Water-soluble Inorganic Ions Research Articles

Antibiotic resistance genes in the coastal atmosphere under varied weather conditions: Distribution, influencing factors, and transmission mechanisms.

Antibiotic resistance genes (ARGs) have escalated to levels of concern worldwide as emerging environmental pollutants. Increasing evidence suggests that non-antibiotic antimicrobial substances expedite the spread of ARGs. However, the drivers and mechanisms involved in the generation and spread of ARGs in the atmosphere remain inadequately elucidated. Co-occurrence networks, mantel test analysis, and partial least squares path modeling were used to analyze the symbiotic relationships of ARGs with meteorological conditions, atmospheric pollutants, water-soluble inorganic ions, bacteria, mobile genetic elements (MGEs), antibacterial biocide and metal resistance genes, and to identify the direct drivers of ARGs. The types and abundance of ARGs exhibited different seasonal distribution. Specifically, the types exhibited a strong alignment with the diversity of air masses terrestrial sources, while the abundance displayed a significant positive correlation with both biocide resistance genes (BRGs) and metal resistance genes (MRGs). The contribution of bacterial communities and MGEs to the generation and spread of ARGs was constrained by the low levels of antibiotics in the atmosphere and the existence of "viral intermediates". Conversely, antibacterial biocides and metals influenced mutation rates, cellular SOS responses, and oxidative stress of bacteria, consequently facilitating the generation and spread of ARGs. Moreover, the co-selection among their derivatives, resistance genes, ensured a stable presence of ARGs. The research highlighted the significant impact of residual antimicrobial substances on both the generation and spread of ARGs. Elucidating the sources of aerosols and the co-selection mechanism linking with ARGs, BRGs, and MRGs were crucial for preserving the stability of ARGs in the atmosphere.

Characteristics of water-soluble inorganic ions and carbonaceous compounds in PM2.5 in the urban area of Hanoi, Vietnam

Characteristics of water-soluble inorganic ions and carbonaceous compounds in PM2.5 in the urban area of Hanoi, Vietnam

Aerosol particles released from grit chambers of nine urban wastewater treatment plants in typical regions: Fugitive characteristics, quantitative drivers, and generation process.

The flow through the grit chamber is non-biochemically treated wastewater, which contains microorganisms mainly from the source of wastewater generation. There are limited reports on aerosol particles generated by grit chambers compared with those produced by biochemical treatment tanks. This study analyzed the fugitive characteristics of aerosol particles produced in grit chambers at nine wastewater treatment plants in three regions of China. There were 160.41-432.13 μg/m3 of total particles and 455 ± 34-2181 ± 221 CFU/m3 of bacteria in aerosol particles. The chemicals in aerosol particles contained 7.35-53.70 μg/m3 of total organic carbon and 36.10-227.94 μg/m3 of water-soluble inorganic ions. The aerated grit chambers produced significantly more aerosol particles than the vortex-type grit chambers. Indoor treatment facilities were more prone to aerosol particle accumulation than outdoor facilities. The microorganisms in wastewater were the main contributing source of dominant microorganisms in aerosol particles, with a degree of explanation of 73.33 % ± 35.56 %. Mantel analysis and the partial least squares path modeling determined that the components and biodiversity of wastewater were direct determinants of aerosol emission levels and biodiversity, respectively. Geographic regions contributed to the differences in aerosol particles, primarily indirectly by affecting the components of wastewater. The bubble bursting trajectory simulation experiment simulated the bioaerosol generation process in aerated grit chambers and predicted droplet behaviours. A higher number of small film droplets corresponded to a higher concentration of bioaerosols. Arcobacter, Aeromonas, Acinetobacter, and Flavobacterium were the major pathogenic genera in aerosol particles produced by grit chambers. The annual probability of infection and the disease burden of these pathogenic bacteria cannot be ignored. This study provides a scientific basis for further understanding of aerosol particle generation and potential hazards in grit chambers of wastewater treatment plants.

Combustion-driven inorganic nitrogen in PM2.5 from a city in central China has the potential to enhance the nitrogen load of North China

Inorganic nitrogen (NH4+ and NO3−) is a significant component of PM2.5, influencing not only regional ecological systems but also on other regions through the migration of air masses. However, few studies have simultaneously investigated the sources of NH4+ and NO3−, and their potential transport pathways remain poorly understood. Here, daily PM2.5 samples were collected in Jiaozuo, a key city in the air pollution transmission channel to the north China, from 1 September to 5 December, 2017. Major water-soluble inorganic ions and the isotope compositions of NH4+ and NO3− in PM2.5 were analyzed. The results indicated substantial amounts of inorganic nitrogen in PM2.5, particularly at high PM2.5 concentrations. The Bayesian isotope mixing model (MixSIAR) results revealed that combustion sources contributed 79.5 % to NO3− and 51.6 % to NH4+. Moreover, the medium to high potential source regions for combustion-related NH3 is basically consistent with combustion-related NOx. Therefore, stringent regulation of combustion emissions has the potential to mitigate inorganic nitrogen pollution in PM2.5 in Jiaozuo. The results of the forward trajectory cluster and PSCF (potential source contribution function) analysis revealed that a significant amount of combustion-driven inorganic nitrogen in PM2.5 from Jiaozuo will transport to downwind area, particularly north China. Combustion-driven inorganic nitrogen levels carried by these air masses exceeded half the average value for cities in North China during the same period. Our study highlights that combustion emissions dominate the inorganic nitrogen sources in PM2.5 and that substantial amounts of combustion-driven inorganic nitrogen can be transported from Jiaozuo to North China, potentially enhancing the nitrogen load in those areas.

The Characteristics of Water-Soluble Inorganic Ions in PM1.0 and Their Impact on Visibility at a Typical Coastal Airport

Water-soluble inorganic ions (WSIIs) can increase the hygroscopicity of aerosols, which will transform aerosols into larger sizes and reduce visibility by enhancing light scattering. To explore the characteristics of WSII concentrations and their impacts on visibility in a coastal airport, in this study, PM1.0 samples at two monitoring sites (including airport site and background site) were collect in spring and summer, and 12 species of ions were detected. In general, secondary water-soluble inorganic ions (SNA, including SO42−, NO3− and NH4+) and Ca2+ were the dominant WSIIs in PM1.0, contributing about 89% to 95% of the total measured ions. The continental contributions of SO42−, K+, and Ca2+ accounted for more than 60% during the whole period, while Na+ and Cl− were mainly from marine sources. The source identification showed that airport emissions were a major source at the sampling site and significantly contributed to the levels of sulfate, nitrate, and ammonium. Agricultural activities were the dominant sources impacting visibility in spring, while airport emissions and secondary inorganic aerosols were the main components affecting visibility in summer. Therefore, improving atmospheric visibility in coastal airport areas should focus on reducing the precursors of secondary particulates and reducing biomass-burning activities.

Source Apportionment of Carbonaceous Matter in Size-Segregated Aerosols at Haikou: Combustion-Related Emissions vs. Natural Emissions

Air pollution can induce diseases and increase the risks of death, and it also has close links with climate change. Carbonaceous matter is an important component of aerosols, but studies quantifying the source apportionment of carbonaceous compositions in different-sized aerosols from a stable carbon isotopic perspective remain scarce. In this study, fine (particulate size < 2.5 μm) and coarse (particulate size 2.5~10 μm) particles were collected from December 2021 to February 2022 (winter) and from June to August 2022 (summer) in the tropical city of Haikou; the concentrations of water-soluble inorganic ions (WSIIs) and total carbonaceous matter (TC) and the stable carbon isotope of TC (δ13C-TC) values in both fine and coarse particles were analyzed. Higher concentrations of TC, SO42−, NO3−, and NH4+ but lower δ13C-TC values in fine particles than those in coarse particles in both winter and summer indicated that combustion-related emissions dominate fine particulate TC sources. The δ13C-TC values coupled with the stable isotope mixing model in R (SIAR) results showed that combustion-related emissions contributed 77.5% and 76.6% to the TC of fine particles in winter and summer, respectively. Additionally, the lowest δ13C-TC values were observed in summertime fine particles; plant physiological activity was identified as an important source of fine particulate TC in summer and contributed 12.4% to fine particulate TC. For coarse particles, higher δ13C-TC values and Ca2+ and Na+ concentrations but lower TC concentrations implied significant contributions from natural emissions (29.2% in winter and 44.3% in summer) to coarse particulate TC. This study underscores that instead of fossil fuels and biomass, clean energy can decrease 45–78% of aerosol TC at Haikou. In addition, our results also provide a dataset for making environmental policy and optimizing the energy structure, which further favors the sustainable development of air quality.

Seasonal trends and light extinction effects of PM2.5 chemical composition from 2021 to 2022 in a typical industrial city of central China

This study investigates the concentrations, chemical compositions, and sources of PM2.5 in Huangshi, China. Daily average PM2.5 levels ranged from 8.43 to 193.08 μg m−3, with an annual mean of 54.13 μg m−3, exceeding China's annual secondary standard of 35 μg m−3. Seasonal mean concentrations peaked in winter and were lowest in summer. Organic carbon (OC) and elemental carbon (EC) had annual means of 4.89 μg m−3 and 0.94 μg m−3, respectively. Water-soluble inorganic ions (WSIIs) accounted for 52.17% of PM2.5, with NO3−, SO42−, and NH4+ being the major components. The NO3−/SO42− ratio averaged 1.65, indicating a transition from coal combustion to vehicle emissions as the primary pollution source. Chemical mass reconstruction revealed that NH4NO3, (NH4)2SO4, and organic matter (OM) accounted for 65.3% of PM2.5 mass. Seasonal variations in light extinction (bext) highlighted the impact of secondary inorganic salts on visibility, with an annual average bext of 346.30 ± 246.98 Mm−1. Airmass clusters and potential source region analysis suggested PM2.5 and its components were primarily originated from local and nearby regions. These findings underscore the effectiveness of local pollution control measures, changing pollution sources, and the necessity for targeted emission controls to improve air quality and visibility in urban areas.

Factors affecting the different growth rates of PM2.5：Evidence from composition variation, formation mechanisms, and importance analysis of water-soluble inorganic ions with case study in northern China

PM2.5 affects air quality, therefore, understanding the mechanism of PM2.5 growth is essential to figure out mitigation measures. Hourly real-time concentrations of water-soluble inorganic ions (WSIIs), including anions and cations, in fine particulate matter (PM2.5) were measured in Baoji, northwest China. During the winter monitoring period, the concentrations of PM2.5 and most WSIIs exhibited similar trends. Mass proportions of SNA [i.e., sulfate (SO42−), nitrate (NO3−), ammonium (NH4+)] in PM2.5 gradually increased with air deterioration, while equivalent ratios of anions to cations also increased. The heterogeneous aqueous reactions and/or gas-phase homogeneous reactions promoted the formation of secondary inorganics, especially during the haze events. Rapid transformations of primary gaseous precursors to secondary pollutants could lead to the substantial formation of SO42− and NO3−. In terms of particle growth rate, the mass proportions of SNA in PM2.5 decreased from General Growth (GG) to Explosive Growth (EG) events. Furthermore, the particle growth rates did not coincide with the pollution levels, while it occurred most frequently during the Transition Period, instead of the Polluted Period. The diurnal variation of SNA at different PM2.5 growth rates has been discussed. The results of the Random Forest (RF) model showed that RH was an important factor for EG of PM2.5, while low RH was a reliable reason for the relatively low mass proportion of SNA. The results of this study could advance our understanding of particle growth and provide scientific evidence to support the establishment of unique air quality control measures under different pollution scenarios in Fenwei Plain, China.

Tourism activities significantly contributed to atmospheric pollutants in a remote town of Tianshan revealed by the continuous observation of two years

The large reduction in tourism activities in 2020 provided a unique opportunity to investigate their contribution on atmospheric pollutants in Bayanbulak, a remote town in Tianshan, China. In this scenic and sensitive region, we measured total suspended particulates (TSP) along with concentrations of polycyclic aromatic hydrocarbons (PAHs), organic carbon (OC), elemental carbon (EC) and water-soluble inorganic ions (WSIIs) during the lockdown in 2020 and compared these to levels in the pre-pandemic period of 2019. The study revealed significant reductions in PAHs, OC, EC, and some WSIIs concentrations during the tourist season (May–October) of 2020 compared with 2019, whereas variations between non-tourist seasons were less pronounced. Furthermore, by comparing pollutant characteristics in tourist seasons of these two years, we found that 5- and 6-ring groups were main PAH constituents in 2019, while 5- and 3-ring groups contributed more to total PAHs in 2020. OC/EC ratio increased from 2019 to 2020, indicating an increase of biomass burning contribution after the lockdown. Using positive matrix factorization, we determined that emissions from tourism-related transportation and combustion of natural gas and coal (mainly for cooking) contributed 21.9% and 46.6%, respectively, to certain atmospheric pollutants in 2019, whereas they decreased significantly to 3% and 19.4% in 2020 with dust and biomass contributions increased substantially. The levels of PAHs, OC, and EC from tourism-related sources were as high as 9.31 ng m−3, 1.28 μg m−3 and 0.11 μg m−3 and decreased by 54.37%, 25.16%, and 9.54%, respectively, compared to 2019. Hence, the impact of tourism must be considered during the assessment of local air pollutant emissions, particularly in remote areas.

Spatiotemporal variations of PM2.5 organic molecular markers in five central cities of the Yangtze River Delta, East China in autumn and winter: Implications for regional and local sources of organic aerosols

Information on the spatiotemporal variations in the composition and sources of organic aerosols (OA) is needed to identify regional influences and to establish effective control measures. Here, 23-h PM2.5 samples were collected in five central cities of the Yangtze River Delta in eastern China, including Nanjing, Suzhou, Wuxi, Changzhou, and Zhenjiang, every three days from 2020/09/01 to 2021/02/28. Each sample was analyzed for water-soluble inorganic ions, organic carbon (OC), elemental carbon (EC), and organic molecular markers (OMMs). Generally, the major components of PM2.5, including NH4+, SO42−, NO3−, OC, and EC, exhibited similar temporal patterns across the five cities. In all OMM groups, the concentrations of PAHs, oxygenated PAHs, and secondary products of isoprene showed strong correlations (r = 0.79 ± 0.050–0.93 ± 0.028) and low coefficient of divergence (COD = 0.22 ± 0.024–0.30 ± 0.033) between sampling sites, indicating a homogeneous spatial distribution of industrial emissions and biogenic secondary OA in autumn and winter. Other OMMs showed wider r (e.g., steranes and hopanes, 0.20–0.80) and COD (0.26–0.69) ranges for all site pairs, probably due to the influence of local emissions. Based on the source apportionment results using Positive matrix factorization, the biomass burning factor dominated the contribution to OC and EC in winter and showed strong correlations (r = 0.84 ± 0.063) between the sampling sites, indicating regional transport of emissions from biomass burning and fossil fuel combustion in the heating season. Traffic-related factors had the greatest spatial heterogeneity (r = 0.27 ± 0.19–0.51 ± 0.16) and contributed significantly to OC at their maximum levels.

Characteristics of PM2.5-bound water-soluble inorganic ions generated during cooking

Commercial cooking is an important source of PM2.5, which adversely affects air quality, posing threats to human health. However, few studies have examined the effects of commercial cooking on outdoor air quality. We aimed to analyze characteristics of outdoor PM2.5 and ions from commercial cooking during cooking and non-cooking times in a popular restaurant area at Nankai University. The acidity and alkalinity of atmospheric PM2.5 based on the equivalent values of anions and cations and the formed compounds based on the ion concentrations and correlations between them were determined. The results showed that the mean PM2.5 concentration at the snack street during cooking times was 120.39 ± 58.52 μg/m3, approximately 1.4 times higher than at the comparison point. The total concentration of water-soluble inorganic ions accounted for approximately half of the PM2.5 emissions at both sampling points. High concentrations of Na+, NO3−, and SO42− were found at both sampling points. We found that NH4NO3, CaSO4, and CaCl2 formed at the snack street, whereas Ca(NO3)2, NH4NO3, and (NH4)2SO4 formed at the comparison point. Based on our analysis of the acid-base balance slopes, the atmospheric PM2.5 was alkaline. These results elucidate the characteristics of PM2.5-bound water-soluble inorganic ions formed during cooking.

Characterization of water-soluble inorganic ions and carbonaceous aerosols in the urban atmosphere in Amman, Jordan

The urban particulate matter (PM) carbonaceous and water-soluble ions were investigated in Amman, Jordan during May 2018–March 2019. The PM2.5 total carbon (TC) annual mean was 7.6 ± 3.6 μg/m3 (organic carbon (OC) 5.9 ± 2.8 μg/m3 and elemental carbon (EC) 1.7 ± 1.1 μg/m3), which was about 16.3% of the PM2.5. The PM10 TC annual mean was 8.4 ± 3.9 μg/m3 (OC 6.5 ± 3.1 μg/m3 and elemental carbon (EC) 1.9 ± 1.1 μg/m3), about 13.3% of the PM10. The PM2.5 total water-soluble ions annual mean was 7.9 ± 1.9 μg/m3 (about 16.9%), and that of the PM10 was 10.1 ± 2.8 μg/m3 (about 16.0%). The minor ions (F−, NO2−, Br−, and PO43−) constituted less than 1% in the PM fractions. The significant fraction was for SO42− (PM2.5 4.7 ± 1.6 μg/m3 (10.0%) and PM10 5.3 ± 1.9 μg/m3 (8.3%)). The NH4+ had higher amounts of PM2.5 (1.3 ± 0.6 μg/m3; 2.7%) than that PM10 (0.9 ± 0.4 μg/m3; 1.4%). During sand and dust storm (SDS) events, TC, Cl−, and NO3− were doubled in PM, SO42− did not increase significantly, and NH4+ slightly decreased. Regression analysis revealed: (1) carbonaceous aerosols come equally from primary and secondary sources, (2) about 50% of the OC came from non-combustion sources, (3) traffic emissions dominate the PM, (4) agricultural sources have a negligible effect, (5) SO42− is completely neutralized by NH4+ in the PM2.5 but there could be additional reactions involved in the PM10, and (6) (NH4)2SO4, was the major species formed by SO42−and NH4+ instead of NH4HSO4. It is recommended to perform long-term sampling and chemical speciation for the urban atmosphere in Jordan.

Single-stage NBI sampler for PM1 mass and five-stage NBI-NMCI sampler for PM1 mass distribution measurements

In recent years, concerns about the health and environmental risks associated with PM1 particles have increased. However, existing PM1 sampling instruments remain to be improved mainly because their PM1 inlets have particle loading and bounce issues. To address these challenges, PM1 inlets based on the Non-Bouncing Impactor (NBI) technique were developed. These inlets employ vacuum oil-wetted glass fiber filter (GFF) substrates to eliminate particle bounce and incorporate a daily vacuum oil injection to prevent particle loading. The 16.7 L/min PM1 NBI, modified from the PM2.5 M-WINS design with a reduced diameter of the single nozzle, was designed to adapt readily with current standard sampling and monitoring systems. The cut-size (Dpa50) of 0.99 ± 0.02 μm was determined by considering the effects of Reynold number and the ratio of jet-to-plate distance and nozzle diameter. Field tests comparing the 16.7 L/min PM1 NBI sampler to the 9-stage NCTU Micro-orifice Cascade Impactor (NMCI9) revealed small sampling biases, with a mean difference of +0.26 ± 2.28 μg/m3 for PM1 measurements when silicone oil-coated aluminum foil (AF) and GFF-AF were used in the NMCI9. The NBI with the oil-wetted GFF substrate effectively removed particles larger than 1.0 μm, resulting in more accurate PM1 mass concentration measurements. Additionally, the development of a 5-stage NMCI with the 30 L/min PM1 NBI as the first stage enabled detailed measurement of PM1 mass distribution in two modes, which was challenging when measuring the entire mass distribution of ambient aerosols. The distribution of size-dependent water-soluble inorganic ions in PM1 showed dominance of SO42− and NH4+ in PM1 compared to PM2.5. In summary, the PM1 NBI enhances accuracy for long-term atmospheric sampling by addressing particle loading and bounce, making it a more reliable standard sampling instrument.

Exploring the relationship between personal exposure to multiple water-soluble components and ROS in size-resolved PMs in solid fuel combustion households

Water-soluble species are the main components of particulate matters (PMs), which have important impacts on visibility, climate change and human health. Here, personal exposure (PE) to size-resolved PMs from housewives using different solid fuels (biomass and coal) was collected during winter in rural Yuncheng city, Fenwei Plain, China. The concentrations of water-soluble organic carbon (WSOC) and reactive oxygen species (ROS) were higher in the biomass group than coal group, whereas the concentrations of water-soluble inorganic ions and water-soluble nitrogen were higher in the coal group than biomass group. Almost all measured water-soluble components in both groups showed a pattern of increasing concentration with decreasing particle size, with more than 50% of WSOC and water-soluble total nitrogen (WSTN) enriched in PM0.25. The Pearson correlation result was in general agreement with the relationship between water-soluble components and ROS found by random forest model. There was a strong positive correlation between ROS and WSOC in PMs in the coal group, especially in PMs <0.25 μm, which may be due to the emission of a large number of transition metals chelated with WSOC from coal combustion. The contribution of Cl− and F− to ROS was greater in the biomass group. NO2− in both coal and biomass groups had a decent positive effect on ROS generation. The strongest positive linear correlation (R = 0.95) between ROS and K+ in total suspended particulates in the biomass group, whereas there was almost no contribution of K+ to ROS when particle size was distinguished or in random forest model, which reflects the specificity of K+ in inducing ROS. The present study provides new insights for a deeper exploration of the relationship between water-soluble components and oxidative potential in PE PMs from domestic combustion sources.

Chemical composition, mutagenicity, and cytotoxicity of urban submicron particulate matter (PM1) in Agra, India

This study, conducted in Agra, India, examined the mass concentrations, chemical compositions, and seasonal variations of submicron particles (PM1). The concentrations of metals, water-soluble inorganic ions (WSIs) including anions (F−, Cl−, NO₃−, SO₄2−) and cations (Ca2+, K+, Mg2+, NH₄+, Na+), organic carbon (OC) and elemental carbon (EC) and polycyclic aromatic hydrocarbons (PAHs) in PM1 extract were determined using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), Ion Chromatography, Thermogravimetric Analysis and Gas Chromatography-Mass Spectrometry (GC–MS) respectively. For morphological observation of PM1 particles, Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray spectrometry (FESEM-EDS) was used. The annual average concentration of PM1 was 82.9 ± 33.4 μg/m3, which exceeds the World Health Organisation's (WHO) safe limit for PM2.5 of 5 μg/m3 by a factor of 17. The PM1 mass composition included metals (31 %), WSIs (28 %), OC and EC (9.8 %), and PAHs (0.4 %). Winter recorded the highest PM1 concentration (96.1 ± 25.8 μg/m3), followed by post-monsoon, summer, and monsoon seasons. The average concentration of PAHs was 364.6 ± 226.6 ng/m3. Positive Matrix Factorization (PMF) identified traffic, emissions from biomass/coal and wood combustion, industrial/stationary sources, and secondary aerosols as potential contributors. The Ames test revealed the presence of frameshift mutations and base pair substitutions, especially in winter and post-monsoon. Additionally, PM1 exhibited cytotoxic effects on V-79 cells, with heightened toxicity during winter and prolonged exposure in other seasons. This study underscores the urgent need to address local emission sources and establish regulatory standards for PM1 in urban areas.

Prenatal exposure to PM2.5 led to impaired respiratory function in adult mice

BackgroundPM2.5 is a complex mixture, with water-soluble inorganic ions (WSII), mainly NH4+, SO42−, and NO3−, constituting major components. Early-life PM2.5 exposure has been shown to induce adverse health consequence but it is difficult to determine whether such an effect occurs prenatally (preconception, gestational) or postnatally in human studies. MethodsFour groups of C57BL/6 J mice were assigned to four exposure conditions: PM2.5 NO3−, PM2.5 SO42−, PM2.5 NH4+ and clean air, and exposure started at 4 weeks old. At 8 weeks old, mice bred within group. The exposure continued during gestation. After delivery, both the maternal and F1 mice (offspring) were kept in clean air without exposure to PM2.5. Respiratory function and pulmonary pathology were assessed in offspring mice at 8 weeks of age. In parallel, placenta tissue was collected for transcriptome profiling and mechanistic investigation. ResultsF1 mice in PM2.5 NH4+, SO42- and NO3− groups had 32.2 % (p=6.0e-10), 30.3 % (p=3.8e-10) and 16.9 % (p=5.7e-8) lower peak expiratory flow (PEF) than the clean air group. Importantly, the exposure-induced lung function decline was greater in male than female offspring. Moreover, exposure to PM2.5 WSII before conception and during gestation was linked to increased airway wall thickness and elevated pulmonary neutrophil and macrophage counts in the offspring mice. At the molecular level, the exposure significantly disrupted gene expression in the placenta, affecting crucial functional pathways related to sex hormone response and inflammation. ConclusionsPM2.5 WSII exposure during preconception and gestational period alone without post-natal exposure substantially impacted offspring’s respiratory function as measured at adolescent age. Our results support the paradigm of fetal origin of environmentally associated chronic lung disease and highlight sex differences in susceptibility to air pollution exposure.

Impacts of the East Asia monsoon on the PM2.5 acidity in Hanoi

This study investigates the acidity of particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) in Hanoi, the capital city of Vietnam, and its influencing factors by analyzing measured concentrations of water-soluble inorganic ions (WSIIs) in 107 24-h samples collected between June 2021 and February 2022. The average sulfate, nitrate, and ammonium concentrations were 5.79, 3.55, and 5.46 μg m−3, respectively. Among the samples, 83 exhibited alkaline aerosols characterized by elevated ammonium-to-sulfate molar concentration ratios (ASMCR) ranging from 2.3 to 9.6, while 24 showed acidic characteristics with ASMCR ranging from 0.5 to 2.5. By employing the Extended Aerosol Inorganic Model E-AIM III, with major WSIIs as the input parameters, the estimated aerosol acidity pH ranged from 8.6 to 10.9 for alkaline aerosols and below 4.5 for acidic aerosols. These variations in ASMCR and aerosol pH highlight the distinct acidic and alkaline aerosol source regions affecting Hanoi's PM2.5 by the monsoon air masses. The Potential Source Contribution Function (PSCF) maps of NH4+ and SO42− revealed the Northeast and Southeast monsoon upwind sources of acidic aerosols over China's Guangdong coastal region and Vietnam's offshore, respectively. Alkaline aerosols were observed during the Northeast and Southwest monsoons, with upwind sources originating in South China, Thailand, and Cambodia. The emergence of the ammonium-rich source areas in South China may be attributed to China's sustained emission control measures, targeting acidic SO2 and NOx emissions while leaving alkaline NH3 emissions largely unaffected. This research provided insights into the intricate relationships between regional emissions, long-range transport, and local meteorological-driven emissions, offering valuable guidance for effective air quality management in urban environments.

Morphology and chemical composition of mineral particles in a special dust storm with high relative humidity in North China

A special dust storm characterized by high PM10 mass concentrations (921.9 ± 632.3 μg m−3) and high relative humidity (RH; 60.1 % ± 11.1 %) was observed on March 22–24, 2023 at a coastal city of North China. Aerosol particles of PM10 were analyzed by a scanning electron microscope coupled with energy dispersive X-ray and an ion chromatograph. The results showed that individual mineral particles were dominated by clay minerals, followed by quartz, feldspar, and carbonate. Bulk water-soluble inorganic ions analysis showed that SO42- mass concentrations varied from 3.7 μg m−3 to 23.3 μg m−3 with an average value of 12.4 μg m−3. However, their mass ratios to PM10 were relatively stable, being 1.15–2.01 % with an average value of 1.49 % ± 0.25 %, similar to the value near the dust sources (Tengger Desert). Although S-containing individual mineral dust varied from 5.2 % to 70.7 %, the average weight ratio of S on individual mineral dust was 2.1 %, much lower than that of non-dust periods (11.0 %). The results suggested limited sulfate formation on mineral dust surfaces even under high RH. In contrast, NO3-, which was very limited in dust sources, varied from 0.21 % to 4.11 % of the total PM10 with an average value of 1.61 % ± 1.07 %. The research highlighted that nitrate formation has exceeded sulfate formation during severe dust storm episodes, which might because the atmospheric compositions in China have changed significantly with a high mass ratio of NO2/SO2 after the implementation of the strict emission control measures.

Yearly variations of water-soluble ions over Xi'an, China: Insight into the importance contribution of nitrate to PM2.5

Water-soluble inorganic ions (WSIIs) in PM2.5 play an important role in the formation of air pollution, which in turn affects climate change and human health. The formation pathways and factors influencing WSIIs have received extensive attention. Here, we analyzed the contents of nine WSIIs in PM2.5, collected from 2015 to 2021 in Xi'an City, China, with the aim of investigating long-term atmospheric pollution changes. Sulfate (SO42−), nitrate (NO3−), and ammonium (NH4+) together contributed to 66.8%–88.1% and Ca2+ accounted for 5.1%–13.1% of total WSIIs. The relative content of SO42− exhibited a gradually decreasing trend (from 49.80% in 2015 to 29.98% in 2021), whereas NO3− was increased in the same time period (from 13.96% in 2015 to 29.92% in 2021). In addition, the nitrogen oxidation rate showed an annual increase in this period, whereas the sulfur oxidation rate decreased, and their fitted curves intersected in 2019. The key finding of this study is that the air pollution pattern in Xi'an has changed from sulfate-dominated to nitrate-dominated particles, as evidenced by the feature importance results of the random forest model. We propose that more attention should be paid to vehicle emissions and road dust as pollution sources. Overall, the findings of this study serve as a useful reference to aid relevant authorities in devising more effective policies for controlling PM2.5 pollution at its source.

Masks As a New Hotspot for Antibiotic Resistance Gene Spread: Reveal the Contribution of Atmospheric Pollutants and Potential Risks.

The consumption of disposable surgical masks (DSMs) considerably increased during the coronavirus pandemic in 2019. Herein, we explored the spread of antibiotic resistance genes (ARGs) and the potential risks of antibiotic resistant bacteria (ARB) on DSMs. At environmentally relevant concentrations, the conjugate transfer frequency (CTF) of ARGs increased by 1.34-2.37 folds by 20 μg/m3 of atmospheric water-soluble inorganic ions (WSIIs), and it increased by 2.62-2.86 folds by 80 ng/m3 of polycyclic aromatic hydrocarbons (PAHs). Total suspended particulates (TSP) further promoted the CTF in combination with WSIIs or PAHs. Under WSII and PAH exposure, gene expression levels related to oxidative stress, cell membrane, and the adenosine triphosphate (ATP) were upregulated. WSIIs predominantly induced cellular contact, while PAHs triggered ATP formation and membrane damage. Molecular dynamics simulations showed that WSIIs and PAHs reduced membrane lipid fluidity and increased membrane permeability through interactions with the phosphatidylcholine bilayer. DSM filtering performance decreased, and the CTF of ARGs increased with the wearing time. The gut simulator test showed that ARB disrupted the human gut microbial community and increased total ARG abundance but did not change the ARG abundance carried by ARB themselves. A mathematical model showed that long-term WSII and PAH exposure accelerated ARG dissemination in DSMs.