiamen, China. This research summarized the major components that pose health risks in different seasons and took risk assessment for different groups. We found that an inter-quartile range (IQR) increase of Ca, Fe, Mn, Pd, Si, and Ti was positively associated with the incidence of asthma in the lag of 0-4 days. In winter, the elements that predisposed the population to asthma attack were the most, such as Al, Ba, Ca, Cr, Cu, Fe, K, Mn, Pd, Si, and Ti, and these elements are at higher risk for longer periods of time. The discrepancy in risk levels and major elements of asthma diagnosis among various age groups were also found in this work. Our results provided insights into the development of specific policies to reduce the risk of asthma attacks due to exposure to PM_2.5-bound trace elements.

Study on the mechanism of the black crust formation on the ancient marble sculptures and the effect of pollution in Beijing area

In Beijing area, the precious stone objects often suffer from the black crusts on the specific parts of the objects, in order to understand the forming mechanism of the black crusts, samples from the stone sculptures in Beijing Stone Carving Art Museum, ZHIHUA Temple and Museum of Western Zhou Yandu Relics were taken and studied. Nondestructive measurement was carried out firstly to acquire main elements of the samples by portable X-ray spectrum (pXRF). Morphology and microstructure of typical black crust samples were examined by ultra-depth of field microscope (UDFM) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). Compositions of black crusts and body rocks were evaluated with X-ray diffraction (XRD), Raman spectra and mapping. Inductively coupled plasma optical emission spectrometry (ICP-OES) and pyrolysis-gas chromatography/mass spectrometry (Py-GCMS) were used to identify the major pollution sources leading to the black crusts.

Through this study, the composition of the black crusts was revealed. Different gypsum crystals and carbonaceous species were found. Pollutant elements analysis and pyrolysis products provide indicators of the pollution sources. As consequence of strong photochemical oxidation processes and the high temperature from June to September in Beijing, more acid rain precursors can be formed. Frequent sulphation process occurs on the CaCO₃/CaMg(CO₃)₂ surface. Combining morphology results and atmospheric data, the formation of black crusts in Beijing can be deduced.

Human health risk assessment of heavy metals from PM2.5 in China's 29 provincial capital cities

After years of governance, China's PM_2.5 pollution has improved significantly, but some problems remain. PM_2.5 is the carrier of many heavy metals, and it has a stronger capacity to carry heavy metals, causing more significant harm to public health. At present, most of the studies on PM_2.5-bound heavy metals in China are based on individual cities, and there are few studies from China's provincial capital cities. Given the above reasons, this paper described the pollution characteristics of PM_2.5-bound heavy metal (Hg, Pb, Cd, As, Cr(VI), Ni) in 29 provincial capital cities in China (except Hohhot and Lhasa). Furthermore, the human health risk assessment recommended by US EPA was used to evaluate the carcinogenic and non-carcinogenic risks of the male adults, the female adults, and the children. The results indicated that (1) the children were facing a higher risk value of PM_2.5-bound heavy metals than the adults; (2) Cr, As, and Pb were the top three elements that contributed to the average non-carcinogenic risk, while Cr(VI), As, and Cd were the three elements with the highest carcinogenic risk; and (3) the concentrations of PM_2.5-bound heavy metals in the provincial capital cities of northern China were worse than those in the South. In response to the above conclusions, this paper put forward: (1) the government should strengthen the management of metallurgical industry and coal-burning industrial enterprises; (2) establish a real-time monitoring system for toxic and harmful heavy metal pollutants carried in the atmosphere as soon as possible; (3) concern on the regional synergies to form pollution control metropolitan areas.

Spatial, temporal and environmental differences in concentrations of lead in the blood of Mute swans from summer and winter sites in Poland

Lead (Pb) is a highly toxic pollutant and represents a serious threat to wildlife, affecting various systems in animal bodies. Especially prone to Pb poisoning are waterbirds, which may inadvertently ingest spent gunshot, fishing sinkers and contaminated sediments. This research thus focused on evaluating Pb concentrations in the blood of 170 Mute swans (Cygnus olor; a widespread species of waterbirds) at their summer (urban locations in Małopolskie and rural locations in Świętokrzyskie regions) and winter (the urban section of Wisła River in Krakow) sites in Poland (Europe). The study concentrated on comparing blood Pb concentrations according to sites and locations, verifying the influence of sex and age factors, examining the impact on hematocrit (Ht), glutathione (GSH) levels and body condition. Mean blood Pb concentrations (measured with ICP-OES) differed significantly between summer and winter sites (Regression by Maximum Likelihood Estimation (RML), p < 0.001) reaching higher values at winter sites. Concentrations did not differ from year to year (RML, p = 0.028). At summer sites, concentrations differed from location to location: swans from urban locations in Małopolskie had higher blood Pb concentrations (0.055 μg/g) than from rural Świętokrzyskie (0.008 μg/g; RML, p < 0.001). In summer and winter birds, neither sex nor age groups differed significantly the concentrations (RML, p > 0.231). Pb concentrations correlated weakly with Ht and GSH levels (Spearman test) and had no influence on body condition (proxied by scaled mass index; GLM, p = 0.246). We concluded that differences between summer and winter sites were dictated mainly by the type of habitat (rural vs. urban) that birds occupied in different seasons.

Children's exposure to size-fractioned particulate matter: Chemical composition and internal dose

The health effects of the particulate matter (PM) depend not only on its aerodynamic diameter (AD) and chemical composition, but also on the time activity pattern of the individuals and on their age. The main objective of this work was to assess the exposure of children to aerosol particles by using personal instruments, to study the particle size and composition of the inhaled PM, and to estimate their transport and deposition into the human respiratory tract (HRT). The average daily PM2.5 exposure was 19 μg/m³ and the size fractions with the greatest contribution to PM2.5 concentrations were 1 < AD <2.5 μm and AD <0.25 μm. Results indicated a contribution of 9% from the mineral aerosol, 7.2% from anthropogenic sulphate, 6.7% from black carbon and 5% from anthropogenic trace elements to the daily exposure to PM2.5. The levels of mineral and marine elements increased with increasing particle size, while anthropogenic elements were present in higher concentrations in the finest particles. Particle size has been shown to influence the variability of daily dose deposited between the extrathoracic and alveolar-interstitial zones. On average, 3% of the PM deposited in the bronchial region, whereas 5% to 8% were found in the bronchiolar region. The level of physical activity had a significant contribution to the total daily dose.

Exploring sources and health risks of metals in Beijing PM2.5: Insights from long-term online measurements

To gain a comprehensive understanding of sources, health risks, and regional transport of PM_2.5-bound metals in Beijing, one-year continuous measurement (K, Fe, Ca, Zn, Pb, Mn, Ba, Cu, As, Se, Cr, and Ni) was conducted from December 2016 to November 2017 and Positive Matrix Factorization analysis (PMF) was applied for source apportionment. It was found that the seasonal variation of sources could vary significantly among metals. Sources of Ca, Ba, As, Se, and Cr did not show much seasonal variations, with the contribution of its predominant source higher than 35% in each season. However, the major sources of K, Fe, Zn, Pb, Mn, Cu, and Ni exhibited obvious seasonal variations. In addition, the characteristics of metals in haze episodes were comprehensively investigated. Haze episodes in Beijing were characterized by higher metal concentrations and health risks, which were about 2- 6 times higher than non-haze periods. Moreover, the types of haze episode were different in winter and spring. Haze episodes in winter were mostly influenced by coal combustion, the contribution of which increased greatly and accounted for about 30% of PM_2.5. The metals such as K, Zn, Pb, As, and Se significantly increased, which were mainly transported from south of Beijing. During haze episodes in spring, dust was an important source, which contributed to higher concentrations of crustal metals that transported from northwest of Beijing. To quickly and effectively identify source regions of metals in Beijing during haze episodes, a new diagnostic ratio method using Ca as a reference was developed. The ratios of some anthropogenic metals to Ca significantly increased when air mass was mainly from south of Beijing during haze episodes while the ratios remained constantly low in non-haze periods, when local emissions dominated. This method could be useful for rapid identification and control of metal pollution in Beijing.

Distribution and chemical speciation of arsenic in different sized atmospheric particulate matters

The distribution and chemical speciation of arsenic (As) in different sized atmospheric particulate matters (PMs), including total suspended particles (TSP), PM₁₀, and PM_2.5, collected from Baoding, China were analyzed. The average total mass concentrations of As in TSP, PM₁₀, and PM_2.5 were 31.5, 35.3, and 54.1 µg/g, respectively, with an order of PM_2.5 >PM ₁₀ > TSP, revealing that As is prone to accumulate on fine particles. Due to the divergent toxicities of different As species, speciation analysis of As in PMs is further conducted. Most of previous studies mainly focused on inorganic arsenite (iAs^III), inorganic arsenate (iAs^V), monomethylarsonate (MMA), and dimethylarsinate (DMA) in PMs, while the identification and sensitive quantification of trimethylarsine oxide (TMAO) were rarely reported. In this study, a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry system was optimized for As speciation including TMAO in PMs. An anion exchange column was used to separate MMA, DMA and iAs^V, while a cation exchange column to separate TMAO and iAs^III. Results showed that iAs^V was the dominate component in all the samples, corresponding to a portion of 79.2% ± 9.3% of the total extractable species, while iAs^III, TMAO and DMA made up the remaining 21%. Our study demonstrated that iAs^III accounted for about 14.4% ± 11.4% of the total extracted species, with an average concentration of 1.7 ± 1.6 ng/m³. It is worth noting that TMAO was widely present in the samples (84 out of 97 samples), which supported the assumption that TMAO was ubiquitous in atmospheric particles.

Characterization and source apportionment of airborne particulate elements in the Athabasca oil sands region

The oil sands industries in Alberta, Canada are potential sources of particulate-bound elements in the region. This study explored the ambient concentrations and size distributions, and conducted source apportionment of 48 particulate elements, based on samples collected in 2016-2017 at four air monitoring sites in the Athabasca oil sands region: Fort McKay (AMS1), Buffalo Viewpoint (AMS4), Wapasu Creek (AMS17), and Stoney Mountain (AMS18). Element concentrations in fine and coarse particulate matter (PM_2.5 and PM_2.5-10 respectively) at the four sites were generally lower than their typical concentrations at other urban and industrial sites in North America. Among all elements, S was the most abundant in PM_2.5 with mean concentrations ranging from 189 ng/m³ (AMS18) to 284 ng/m³ (AMS1). Of the trace, toxic elements in PM_2.5, Zn was the most abundant with mean concentrations ranging from 3.43 ng/m³ (AMS18) to 5.37 ng/m³ (AMS4). Positive Matrix Factorization (PMF) modeling of the element concentrations in PM_2.5 was used for source apportionment for Zone1 (including AMS 1, 4, and 17, situated closer to industrial activities) and for Zone2 (including AMS18, a background site). The sources of elements for Zone1, included crustal dust, bitumen processing, haul road dust, and biomass burning that explained ~33%, ~43%, ~15%, and ~9% of the total resolved elemental mass, respectively. The sources of elements for Zone2, included Pb-rich source, biomass burning, fugitive oil sands, crustal dust, and bitumen processing explaining ~8%, ~7%, ~3%, ~22%, and ~60% of the total resolved elemental mass, respectively. Elemental mass concentrations of the bitumen processing source factor at Zone2 was two-thirds of that in Zone1. Overall, mass proportions of the bitumen processing source factor at all four sites were significant, suggesting that the oil sands industries played a key role in ambient element concentration levels in the region.

Atmospheric lead pollution in a typical megacity: Evidence from lead isotopes

Atmospheric lead (Pb) pollution has adverse health effects on humans, while the sources and atmospheric process of Pb are key scientific problems. In this study, the concentrations and isotopic composition of Pb in fine particulate matter (PM_2.5), coal and street dust samples collected from a typical megacity Beijing were analyzed to identify the sources of atmospheric Pb. Results showed that the Pb concentrations in PM_2.5 were high in winter (168.1 ± 32.0 ng/m³) and low in summer (27.7 ± 9.1 ng/m³), whereas Pb isotopic values presented opposite variation trends. The abnormally elevated Pb concentrations in winter were probably related to coal combustion, while declined Pb concentration in summer may be attributed to favorable meteorological parameters such as high temperature, high wind speed, and frequent rain events. Pb isotopic ratios indicated that anthropogenic sources (coal combustion and vehicle exhaust) and natural sources were the main contributors to Pb in PM_2.5. Combined with the binary model, the anthropogenic sources predominantly contributed to Pb in the Beijing atmosphere by approximately 85% annually, while the natural sources accounted for the rest of 15%. More specifically, the contribution of natural sources was about 9.4% in spring, 29.7% in summer, 16.0% in autumn and 6.1% in winter, suggesting that natural sources might contribute more lead into the atmosphere during clear days. Furthermore, the contribution of the vehicle exhaust to atmospheric Pb was nonnegligible in megacity, highlighting that the ownership of motor vehicles in megacity should be regulated and more efforts should be paid to strengthen vehicle emission standard. This study may enrich the reservoir of Pb isotopic composition in nature and provides a new method to investigate the Pb migration and transformation in the environment, and also serve as a theoretical reference for pollution control measures.

A comparison of waste recycling facilities for their contribution of heavy metals and trace elements in ambient air

A multi-elemental analysis, including heavy metals and trace elements in ambient air samples, was conducted for computers, wires, lead batteries, and iron extraction facilities in Lahore by proton-induced X-ray emission (PIXE) spectroscopy. The data obtained from PIXE analysis revealed the presence of Mg, Al, Zn, S, Pb, K, Ti, Fe, Si, K, and Cr elements at e-waste recycling facilities. The computer dismantling site revealed a higher concentration of Fe (634.7 μg/m³), Al (176.8 μg/m³), Pb (135.4 μg/m³) and Zn (122.5 μg/m³) in the air samples. The decreasing order of heavy metals and trace elements contribution at the computer dismantling site was as Si > Fe > Al > Pb > Zn > Mg > Ca > Cr > K > S > Ti. Similarly, at wires/cables burning site, a higher concentration of Fe, Al, and Pb (829.8 μg/m³, 184.5 μg/m³ and 115.6 μg/m³, respectively) were observed, and the elements revealed a descending trend as Si > Fe > Al > Zn > Pb > Mg > Ca > Cr > Ti > K > S. The lead batteries dismantling site showed the highest Pb concentration (141.2 μg/m³) due to the disassembling of lead acid batteries. Al, Zn, Fe, and Cr also revealed higher concentration in air samples and exhibited a declining trend as Si > Fe > Al > Pb > Zn > Cr > Ca > Mg > Ti > K > S. However, the highest concentration of Fe (865.7 μg/m³) was detected in air samples of iron extraction sites besides Al and Zn. The descending order of trace elements contribution was Si > Fe > Al > Zn > Mg > K > Ca > Ti > S. Furthermore, the correlation between workers' awareness and their possible health impacts were also examined in the study. Most of the workers were less aware of the hazardous impacts. Majority of workers and residents were suffering from a respiratory illness (27.5% and 32.5%), kidney failure (15% and 22.5%), and neurological disorders (15% and 7.5%), respectively, due to exposure of airborne particulate matter which could be correlated with the higher concentration of heavy metals such as Pb, Cr, Zn, and Fe in the ambient air at the e-waste recycling sites.

Characteristics, Accumulation, and Potential Health Risks of Antimony in Atmospheric Particulate Matter

Antimony (Sb), a priority pollutant listed by the U.S. Environmental Protection Agency (USEPA), can cause adverse effects on human health, with particular impacts on skin, eyes, gastrointestinal tract, and respiratory system. In this study, a database of Sb concentrations in the global atmosphere was developed through a survey of measurements published in more than 600 articles, which was then used to assess the health risks of Sb exposure based on a USEPA assessment model. Most measurements showed Sb concentrations of less than ∼10 ng m-3, but those at several contaminated sites exhibited Sb concentrations of more than 100 ng m-3. For measurements conducted in urban environments, Sb concentrations in the total suspended particles (TSP) and particles of less than 10 (PM10) or 2.5 μm (PM2.5) were the highest in Asia, followed by Europe, South America, and North America. Sb concentrations were generally higher in winter and fall than during other seasons in TSP and PM10 samples. A significant correlation was observed between Sb and As in TSP and PM2.5 on a global scale. Sb was mainly derived from anthropogenic sources, especially traffic emission, industrial emission, and fossil combustion. Hazard quotients (HQ) of Sb in TSP, PM10, and PM2.5 were higher for children than adults because of their lighter body weight, inferior physical resistance, and higher ingestion probability. The global database for atmospheric Sb concentrations demonstrates a relatively low noncarcinogenic risk in most regions. Long-term monitoring is still required to identify the sources and growth potentials of Sb so that effective control policies can be established.

Association of blood lead levels with preeclampsia: A cohort study in China

BACKGROUND

Preeclampsia is the main cause of maternal and perinatal death, especially in developing countries. Multiple studies suggest that blood lead levels in pregnancy are a risk factor for preeclampsia, even with low levels of blood lead. But less knows the dose-effect relationship of preeclampsia in low blood lead levels.

OBJECTIVES

This study aims to assess the association between blood lead levels and preeclampsia and to explore its dose-effect relationship between low blood lead levels and preeclampsia.

METHODS

The retrospective cohort study was consecutively conducted in a comprehensive tertiary hospital in Foshan city of Guangdong Province, China, from August 1, 2019, to November 30, 2019. Blood lead levels were measured in maternal whole blood in 12-27 (+6) weeks of pregnancy, using atomic absorption spectrometer. Preeclampsia diagnosis was ascertained from the electronic medical records system. The risk of preeclampsia was estimated by multivariable logical regression analysis, and a two-stage linear regression model was established to find out the dose-effect.

RESULTS

A total of 2174 people were included in this study, and 59 (2.7%) women developed preeclampsia. The dose-effect analysis revealed a non-linear association between blood lead levels and the risk of preeclampsia, with a cut-off point at 4.2 μg/dl. When blood lead levels were over 4.2 μg/dl, the risk of preeclampsia increased significantly with an increase in blood lead levels (OR = 2.05, 95%CI: 1.50, 2.81). In the multivariate regression models, per 1 μg/dl increment in blood lead levels was associated with 43% higher risk of developing preeclampsia (OR = 1.43,95%CI:1.17,1.74). Moreover, the association between blood lead levels and preeclampsia was stable in different subgroups.

CONCLUSIONS

Low levels of lead exposure had a dose-effect relationship of preeclampsia, with a cut-off point at 4.2 μg/dl. Blood lead levels had a non-linear association with preeclampsia. When the blood lead levels were higher than 4.2 μg/dl, the risk of preeclampsia increases by 105% for every 1 μg/dl increase in blood lead levels.

Insights into measurements of water-soluble ions in PM2.5 and their gaseous precursors in Beijing

To better understand the characteristics and transformation mechanisms of secondary inorganic aerosols, hourly mass concentrations of water-soluble inorganic ions (WSIIs) in PM_2.5 and their gaseous precursors were measured online from 2016 to 2018 at an urban site in Beijing. Seasonal and diurnal variations in water-soluble ions and gaseous precursors were discussed and their gas-particle conversion and partitioning were also examined, some related parameters were characterized. The (TNH₃) _Rich was also defined to describe the variations of the excess NH₃ in different seasons. In addition, a sensitivity test was carried out by using ISORROPIA II to outline the driving factors of gas-particle partitioning. In Beijing, the relative contribution of nitrate to PM_2.5 has increased markedly in recent years, especially under polluted conditions. In the four seasons, only a small portion of NO₂ in the atmosphere was converted into total nitrate (TNO₃)_, and more than 80% of TNO₃ occurred in the form of nitrate due to the abundant ammonia. The concentration of total ammonia (TNH₃) was much higher than that required to neutralize acid gases, and most of the TNH₃ occurred as gaseous NH₃. The nitrous acid (HONO) concentration was highly correlated with NH₃ concentration and had increased significantly in Beijing compared with previous studies. The total chloride (TCl) was the highest in winter, and ε(Cl^-) was more sensitive to variations in the ambient temperature (T) and relative humidity (RH) than ε(NO₃^-).

Monitoring and evaluating the control effect of dust suppressant on heavy metals based on ecological and health risks: a case study of Beijing

Dust suppressant is widely applied to control the road dust pollution, while the unified statement on its control effect has not been obtained. To fill this gap, an experiment was conducted at four typical sites in Beijing, where dust suppressant and water were sprayed at test and control sites, respectively. Samples were collected to analyze the concentrations of PM_2.5, PM₁₀, and heavy metals. With the application of potential ecological risk index and probabilistic health risk assessment, the ecological and health risks of heavy metals were obtained. Results showed that compared with control sites, the total concentrations of heavy metals in PM₁₀ and PM_2.5 at test sites decreased by 1555.40 and 784.95 ng/m³ in 14 days, with the suppression rate of 11.95% and 12.06%. Especially, the total ecological risks of heavy metals in PM₁₀ reduced from 165.77 to 143.64, with their ecological hazard level changed from medium to slight. The carcinogenic risks of PM_2.5 and PM₁₀ reduced by 0.60E-05 and 1.52E-06, respectively. As for the non-carcinogenic risks, there were a reduction of 5.78% and 12.28% for PM_2.5 and PM₁₀, respectively. Notably, the ecological risk of Pb was the highest; Cr and Zn contributed the most to carcinogenic and non-carcinogenic risk. Finally, to mitigate road dust pollution from an integration perspective, some preventive measures were proposed.

Evaluating the size distribution characteristics and sources of atmospheric trace elements at two mountain sites: comparison of the clean and polluted regions in China

Size-resolved trace metal concentrations at two background sites were assessed during a 1-year observation campaign, with the measurements performed in parallel at two mountain sites, where Mt. Dinghu (DHS) located in the rural region of Pearl River Delta (PRD) and Mt. Gongga (GGS) located in the Tibetan Plateau region. In total, 15 selected trace elements (Mg, Al, K, V, Mn, Fe, Cu, Zn, As, Mo, Ag, Cd, Ba, Tl, and Pb) in aerosol samples were determined using inductively coupled plasma mass spectrometry (ICPMS). The major metals in these two mountain sites were Fe, K, Mg, and Ca with concentrations ranging between 241 and 1452 ng/m³, 428 and 1351 ng/m³, 334 and 875 ng/m³, and 376 and 870 ng/m³, respectively, while the trace metals with the lowest concentrations were Mo, Ag, Cd, and Tl with concentrations lower than 4 ng/m³ in DHS and 2 ng/m³ in GGS. The pronounced seasonal variability in the trace elements was observed in DHS, with lower concentrations in spring and summer and relatively high in winter and autumn, whereas seasonal variance of trace elements is hardly observed in Mt. Gongga. The size distribution pattern of crustal elements of Al, Mg, K, Ba, and Fe was quite similar in DHS and GGS, which were mainly found in coarse particles peaked at 4.7-5.8 μm. In addition, V, Mo, Ag, and Tl were also concentrated in coarse particles, although the high enrichment factor (EF > 100) of which suggested anthropogenic origin, whereas trace metals of Cd, Mn, Zn, As, Cu, and Pb concentrated in fine mode particles. Specifically, these trace metals peak at approximately 1.5 μm in DHS, while those in GGS peaked at diameter smaller than 0.3 μm, indicating the responsible for long-range transport from the far urban and industrialized areas. Multivariate receptor model combined with the enrichment factor results demonstrated that the trace elemental components at these two background sites were largely contributed from the fossil fuel combustion (55.4% in DHS and 44.0% in GGS) and industrial emissions factors (20.1% vs. 26.5%), which are associated with long distance transport from the coastal area of Southeast China and the Northwestern India, respectively, as suggested by the backward air mass trajectory analysis. Local sources from soil dust contributed a minor variance for trace elements in DHS (9.7%) and GGS (13.8%), respectively.

Temporal Changes in Air Quality According to Land-Use Using Real Time Big Data from Smart Sensors in Korea

This study analyzed the changes in particulate matter concentrations according to land-use over time and the spatial characteristics of the distribution of particulate matter concentrations using big data of particulate matter in Daejeon, Korea, measured by Private Air Quality Monitoring Smart Sensors (PAQMSSs). Land-uses were classified into residential, commercial, industrial, and green groups according to the primary land-use around the 650-m sensor radius. Data on particulate matter with an aerodynamic diameter <10 µm (PM10) and <2.5 µm (PM2.5) were captured by PAQMSSs from September‒October (i.e., fall) in 2019. Differences and variation characteristics of particulate matter concentrations between time periods and land-uses were analyzed and spatial mobility characteristics of the particulate matter concentrations over time were analyzed. The results indicate that the particulate matter concentrations in Daejeon decreased in the order of industrial, housing, commercial and green groups overall; however, the concentrations of the commercial group were higher than those of the residential group during 21:00-23:00, which reflected the vital nighttime lifestyle in the commercial group in Korea. Second, the green group showed the lowest particulate matter concentration and the industrial group showed the highest concentration. Third, the highest particulate matter concentrations were in urban areas where commercial and business functions were centered and in the vicinity of industrial complexes. Finally, over time, the PM10 concentrations were clearly high at noon and low at night, whereas the PM2.5 concentrations were similar at certain areas.

Particle-induced oxidative damage by indoor size-segregated particulate matter from coal-burning homes in the Xuanwei lung cancer epidemic area, Yunnan Province, China

Size-segregated samples of airborne particulate matter were collected at the coal-burning homes of the Hutou high lung cancer epidemic village and a comparison site Xize village of the Xuanwei County, Yuanan Province, by an Anderson Cascade Impact Sampler in winter and spring to study the toxicological characteristics of different-sized particles. The DNA damage caused by the water-soluble fractions of these size-segregated particles was analyzed by the plasmid scission assay, and the trace element compositions were determined by Inductively Coupled Plasma Mass Spectrometry. The DNA damage rate from the airborne particles in the high lung cancer incidence area was higher than that in Xize village. The different-sized particles have highly varying DNA damage rates, with the values being greater in the small size range than in the large size range. The particle-induced DNA damage rates had a significantly positive correlation with total water-soluble trace elements. Further analysis of the individual elements indicated that the water-soluble heavy metals Zn, Cu, Cd, Rb, Cs, and Sb had a positive correlation with the particle-induced DNA damage, implying that these water-soluble heavy metals played an important role in the DNA damage. The Sr had a negative correlation with the particle-induced DNA damage, suggesting that the water-soluble Sr might counter DNA damage. The mass concentrations of the total and individual water-soluble trace elements were mostly enriched in the small particle size ranges, thus implying the indoor airborne particles in the small size ranges would have a higher health risk.

Pollution characteristics and chronic health risk assessment of metals and metalloids in ambient PM2.5 in Licheng District, Jinan, China

PM_2.5 samples were collected at the Wangsheren primary school site in Licheng District of Jinan, China, during 2016. Eleven metals and metalloids including Al, As, Be, Cd, Cr, Hg, Mn, Ni, Pb, Sb and Se in PM_2.5 were measured by inductively coupled plasma-mass spectroscopy. The annual average mass concentration of PM_2.5 was found to be 88.7 μg m^-3. The highest PM_2.5 concentrations were obtained during the heating seasons of winter and spring. The concentrations of metals and metalloids in PM_2.5 were in a descending order of Al, Pb, Mn, As, Se, Cr, Sb, Ni, Cd, Hg and Be. The enrichment factors showed that Pb, Mn, As, Se, Cr, Sb, Ni, Cd, Hg originated from anthropogenic sources. Factor analysis indicated that the main sources of the metals were coal combustion dust, soil dust, metallurgical industry, brake abrasion of vehicles and other mixed sources. Coal combustion dust was the primary source of metal pollution in PM_2.5. Non-carcinogenic risks associated with exposure through the respiratory system were between 6.30 × 10^-4 and 7.62 × 10^-1, which were lower than the safe limit (1). The carcinogenic risks of Cr, As and Cd were 3.17 × 10^-5, 1.52 × 10^-5, 2.22 × 10^-6, respectively, which were higher than the precautionary criterion (10^-6/year). This study indicates that the air pollution of PM_2.5 is of public health concern in Licheng District of Jinan, particularly related to potential carcinogenic metals of As, Cr and Cd. Intervention action is needed to reduce the emission sources of these elements, especially coal combustion in winter heating season.

Assessment of Air Quality in School Environments in Hanoi, Vietnam: A Focus on Mass-Size Distribution and Elemental Composition of Indoor-Outdoor Ultrafine/Fine/Coarse Particles

Indoor and outdoor ultrafine, accumulation mode, and coarse fractions collected at two preschools (S1 and S2) in Hanoi capital, Vietnam were characterized in terms of mass-size distribution and elemental composition to identify major emission sources. The sampling campaigns were performed simultaneously indoors and outdoors over four consecutive weeks at each school. Indoor average concentrations of CO2 and CO at both schools were below the limit values recommended by American Society of Heating, Refrigerating and Air-Conditioning Engineers (1000 ppm for CO2) and World Health Organization (7 mg/m3 for CO). Indoor concentrations of PM2.5 and PM10 at S1 and S2 were strongly influenced by the presence of children and their activities indoors. The indoor average concentrations of PM2.5 and PM10 were 49.4 µg/m3 and 59.7 µg/m3 at S1, while those values at S2 were 7.9 and 10.8 µg/m3, respectively. Mass-size distribution of indoor and outdoor particles presented similar patterns, in which ultrafine particles accounted for around 15–20% wt/wt while fine particles (PM2.5) made up almost 80% wt/wt of PM10. PM2.5–10 did not display regular shapes while smaller factions tended to aggregate to form clusters with fine structures. Oxygen (O) was the most abundant element in all fractions, followed by carbon (C) for indoor and outdoor particles. O accounted for 36.2% (PM0.5–1) to 42.4% wt/wt (PM0.1) of indoor particles, while those figures for C were in the range of 14.5% (for PM0.1) to 18.1% (for PM1–2.5). Apart from O and C, mass proportion of other major and minor elements (Al, Ca, Cr, Fe , K, Mg, Si, Ti) could make up to 50%, whereas trace elements (As, Bi, Cd, Co, Cr, Cu, La, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sn, Sr, and Zn) accounted for less than 0.5% of indoor and outdoor airborne particles. There were no significant indoor emission sources of trace and minor elements. Traffic significantly contributed to major and trace elements at S1 and S2.

Does atmospheric processing produce toxic Pb-containing compounds? A case study in suburban Beijing by single particle mass spectrometry

A single particle aerosol mass spectrometry (SPAMS) was deployed to investigate the mixing state and chemical processing of Pb-rich particles in suburban Beijing. Based on a large dataset of mass spectra, Pb-rich particles were classified into Pb-O-Cl-N-S (55%), Pb-N (17%), Pb-N-S (15%), and Pb-EC (7%). Residual coal combustion, industrial activities, and meteorological conditions were identified as main factors regulating the variations of Pb-rich particles in the atmosphere. The highest abundance of the Pb-rich particles was observed during heating period (HP) primarily due to the increase in coal usage. Pb in Pb-O-Cl-N-S type was identified in forms of PbO, PbCl_2, and Pb(NO₃)₂. Dominantly presented in the form of Pb(NO₃)₂, Pb-N type represented the completely transformed Pb-rich particles from PbO/PbCl₂ by atmospheric processes. It is found that PbCl₂ and PbO could be transformed to Pb(NO₃)₂, highly dependent on the amount of NO₂ and RH. Significant enhancement of nitrate in Pb-O-Cl-N-S particles was observed when the RH was greater than 60%, emphasizing the importance of heterogeneous hydrolysis of N₂O₅ on the formation of Pb(NO₃)_2. Compared with non-carcinogenic PbCl₂/PbO and insoluble PbO, soluble and carcinogenic Pb(NO₃)₂ produced by atmospheric processes may significantly enhance negative effects of Pb-rich particles on human health and the ecosystem.

Size-resolved measurements of PM2.5 water-soluble elements in Iasi, north-eastern Romania: Seasonality, source apportionment and potential implications for human health

The present paper reports the first size-resolved element measurements in the PM_2.5 fraction collected throughout 2016 in the Iasi urban area in north-eastern Romania. Concentrations of water-soluble elements (Ag, Al, As, B, Ba, Be, Bi, Cd, Co, Cu, Cr, Fe, Ga, Mg, Mn, Mo, Ni, Pb, Rb, Se, Sr, Te, Ti, U, V, Zn) were determined using inductively coupled plasma mass spectrometry. Several water-soluble heavy metals (Al, Fe, Zn, As, Cr, Pb) exhibit clear seasonal patterns with maxima over the cold season and minima over the warm season. Elements as Al, Fe, Mg, Zn, Ni, Mn, and Cu present the highest levels in the PM_2.5 fraction, indicating significant contributions from soil-dust resuspension or brake lining and tires. Clear fine mode size-dependent distributions were observed for anthropogenic source-origin elements (Pb, Zn, Cd, V, etc.) due to an acidity-driven metals dissolution process. Positive matrix factorization, concentration weighted trajectory and bivariate polar plot analyses were applied to the entire PM_2.5 database. Based on relative concentrations of various elements, five factors associated with specific sources were identified. The most important contributions to the total PM_2.5 mass concentration (during the total period) come from secondary formation of the ammonium sulfate form (~44%) and from nitrate (~37%). Resuspended dust accounts for a contribution of about 16%, while biomass burning mixed with NaCl salt/sea-salt sources contribute as much as ~3%. Traffic and industrial sources seem to yield little contribution (<0.05%). An assessment investigation of non-carcinogenic and carcinogenic health risks revealed water-soluble arsenic and chromium (VI) as elements with the largest incremental carcinogenic risks. Both metals have traffic and industrial related sources and therefore it is believed that in the future, at the local/regional level, these sources should receive attention by implementing appropriate emission control measures.

Lead isotope trends and sources in the atmosphere at the artificial wetland

With the rapid development of industry, studies on lead pollution in total suspended particulate matter (TSP) have received extensive attention. This paper analyzed the concentration and pollution sources of lead in the Cuihu Wetland in Beijing during the period of 2016–2017. The results show that the lead contents in TSP in the Cuihu Wetland were approximately equal in summer and spring, greater in winter, and greatest in autumn. The corresponding lead concentrations were 0.052, 0.053, 0.101, and 0.115 ng/m³, respectively. We compared the ²⁰⁶Pb/²⁰⁷Pb data with other materials to further understand the potential sources of atmospheric lead. The mean values of ²⁰⁶Pb/²⁰⁷Pb from spring to winter were 1.082, 1.098, 1.092, and 1.078, respectively. We found that the lead sources may be associated with coal burning, brake and tire wear, and vehicle exhaust emissions. We also calculated the enrichment factor values for the four seasons, and the values were all much greater than 10, indicating that the lead pollution is closely related to human activities.

Assessment of trends and emission sources of heavy metals from the soil sediments near the Bohai Bay

Anthropogenic emission sources (mainly vehicular and industrial emission) are one of the major emission sources of the heavy metals in aquatic ecosystems which have significant potential to perturb the marine geochemistry and ecosystem as well as human life also. In the present study, we tried to investigate the accumulation of heavy metals (Zn, Cr, Ni, Cu, Pb, Co, As, Cd, and Hg) at two sediment cores near the Bohai Bay in Southern Tianjin and reconstruct their historical trends over the last hundred years to understand the impacts of anthropogenic activities. The concentration of Zn and Cr is found maximum than the other studied heavy metals. Results suggest that in the mid-twentieth century, the maximum concentrations of Zn, Cr, Ni, Cu, and Pb are mainly because of the opening of Dagang Oilfield which emits a huge amount of heavy metals into the environment. Source apportionment analysis has been carried out using positive matrix factorization (PMF) model which suggests three major emission sectors of heavy metals, i.e., coal combustion, manufacturing, and smelting dust, having different contribution 32%, 40%, and 28% respectively to the total heavy metal burden. Industrial emissions are found to be the major sources of Cr, Ni, and Co while Pb is mainly originated from the coal combustion. The risk assessment analysis shows the value of mean effects range median (ERM) quotients ~ 0.17 for the two sediment cores which suggest nearly 21% toxicity of the studied metals indicating towards the policymakers for the mitigation of air pollution surrounding Tianjin.

Temporal Variation and Chemical Components of Rural Ambient PM2.5 during Main Agricultural Activity Periods in the Black Soil Region of Northeast China

Agricultural emissions are crucial to regional air quality in the autumn and spring due to the intense agricultural activities in Northeast China. However, information on rural ambient particulate matter (PM) in Northeast China is rare, limiting the accurate estimation of agricultural atmospheric particulate matter emissions. In this study, we monitored hourly ambient PM2.5 (PM with a diameter of less than 2.5 μm) concentrations and analyzed daily chemical components (i.e., water-soluble ions, trace elements, organic carbon, and element carbon) at a rural site in Northeast China during the autumn and spring and assessed the impact of agricultural activities on atmospheric PM2.5 concentrations. The results showed that the daily average concentrations of PM2.5 were 143 ± 109 (range: 39–539) μg m−3 from 19 October to 23 November 2017 (i.e., typical harvesting month) and 241 ± 189 (range: 97–976) μg m−3 from 1 April to 13 May 2018 (i.e., typical tilling month). In autumn, the ambient PM2.5 concentrations were high with a Southwest wind, while a Southeast wind caused high PM2.5 concentrations during spring in the rural site. The concentrations of selected water-soluble ions, trace elements, and carbonaceous fractions accounted for 33%, 4%, and 26% of PM2.5 mass concentrations, respectively, in autumn and for 10%, 5%, and 3% of PM2.5 mass concentrations, respectively, in spring. On the basis of the component analysis, straw burning, agricultural machinery, and soil dust driven by wind and tilling were the main contributors to high rural PM2.5 concentrations. In addition, the increasing coal combustion around the rural site was another important source of PM2.5.

Impact of New Year's Eve fireworks on the size resolved element distributions in airborne particles

New Year's Eve fireworks represent one of the most unusual atmospheric pollution events in the course of a year. A majority of particles aerosolized by burning of fireworks consist of metals and their compounds used in firework displays. In this study, ambient particulate matter was sampled using a 14 stage cascade impactor in two European cities during turn of the years 2016/17 and 2017/18. Concentrations of 33 elements were determined by inductively coupled plasma mass spectrometry. To assess the impact of New Year's Eve fireworks on ambient air quality, chemically resolved size distributions of particles with diameters between 15 nm and 10 μm collected during fireworks episodes were compared to ones collected in normal winter weeks. For some metals a distinct shift of their concentration maximum related to fireworks could be observed, which is in between the maxima for accumulation and coarse mode particles. Concentrations of these elements (Sr, Ba, Mg, Bi, Al, Cu and K) were also higher during weeks with fireworks episodes than during control weeks. Although New Year's Eve fireworks only take place once a year, these results show that air pollution caused by fireworks can be a potential health risk, especially for people with pre-existing diseases.

Different health effects of indoor- and outdoor-originated PM2.5 on cardiopulmonary function in COPD patients and healthy elderly adults

Numerous research has explored the associations of outdoor or indoor fine particulate matter (PM_2.5 ) and health effects; however, few studies compared the effects of indoor PM_2.5 originated from outdoor (PM_2.5,os ) and indoor sources (PM_2.5,is ). To assess the associations of PM_2.5,os and PM_2.5,is with cardiopulmonary function in patients with chronic obstructive pulmonary disease (COPD) and healthy elderly adults, blood pressure (BP) and pulmonary function were repeatedly examined in 43 COPD patients and their 32 healthy spouses in Beijing, China. Iron was used as tracer element to separate PM_2.5,os and PM_2.5,is . Mixed-effects models were applied to assess the associations of PM_2.5,os or PM_2.5,is and health effects after controlling for potential confounders. There was a reduction in forced expiratory volume in first second (FEV₁ ) in COPD patients associated with PM_2.5,is during the heating season. PM_2.5,os was positively associated with diastolic BP (DBP) in healthy elderly adults during the heating season. There was a reduction in peak expiratory flow (PEF) in healthy elderly adults associated with PM_2.5,os during the non-heating season. Exposure to indoor- and outdoor-originated PM_2.5 had different health effects on cardiopulmonary function in different populations. The results provide supporting evidence for improving indoor air quality to promote public health among susceptible population.

Arsenic speciation in aerosols of a respiratory therapeutic cave: A first approach to study arsenicals in ultrafine particles

Arsenic is ubiquitous in the environment and of special concern due to its varying toxicity depending on the chemical form present. Less is known about arsenic in air, especially about organoarsenicals, their sources and fate. There is also a lack of knowledge regarding arsenic in airborne nanoparticles that are critical for understanding with respect to human health effects due to their size. Here we show results from an arsenic speciation analysis in size-resolved airborne particles with aerodynamic diameters down to 15 nm. Analysis of aerosols from a respiratory therapeutic cave showed temporarily higher concentrations of trimethylarsine oxide than inorganic arsenic and substantial amounts of organoarsenicals, especially in smaller particles. Our method provides guidance for future studies investigating arsenicals in ultrafine particles and their health implications. Furthermore, the method developed can be used to widely monitor particle-bound organoarsenicals to fully understand the importance of As biovolatilization in the environment.

Characteristics and sources of trace elements in PM2.5 in two megacities in Sichuan Basin of southwest China

To characterize major trace elements in PM_2.5 and associated sources in two megacities, Chengdu (CD) and Chongqing (CQ), in Sichuan Basin of southwest China, daily PM_2.5 samples were collected at one urban site in each city from October 2014 to July 2015 and were analyzed for their contents of thirteen trace elements including four crustal elements (Al, Ca, Fe, and Ti), eight trace metals (K, Cr, Zn, Cu, Mn, Pb, Ni, and V), and As. Multiple approaches including correlation analysis, enrichment factor, principal component analysis, and conditional probability function (CPF) were applied to identify potential sources of these elements. Most of the measured trace elements in Sichuan Basin were found to have lower concentrations than in the other regions of China. K and Fe were the most abundant elements at CD with an annual mean concentrations of 720 ± 357 and 456 ± 248 ng m^-3, accounting for 34.6% and 21.9% of the total analyzed trace elements, respectively. Ca presented the highest concentration among all of the elements at CQ with annual mean of 824 ± 633 ng m^-3 (29.1% of the total). Crustal elements had the highest concentrations in spring while heavy metals had distinct seasonal variations typically with the highest concentrations in winter and the lowest in summer. Ti and Al were identified to be primarily from soil while most of the analyzed heavy metals (Cr, Mn, Cu, Zn, Pb, Ni) and As were from anthropogenic sources associated with coal combustion, industrial emission from glassmaking production and iron/steel manufacturing, and non-exhaust vehicle emission.

Chemical composition of outdoor and indoor PM2.5 collected during haze events: Transformations and modified source contributions resulting from outdoor-to-indoor transport

Changes in the chemical constitution and sources of ambient PM_2.5 following the infiltration of air into indoor environments were investigated. We collected PM_2.5 samples from air inside and outside 31 rooms in Beijing residences during hazy episodes. We calculated the indoor-to-outdoor ratios and the correction (kⁱ ) of each infiltration factor for each chemical component of PM_2.5 to determine the effects of infiltrative behavior. The outdoor and indoor mass concentrations of PM_2.5 during the sampling period were 70-460 and 10-315 μg/m³ , respectively. Differences in the average indoor-to-outdoor ratios of PM_2.5 mass and each component (mean value ± standard deviation: PM_2.5 mass = 0.53 ± 0.26, organic matter = 0.75 ± 0.34, elemental carbon = 0.62 ± 0.31, trace elements = 0.62 ± 0.26, SO 4 2 - = 0.67 ± 0.32 , NH 4 + = 0.53 ± 0.54 , NO 3 - = 0.45 ± 0.36 , Cl^- = 0.37 ± 0.35, and crustal dust = 0.30 ± 0.19) may be attributed to size distribution, chemical properties, temperature, and humidity. The positive matrix factorization model was applied to calculate the source contributions to equivalent population exposure (Indoor concentration·Indoor time fraction + Outdoor concentration·Outdoor time fraction). The contributions of fossil fuel combustion, secondary source, vehicle exhaust, and mixed dust to the equivalent PM_2.5 population source exposure were 37%, 24%, 22%, and 17%, respectively.

Bioaccessibility and exposure assessment of trace metals from urban airborne particulate matter (PM10 and PM2.5) in simulated digestive fluid

We describe a batch-extraction with simulated digestive fluid (salivary fluid, gastric fluid and intestinal fluid) to estimate the bioaccessibility of inhaled trace metals (TMs) in particulate matter less than 10 and 2.5 μm in aerodynamic diameter (PM₁₀ and PM_2.5). Concentrations of the assayed TMs (As, Cd, Cr, Ni, Mn, Cu, Zn, Sb, Hg and Pb) were determined in PM₁₀ and PM_2.5 samples by inductively coupled plasma-mass spectrometry. The TMs with the largest soluble fractions for airborne PM collected from winter and summer in saliva were Mn and Sb, respectively; in seasons this became Co in gastric fluid and Cu in intestinal fluid. Clearly, bioaccessibility is strongly dependent on particle size, the component of simulated digestive fluids (e.g., pH, digestive enzymes pepsin and trypsin), and the chemical properties of metal ions. The particle size and seasonal variation affected the inhaled bioaccessible fraction of PM-bound TMs during mucociliary clearance, which transported PM from the tracheal and the bronchial region to the digestive system. This study provides direct evidence for TMs in airborne PM being bioaccessible TMs are likely to possess an enhanced digestive toxic potential due to airborne PM pollution.

Highly time-resolved aerosol characteristics during springtime in Weizhou Island

A single particle aerosol mass spectrometer was deployed to measure the changes of single particle species and sizes during March 2015 in Weizhou Island of the Beibu Gulf, Guangxi province, South China. In this campaign, a total of 3,100,597 particles were sized, and 25.8% particles with both positive and negative mass spectrum were collected and 24.8% characterized in combination with the ART-2a neural network algorithm. The distribution of sized particles was mainly in from 520 to 600nm, and the diameters ranging from 340 to 1000nm accounted for above 90%. Eight types of particles were classified: Elemental Carbon containing (EC), Organic Carbon containing (OC), EC and OC combined containing particles, Na containing particles, K containing particles (K), Levoglucosan containing particles, mineral containing particles, and Heavy Metal containing particles (HM). EC, OC and K were the major containing particles, which accounted for 84.3% in the eight types particles. The relative ratio and size distribution of the three types were EC (48.1%, 620nm), OC (12.7%, 440nm), and K (23.5%, 600nm), respectively. The three types of particles were a bit increasing ratios compared with those in clean periods during haze pollution periods. Combined with the back-trajectory results from the Hysplit-4 model and local pollution sources revealed that the ambient air quality on the Weizhou Island may be influenced by biomass burning in the Indochina Peninsula (biomass burning in the Indochina Peninsula) from the transportation on higher level atmospheric layer and by mainland of south China located northeast of Weizhou Island on the ground.

Particulate matter pollution in Kunshan High-Tech zone: Source apportionment with trace elements, plume evolution and its monitoring

Particulate matter (PM) in the Kunshan High-Tech zone is studied during a three-month campaign. PM and trace elements are measured by the online pollution monitoring, forecast-warning and source term retrieval system AS3. Hourly measured concentrations of PM₁₀, PM_2.5 and 16 trace elements in the PM_2.5 section (Ca, Pb, Cu, Cl, V, Cr, Fe, Ti, Mn, Ni, Zn, Ga, As, Se, Sr, Ba) are focused. Source apportionment of trace elements by Positive Matrix Factorization modeling indicates that there are five major sources, including dust, industrial processing, traffic, combustion, and sea salt with contribution rate of 23.68%, 21.66%, 14.30%, 22.03%, and 6.89%, respectively. Prediction of plume dispersion from concrete plant and traffic emissions shows that PM₁₀ pollution of concrete plant is three orders of magnitude more than that of the traffic. The influence range can extend to more than 3km in 1hr. Because the footprint of the industrial plumes is constantly moving according to the local meteorological conditions, the fixed monitoring sites scattered in a few hundred meters haven't captured the heaviest pollution plume at the local scale of a few km². As a more intensive monitoring network is not operationally possible, the use of online modeling gives accurate and quantitative information of plume location, which increases the spatial pollution monitoring capacity and improves the understanding of measurement data. These results indicate that the development of the AS3 system, which combines monitoring equipment and air pollution modeling systems, is beneficial to the real-time pollution monitoring in the industrial zone.

Size distribution and source of heavy metals in particulate matter on the lead and zinc smelting affected area

In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter (PM) and the source samples were collected in Zhuzhou, Hunan Province from December 2011 to January 2012 and the results were discussed and interpreted. Atmospheric particles were collected with different sizes by a cascade impactor. The concentrations of heavy metals in atmospheric particles of different sizes, collected from the air and from factories, were measured using an inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that the average concentration of PM, chromium (Cr), arsenic (As), cadmium (Cd) and lead (Pb) in PM was 177.3 ± 33.2 μg/m³, 37.3 ± 8.8 ng/m³, 17.3 ± 8.1 ng/m³, 4.8 ± 3.1 ng/m³ and 141.6 ± 49.1 ng/m³, respectively. The size distribution of PM displayed a bimodal distribution; the maximum PM size distribution was at 1.1-2.1 μm, followed by 9-10 μm. The size distribution of As, Cd and Pb in PM was similar to the distribution of the PM mass, with peaks observed at the range of 1.1-2.1 μm and 9-10 μm ranges while for Cr, only a single-mode at 4.7-5.8 μm was observed. PM (64.7%), As (72.5%), Cd (72.2%) and Pb (75.8%) were associated with the fine mode below 2.1 μm, respectively, while Cr (46.6%) was associated with the coarse mode. The size distribution characteristics, enrichment factor, correlation coefficient values, source information and the analysis of source samples showed that As, Cd and Pb in PM were the typical heavy metal in lead and zinc smelting affected areas, which originated mainly from lead and zinc smelting sources.

Indoor-outdoor association of particulate matter and bounded elemental composition within coarse, quasi-accumulation and quasi-ultrafine ranges in residential areas of northern India

Attempts have been made to comprehend size distribution pattern of Particulate Matter (PM) and associated elemental concentration within coarse (2.5-10μm), quasi-accumulation (q-Acc) (0.25-2.5μm) and quasi-ultrafine (q-UF) (<0.25μm) ranges at indoors and outdoors of residential homes of Agra. Overall, the average mass concentrations of PM₁₀ and PM_2.5 in indoors were found to be 263.24±59.24 and 212.01±38.06μgm^-3 while in outdoors the concentrations accounted to 194.28±15.25 and 152.88±16.31μgm^-3 respectively; exceeding WHO standards. In view of geographical variation, significantly higher (t=2.461; P=0.044) PM mass was found in outdoor samples of roadside location when compared to homes located far away from busy traffic; whereas indoor concentration exhibited non-significant relationship (t=1.887; P=0.095) between the two categorized homes. Findings of size partitioning trend through deployment of Sioutas Cascade Impactor evidenced presence of high proportion of PM and elemental concentrations within q-Acc and q-UF modes with their distribution pattern and probable emission sources conferred upon. Absence of modal peak in coarse range indicated predominance of anthropogenic emissions with presumed wash-out of coarse particles during frequent precipitation coincidental with sampling event. Seeming modal shifts for some elements (K, Cd, Zn) from q-Acc to q-UF were perceived during infiltration process. Presence of high traffic emission in homes near busy road stemmed the shifting of particles (Cu, K, Co, Zn) towards finer size (preferably q-UF mode) thus exposing residents to adverse health effects through their penetration (Finf=0.14) into indoor environment. Flat slopes (0.11) and poor correlation (8.4%) for metals in coarser range obtained through regression model hypothesized their high deposition velocities and low penetration efficiency. Our findings suggest enhanced resident exposure to fine particles (81%) especially q-UF range (37%) through indoor and outdoor (through infiltration) sources along with complexity of size distribution of airborne particles that prerequisites surplus consideration to achieve a healthier environment within residential area.

The influence of air cleaners on indoor particulate matter components and oxidative potential in residential households in Beijing

In many developing regions with poor air quality, the use of air filtration devices to clean indoor air is growing rapidly. In this study, we collected indoor, outdoor and personal exposure filter-based samples of fine particulate matter (PM_2.5) with both properly operating, and sham air cleaners in six Beijing residences from July 24th to August 17th, 2016. Mass concentrations of PM_2.5 and several health relevant components of PM_2.5 including organic carbon, elemental carbon, sulfate, nitrate, ammonium, and 21 selected metals, were analyzed to evaluate the effectiveness of air cleaners. The effect of air purification on PM_2.5 reactive oxygen species (ROS) activity, a metric of the oxidative potential of the aerosol, was also evaluated. The average indoor PM_2.5 concentration during true filtration was 8.47μg/m³, compared to 49.0μg/m³ during sham filtration; thus, air cleaners can significantly reduce the indoor PM_2.5 concentration to well below WHO guideline levels and significantly lower all major components of PM_2.5. However, the utility of air cleaners in reducing overall personal exposure to PM_2.5 and its components was marginal in this study: the average personal exposure PM_2.5 concentration was 67.8 and 51.1μg/m³ during true and sham filtration respectively, and it is likely due to the activity patterns of the subjects. Short-term exposure contributions from environments with high PM_2.5 concentrations, including exposure to traffic related emissions as well as uncharacterized indoor microenvironments, likely add substantially to the total PM_2.5 exposure burden. The toxicity assay indicates that the air cleaners can also significantly reduce ROS activity in the indoor environment; however, this decrease did not translate to a reduction in personal exposure. Elemental carbon, lead, and arsenic were well-correlated with the ROS activity, thus adding to the knowledge base of drivers for ROS activity.

Puerarin inhibits vascular smooth muscle cells proliferation induced by fine particulate matter via suppressing of the p38 MAPK signaling pathway

Background

Fine particulate matter (PM2.5) is a major risk factor for the development and progression of atherosclerosis. Proliferation and infiltration of vascular smooth muscle cells (VSMCs) from the blood vessel media into the intima is a crucial step in the pathophysiology of atherosclerosis. Puerarin, a natural extract from Radix Puerariae, possesses significant anti-atherosclerosis properties. However, the underlying molecular mechanisms responsible for the effect of puerarin on the VSMCs proliferation induced by PM2.5 remain unclear. The present study was designed to examine the effect of puerarin on PM2.5-induced VSMCs proliferation, and to explore the p38 mitogen-activated protein kinase (p38 MAPK) signal mechanism involved.

Methods

VSMCs viability was measured by CCK-8 assay, VSMCs proliferation was assessed by BrdU immunofluorescence, the levels of superoxide dismutase (SOD) and malonaldehyde (MDA) were assayed by colorimetric assay kits, the levels of nitric oxide (NO) and endothelin-1 (ET-1) were determined by nitrate reductase method and radioimmunoassay, the levels of vascular cell adhesion molecule-1 (VCAM-1), interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were measured by ELISA. The protein expressions of phospho-p38 MAPK (p-p38 MAPK) and proliferating cell nuclear antigen (PCNA) in the VSMCs were subjected by Western blot.

Results

Compared to the PM2.5-treated cells, in addition to inhibiting the PM2.5-induced VSMCs proliferation, puerarin also down-regulated the protein expressions of p-p38 MAPK and PCNA, decreased the levels of ET-1, VCAM-1, IL-6, TNF-α and MDA, increased the levels of NO and SOD. Moreover, the anti-proliferative effects of puerarin were significantly enhanced by the co-incubation of puerarin with SB203580, a selective inhibitor of p38 MAPK, as compared to the puerarin-treated cells.

Conclusion

These results suggest that puerarin might suppress the PM2.5-induced VSMCs proliferation via the inhibition of the p38 MAPK signaling pathway.

Source Apportionment and Influencing Factor Analysis of Residential Indoor PM2.5 in Beijing

In order to identify the sources of indoor PM2.5 and to check which factors influence the concentration of indoor PM2.5 and chemical elements, indoor concentrations of PM2.5 and its related elements in residential houses in Beijing were explored. Indoor and outdoor PM2.5 samples that were monitored continuously for one week were collected. Indoor and outdoor concentrations of PM2.5 and 15 elements (Al, As, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Pb, Se, Tl, V, Zn) were calculated and compared. The median indoor concentration of PM2.5 was 57.64 μg/m³. For elements in indoor PM2.5, Cd and As may be sensitive to indoor smoking, Zn, Ca and Al may be related to indoor sources other than smoking, Pb, V and Se may mainly come from outdoor. Five factors were extracted for indoor PM2.5 by factor analysis, explained 76.8% of total variance, outdoor sources contributed more than indoor sources. Multiple linear regression analysis for indoor PM2.5, Cd and Pb was performed. Indoor PM2.5 was influenced by factors including outdoor PM2.5, smoking during sampling, outdoor temperature and time of air conditioner use. Indoor Cd was affected by factors including smoking during sampling, outdoor Cd and building age. Indoor Pb concentration was associated with factors including outdoor Pb and time of window open per day, building age and RH. In conclusion, indoor PM2.5 mainly comes from outdoor sources, and the contributions of indoor sources also cannot be ignored. Factors associated indoor and outdoor air exchange can influence the concentrations of indoor PM2.5 and its constituents.

Assessment of long-term exposure to airborne dioxin and cadmium concentrations in the Lyon metropolitan area (France)

Identifying the long-term effects of airborne pollutants requires the computation of the spatial and temporal variability of their concentration in air to estimate the exposure of the population. To estimate exposure levels of individuals in a breast cancer case control study nested in a national prospective cohort, we determine here the differential impact of a variety of cadmium and dioxin sources on urban air over a large urban area and over a period of almost 20years. To that end, we couple an emission model, to estimate dioxin and cadmium atmospheric annual releases, with an urban dispersion model in order to compute pollutant concentration fields at a fine temporal (1h) and spatial (25m) resolution. The reliability of the modelling chain is compared to two types of measurement: i) localized industrial emissions and ii) dioxin and cadmium air monitoring data (from 2007 to 2008), collected at a fixed station, placed in the city centre, as well as at three mobile short-term dioxin monitoring stations, located in the suburbs (the latter providing dioxin data, only). Comparisons between measured and estimated emissions show non-negligible difference, with a correlations for dioxin (r_s=0.42) and cadmium (r_s=0.41). Despite this, mean values between estimated emissions and emission measurements are close to each other, in particular for cadmium. Weekly average modelled concentrations show an overall good agreement with weekly average measured concentrations in spring and summer but are generally lower than monitored data in winter due to peak concentrations from diffuse sources representing an important proportion of emissions in 2007/2008. The model provides better results for cadmium than for dioxin. Despite the relevant errors in the model predictions, the model meets the validation criteria, defined by Chang and Hanna for an urban dispersion model. Simulation scenarios of air pollutant concentrations, reconstructed over the last 20years, show the effects of the variability of the pollutant sources over time with decreasing levels of dioxin and cadmium concentrations in air. This is primarily due to the reduction in localized industrial releases, which results in a general trend of homogenization of the exposure of the population. The model further allows us to dissociate the contribution of different types of pollutant sources on the population exposure. The impact on local concentrations due to industrial emissions, which were originally responsible for the major impact on air quality, is shown to drop over the years by 99% and 92% for dioxin and cadmium, respectively. Today, the major contributions are due to diffuse miscellaneous sources in the case of dioxin and to traffic-related emissions for cadmium. Average modelled concentrations at the study subjects' residential locations range from 10.2 to 82.1fg-TEQ/m³ for dioxin and 0.10 to 1.6ng/m³ for cadmium and are comparable with data from the literature. The study results will be essential to increase the accuracy of the assessment of long-term airborne dioxin and cadmium exposure and improve the results of epidemiological studies.

Characteristics of elemental and Pb isotopic compositions in aerosols (PM10-2.5) at the Ieodo Ocean Research Station in the East China Sea

A total of 82 aerosol samples (PM_10-2.5) were collected from June 18, 2015 to October 1, 2016 at the remote sea site, the Ieodo Ocean Research Station (IORS), in the East China Sea. Samples were analyzed for 10 elements (Al, Fe, Cu, Zn, As, Mo, Cd, Sb, Tl, and Pb) as well as Pb isotopic composition to characterize temporal variations in elemental concentration levels, and to identify the potential source regions of atmospheric pollutants transported over the remote East China Sea. The results showed that the annual average element concentrations were lowest compared to those at different sites in East Asia, suggesting a very clean background area of IORS, with values ranging from 114 ng m^-3 for Al to 0.045 ng m^-3 for Tl. Concentrations averaged seasonally for all the elements revealed the highest levels occurring between winter and spring, and the lowest levels in summer. High enrichment factors (EF) of more than 100 for trace elements suggest that these elements originated mostly from anthropogenic sources. Coupling the Pb isotopic composition with a back trajectory analysis identified the potential source regions for each sample. Our approach identified China as a dominant contributor affecting atmospheric composition changes at IORS, the remote area of the East China Sea. As the largest anthropogenic emission source in East Asia, China contributed to almost 100% of the elemental concentration levels in winter and spring, ∼53% in summer and ∼63% in autumn. Because IORS's ambient air is sensitive to even slight changes in pollutant loading due to the significantly low pollution levels, long-term monitoring of air quality at IORS will provide invaluable information on the progress and efforts of atmospheric pollution management linked to emission controls in East Asian countries, especially China.

Spatial and Temporal Distributions of Air Pollutants and Size Distribution of Aerosols over Central and Eastern China

The origins and spatial and temporal distributions of air pollutants (PM_2.5, PM₁₀, CO, SO₂, NO₂ and O₃) during May to June of 2015 were investigated using data from 1490 monitoring sites in China. Aerosol number concentrations and meteorological data from Shijiazhuang, Nanjing, and Suzhou were combined with the MIX Asian emission data and the HYSPLIT model. Furthermore, the diurnal variation, size distribution, and main sources of air pollutants and aerosols were selectively characterized in the North China Plain (NCP) and the Yangtze River Delta (YRD). High values of particulate matter concentrations (PM), including PM_2.5 and PM₁₀, occurred in the northwestern and central regions of eastern China. Elevated PM_2.5 and PM₁₀ concentrations represented natural dust sources and anthropogenic resident, power plant, industry, and traffic emissions sources, respectively. The concentrated distributions of SO₂ were similar to those of PM. The CO concentrations were distributed uniformly in China. High O₃ values occurred above the Qinghai province. During the observation period, the air masses mainly originated from the northwest NCP and from the southwest or northeastern ocean in the YRD, resulting in high concentrations of PM_2.5, PM₁₀, SO₂, and CO in the NCP, the average values of which were 61.8 ± 40.0, 118.8 ± 66.4, 24.1 ± 24.6 μg m^-3, and 1.2 ± 0.9 mg m^-3, respectively, and were 1.2, 1.4, 1.5, and 1.3 times larger than those in the YRD. NO₂ had higher concentrations in the YRD with an average of 43.7 ± 24.8 μg m^-3, which was 1.2 times larger than that in the NCP. The diurnal variations of PM, NO₂ and CO had bimodal distributions and SO₂ and O₃ had unimodal distributions in the NCP and YRD. The aerosol number concentrations had average values of 12,661 ± 5266, 11,189 ± 5905, and 12,797 ± 5931 cm^-3 in Shijiazhuang, Nanjing, and Suzhou. Their diurnal variations displayed trimodal peaks at 18:00-21:00, 11:00-14:00, and 06:00-08:00, and their spectra distributions were all unimodal with peaks at 60-70, 60-70, and 100-110 nm, respectively.

Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China

Fine-particle pollution associated with winter haze threatens the health of more than 400 million people in the North China Plain. Sulfate is a major component of fine haze particles. Record sulfate concentrations of up to ~300 μg m^-3 were observed during the January 2013 winter haze event in Beijing. State-of-the-art air quality models that rely on sulfate production mechanisms requiring photochemical oxidants cannot predict these high levels because of the weak photochemistry activity during haze events. We find that the missing source of sulfate and particulate matter can be explained by reactive nitrogen chemistry in aerosol water. The aerosol water serves as a reactor, where the alkaline aerosol components trap SO₂, which is oxidized by NO₂ to form sulfate, whereby high reaction rates are sustained by the high neutralizing capacity of the atmosphere in northern China. This mechanism is self-amplifying because higher aerosol mass concentration corresponds to higher aerosol water content, leading to faster sulfate production and more severe haze pollution.