We present a novel method referred to as Particle Beam Deflection Imaging (PBDI) for the simultaneous characterization of the size and electric charge distribution of submicrometer (currently ...∼200–800 nm) aerosol particles in real-time (currently ≤30 s). It combines aerodynamic and electrostatic particle deflection, providing two-dimensional information on size and charge in a single two-dimensional light scattering image. The image allows one to extract information on charge-averaged and charged-resolved particle size distributions, and on size-dependent bipolar charge distributions. The current prototype has a size resolution of <50 nm and can resolve individual charge states. Compared to Scanning Mobility Particles Sizers (SMPS), the PBDI offers the advantage of providing simultaneous size and charge information at higher size resolution in a significantly shorter measurement time, hence allowing real-time characterization of volatile aerosol particles.
•Size and charge of submicrometer aerosol particles are characterized simultaneously.•Aerodynamic and electrostatic deflection yield 2-dimensional information.•Resolution of <50 nm and sensitivity to individual charge states is demonstrated.•The method enables real-time characterization of volatile particles.
Primary biological aerosol particles (PBAPs) play an important role in affecting atmospheric physical and chemical properties. Aerosol samples were collected at Cape Hedo, Okinawa Island, Japan, from ...October 2009 to February 2012 and analyzed for five primary saccharides and four sugar alcohols as PBAP tracers. We detected high levels of sucrose in spring when blossoming of plants happens and prolifically emits pollen to the air. Concentrations of glucose, fructose, and trehalose showed levels higher than the other saccharides in spring in 2010. In comparison, primary saccharide levels were mutually comparable in spring, summer, and autumn in 2011, indicating the interannual variability of their local production in subtropical forests, which is driven by local temperature and radiation. High trehalose events were found to be associated with Asian dust outflows, indicating that Asian dust also contributes to PBAPs at Okinawa. Sugar alcohols peaked in summer and correlated with local precipitation and temperature, indicating high microbial activities. Positive matrix factorization analysis confirmed that the PBAPs are mainly derived from local vegetation, pollen, and fungal spores. A higher contribution of PBAP tracers to water‐soluble organic carbon (WSOC) was found in summer (14.9%). The annual mean ambient loadings of fungal spores and PBAPs were estimated as 0.49 µg m−3 and 4.12 µg m−3, respectively, using the tracer method. We report, for the first time, year‐round biomarkers of PBAP and soil dust and their contributions to WSOC in the subtropical outflow region of the Asian continent.
Key Points
PBAPs in Okinawa aerosols are largely affected by sources from local forest
PBAP emissions from forest contribute largely to WSOC in aerosols
Ambient fungal spore and PBAP loadings at Okinawa are estimated
Tracheostomized patients undergoing liberation from mechanical ventilation (MV) are exposed to the ambient environment through humidified air, potentially heightening aerosol particle dispersion. ...This study was designed to evaluate the patterns of aerosol dispersion during spontaneous breathing trials in such patients weaning from prolonged MV.
Particle Number Concentrations (PNC) at varying distances from tracheostomized patients in a specialized weaning unit were quantified using low-cost particle sensors, calibrated against a Condensation Particle Counter. Different oxygen delivery methods, including T-piece and collar mask both with the humidifier or with a small volume nebulizer (SVN), and simple collar mask, were employed. The PNC at various distances and across different oxygen devices were compared using the Kruskal-Wallis test.
Of nine patients receiving prolonged MV, five underwent major surgery, and eight were successfully weaned from ventilation. PNCs at distances ranging from 30 cm to 300 cm showed no significant disparity (H(4) = 8.993, p = 0.061). However, significant differences in PNC were noted among oxygen delivery methods, with Bonferroni-adjusted pairwise comparisons highlighting differences between T-piece or collar mask with SVN and other devices.
Aerosol dispersion within 300 cm of the patient was not significantly different, while the nebulization significantly enhances ambient aerosol dispersion in tracheostomized patients on prolonged MV.
Primary biological particles are an important subset of atmospheric aerosols. They have significant impacts on climate change and public health. Tianjin is a coastal megacity in the North China ...Plain, which is affected by both anthropogenic activities and marine air masses. To study the abundance and dynamic change of bioaerosols in Tianjin, fluorescent biological aerosol particles (FBAPs) in Tianjin were investigated by a wideband integrated bioaerosol sensor (WIBS-4A) in terms of number concentrations and size distributions in summer (11th –25th August 2018). Meanwhile, total suspended particles were collected and analyzed for chemical compounds to identify potential sources of bioaerosols. WIBS data showed that fluorescent biological particles exhibited two peaks at sunrise (~7:00) and in the evening (~20:00), which were probably caused by the enhancement of fungal spores and bacteria. Three rain events occurred during the observation period. Precipitation enhanced the abundance of biological particles, which were likely released from vegetation leaves, resuspended from soil surfaces, and/or carried by raindrops from high altitudes. The abundance of biological particles showed no significant correlation with Na+ (r = −0.17), indicating the air masses from marine areas carried limited biological particles compared to those from continental areas.
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•Real-time fluorescent aerosol particles (FAPs) were characterized in the coastal megacity Tianjin in summer.•Abundance of FAPs increased during precipitation, while that of non-FAPs decreased.•The size distribution of FAPs was dominant in 1–3 μm while non-FAPs peaked at 1 μm during precipitation.
Efficient and accurate calculation of Mie scattering parameters for aerosol particles holds significant scientific value and practical implications across various fields such as climate change and ...environmental science. Traditional multilayer Mie scattering computations are challenged in effectively handling particles that exhibit radial refractive index gradients, leading to low computation speed and accuracy. This paper proposes a novel method driven by deep learning, named RIMie, to offer accuracy and efficient Mie parameters prediction, addressing major challenges in computational efficiency and accuracy. This study provides an efficient and accurate deep learning strategy for calculating Mie scattering parameters of complex aerosol particles, markedly outperforming existing methods.
•Novel approach predicts complex particle Mie scattering.•LSTM network boosts accuracy and efficiency in scattering prediction.•Optimizes quantification method for aerosol particle scattering.•Offers significant implications for improving climate modeling accuracy.
A large fraction of atmospheric aerosols can be characterized as primary organic aerosol (POA) and secondary organic aerosol (SOA). Knowledge of the phase behavior, that is, the number and type of ...phases within internal POA + SOA mixtures, is crucial to predict their effect on climate and air quality. For example, if POA and SOA form a single phase, POA will enhance the formation of SOA by providing organic mass to absorb SOA precursors. Using microscopy, we studied the phase behavior of mixtures of SOA proxies and hydrocarbon-like POA proxies at relative humidity (RH) values of 90%, 45%, and below 5%. Internal mixtures of POA and SOA almost always formed two phases if the elemental oxygen-to-carbon ratio (O/C) of the POA was less than 0.11, which encompasses a large fraction of atmospheric hydrocarbon-like POA from fossil fuel combustion. SOA proxies mixed with POA proxies having 0.11 ≤ O/C ≤ 0.29 mostly resulted in particles with one liquid phase. However, two liquid phases were also observed, depending on the type of SOA and POA surrogates, and an increase in phase-separated particles was observed when increasing the RH in this O/C range. The results have implications for predicting atmospheric SOA formation and policy strategies to reduce SOA in urban environments.
Measurements of ambient aerosol particles at the University of León, León, Spain, were made in May and June 2015 with a Wideband Integrated Bioaerosol Spectrometer (WIBS). The WIBS detects ...Fluorescing Aerosol Particles (FAP) in the size range from 0.5 to 20 μm. These measurements were complemented with an analysis of pollen concentrations assessed with optical microscopy of samples captured with a volumetric Hirst spore trap. The total particle, FAP and pollen concentrations show clear, daily cycles. Whereas the total particle concentrations maximize at 0800 and 2200 UTC, the FAP concentrations have peaks at midnight and 0800 UTC while the pollen has a broad peak between 1200 and 2000 UTC. The FAP larger than 2 μm represent 15–35% of the total particle population in this size range, maximizing at midnight UTC. Similar to what has been found by investigators at other locations, there is a strong positive correlation of the WIBS measured FAP with relative humidity; however, the pollen concentration is positively correlated with the temperature and anti-correlated with the relative humidity. Back trajectory analysis indicates that the largest FAP to total particle fractions are found in air masses arriving from the northeast with the second largest coming from the southwest. Given the location of the university in relation to the city and forested areas, this implies that the higher concentration FAP are coming from rural, probably natural, sources; however, more local, anthropogenic sources cannot be ruled out as a secondary source. The majority of the FAP that are identified from microscopy are fungal spores (Cladosporium, Aspergillus, Alternaria, Oidium) and pollen grains (mainly Poaceae, Quercus, Plantago, Rumex and Urticaceae). A comparison of the fluorescence fingerprints between laboratory generated FAP and the ambient particles showed some similarities; however, a significant fraction of the FAP are those whose fluorescence patterns do not match any of those that have been previously classified in the laboratory.
•A WIBS and a Hirst-type volumetric trap measured bioaerosols simultaneously in Leon.•The bioaerosol sizes determined by the WIBS are consistent with microscope images.•The WIBS Type III class and Hirst pollen concentration were of comparable magnitude.•Use of the WIBS and biolibrary is a potential approach for pollen classification.•The WIBS could become a useful tool for pollen quantification in real time.
Atmospheric deposition (AD) of nutrients and its impact on the sea surface requires consideration of interfacial processes within the sea surface microlayer (SML), the ocean-atmosphere boundary layer ...of major importance for many global biogeochemical and climate-related processes. This study comprised a comprehensive dataset, including dissolved NO3−, NH4+ and PO43− in ambient aerosol particles, wet deposition and sea surface samples collected from February to July 2019 at a central Adriatic coastal site. The aerosol mean concentration of dissolved nitrogen (DIN = NO3− + NH4+) and PO43− were 48.8 ± 82.8 μmol m−3 and 0.8 ± 0.6 μmol m−3, respectively, while their total fluxes (dry + wet) ranged from 24.2 to 212.3 μmol m−2 d−1 (mean 123.2 ± 53.2 μmol m−2 d−1) and from 1.2 to 2.1 μmol m−2 d−1 (mean 1.5 ± 0.3 μmol m−2 d−1), respectively. Intensive local episodes of open biomass burning (BB) significantly increased aerosol DIN concentrations as well as DIN deposition fluxes, particularly altering the molar DIN/PO43− ratio of atmospheric samples. The DIN temporal patterns showed high variability in the SML (range 0.2–24.6 μmol L−1, mean 5.0 ± 7.1 μmol L−1) in contrast to the underlying water samples (range 0.5–4.2 μmol L−1, mean 1.9 ± 1.2 μmol L−1), with significant increases during BB periods. Variability in abundance of heterotrophic bacteria and autotrophs in the SML along with concentrations of bulk dissolved and particulate organic carbon as well as dissolved and particulate lipids and carbohydrates, gel particles and surfactants followed DIN enhancements with a two-week delay. This study showed that AD can affect the short-term scale enrichments of organic matter in the SML, especially when accompanied by BB emissions typical of the overall Mediterranean coastal environment. This could have strong implications for global air-sea exchange processes, including those of climate relevant gases, mediated by the SML.
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•Adriatic coastal area: simultaneous atmospheric and seawater field measurements•Nutrient variability in aerosols, rainwater and atmospheric deposition (AD) fluxes•Local open-fire biomass burning (BB) affected chemistry of atmospheric samples.•AD impacted nutrient levels and N:P ratios in the sea surface microlayer (SML).•The SML plankton development and organic matter enrichments followed BB episodes.
•The state-of-the-art degradable nanofiber filters for air filtration are presented.•The categories of degradable nanofiber filters are according to the filter composition.•The functionalities of ...degradable filters are included.•Challenges and future development are demonstrated.
Air pollution has posed a great threat to public health around the globe. Filters can be considered the effective protective equipment to reduce the transmissions of aerosol particles. However, the widespread use of non-degradable filters created a massive disruption in the waste disposal system. Nanofiber filters can achieve high removal efficiency and low pressure drop simultaneously. Benefit from the advantages of degradability and environmental sustainability, degradable nanofiber filters are believed to be efficient filtration media for a sustainable ecosystem. Here, this review focuses on the state-of-the-art degradable nanofiber filters for the removal of particulate matter. According to the filter composition, diverse categories and desired filtration performance are introduced in detail. In addition, various functionalities of the degradable nanofiber filters are classified. Finally, we discuss and suggest several possible directions for future challenges. This review provides a comprehensive insight into environmentally friendly air filters, which can deal with future demands in a more sustainable fashion.
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