This study discusses the annual and seasonal variations of PM2.5 and PM10 concentrations over Delhi for the five-year period from 2018 to 2022, along with the influence of meteorological factors on their variability. The overall annual average concentrations of PM2.5 and PM10 were found to be 104.1±78.0 and 213.2±117.8 µgm−3, respectively—approximately 2.5 and 3.5 times higher than India's National Ambient Air Quality Standards. A highly significant difference in annual PM2.5 and PM10 concentrations was observed (p = 0.000), with a strong positive correlation (r = 0.91) between them. Notably, for PM2.5, the rate of decrease in 2019–2020 (12.9
Water-based aerosol is widely used as an effective strategy in crop frost protection, fugitive dust control, emergency fire suppression, and electro-optical countermeasures on the battlefield, owing to the preponderance of high efficiency, low cost, and eco-friendliness. Unfortunately, the poor stability of the water-based aerosol caused by the rapid evaporation and sedimentation of the aerosol droplets, still remains a huge challenge for all-day interference. Although various strategies have been exploited, such as selecting additives with various compositions and proportions, the mechanism on meliorating the intrinsic stability of the water-based aerosol is still confusing. Herein, we systematically analyzed the formation process of the water-based aerosol, and the nucleation behavior is one of the key factors influencing the stability of water-based aerosols. A series of carbon-based nanoparticles with tunable surface properties was screened as heterogeneous nucleation additives to reduce the nucleation energy barrier, decrease the droplet size and uniform the droplet distribution of the water-based aerosols. And the nano graphite powder was identified as the most effective nucleation seed. The nucleation energy barrier was reduced from 1.63 × 10–19 J to 1.01 × 10–20 J with carbon nanoparticle additives. The effective stable duration was improved from 64 min to 125 min compared with that of the water-based aerosol without any modification, and retaining over 60
Rural PM2.5 in the North China Plain (NCP) is influenced by residential combustion, agricultural activities, and regional secondary formation, yet the aerosol evolution during the non-heating to heating transition is poorly understood. Daytime and nighttime PM2.5 samples were collected at Gucheng, a typical rural NCP site, during 2019/2020. Organic carbon (OC), elemental carbon (EC), and inorganic ions were measured to characterize aerosol composition and sources. Mean PM2.5 increased from 44.9 µg m− 3 in autumn to 66.6 µg m− 3 in winter, driven mainly by a doubling of organic matter (OM) from 13.3 to 27.2 µg m− 3, whereas secondary inorganic aerosol (SNA) increased modestly from 15.0 to 18.5 µg m− 3. Accordingly, OM/SNA increased from 0.89 to 1.47 and reached 1.81 during winter nighttime. Nitrate remained important (23.2
Atmospheric brown carbon (BrC) exhibits substantial variability in both atmospheric light absorption and mass-normalized absorption efficiency, yet their responses to changing aerosol conditions are not necessarily synchronous. Here, year-long PM2.5 samples collected in Southwest China were used to investigate the period-dependent optical properties of methanol-soluble BrC and the roles of organic carbon (OC) and measured chromophores. Abs365 was markedly enhanced during the late dry season (LDS), coinciding with elevated OC and chromophore concentrations due to long-range transport of biomass burning emission in South/Southeast Asian countries. Abs365 was strongly correlated with OC over the whole campaign (r = 0.88) and particularly during the LDS period (r = 0.916), demonstrating the dominant influence of organic aerosol loading on bulk absorption. However, MAC365 during the LDS period decreased to about two-thirds of its level in the early dry season and wet season, which probably caused by the simultaneous production of weak or non-absorbing organic materials in atmospheric aging processes during long-range transport. Overall, the results demonstrate a clear period-dependent decoupling between atmospheric BrC absorption and OC-normalized absorption efficiency, with enhanced LDS absorption driven primarily by increased organic aerosol loading rather than higher intrinsic absorptivity. Year-long measurements reveal distinct period-dependent variations in methanol-soluble BrC absorption. Enhanced Abs365 during the LDS period was mainly driven by increased organic aerosol loading. Abs365 and MAC365 varied independently, highlighting distinct effects of aerosol loading and composition.
Particulate matter (PM) source apportionment remains fundamental to air quality management, particularly under increasingly stringent air quality standards that require robust identification of emission sources. This review combines bibliometric analysis to examine the development and recent implementation of four widely used receptor models: Positive Matrix Factorization (PMF), Chemical Mass Balance (CMB), UNMIX, and the Constrained Physical Receptor Model (COPREM). Bibliometric analysis of Scopus-indexed literature (1970–2024) describes publication trends, geographical distribution, and research themes, while studies published during 2020–2024 were further evaluated to identify representative methodological developments and current applications. PMF remained the dominant model (84
