Microorganisms are ubiquitous in the environment, and the atmosphere is no exception. However, airborne bacterial communities are some of the least studied. Increasing our knowledge about these communities and how environmental factors shape them is key to understanding disease outbreaks and transmission routes. We describe airborne bacterial communities at two different sites in Tenerife, La Laguna (urban, 600 m.a.s.l.) and Izaña (high mountain, 2,400 m.a.s.l.), and how they change throughout the year. Illumina MiSeq sequencing was used to target 16S rRNA genes in 293 samples. Results indicated a predominance of Proteobacteria at both sites (>65%), followed by Bacteroidetes, Actinobacteria, and Firmicutes. Gammaproteobacteria were the most frequent within the Proteobacteria phylum during spring and winter, while Alphaproteobacteria dominated in the fall and summer. Within the 519 genera identified, Cellvibrio was the most frequent during spring (35.75%) and winter (30.73%); Limnobacter (24.49%) and Blastomonas (19.88%) dominated in the summer; and Sediminibacterium represented 10.26 and 12.41% of fall and winter samples, respectively. Sphingomonas was also identified in 17.15% of the fall samples. These five genera were more abundant at the high mountain site, while other common airborne bacteria were more frequent at the urban site (Kocuria, Delftia, Mesorhizobium, and Methylobacterium). Diversity values showed different patterns for both sites, with higher values during the cooler seasons in Izaña, whereas the opposite was observed in La Laguna. Regarding wind back trajectories, Tropical air masses were significantly different from African ones at both sites, showing the highest diversity and characterized by genera regularly associated with humans (Pseudomonas, Sphingomonas, and Cloacibacterium), as well as others related to extreme conditions (Alicyclobacillus) or typically associated with animals (Lachnospiraceae). Marine and African air masses were consistent and very similar in their microbial composition. By contrast, European trajectories were dominated by Cellvibrio, Pseudomonas, Pseudoxanthomonas, and Sediminibacterium. These data contribute to our current state of knowledge in the field of atmospheric microbiology. However, future studies are needed to increase our understanding of the influence of different environmental factors on atmospheric microbial dispersion and the potential impact of airborne microorganisms on ecosystems and public health.

The present study focuses on the two consecutive and markedly intense Saharan dust intrusion episodes that greatly affected southern Spain (Málaga) and, to a lesser extent, the Canary Islands (Tenerife), in March 2022. These two episodes were the result of atypical meteorological conditions in the region and resulted in record levels of aerosols in the air at the Málaga location. The activity levels of various natural and artificial radionuclides (⁷Be, ²¹⁰Pb, ⁴⁰K, ¹³⁷Cs, ²³⁹Pu, ²⁴⁰Pu, ^239+240Pu) and radioactive indicators (gross alpha and gross beta) were impacted by these events and the results are described herein. These episodes caused, for example, the activities of ¹³⁷Cs in aerosol samples at the Málaga monitoring station to reach the highest concentrations ever recorded since high-volume aerosol monitoring started at this site in 2009. A link between the activity levels of ¹³⁷Cs, ⁴⁰K and gross alpha in the atmospheric aerosols and daily PM10 concentrations during the episodes is also reported. In addition, isotopic ratios are discussed in the context of the source and destination of the various anthropogenic radionuclides measured. The atmospheric residence time of aerosols during these episodes is also evaluated because it concerns how intrusions to the Canary Islands should be analysed. Finally, for the first time, the concentrations of ¹³⁷Cs deposition by rainwater during a Saharan dust intrusion are reported and the deposition rate of these radionuclides during these episodes is discussed.

The international journal of Aerosol and Air Quality Research (AAQR) covers all aspects of aerosol science and technology, atmospheric science and air quality related issues.

Microalgal-bacterial membrane photobioreactors (MPBRs) have emerged as a transformative wastewater treatment technology for reducing carbon emissions whilst achieving high quality effluent. However, membrane fouling negatively affects process performance by increasing energy consumption and reducing membrane lifespan. In this study, light/dark photoperiods were varied to optimize treatment performance and biomass properties and reduce membrane fouling. Increasing the length of the light period favored higher production of biomass but decreased bioflocculation. An intermediate photoperiod of 16/8 h achieved high values of biomass concentration (3.21 ± 0.45 g L⁻¹) and nutrient removal rates (4.71 mg N L⁻¹ d⁻¹ and 0.67 mg P L⁻¹ d⁻¹, respectively), while preventing accumulation of biopolymer clusters (≤5.5 mg DOC L⁻¹) in the suspension. In addition, short-term fouling—associated with floc deposition forming a cake layer—was minimized at intermediate photoperiods, thus increasing the sustainable (i.e., threshold) permeate flux. Under these sustainable flux conditions, membrane fouling was mainly determined by the biopolymer cluster content, with best performance being attained at 16/8 h. The above results reveal that the photoperiod is a crucial parameter for controlling membrane fouling in microalgal-bacterial membrane photobioreactors.

Culturable eubacterial isolates were collected at various altitudes in Earth’s atmosphere, including ~1.5 m above ground in Tallahassee, FL, USA; ~10.0 m above sea level over the mid-Atlantic ridge (~15° N); ~20 km above ground over the continental United States; ~20 km above sea level over the Pacific Ocean near southern California; and from the atmosphere of Carlsbad Cavern, Carlsbad Cavern National Park, NM, USA. Isolates were screened for the presence of inducible virus-like particles (VLP) through the use of mitomycin C and epifluorescent direct counts. We determined that 92.7% of the isolates carried inducible VLP counts in exposed versus non-exposed culture controls and that the relationship was statistically significant. Further statistical analyses revealed that the number of isolates that demonstrated VLP production did not vary among collection sites. These data demonstrate a high prevalence of VLP generation in isolates collected in the lower atmosphere and at extreme altitudes. They also show that species of eubacteria that are resistant to the rigors of atmospheric transport play a significant role in long-range atmospheric inter- and intra-continental dispersion of VLP and that long-range atmospheric transport of VLP may enhance rates of evolution at the microbial scale in receiving environments.