Search Results (81)

In this study, we introduced a novel Trajectory-Channel Transport Model (TCTM) to unravel spatiotemporal dynamics of PM_2.5 pollution. By integrating high-resolution simulations from the Weather Research and Forecasting (WRF) model with the Nested Air-Quality Prediction Modeling System (WRF-NAQPMS) and 72 h backward-trajectory analysis, TCTM enables the precise identification of source regions, the delineation of key transport corridors, and a quantitative assessment of regional contributions to receptor sites. Focusing on four Yangtze River Delta cities (Hangzhou, Shanghai, Nanjing, Hefei) during a January 2020 pollution event, the results demonstrate that TCTM’s Weighted Concentration Source (WCS) and Source Pollution Characteristic Index (SPCI) outperform traditional PSCF and CWT methods in source-attribution accuracy and resolution. Unlike receptor-based statistical approaches, TCTM reconstructs pollutant transport processes, quantifies spatial decay, and assigns contributions via physically interpretable metrics. This innovative framework offers actionable insights for targeted air-quality management strategies, highlighting its potential as a robust tool for pollution mitigation planning. Full article

In recent years, with the rapid socioeconomic development of Wuxi City, the frequent occurrence of severe air pollution events has attracted widespread attention from both the local government and the public. Based on the real-time monitoring data of criteria pollutants and GDAS (Global Data Assimilation System) reanalysis data, the spatiotemporal variation patterns, meteorological influences, and potential sources of major air pollutants in Wuxi across different seasons during 2019 (pre-COVID-19) and 2023 (post-COVID-19 restrictions) are investigated using the Pearson correlation coefficient, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) models. The results demonstrate that the annual mean PM_2.5 concentration in Wuxi decreased significantly from 39.6 μg/m³ in 2019 to 29.3 μg/m³ in 2023, whereas the annual mean 8h O₃ concentration remained persistently elevated, with comparable levels of 104.6 μg/m³ and 105.0 μg/m³ in 2019 and 2023, respectively. The O₃ and particulate matter (PM) remain the most prominent air pollutants in Wuxi’s ambient air quality. The hourly mass concentrations of criteria pollutants, except O₃, exhibited characteristic bimodal distributions, with peak concentrations occurring post-rush hour during morning and evening commute periods. In contrast, O₃ displayed a distinct unimodal diurnal pattern, peaking between 15:00 and 16:00 local time. The spatial distribution patterns revealed significantly elevated concentrations of all monitored species, excluding O₃, in the central urban zone, compared to the northern Taihu Lake region. The statistical analysis revealed significant correlations among PM concentrations and other air pollutants. Additionally, meteorological parameters exerted substantial influences on pollutant concentrations. The PSCF and CWT analyses revealed distinct seasonal variations in the potential source regions of atmospheric pollutants in Wuxi. In spring, the Suzhou–Wuxi–Changzhou metropolitan cluster and northern Zhejiang Province were identified as significant contributors to PM_2.5 and O₃ pollution in Wuxi. The potential source regions of O₃ are predominantly distributed across the Taihu Lake-rim cities during summer, while the eastern urban agglomeration adjacent to Wuxi serves as major potential source areas for O₃ in autumn. In winter, the prevailing northerly winds facilitate southward PM_2.5 transport from central-northern Jiangsu, characterized by high emissions (e.g., industrial activities), identifying this region as a key potential source contribution area for Wuxi’s aerosol pollution. The current air pollution status in Wuxi City underscores the imperative for implementing more stringent and efficacious intervention strategies to ameliorate air quality. Full article

Aerosol optical depth (AOD) data from 2020 to 2022 during the COVID-19 pandemic in a typical desert industrial city, Wuhai, was analyzed to investigate aerosol optical properties, origins of different types of aerosols, and the impacts of the COVID-19 lockdown on desert pollution. Results show that annual AOD (500 nm) and Ångström exponent α were 0.36 ± 0.12 and 0.75 ± 0.22 in 2020, 0.30 ± 0.12 and 0.75 ± 0.14 in 2021, and 0.28 ± 0.09 and 0.74 ± 0.19 in 2022, respectively, representing a slightly polluted environment characterized by a mixture of coarse-mode dust aerosols and fine-mode anthropogenic aerosols. Seasonal analysis reveals that the highest AOD primarily occurred in spring due to frequent dust events, while the lowest AOD was observed in winter. Potential Source Contribution Function (PSCF) identified the Alxa Desert as a major potential source during the entire year, and anthropogenic industrial and mining activities in northern Ningxia and southern Inner Mongolia were also important contributors, particularly outside of the winter season. The prevailing wind direction in Wuhai was from the northwest (NW-quadrant), originating from the depopulated desert or Gobi area, accounting for 85.11% in spring, 61.45% in summer, 68.09% in autumn, and 100% in winter. The remaining air masses came from southeastern (SE-quadrant) densely populated areas. Despite the dominance of NW air flows, SE anthropogenic air masses resulted in the highest AOD of 0.47 ± 0.24 in spring, 0.38 ± 0.23 in summer, and 0.32 ± 0.17 in autumn, with corresponding finest particle sizes of 0.83 ± 0.31, 0.91 ± 0.30, and 1.02 ± 0.22 in α. This suggests that anthropogenic influence remains significant even under strict control measures during the COVID-19 lockdown. In winter, the northwest air masses contributed to the highest pollution of 0.49 ± 0.39 (AOD) and finest particle size of 0.90 ± 0.32 (α), likely associated with the coal/straw burning for winter heating. In addition, the particles leading to moderate pollution primarily ranged around 0.2–0.25 µm, and fine particle pollution persists throughout the year. Full article

Phlai (Zingiber montanum) has long been valued for its anti-inflammatory and analgesic properties in traditional medicine. This study aimed to develop and assess the physical stability, chemical composition, and clinical efficacy of a novel Phlai spray cool formula (PSCF) compared to a diclofenac spray (DS) in patients with chronic myofascial pain syndrome. The chemical analysis revealed curcumin (28.73 ± 5.73 mg/100 g), β-sitosterol (50.92 ± 1.27 mg/100 g), and lauric acid (38.86 ± 1.72 g/100 g) as key active compounds. PSCF demonstrated stable physicochemical properties, including pH and peroxide value across storage conditions. In a randomized controlled trial involving 66 participants, PSCF and DS groups exhibited comparable reductions in pain intensity, as measured by the Visual Analog Scale (VAS), from baseline to week 2. Both groups also showed significant improvements in neck disability index (NDI), pressure pain threshold (PPT), and cervical range of motion (CROM). By week 2, the increase in CROM for flexion and extension reached 23.54 ± 4.09° and 19.43 ± 3.20°, respectively, with no significant intergroup differences. The SF-36 health survey indicated notable improvements in overall health status and quality of life, particularly in physical and emotional domains. The analgesic effects of PSCF are attributed to the combined action of menthol, β-sitosterol, and curcumin. The study demonstrated that PSCF offers a therapeutic effect comparable to diclofenac spray without adverse reactions, highlighting its potential as an alternative topical analgesic for chronic myofascial pain management. Full article

Aerosol transport flux LiDAR was used to observe heavy pollution events in Luohe City during January 2022 and was combined with monitoring data of ground meteorological parameters and conventional pollutants to analyze the vertical optical properties of aerosols, transport sources, and causes of heavy pollution. Two pollution events (January 2nd–5th and 13th–20th, 2022) were effectively monitored and divided into four pollution phases according to PM_2.5 concentrations and relative humidity (RH). The results showed that all ground PM_2.5/PM₁₀ values were above 0.5 throughout the pollution, indicating a predominance of fine particulate matter. Analysis of the vertical distribution of aerosol flux LiDAR data showed that the inversion layer was distributed below 1 km; the vertical profile of extinction coefficient showed that all the pollution events were dominated by local emissions, while the contribution of regional transmission during the January 2nd to 5th was also quite prominent; kriging interpolation results showed that this pollution covered the most central and eastern regions of China during January 2022. The flux LiDAR monitoring results showed that there were three main transmission channels of PM_2.5: east (Zhoukou, Lu–Wan–Yu–Su junction), northeast (Lu–Yu junction), and southeast (YRD). The analysis of the clustered backward trajectories, potential source contribution function (PSCF), and concentration-weighted trajectory (CWT) models showed that the potential transmission sources of PM_2.5 were mainly in junction zones of Lu–Wan–Yu–Su as well as Shaanxi Province, with PSCF values above 0.7 and CWT values above 70 μg/m³. This study could provide a scientific basis for the prevention and control of local pollution. Full article

To investigate concentration and potential sources of total gaseous mercury (TGM) in a concentrated non-ferrous metals smelting area in southwest China, a high temporal resolution automatic mercury meter was used to measure TGM in the environment and the emissions from major sources of Mengzi city. The average concentration of TGM in urban air was 2.1 ± 3.5 ng·m⁻³ with a range of 0.1~61.1 ng·m⁻³ over the study period. The highest TGM concentration was in fall (3.3 ± 4.3 ng·m⁻³). The daytime TGM concentration (2.8 ± 3.5 ng·m⁻³) was significantly higher than that in the nighttime (1.6 ± 1.1 ng·m⁻³), which may be attributed to the increased emissions of mercury from the high volume of vehicle activity during the day. To discuss the contributions of local sources and long-range transport, eight pollution events were identified based on the ratio of ΔTGM/ΔCO (Carbon Monoxide), which can be found that local sources are a key contributor to the major TGM pollution events. Concentrations of TGM in flue gases from eight non-ferrous industrial sources were also measured in Mengzi, which were found that the highest TGM emission concentration was up to 4.6 mg·m⁻³. Simultaneously, the concentrations of TGM in ambient air around these industries and Xidu Tunnel were also detected, the concentrations were 1 to 4 times higher than that in the urban air sampling site. Based on the analysis of air mass and PSCF, when northwest wind happened, these emissions of industries and vehicles can be identified as the primary sources of TGM in urban air of Mengzi. Full article

Data on particulate matter, gaseous pollutants, and AQI values from three cities (Haikou, Sanya, and Danzhou) between January 2018 and December 2022 were obtained in order to analyze the spatiotemporal distribution characteristics of air pollution, the correlation between pollutants with meteorological conditions, and the potential sources in Hainan Island. The spatiotemporal distribution’s characteristics demonstrated that the annual mean concentrations of SO₂, NO₂, CO, O₃, PM₁₀ and PM_2.5 were 4.34 ± 1.11 μg m⁻³, 9.87 ± 1.87 μg m⁻³, 0.51 ± 0.06 mg m⁻³, 73.04 ± 6.36 μg m⁻³, 27.31 ± 3.63 μg m⁻³, and 14.01 ± 2.02 μg m⁻³, respectively. The yearly mean concentrations were trending downward in the past few years and were below the National Ambient Air Quality Standard (NAAQS) Grade II. Summer was the season with the lowest concentrations of all pollutants (3.84 μg m⁻³, 7.34 μg m⁻³, 0.42 mg m⁻³, 52.80 μg m⁻³, 18.67 μg m⁻³ and 8.67 μg m⁻³ for SO₂, NO₂, CO, O₃, PM₁₀ and PM_2.5, respectively), and afternoons were the time with the lowest concentrations of pollutants (except for 78.04 μg m⁻³ for O₃). The influence of meteorological conditions on pollutants was examined: there was a prominent positive correlation between temperature and O₃ in summer, and relative humidity largely influenced the concentrations of PM. The pollution in Hainan was affected more by regional transport; according to the backward trajectory results, Hainan is susceptible to air masses from Guangdong and Fujian to the northeast, the Indochina Peninsula to the southwest, and the South China Sea to the southeast. The results of PSCF and CWT analyses indicated that Guangdong, Jiangxi, Hunan, and Fujian were the primary potential sources of PM_2.5 and O₃. Full article

During the past decade, the air quality has been greatly improved in China since the implementation of the “Clean Air Act”. However, haze events are still being reported in some regions of China, and the pollution mechanism remains unclear. In this study, we investigate the chemical characteristics of the pollution mechanism of the PM_2.5 composition in Suzhou from October 18 to December 15, 2020. A notable declining trend in temperature was observed from 18 to 27 November, which indicates the seasonal transition from fall to the winter season. Four representative periods were identified based on meteorological parameters and the PM_2.5 mass concentrations. The heavy pollution period had the typical characteristics of a relatively low temperature, a high relative humidity, and mass loadings of atmospheric pollutants; nitrate was the dominant contributor to the haze pollution during this period. The nitrate formation mechanism was driven by the planetary boundary layer dynamics. The potential source contribution function model (PSCF) showed that the major PM_2.5 composition originated from the northwest direction of the sampling site. The aerosol liquid water content presented increasing trends with an increasing relative humidity. The pH was the highest during the heavy pollution period, which was influenced by the aerosol liquid water content and the mass loadings of NO₃⁻, SO₄²⁻, NH₄⁺, and Cl⁻. The comprehensive analysis in this paper could improve our understanding of the nitrate pollution mechanism and environmental effects in this region. Full article

Studies of the impact of biomass burning and the emissions of trace gases from biomass burning, especially using long-term observations, are scarce in China. We utilize solar absorption spectra obtained via ground-based high-resolution Fourier transform infrared (FTIR) spectroscopy to retrieve the atmospheric total columns and vertical profiles of carbon monoxide (CO), formaldehyde (H₂CO), and hydrogen cyanide (HCN) in Hefei, China. Seasonal and interannual variability in the three gases from 2016 to 2022 are analyzed. Atmospheric CO shows significant seasonal variations, peaking during spring and winter, and declining during summer, with a seasonal amplitude of 8.07 × 10¹⁷ molecules cm⁻² and a seasonal variability of 29.35%. H₂CO and HCN have similar seasonal patterns to each other, with high concentrations in summer and low concentrations in winter. The seasonal amplitude of H₂CO and HCN are 1.89 × 10¹⁶ molecules cm⁻² and 2.32 × 10¹⁵ molecules cm⁻², respectively, with a seasonal variability of 133.07% and 34.69%, respectively. The means of the annual variation rate for CO, H₂CO, and HCN are (−2.67 ± 2.88)% yr⁻¹, (2.52 ± 12.48)% yr⁻¹ and (−3.48 ± 7.26)% yr⁻¹, respectively. To assess the influence of biomass burning on the variations in column concentrations of the three gases, the correlation between CO, H₂CO, and HCN was analyzed. The months during which the monthly correlation coefficient between CO and H₂CO with HCN exceeds 0.8, and the fire radiative power (FRP) observed by satellites is larger than its monthly average are regarded as a biomass-burning occurrence in Anhui province. Additionally, the enhancement ratios of ΔH₂CO/ΔCO and ΔHCN/ΔCO were calculated for the periods impacted by the biomass burning. Finally, backward trajectory cluster analysis and the potential source contribution function (PSCF) calculation identified the air mass transport pathways and the potential source areas at the Hefei site. Full article

To assess the impact of air pollution on human health in multiple urban areas in Greece, hourly concentrations of common air pollutants (CO, NO₂, O₃, SO₂, PM₁₀, and PM_2.5) from 11 monitoring stations in six major Greek cities (Athens, Thessaloniki, Patra, Volos, Ioannina, and Kozani), were used to implement the U.S. EPA’s Air Quality Index (AQI) during a seven-year period (2016–2022). In Athens, the capital city of Greece, hourly PM₁₀ and PM_2.5 concentrations were also studied in relation to the prevailing wind patterns, while major PM₁₀ episodes exceeding the official daily EU limit (50 μg/m³) were analyzed using the Potential Source Contribution Function (PSCF) in terms of the air mass origin. According to the AQI results, PM₁₀ and PM_2.5 were by far the most hazardous pollutants associated with moderate and unhealthy conditions in all the studied areas. In addition, in Athens, Thessaloniki, and Patra, where the benzene levels were also studied, a potential inhalation cancer risk (>1.0 × 10⁻⁶) was detected. In Athens, Saharan dust intrusions were associated with downgraded air quality, whilst regional transport and the accumulation of local emissions triggered increased PM₁₀ and PM_2.5 levels in traffic sites, especially during cold periods. Our study highlights the need for the development of early warning systems and emission abatement strategies for PM pollution in Greece. Full article

The lack of vertical observation of reactive nitrogen oxides in agricultural areas has posed a significant challenge in fully understanding their sources and impacts on atmospheric oxidation. Ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) observations were conducted in the agricultural regions of the North China Plain (NCP) during the summer of 2019 to measure the vertical distributions of aerosols, nitrogen dioxide (NO₂), and nitrous acid (HONO). This study aimed at revealing the spatiotemporal distribution, sources, and environmental effects of reactive nitrogen oxides in the NCP agricultural areas. Our findings indicated that the vertical profiles of aerosols and NO₂ exhibited a near-Gaussian distribution, with distinct peak times occurring between 8:00–10:00 and 16:00–18:00. HONO reached its maximum concentration near the surface around 8:00 in the morning and decreased exponentially with altitude. After sunrise, the concentration of HONO rapidly decreased due to photolysis. Additionally, the potential source contribution function (PSCF) was used to evaluate the potential sources of air pollutants. The results indicated that the main potential pollution sources of aerosols were located in the southern part of the Hebei, Shanxi, Shandong, and Jiangsu provinces, while the potential pollution sources of NO₂ were concentrated in the Beijing–Tianjin–Hebei region. At altitudes exceeding 500 m, the heterogeneous reactions of NO₂ on aerosol surfaces were identified as one of the important contributors to the formation of HONO. Furthermore, we discussed the production rate of hydroxyl radicals (OH) from HONO photolysis. It was found that the production rate of OH from HONO photolysis decreased with altitude, with peaks occurring in the morning and late afternoon. This pattern was consistent with the variations in HONO concentration, indicating that HONO was the main contributor to OH production in the agricultural regions of the NCP. This study provides a new perspective on the sources of active nitrogen in agricultural regions and their contribution to atmospheric oxidation capacity from a vertical perspective. Full article

To thoroughly investigate the impact of meteorological conditions and emission changes on winter PM_2.5 variation in the Yangtze River Delta (YRD) from 2015 to 2019, we leveraged advanced modeling techniques, namely, the Weather Research and Forecasting (WRF) model and the Nested Air Quality Prediction Model System (NAQPMS). The results revealed that a notable trend of high-PM_2.5-concentration regions shifted from coastal areas towards to the inland regions. While emission reduction can effectively reduce the concentration of PM_2.5, meteorological changes exert a significant impact on PM_2.5 concentration. Unfavorable meteorological changes in 2018 and 2019 emerged as crucial factors driving PM_2.5 pollution in the region (up 0~50 µg·m⁻³). Our findings also shed light on the potential sources and transport pathways of PM_2.5 pollution in key cities within the YRD, indicating that the coastal channel of Hebei–Shandong–Jiangsu and the inland channel bordering Hebei, Henan, Shandong, and Anhui serve as major contributors. Light and moderate pollution was predominantly influenced by the medium-distance coastal channel (48~70%). Remarkably, short-distance inland (19~54%) and coastal transportation (33~53%) channels emerged as the primary causes of severe PM_2.5 pollution in the YRD. To effectively combat this issue, it is imperative to bolster key control and prevention measures in these regions. Full article

Small- and medium-sized enterprises (SMEs) frequently face challenges in obtaining financial assistance from traditional banks. Platform Supply Chain Finance (PSCF) has emerged as a promising solution for financing issues among SMEs, with an added focus on integrating sustainability aspects. This study focused on a two-tier supply chain as its primary research topic to find strategies to enhance supplier financial viability and improve the efficiency and profitability of the main manufacturing enterprise. In this study, we establish three distinct hypotheses corresponding to the three models involving supplier and manufacturer participation, encompassing parameters such as production batch size, pricing, and supply chain profit. First, it examined financing decisions through the lens of core enterprise-led platform finance. Second, it applied the Stackelberg game theory to investigate financing decisions in three distinct modes: traditional finance, platform internal finance, and external platform finance. Suppliers, manufacturers, and banks can be seen as participants in a Stackelberg game. In this game, suppliers act as leaders, making production and procurement decisions first, while manufacturers and banks act as followers, adjusting their behavior based on the suppliers’ decisions. Finally, it performed a comparative analysis of decisions and supply chain efficiency across these modes. When the risk regulation cost coefficient falls below a certain threshold, suppliers are willing to set up their own PSCF and there is an optimal level of risk regulation effort within the interval (0, 1). We compare platform finance with traditional finance and find that the traditional finance model maximizes profits for suppliers, while the external financing model maximizes profits for manufacturers and the overall supply chain profit. Findings provide insights for platforms, suppliers, manufacturers, and banks to implement optimal financing and channel structures to increase their profits and promote the sustainable development of the financial supply chain. In addition, future research on blockchain platform models would be highly meaningful. Full article

In this study, online ambient volatile organic compounds (VOCs) were collected at an urban site of Zhengzhou in Central China during February 2018. The VOCs characteristics, source contributions and the Chinese New Year (CNY) effects have been investigated. During the sampling period, three haze periods have been identified, with the corresponding VOCs concentrations of (92 ± 45) ppbv, (62 ± 18) ppbv and (83 ± 34) ppbv; in contrast, the concentration during non-haze days was found to be (57 ± 27) ppbv. In addition, the festival effects of the CNY were investigated, and the concentration of particulate matter precursor decreased significantly. Meanwhile, firework-displaying events were identified, as the emission intensity had been greatly changed. Both potential source contribution function (PSCF) and the concentration weighted trajectory (CWT) models results indicated that short-distance transportation was the main influencing factor of the local VOCs pollution, especially by transport from the northeast. Source contribution results by the positive matrix factorization (PMF) model showed that vehicle exhaust (24%), liquid petroleum gas and natural gas (LPG/NG, 23%), coal combustion (21%), industrial processes (16%) and solvent usages (16%) were the major sources of ambient VOCs. Although industry and solvents have low contribution to the total VOCs, their secondary organic aerosol (SOA) contribution were found to be relatively high, especially in haze-1 and haze-3 periods. The haze-2 period had the lowest secondary organic aerosol potential (SOAp) during the sampling period; this is mainly caused by the reduction of industrial and solvent emissions due to CNY. Full article

To measure the long-range transport of PCDD/Fs, a background sampling site at Mt. Lulin station (Taiwan) was selected based on meteorological information and its location relative to burning events in Southeast Asia. During regular sampling periods, a higher concentration of PCDD/Fs was recorded in 2008 at Mt. Lulin station during La Niña events, with levels reaching 390 fg I-TEQ/m³. In contrast, a higher concentration of 483 fg I-TEQ/m³ was observed in 2013 during biomass burning events. This indicates that La Niña affects the ambient PCDD/F concentrations. The ratio of ΣPCDD/ΣPCDF was 0.59, suggesting significant long-range transport contributions from 2007 to 2023. From 2007 to 2015, the predominant species was 2,3,4,7,8-PCDF, accounting for 25.3 to 39.6% of the total PCDD/Fs. From 2018 onward, 1,2,3,7,8-PCDD became more dominant, accounting for 15.0 to 27.1%. According to the results from the receptor model PMF (n = 150), the sources of PCDD/Fs were identified as dust storms and monsoon events (19.3%), anthropogenic activity (28.5%), and biomass burning events (52.2%). The PSCF values higher than 0.7 highlighted potential PCDD/F emission source regions for Mt. Lulin during biomass burning events, indicating high PSCF values in southern Thailand, Cambodia, and southern Vietnam. Full article