IRF4 and STAT3 activities are associated with the imbalanced differentiation of T-cells in responses to inhalable particulate matters.

BACKGROUND: Particulate Matter (PM) is known to cause inflammatory responses in human. Although prior studies verified the immunogenicity of PM in cell lines and animal models, the effectors of PM exposure in the respiratory system and the regulators of the immunogenicity of PM is not fully elucidated. METHODS: To identify the potential effector of PM exposure in human respiratory system and to better understand the biology of the immunogenicity of PM, We performed gene-expression profiling of peripheral blood mononuclear cells from 171 heathy subjects in northern China to identify co-expressed gene modules associated with PM exposure. We inferred transcription factors regulating the co-expression and validated the association to T-cell differentiation in both primary T-cells and mice treated with PM. RESULTS: We report two transcription factors, IRF4 and STAT3, as regulators of the gene expression in response to PM exposure in human. We confirmed that the activation of IRF4 and STAT3 by PM is strongly associated with imbalanced differentiation of T-cells in the respiratory tracts in a time-sensitive manner in mouse. We also verified the consequential inflammatory responses of the PM exposure. Moreover, we show that the protein levels of phosphorylated IRF4 and STAT3 increase with PM exposure. CONCLUSIONS: Our study suggests the regulatory activities of IRF4 and STAT3 are associated with the Th17-mediated inflammatory responses to PM exposure in the respiratory tracts, which informs the biological background of the immunogenicity of particulate matters.

Impacts of Seasonal Variation on Organochlorine Pesticides in the East China Sea and Northern South China Sea.

To investigate the characteristics of historic-use organochlorine pesticides (OCPs) in the marginal seawater of China, we examined the seasonal and spatial distributions of hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and dichlorodiphenyltrichloroethane (DDTs) in the northern South China Sea (NSCS, 18-23° N) and East China Sea (ECS, 26-32° N). Seasonally, in the NSCS, the significantly higher concentrations (p < 0.05) of HCB, HCHs, and DDTs were found in summer, autumn, and summer through autumn, respectively. In the ECS, the higher concentrations were found in summer through winter, autumn, and summer. Spatially, HCB concentrations were significantly higher in the NSCS than in the ECS during all seasons except winter. During all four seasons, concentrations of HCHs were significantly higher in the NSCS than in the ECS. In summer and autumn, concentrations of DDTs were significantly higher in the NSCS than in the ECS, while no significant differences were found in spring and winter. Generally, regional usage, river-influenced coastal plumes, phytoplankton abundances, and ocean currents played crucial roles in the input, transport, degradation, and dilution of OCPs. These dynamic factors along with the seasonally alternating monsoon directly influenced the seasonal and spatial characteristics of OCPs. Furthermore, the profiles and diagnostic ratios of HCHs and DDTs revealed highly weathered OCP residues, attributed to eroded soils carried by surface runoff and long-range oceanic and atmospheric transport.

Effects of diesel exhaust particles on the condition of mouse ocular surface.

In order to evaluate the effects of diesel exhaust particles (DEP) on the ocular surface, different concentrations (100 and 1000 µg/ml) of DEP eye drops were administered on the mouse ocular surface for a period of 28 days. After DEP treatment, the corneal epithelial permeability to Oregon Green Dextran was studied, which increased proportionally with time. Also, the number of corneal epithelial cell layers significantly increased, which was accompanied with a high Ki67 expression. On the other hand, the number of goblet cells in the conjunctival fornix were reduced, and apoptotic cells were detected in the corneal and conjunctival epithelium by TUNEL assay in the DEP treated group, along with increased Caspase 3/8 expression. Furthermore, the number of CD4 positive cells significantly increased in the conjunctiva, while NF-κB p65 (phospho S536) expression was elevated in the cornea and also the conjunctiva. Our data revealed that the topical administration of DEP on the ocular surface in mouse disrupted the organized structure of the ocular surface and induced an inflammation of the cornea and conjunctiva.

Properties and cellular effects of particulate matter from direct emissions and ambient sources.

The pollution of particulate matter (PM) is of great concern in China and many other developing countries. It is generally recognized that the toxicity of PM is source and property dependent. However, the relationship between PM properties and toxicity is still not well understood. In this study, PM samples from direct emissions of wood, straw, coal, diesel combustion, cigarette smoking and ambient air were collected and characterized for their physicochemical properties. Their expression of intracellular reactive oxygen species (ROS) and levels of inflammatory cytokines (i.e., tumor necrosis factor-α (TNF-α)) was measured using a RAW264.7 cell model. Our results demonstrated that the properties of the samples from different origins exhibited remarkable differences. Significant increases in ROS were observed when the cells were exposed to PMs from biomass origins, including wood, straw and cigarettes, while increases in TNF-α were found for all the samples, particularly those from ambient air. The most important factor associated with ROS generation was the presence of water-soluble organic carbon, which was extremely abundant in the samples that directly resulted from biomass combustion. Metals, endotoxins and PM size were the most important properties associated with increases in TNF-α expression levels. The association of the origins of PM particles and physicochemical properties with cytotoxic properties is illustrated using a cluster analysis.

Size-segregated characteristics of water-soluble oxidative potential in urban Xiamen: Potential driving factors and implications for human health.

Oxidative potential (OP), defined as the ability of particulate matter (PM) to generate reactive oxygen species (ROS), has been considered as a potential health-related metric for PM. Particles with different sizes have different OP and deposition efficiencies in the respiratory tract and pose different health risks. In this study, size-segregated PM samples were collected at a coastal urban site in Xiamen, a port city in southeastern China, between August 2020 and September 2021. The water-soluble constituents, including inorganic ions, elements and organic carbon, were determined. Total volume-normalized OP based on the dithiothreitol assay was highest in spring (0.241 ± 0.033 nmol min-1 m-3) and lowest in summer (0.073 ± 0.006 nmol min-1 m-3). OP had a biomodal distribution with peaks at 0.25-0.44 µm and 1.0-1.4 µm in spring, summer, and winter and a unimodal pattern with peak at 0.25-0.44 µm in fall, which were different from the patterns of redox-active species. Variations in the seasonality of fine and coarse mode OP and their correlations with water-soluble constituents showed that the size distribution patterns of OP could be attributed to the combined effects of the size distributions of transition metals and redox-active organics and the interactions between them which varied with emissions, meteorological conditions and atmospheric processes. Respiratory tract deposition model indicated that the deposited OP and the toxic elements accounted for 47.9 % and 36.8 % of their measured concentrations, respectively. The highest OP doses and the excess lifetime carcinogenic risk (ELCR) were found in the head airway (>70 %). However, the size distributions of OP deposition and ELCR in the respiratory tract were different, with 63.9 % and 49.4 % of deposited ELCR and OP, respectively, coming from PM2.5. Therefore, attention must be paid to coarse particles from non-exhaust emissions and road dust resuspension.

Seasonal variation for the ratio of BaP to BeP at different sites in Great Xiamen Bay.

From March 2008 to February 2009, PM(10) samples were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) at eight sampling sites in Great Xiamen Bay, China. Analyses of the seasonal and spatial variations of these compounds revealed the following results. Significantly high levels of PAHs were found in the winter compared to the summer, sometimes exceeding 100 ng m(-3), and the spatial variations were influenced most by the sampling site surroundings. Composition profiles of PAHs of an urban and a rural site were shown to be very similar with a positive correlation coefficient larger than 0.9 at the 0.01 level of significance for the same season. Diagnostic ratios, together with principal component and multiple linear regression analysis, showed that more PAHs were from grass/wood/coal combustion in winter than in other seasons. The ratios of benzo[a]pyrene to benzo[e]pyrene (BaP-BeP) in winter and fall were 0.6-1.7 times higher than those in spring and summer, suggesting the importance of local emissions of PAHs. The BaP-BeP ratios in Kinmen were generally lower than those in Xiamen, indicating that the aging degree of PAHs was higher in Kinmen than in Xiamen. The external input of PAHs from upwind urban and industrial areas was one of the key factors causing high levels of PAHs in PM(10) in Great Xiamen Bay in winter.

Diurnal variation of nitrated polycyclic aromatic hydrocarbons in PM10 at a roadside site in Xiamen, China.

Intensive daytime and nighttime sampling was carried out from 23 Oct to 31 Dec 2008 to investigate the occurrence of nitrated polycyclic aromatic hydrocarbons (NPAHs) in PM10 at a roadside site in Xiamen, China. At the same time, six PM10 samples were collected from a nearby roadway tunnel for comparison. Six NPAHs, namely 9-nitroanthracene, 2- and 3-nitrofluoranthene, 1-nitropyrene, 7-nitrobenz[a]anthracene, and 6-nitrobenzo[a]pyrene, were identified and quantified using GC/MS in negative ion chemical ionization mode. The average total concentration of six NPAHs (sigmaNPAHs) in the cold season (26 Nov-31 Dec) was 2.3 (daytime) and 9.9 (nighttime) times higher than those in the warm season. Significant statistical difference (p < 0.01, 2-tailed) of sigmaNPAHs between daytime and nighttime was found during both the warm and cold seasons. NPAHs were significantly positively correlated with their parent PAHs and nitrogen dioxide but negatively correlated with ambient temperature. The ratio of 2 + 3-nitrofluoranthene to 1-nitropyrene exhibited a similar diurnal pattern as sigmaNPAHs and was generally greater than 5, indicating the importance of secondary atmospheric formation. The diurnal variations of NPAHs were all influenced by the diurnal variations of PAHs, nitrogen dioxide, sunlight, and temperature. The daily inhalable exposure to the six NPAHs in the tunnel was much higher than the roadside values in the warm season but only slightly higher than those in the cold season.

[Atmospheric NH3 Emission Inventory and Its Tempo-spatial Changes in Xiamen-Zhangzhou-Quanzhou Region from 2015 to 2020].

Based on the district and county activity level data of different types of atmospheric ammonia (NH3) emission sources in the Xiamen-Zhangzhou-Quanzhou (XZQ) Region and the modified emission factors, an ammonia emission inventory with a spatial resolution of 1 km×1 km in 2017 was established. In addition, the annual variations in NH3 emission from 2015 to 2020 in this region were analyzed. The results showed that the emission of NH3 in the XZQ Region in 2017 was 27.40 kt with livestock and poultry breeding, farmland ecosystem, human emission, fuel combustion, and waste treatment accounting for 42.48%, 22.04%, 14.71%, 7.08%, and 5.69% of the total emission, respectively. The order of emission density of NH3 was Xiamen (1.94 t·km-2)>Quanzhou (1.07 t·km-2)>Zhangzhou (0.95 t·km-2). High values of emission density were mainly concentrated in the coastal urban areas with a concentrated population and the inland township areas with developed livestock and poultry breeding and planting industries. The monthly variation in NH3 emissions was consistent with the pattern of temperature change, with high values in summer. Due to the different economic structure and development level in different cities, NH3 emissions in Quanzhou City showed a decline from 2015 to 2020, whereas there were fluctuations in the trends of ammonia emissions in Xiamen and Zhangzhou cities. The relationship between NH3 emission intensity and per capita GDP was significantly negative.

Solubility of aerosol minor and trace elements in Xiamen Island, Southeast China: Size distribution, health risk and dry deposition.

Aerosol element solubility is essential to evaluate the damage to the environment and human health. In this work, the size distribution of total and soluble elements in eight particle size ranges with diameter <0.25, 0.25-0.44, 0.44-1.0, 1.0-1.4, 1.4-2.5, 2.5-10, 10-16 and >16 µm was investigated in Xiamen Island, southeast China from March 2018 to June 2020. The results showed that both total and soluble elements exhibited significant size dependence without obvious seasonal variations, and their relative contributions to PM1 mass were much lower than in particles larger than 1 µm. The correlations between some elements in soluble fraction were quite different from those in total fraction and the correlations also varied with particle size due to their different solubility. The solubility of Al, Fe, Ag and Cr was relatively low compared with other elements. Moreover, the solubility of Na, Mg, Ca, Mn and Ag was less dependent on particle size while Al, Fe and other trace elements exhibited the highest solubility in PM1 and the lowest in PM>10. Overall, the solubility of elements is primarily a function of aerosol origin and size. The carcinogenic risks of metal exposure via inhalation for children (3.31 × 10-6) and adults (4.42 × 10-6) were slightly higher than the guideline of cancer risk with >60 % from V. As for non-carcinogenic risk, the hazard index values for children and adults were 1.59 and 0.53, respectively, with Mn, V and Ni together accounting for >85 % of the risk. >85 % of the size-dependent dry deposition fluxes of the selected soluble elements over the Xiamen Bay were contributed by particles larger than 10 µm due to their high deposition velocities. The atmospheric inputs of bioavailable Fe and Cu to the sea exceeded the required amounts relative to inorganic nitrogen to meet the growth of phytoplankton.

Size distributions and dry deposition fluxes of water-soluble inorganic nitrogen in atmospheric aerosols in Xiamen Bay, China.

Size-segregated aerosol particles were collected using a high volume MOUDI sampler at a coastal urban site in Xiamen Bay, China, from March 2018 to June 2020 to examine the seasonal characteristics of aerosol and water-soluble inorganic ions (WSIIs) and the dry deposition of nitrogen species. During the study period, the annual average concentrations of PM1, PM2.5, PM10, and TSP were 14.8 ± 5.6, 21.1 ± 9.0, 35.4 ± 14.2 µg m-3, and 45.2 ± 21.3 µg m-3, respectively. The seasonal variations of aerosol concentrations were impacted by the monsoon with the lowest value in summer and the higher values in other seasons. For WSIIs, the annual average concentrations were 6.3 ± 3.3, 2.1 ± 1.2, 3.3 ± 1.5, and 1.6 ± 0.8 µg m-3 in PM1, PM1-2.5, PM2.5-10, and PM>10, respectively. In addition, pronounced seasonal variations of WSIIs in PM1 and PM1-2.5 were observed, with the highest concentration in spring-winter and the lowest in summer. The size distribution showed that SO4 2-, NH4 + and K+ were consistently present in the submicron particles while Ca2+, Mg2+, Na+ and Cl- mainly accumulated in the size range of 2.5-10 µm, reflecting their different dominant sources. In spring, fall and winter, a bimodal distribution of NO3 - was observed with one peak at 2.5-10 µm and another peak at 0.44-1 µm. In summer, however, the fine mode peak disappeared, likely due to the unfavorable conditions for the formation of NH4NO3. For NH4 + and SO4 2-, their dominant peak at 0.25-0.44 µm in summer and fall shifted to 0.44-1 µm in spring and winter. Although the concentration of NO3-N was lower than NH4-N, the dry deposition flux of NO3-N (35.77 ± 24.49 µmol N m-2 d-1) was much higher than that of NH4-N (10.95 ± 11.89 µmol N m-2 d-1), mainly due to the larger deposition velocities of NO3-N. The contribution of sea-salt particles to the total particulate inorganic N deposition was estimated to be 23.9-52.8%. Dry deposition of particulate inorganic N accounted for 0.95% of other terrestrial N influxes. The annual total N deposition can create a new productivity of 3.55 mgC m-2 d-1, accounting for 1.3-4.7% of the primary productivity in Xiamen Bay. In light of these results, atmospheric N deposition could have a significant influence on biogeochemistry cycle of nutrients with respect to projected increase of anthropogenic emissions from mobile sources in coastal region. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10874-021-09427-8.

[Characterization and Health Risk Assessment of Heavy Metals in PM2.5 in Xiamen Port].

PM2.5 samples at Haitian and Songyu container terminals in Xiamen Port were collected in summer and autumn/winter in 2020 and analyzed for 20 elements to investigate their temporal-spatial distribution features, sources, and health risk. The results showed that the levels of PM2.5 were relatively low and did not show significant spatial and diurnal differences. Ca and Si were the main crustal elements, and Zn and Mn were the main heavy metals in PM2.5. Compared with GB 3095-2012 guidelines, Cr(Ⅵ) was in the range of 27.4-28.6 times above the standard. Under the influence of monsoon and port throughput, the concentrations of some elements in summer were higher than those in autumn/winter. Significant diurnal variations were observed for Cu, Zn, SO2, and NO2 but not for V and Ni. Industrial sources were identified as the primary contributor (55.2%-59.4%), followed by traffic (28.7%-31.3%), ship emissions (7.1%-7.7%), and sea salt plus construction dust (4.8%-5.8%). The results of health risk assessment showed that heavy metals in PM2.5in Xiamen Port had potential carcinogenic risk (ECR>1(10-5) to people living near the port, and Cr(Ⅵ), V, and As together accounted for 97.3%-97.5% of the total risks; however, the non-carcinogenic risk was negligible (HI<1), and the major contributors were V, Mn, Ni, and As (89.6%-91.2%). The relative contributions of each contributor to ECR was in the order of traffic (47.2%-49.4%)>industrial (23.8%-24.2%)>ship emissions (16.9%-20.8%)>sea salt plus construction dust (5.7%-12.1%), and the relative contribution to HI was in the order of traffic (38.7%-42.3%)>industrial (24.5%-28.2%)>ship emissions (24.1%-27.2%)>sea salt plus construction dust (5.4%-9.6%).

[Response of Air Quality to COVID-19 Lockdown in Xiamen Bay].

Air pollutant concentrations in the Xiamen Bay cities during the period before and after COVID-19 lockdown(from January 11 to February 21, 2020) were studied to determine the influence of human activities on air quality in this region. During the Chinese Spring Festival holiday and the lockdown period, the concentrations of SO2, NO2, CO, PM10, and PM2.5 decreased by 6%-22%, 53%-70%, 34%-48%, 47%-64%, and 53%-60%, respectively. However, the changes in O3 concentrations were not consistent with the variations of human activities. The reduction rates for PM2.5, PM10, CO, and NO2 during the Spring Festival were greater than in previous years(2018 and 2019), but the reduction rates for SO2 were comparable. The concentrations of NO2 increased sharply(38%-138%), and much higher those of SO2(2%-42%), after the resumption of socioeconomic activities, indicating the importance of traffic reductions due to the lockdown measures on NO2. Higher wind speeds and rainfall after the Spring Festival were also favorable for the decline of SO2, NO2, and PM. The spatio-temporal distributions of the six criterial pollutants in the Xiamen Bay city cluster were obtained based on the Inverse Distance Weight method. The variability in regions with high NO2 concentrations was strongly linked to traffic emissions, while spatial patterns for CO and SO2 changed little over the six-week study period. The concentrations of PM2.5 and PM10 increased notably in the region, linked to more construction activity, but changed comparatively little in regions with dense populations and traffic networks. O3 remained relatively stable but low-value regions corresponded to those regions with high NO2 concentrations, indicating the significant titration effect of NO2 on O3. These results provide valuable information that can inform O3 pollution reduction measures.

Size distributions and health risks of particle-bound toxic elements in the southeast coastland of China.

Size-fractionated samples were collected at five coastal urban sites in Fujian Province, southeast China, in 2016 and 2017 to determine the trace elements using ICP-MS. Ca, Fe, Al, Mg, and K were the most abundant elements among the studied elements in TSP, much higher than those of heavy metals. The annual mean concentrations of Pb, As, V, Ni, Cd, and Mn were within the acceptable limits of the World Health Organization and the Ministry of Ecology and Environment of China while Cr(VI) exceeded the limits. Most elements exhibited clear seasonal patterns with maxima over the cold season and minima over the warm season. The spatial variabilities in concentrations of the measured elements were not significant except Ni and V. However, the size distribution pattern of each element was quite similar across the region. Characteristic size distributions of elements allowed identification of three main groups: (a) unimodal distribution in the coarse fraction for Ca, Al, Mg, and Ba; (b) unimodal distribution in the fine fraction for Pb, Se, As, Ag, V, Ni, Zn, and Cd; and (c) bimodal or multimodal distribution for Fe, Mn, Cr, K, and Cu. The combination of the size-fractionated concentrations, enrichment factors, correlation coefficients, and factor analysis offered the identification of mixed sources such as vehicular exhaust and wear, heavy fuel oil combustion, and resuspension of road dust. Non-carcinogenic health risks associated with inhalable exposure to airborne metals were higher than the safety threshold (hazard index > 1) across the region, suggesting non-carcinogenic health risks via inhalation. Mn, V, and Ni contributed 74-83% of the total non-carcinogenic risk. The assessment investigation of carcinogenic health risks revealed V and Cr(VI) as elements with the largest carcinogenic risks, accounting for more than 95% of the overall inhalation risk. Nevertheless, the carcinogenic risks for children and adults were between 10-6 and 10-4, within the range considered acceptable by the US EPA. In terms of the size-fractionated risk, PM2.5 contributed 43-50% and 39-44% of the total non-carcinogenic and carcinogenic risks, respectively, indicating the potential health hazard of coarse particle-bound toxic metals was not negligible.

Field-based measurements of major air pollutant emissions from typical porcelain kiln in China.

China has been famous for its porcelains for millennia, and the combustion processes of porcelain production emit substantial amounts of air pollutants, which have not been well understood. This study provided firsthand data of air pollutant emissions from biomass porcelain kilns. The emission factor of PM2.5 was 0.95 ± 1.23 g/kg during the entire combustion cycle, lower than that of biomass burning in residential stoves and coal burning in brick kilns, attributed to the removal effects of the long-distance transport in dragon kilns. The temporal trend of particle pollutants, including particulate matters (PMs) and particulate polycyclic aromatic hydrocarbons (PAHs) (low at ignition phase and high at the end) again indicated the removal effects of the special structure, while gaseous pollutants, such as gaseous PAHs, exhibited the opposite result. The GWC100 was estimated as 1.4 × 106 and 0.5 × 106 kg CO2e/yr for the scenarios in which 50% and 100% of the wood was renewable, respectively. The GWC100 of dragon kilns is nearly equal to that of 745 households using wood-fueled stoves. These results indicate the necessity of pollution controls for biomass porcelain kilns to estimate the emission inventory and climate change.

Phenotypic and transcriptomic changes in the corneal epithelium following exposure to cigarette smoke.

Cigarette smoke extract (CSE), a complex mixture of compounds, contributes to a range of eye diseases; however, the underlying pathophysiological responses to tobacco smoke remain ambiguous. The purpose of the present study was to evaluate the cigarette smoke-induced phenotypic and transcriptomic changes in the corneal epithelium with a view to elucidating the likely underlying mechanism. Accordingly, for the first time, we characterized the genome-wide effects of CSE on the corneal epithelium. The ocular surface of the mice in the experimental groups was exposed to CSE for 1 h per day for a period of one week, while mice in the control group were exposed to preservative-free artificial tears. Corneal fluorescein staining, in vivo confocal microscopy and scanning electron microscopy were performed to examine the corneal ultrastructure. Transcriptome sequencing and bioinformatics analysis were performed followed by RT-qPCR to validate gene expression changes. The results indicate that CSE exposure disrupted the structural integrity of the superficial epithelium, decreased the density of microvilli, and compromised the corneal epithelial barrier intactness. RNA-seq revealed 667 differentially expressed genes, and functional analysis highlighted the enhancement of several biological processes such as antioxidant activity and the response to oxidative stress. Moreover, the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that glutathione metabolism and drug metabolism cytochrome P450 were the most relevant pathways contributing to the effects of CSE on the corneal epithelium. Protein-protein interaction (PPI) network analysis illustrated that GCLC, NQO1, and HMOX1 were the most relevant nodes. In conclusion, the present study indicates that CSE exposure induces changes in the phenotype and genotype of the corneal epithelium. The antioxidant response element is essential for counteracting the effects of cigarette smoke on this tissue layer. These results shed novel insights into how cigarette smoke damages this ocular surface.

Dry deposition of polycyclic aromatic hydrocarbons and its influence on surface soil contamination in Tianjin, China.

ISCLT3 dispersion model was applied to calculate the flux of dry deposition of polycyclic aromatic hydrocarbons (PAHs) in Tianjin, China based on a high resolution emission inventory. Field observations of dry deposition at 22 sampling sites were used for model validation. The mean deposition flux densities (and standard deviation) of 15 PAHs were 4.62 +/- 2.99 microg m(-2) d(-1) and 2.75 +/- 1.78 microg m(-2) d(-1) in the heating and the non-heating seasons, respectively, with a time-weighted annual mean of 3.37 +/- 1.81 microg m(-2) d(-1) (based on the durations of the heating and non-heating seasons). High fluxes occurred in the urbanized areas as well as near two coke and gasification facilities. It was revealed that PAH concentrations in surface soil were correlated significantly with both dry deposition and soil organic matter content. Accordingly, a linear regression model was developed for predicting surface soil PAH concentration based on deposition flux density and soil organic matter content.

Nitrogen isotope composition of ammonium in PM2.5 in the Xiamen, China: impact of non-agricultural ammonia.

Since NH3 is a significant precursor to ammonium in PM2.5 and contributes significantly to atmospheric nitrogen deposition but largely remains unregulated in China, the insight into the source of NH3 emissions by the isotopic investigation is important in controlling NH3 emissions. In this study, atmospheric concentrations of NH3 and water-soluble ion composition in PM2.5 as well as nitrogen isotope ratios in NH4+ (δ15N-NH4+) in Xiamen, China, were measured. Results showed that average NH3 concentration for the five sites in Xiamen was 7.9 µg m-3 with distinct higher values in the warm season and lower values in the cold season, and PM2.5 concentration for the two sites (urban and suburban) was 59.2 µg m-3 with lowest values in summer. In the PM2.5, NH4+ concentrations were much lower than NH3 and showed a stronger positive correlation with NO3- than that with SO42- suggesting the formation of NH4NO3 and equilibrium between NH3 and NH4+. Although the concentrations of NH3 at the urban site were significantly higher than those at the suburban site, no significant spatial difference in NH4+ and δ15N-NH4+ was obtained. The distinct heavier δ15N-NH4+ values in summer than in other seasons correlated well with the equilibrium isotopic effects between NH3 and NH4+ which depend on temperature. The initial δ15N-NH3 values were in the range of waste treatment (- 25.42‰) and fossil fuel combustion (- 2.5‰) after accounting for the isotope fractionation. The stable isotope mixing model showed that fossil fuel-related NH3 emissions (fossil fuel combustion and NH3 slip) contributed more than 70% to aerosol NH4+. This finding suggested that the reduction of NH3 emissions from urban transportation and coal combustion should be a priority in the abatement of PM2.5 pollution in Xiamen.

Chemical characteristics, source apportionment, and regional transport of marine fine particles toward offshore islands near the coastline of northwestern Taiwan Strait.

This study aims to investigate the spatiotemporal variation, chemical composition, and source apportionment of marine fine particles (PM2.5) as well as their regional transport toward the Matsu Islands located near the coastline of northwestern Taiwan Strait. Four offshore island sites located at the Matsu Islands were selected to conduct both regular and intensive sampling of marine PM2.5. Water-soluble ionic species, metallic elements, and carbonaceous contents were then analyzed to characterize the chemical characteristics of marine PM2.5. In order to identify the potential sources and their contributions to marine PM2.5, chemical mass balance (CMB) receptor model was employed along with the backward trajectory simulation to resolve the source apportionment of marine PM2.5 and to explore their transport routes in different seasons. The results showed that high PM2.5 concentrations were commonly observed during the northeastern monsoon periods. Additionally, marine PM2.5 concentration decreased from the west to the east with the highest PM2.5 at the Nankang Island and the lowest PM2.5 at the Donyin Island in all seasons, indicating an obvious concentration gradient of PM2.5 transported from the continental areas to the offshore islands. In terms of chemical characteristics of PM2.5, the most abundant water-soluble ions of PM2.5 were secondary inorganic aerosols (SO42-, NO3-, and NH4+) which accounted for 55-81% of water-soluble ions and 29-52% of marine PM2.5. The neutralization ratios of PM2.5 were always less than unity, indicating that NH4+ cannot solely neutralize nss-SO42+ and NO3- in marine PM2.5 at the Matsu Islands. Although crustal elements (Al, Ca, Fe, K, and Mg) dominated the metallic content of marine PM2.5, trace anthropogenic metals (Cd, As, Ni, and Cr) increased significantly during the northeastern monsoon periods, particularly in winter. Organic carbons (OCs) were always higher than elemental carbons (ECs), and the mass ratios of OC and EC were generally higher than 2.2 in all seasons, implying that PM2.5 was likely to be aged particles. During the poor air quality periods, major air mass transport routes were the northern transport and the anti-cyclonic circulation routes. Source apportionment results indicated that fugitive soil dusts and secondary aerosols were the major sources of marine PM2.5 at the Matsu Islands, while, in winter, biomass burning contributed up to 15% of marine PM2.5. This study revealed that cross-boundary transport accounted for 66~84% of PM2.5 at the Matsu Islands, suggesting that marine PM2.5 at the Matsu Islands has been highly influenced by anthropogenic emissions from neighboring Fuzhou City as well as long-range transport from Northeast Asia.

Characterization of TSP-bound n-alkanes and polycyclic aromatic hydrocarbons at rural and urban sites of Tianjin, China.

Total suspended particle (TSP) was collected and analyzed at rural and urban sites in Tianjin, China during the domestic heating season (from 15 November to 15 March) of 2003/4 for n-alkanes and 16 polycyclic aromatic hydrocarbons (PAHs). The normalized distribution of n-alkanes with the peak at C22, C23, C24 or C25 suggested that fossil fuel utilization was the major source of particulate n-alkanes at both sites. PAHs normalized distribution for each sample was similar and the higher molecular weight PAH dominated the profile (around 90%) indicating a stronger combustion source at both sites. Precipitation and wind were the most important meteorological factors influencing TSP and PAHs atmospheric concentrations. In the urban area the emission height had significant influence on PAHs levels at different heights under the relative stable atmospheric conditions. Coal combustion was the major source for TSP-bound PAHs at both sites based on some diagnostic ratios.

A hydrogel actuator with flexible folding deformation and shape programming via using sodium carboxymethyl cellulose and acrylic acid.

Hydrogel actuator is an intelligent material, which can work as artificial muscle. However, most present hydrogel actuators, due to the inferior mechanical property and uncontrolled folding property, have always resulted in slipping off or the failure of grasping an object with specific shape and required weight. In order to solve this problem, here a tough hydrogel actuator with programmable folding deformation has been prepared by combining the "selective implanting method" and "ionic coordination". The shape and folding angle (from 0 to 180 o) of hydrogel actuator can be precisely controlled by altering the location and size of the implanting parts that seems like the joints of finger. The ionic coordination is not only the force to trigger the folding of hydrogel, but also utilized to reinforce the mechanical property. We believed the superior mechanical and shape-programmable property can endow the hydrogel actuator with great application prospect in soft machine.