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Submicron atmospheric particles in the Amazon Basin were characterized by a high‐resolution aerosol mass spectrometer during the wet season of 2008. Patterns in the mass spectra closely resembled those of secondary‐organic‐aerosol (SOA) particles formed in environmental chambers from biogenic precursor gases. In contrast, mass spectral indicators of primary biological aerosol particles (PBAPs) were insignificant, suggesting that PBAPs contributed negligibly to the submicron fraction of particles during the period of study. For 40% of the measurement periods, the mass spectra indicate that in‐Basin biogenic SOA production was the dominant source of the submicron mass fraction, contrasted to other periods (30%) during which out‐of‐Basin organic‐carbon sources were significant on top of the baseline in‐Basin processes. The in‐Basin periods had an average organic‐particle loading of 0.6 μg m−3 and an average elemental oxygen‐to‐carbon (O:C) ratio of 0.42, compared to 0.9 μg m−3 and 0.49, respectively, during periods of out‐of‐Basin influence. On the basis of the data, we conclude that most of the organic material composing submicron particles over the Basin derived from biogenic SOA production, a finding that is consistent with microscopy observations made in a concurrent study. This source was augmented during some periods by aged organic material delivered by long‐range transport.

The Arctic is sensitive to cloud radiative forcing. Due to the limited number of aerosols present throughout much of the year, cloud formation is susceptible to the presence of cloud condensation nuclei and ice nucleating particles (INPs). Primary biological aerosol particles (PBAP) contribute to INPs and can impact cloud phase, lifetime, and radiative properties. We present yearlong observations of hyperfluorescent aerosols (HFA), tracers for PBAP, conducted with a Wideband Integrated Bioaerosol Sensor, New Electronics Option during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition (October 2019–September 2020) in the central Arctic. We investigate the influence of potential anthropogenic and natural sources on the characteristics of the HFA and relate our measurements to INP observations during MOSAiC. Anthropogenic sources influenced HFA during the Arctic haze period. But surprisingly, we also found sporadic “bursts” of HFA with the characteristics of PBAP during this time, albeit with unclear origin. The characteristics of HFA between May and August 2020 and in October 2019 indicate a strong contribution of PBAP to HFA. Notably from May to August, PBAP coincided with the presence of INPs nucleating at elevated temperatures, that is, >−9°C, suggesting that HFA contributed to the “warm INP” concentration. The air mass residence time and area between May and August and in October were dominated by the open ocean and sea ice, pointing toward PBAP sources from within the Arctic Ocean. As the central Arctic changes drastically due to climate warming with expected implications on aerosol–cloud interactions, we recommend targeted observations of PBAP that reveal their nature (e.g., bacteria, diatoms, fungal spores) in the atmosphere and in relevant surface sources, such as the sea ice, snow on sea ice, melt ponds, leads, and open water, to gain further insights into the relevant source processes and how they might change in the future.

A global COVID-19 pandemic, rising asthma and allergies, along with climate change impacting storm intensity and frequency, point to an urgent need to unify U.S. atmospheric biology research. To this end, we briefly define atmospheric biology, summarize its fragmented history, and then outline how to unify the field to provide benefits for the U.S. science community and its citizens. Atmospheric biology refers to the study of concentrations, sources, sinks, transformation, and impacts of airborne microorganisms inclusive of pollen, fungal spores, algae, lichens, bacteria, viruses, cellulose fibers, and other biomolecules or fragments of cells. Here our focus is biological particles, both respirable (PM10) and systemic (PM2.5). Due to its interdisciplinary dependencies and broadness of scales from nanometers to kilometers, atmospheric biology research is highly fragmented in the U.S. science community. It lacks shared paradigms and common vocabulary. This deficit calls for recognizing atmospheric biology as a research community in its own right, thereby linking human health to climate change. We need to recognize atmospheric biology’s importance to national security and science diplomacy. Advanced atmospheric biology research is being conducted in Europe, Russia, and China, not in the United States.

  Climate and land use changes together are altering the particle content of desert dust storms on regional and local scales. These storms now carry a wide variety of pollutants and pathogens arising from urbanization, industrialization, mass transportation, warfare, or aerosolized waste in locations worldwide where deserts are intertwined with built infrastructure, transportation centers, and high-density human habitation. Accordingly, the modern desert dust storm has an anthropogenic particle load which presumably sets it apart from pre-industrial dust storms. Evidence for how particle content for modern dust storms is changing over the Arabian Peninsula holds relevance because dust storms are now more frequent and more severe. Furthermore, the Arabian Peninsula has asthma rates which are the highest worldwide. How the modern desert dust storm contributes to asthma and human health is a nascent issue. Meanwhile, public health decisions can benefit from a climate × health framework for dust storms, as proposed here. An imperative is testing each dust storm’s particle content type, and for this, we propose the A-B-C-X model. Sampling a dust storm for its particle content data and then archiving samples for future analyses is advised. A storm’s particle content data, once combined with its atmospheric data, allows a particle’s source, transport, and deposition to be determined. In closing, the modern desert dust storm’s changing particle content has far-reaching consequences for public health, transboundary issues, and international climate dialog. Significance  Locally and regionally sourced particle pollution is a growing problem in deserts worldwide. Proposed here is a climate × health framework for studying how dust storm particles, entrained from both natural and engineered systems, may be contributing to declining human respiratory health.

Ambient bioaerosols affect ecosystems and public health, but their seasonal variations and their contributions to aerosol particles are limitedly understood. Ambient bioaerosols in PM2.5 and PM10 samples were measured in Huangshi City, Hubei Province of China from April 2018 to December 2018. Bioaerosols were measured using a fluorescence microscope after staining with 4′, 6-diamino-2-phenylindole dihydrochloride (DAPI) following a direct staining technique. The bioaerosol number concentrations ranged from 0.12 to 15.69 # cm−3 for PM2.5 and 0.22 to 18.20 # cm−3 for PM10, with averages of 2.79 # cm−3 and 4.66 # cm−3, respectively. The bioaerosol concentrations of PM2.5 and PM10 varied significantly by seasons and were arranged in the following descending order: spring > fall > winter > summer. Bioaerosol numbers were dominated by fine particles of 0.37–2.5 μm diameter, while the spring bioaerosol particles were detected at the peak concentration of 0.56–1 μm diameter. Bioaerosol fractions accounted for 18.3 ± 10.6% PM10 mass and 13.7 ± 12.5% PM2.5 mass. Bioaerosol concentrations were increased during the haze event, but the increased amounts were not as large as those of the dust event, and higher bioaerosol contributions to PM were observed in the dust event than in the haze event. As enhanced emission controls have reduced PM concentrations in China, bioaerosols can be important contributors to PM mass.

AbstractThe main components of solid atmospheric aerosol are soil and rock particles raised from the earth’s surface by wind erosion, and primary biological aerosol particles. In the composition of atmospheric aerosol, many pollutants, both mineral and organic, appear in areas with intensive human activity. Summer dust (solid atmospheric fallouts) that fell out of atmosphere was collected at two sites in Moscow (the territory of the Leo Tolstoy Museum-Estate in Khamovniki and the Botanical Garden of the Biological Faculty of Moscow State University). Morphological and microbiological studies were carried out in order to characterize the composition of the organic part of urban solid atmospheric fallouts and its possible impact on soils and the urban ecosystem as a whole. It has been found that the composition of the organic part of the samples was identical and included: the representatives of aeroplankton and other particles of biological origin, and also fragments of oil films, plastic fibers, carbon particles, etc., which indicated the hydrocarbon and microplastic pollution brought from the atmosphere. The composition of the studied groups of microorganisms in atmospheric fallouts and in urban soils was similar and indicated close ecological links between urban dust aerosol and soils. The biomass of the studied groups of microorganisms of atmospheric solids was dominated by fungi, many of which are potentially pathogenic and allergenic organisms. Apparently, atmospheric solid aerosols are carriers of microbiological pollution associated with animal feces in the city. The presence of such particles in the air indicates insufficient soil activity as a “bacterial filter”.

Biological aerosol particles are recently gaining increased attention, but global estimates of their emissions are unclear. Traditional organic tracers for biological particles have not been able to capture the diversity of biological sources such as residential wood burning. Here, we have analyzed protein content in air particulate matter over a year in a suburban area near Shibuya, in order to identify contributions from biological sources. Aerosols were separated into five size fractions using a high-volume cascade impactor. Amino acid profiles were obtained from acid hydrolysates by high-performance liquid chromatography and were subsequently used in a receptor model for source apportionment. Results show that protein content ranged from 0.5 to 2 % throughout the year in all size fractions. We observed contributions from seasonally variable emission sources such as pollen and fallen leaves in coarse particles, larger than 7 µm, at elevated concentrations during spring and winter. We also found contributions from pollen and fallen leaves in the smallest size fraction, lower than 1.1 µm, after spring. This finding indicates that sources are broken up to smaller particles in the urban environment. Overall, our findings demonstrate that protein content can be used as marker for biological aerosol particles, and that protein amino acid composition can distinguish multiple sources.

The paper presents the results of the morphological study of aerosol particles in the urban air of Moscow (Russia) in 2019–2022 by scanning electron microscopy (SEM). Our monitoring revealed mineral and anthropogenic particles, and also primary bioaerosols (PBA), such as pollen, spores, plant fibers, etc., typical for the urban environment. Moreover, in July 2021, brochosomes, lipid secretions of semi-hard-winged insects Cicadellidae (or leafhopper), were found in several aerosol samples. They are quasi-spherical hollow porous semi-regular polyhedra (truncated icosahedra) of 0.2–0.7 microns in size, consisting mainly of carbon and oxygen. Despite the prevalence and diversity of leafhoppers, identification of their secretions in atmospheric aerosols in situ is rather rare: single articles from South Korea, Spain, the Himalayas, and the United States. In this sense, the results obtained are interesting and novel. PBA particles cover a wide size range and have a complex and diverse shape, which determines the distance and efficiency of their atmospheric transport. Pollen and fungal spores have a high allergenic potential and can have harmful effects on human health. Any new information about PBA can be useful for studying the development and dynamics of ecosystems.

The polyols arabitol and mannitol, recently proposed as source tracers for fungal spores, were used in this study to estimate fungal contributions to atmospheric aerosol. Airborne particulate matter (PM2.5 and PM10) was collected at Jianfengling Mountain, a tropical rainforest on Hainan Island situated off the south China coast, during spring and analyzed for arabitol and mannitol by high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). The average concentrations of arabitol and mannitol exhibited high values with averages of 7.0 and 16.0 ngm − 3 respectively in PM2.5 and 44.0 and 71.0ngm − 3 in PM10. The two tracers correlated well with each other, especially in the coarse mode aerosol (PM2.5 − 10), indicating they were mainly associated with coarse aerosol particles and had common sources. Arabitol and mannitol in PM10 showed significant positive correlations with relative humidity, as well as positive correlations with average temperature, suggesting a wet emissions mechanism of biogenic aerosol in the form of fungal spores. We made estimations of the contribution of fungal spores to ambient PM mass and to organic carbon, based on the observed ambient concentrations of these two tracers. The relative contributions of fungal spores to the PM10 mass were estimated to range from 1.6 to 18.2%, with a rather high mean value of 7.9%, and the contribution of fungal spores to organic carbon in PM10 ranged from 4.64 to 26.1%, with a mean value of 12.1%, implying that biological processes are important sources of atmospheric aerosol.

The Amazon experiences fires every year, and the resulting biomass burning aerosols, together with cloud particles, influence the penetration of sunlight through the atmosphere, increasing the ratio of diffuse to direct photosynthetically active radiation (PAR) reaching the vegetation canopy and thereby potentially increasing ecosystem productivity. In this study, we use the NASA Goddard Earth Observing System (GEOS) model with coupled aerosol, cloud, radiation, and ecosystem modules to investigate the impact of Amazon biomass burning aerosols on ecosystem productivity, as well as the role of the Amazon’s clouds in tempering this impact. The study focuses on a seven-year period (2010-2016) during which the Amazon experienced a variety of dynamic environments (e.g., La Niña, normal years, and El Niño). The direct radiative impact of biomass burning aerosols on ecosystem productivity—called here the aerosol diffuse radiation fertilization effect —is found to increase Amazonian Gross Primary Production (GPP) by 2.6% via a 3.8% increase in diffuse PAR (DFPAR) despite a 5.4% decrease in direct PAR (DRPAR) on multiyear average during burning seasons. On a monthly basis, this increase in GPP can be as large as 9.9% (occurring in August 2010). Consequently, the net primary production (NPP) in Amazon is increased by 1.5%, or ~92 Tg C a-1– equivalent to ~37% of the average carbon lost due to Amazon fires over the seven years considered. Clouds, however, strongly regulate the effectiveness of the aerosol diffuse radiation fertilization effect. The efficiency of this fertilization effect is the highest in cloud-free conditions and linearly decreases with increasing cloud amount until the cloud fraction reaches ~0.8, at which point the aerosol-influenced light changes from being a stimulator to an inhibitor of plant growth. Nevertheless, interannual changes in the overall strength of the aerosol diffuse radiation fertilization effect are primarily controlled by the large interannual changes in biomass burning aerosols rather than by changes in cloudiness during the studied period.