Time- and size-resolved bacterial aerosol dynamics in highly polluted air: new clues for haze formation mechanism

Abstract

27Aerosol chemistry is often studied without considering microbial involvements. 28 Here, we have applied a high-volume (1 m 3 /min) aerosol sampler and the Orifice Uniform Deposit Impactor (NanoMoudi) along with molecular and microscopic 30 methods to investigate time-and size-resolved bacterial aerosol dynamics in air. Under 31 high particulate matter (PM) polluted episodes, bacterial aerosols were detected to 32 have a viability up to 50-70% in the 0.56-1 μm size range, at which elevated levels of 33 SO4 2-, NO 3and NH 4+ were concurrently observed. Engineered or acclimated for both 34 pharmaceuticals and wastewater treatment, bacteria such as Psychrobacter spp., 35Massilia spp., Acinetobacter lwoffii, Exiguobacterium aurantiacum, and Bacillus 36 megaterium were shown to have experienced massive abundance shifts in polluted air 37 on early mornings and late afternoons, on which were previously reported to witness 38 rapid new particle formation events. For example, Acinetobacter spp. were shown to 39 account for > 96% abundance at a corresponding PM2.5 level of 208 μg/m 3 . The 40 bacterial aerosol changes corresponded to the observed PM2.5 mass peak shift from 41 3.2-5.6 μm to the high viability size range of 0.56-1μm. Additionally, it is interesting 42 that elevated levels of soluble Na, Ca, Mg, K, Al, Fe and P elements that are required 43 for bacterial growth were observed to co-occur with those significant bacterial aerosol 44 structure shifts in the air. For particular time-resolved PM2.5 pollution episodes, 45 Acinetobacter and Massilia were shown to alternate in dominating the time-resolved 46 aerosol community structures. The results from a HYSPLIT trajectory model simulation 47 suggested that the role by air mass transport in affecting the observed bacterial 48 3 aerosol dynamics could be minor. As an evidence, we found that Acinetobacter, 49 Psychrobacter, Exiguobacterium, and Bacillus genera were emitted into the air with a 50 level of > 3000 CFU/m 3 from a pharmaceutical plant. In addition, high level of VOCs up 51 to 15,030 ppbv, mainly Acetone (61%) and Acetaldehyde (11%), were also detected in 52 the air inside the plant. All the data including size-resolved viability and time-resolved 53 bacterial aerosol dynamics together with their growth conditions detected in the air 54 suggested that airborne bacteria in the size range of 0.56-1μm could have played 55 important roles for haze formation in Beijing. The results about time-and size-resolved 56 bacterial aerosol dynamics from this work provide a fresh understanding of aerosol 57 chemistry especially in highly polluted air. It is hoped that these findings could lend a 58 support in future cost-effective air pollution control practices. 59 60 Keywords: Bacterial aerosol dynamics in the air, Particulate matter, Size-and Time-61 resolved bacterial aerosol, Aerosol chemistry 62 63

Effect of temperature and humidity on dynamics and transmission of Pseudomonas amygdali pv. lachrymans aerosols

“…In this study, Pal aerosols with sizes of 0.65-2.1 mm were also profoundly affected by RH, and the concentration of Pal in aerosols in the 0.65-2.1 mm size range was relatively higher even under dry conditions. Our result was consistent with previous research showing that bacteria in smallersized aerosols (0.56-1 mm) have a higher viability (50%-70%) (Zhang et al, 2019). In addition, the distribution of Pal aerosols at 35°C and 65% RH was mainly 2.1-3.3 mm, which was similar to the P. glyinea aerosols collected in infected soybean plots during rainstorms and sprinkler irrigation (Venette and Kennedy, 1975).…”

Critical review of antibiotic resistance genes in the atmosphere

“…43 Shifts in relative abundance profiles of individual ARGs while in the air could also lead to variability throughout the day; however, these mechanisms are still not understood. 44…”

“…43 Shis in relative abundance proles of individual ARGs while in the air could also lead to variability throughout the day; however, these mechanisms are still not understood. 44 There was also some indication that specic ARGs were associated with different regions, like blaTEM in urban areas and sul1 near the Pearl River Delta, while the ARG tetW was more widespread in both urban and rural regions in China. 45 tet ARGs (tetA and tetB) and ARGs conferring resistance to aminoglycoside (sat) and b-lactam were also found to be abundant in an estuary area in one study.…”