Fluorescent biological aerosol particle measurements at a tropical high-altitude site in southern India during the southwest monsoon season

Abstract

Abstract. An ultraviolet aerodynamic particle sizer (UV-APS) was continuously operated for the first time during two seasons to sample the contrasting winds during monsoon and winter to characterize the properties of fluorescent biological aerosol particles (FBAPs), at a high-altitude site in India. Averaged over the entire monsoon campaign (1 June–21 August 2014), the arithmetic mean number and mass concentrations of coarse-mode (> 1 µm) FBAPs were 0.02 cm−3 and 0.24 µg m−3, respectively, which corresponded to ∼ 2 and 6 % of total aerosol loading, respectively. Average FBAP number size distribution exhibited a peak at ∼ 3 µm, which is attributed to the fungal spores, as supported by scanning electron microscope (SEM) images, and these results are consistent with previous studies made for FBAPs. During 11 weeks of measurements the variability of the total coarse-mode particle number (TAP) concentration was high compared to that observed in FBAP number concentrations. The TAP and FBAP number concentrations measured at this site were strongly dependent on changes in wind direction and rainfall. During periods of westerly/southwesterly winds with heavy persistent rainfall, the TAP and FBAP concentrations exhibited very low values (1.3 and 0.005 cm−3, respectively) with no significant diurnal variations, whereas during periods of northerly winds with scattered rainfall FBAPs exhibited relatively high concentration values (0.05 cm−3) with pronounced diurnal variations, which were strongly coupled with diurnal variations in meteorological parameters. The campaign-averaged FBAP number concentrations were shown to correlate with daily patterns of meteorological parameters and were positively correlated with relative humidity (RH; R2 = 0.58) and negatively with temperature (R2 = 0.60) and wind speed (R2 = 0.60). We did not observe any significant positive correlation with precipitation as reported by previous researchers from selected areas. These measurement results confirm the fact that the ratio of PBAPs to TAP is strongly dependent on particle size and location and thus may constitute a significant proportion of total aerosol particles.

Review: The Use of Real-Time Fluorescence Instrumentation to Monitor Ambient Primary Biological Aerosol Particles (PBAP)

“…Conversely, fragmented rainfall coupled with a northerly wind saw a tenfold increase in fluorescent particles with diurnal variations evident. Finally, campaign-averaged fluorescent number concentrations showed reasonable correlation with daily patterns of meteorological parameters: relative humidity had an R 2 = 0.58 (positive correlation); temperature showed a negative correlation (R 2 = 0.60) and finally wind speed exhibited a negative correlation (R 2 = 0.60) [87]. There are numerous situations where human activity directly contributes to the release of BPAP.…”

“…Mean fluorescent particle numbers of 20 L −1 were recorded during the campaign for the monsoon season [87]. Interestingly, this number accounted for only~2% of the total particle load that was found at the site, which was much lower than the fractions noted at the many of the other field locations mentioned above.…”

Real-time sensing of bioaerosols: Review and current perspectives

“…The Ultraviolet Aerodynamic Particle Sizer (UV-APS; TSI, Shoreview, MN, USA) was marketed widely and, though discontinued, is still used for research purposes. The UV-APS has been applied to both indoor (Bhangar et al 2016;Kanaani et al 2008;Pereira et al 2017) and outdoor PBAP analyses (Hallar et al 2011;Huffman et al 2013;P€ oschl et al 2010;Schumacher et al 2013;Valsan et al 2016;Wei et al 2016) as well as to investigate airborne microorganism viability and dynamics (Agranovski et al 2003a;Agranovski et al 2004;Pan et al 2014a;Saari et al 2015). Pulsed 355nm light from a Nd:YAG laser excites fluorescence and the integrated intensity from 420 to 575 nm is measured (Brosseau et al 2000;Hairston, Ho, and Quant 1997).…”

Systematic characterization and fluorescence threshold strategies for the wideband integrated bioaerosol sensor (WIBS) using size-resolved biological and interfering particles

“…Both the WIBS and UV-APS, in various version updates, have been applied to many types of studies regarding outdoor aerosol characterization. For example, they have been important instruments: in the study of ice nuclei Mason et al, 2015;Twohy et al, 2016), toward the understanding of outdoor fungal spore concentrations (Gosselin et al, 2016;Saari et al, 2015a;O'Connor et al, 2015b), to investigate the concentration and properties of bioaerosols from long-range transport (Hallar et al, 2011), in tropical aerosol Whitehead et al, 2010Whitehead et al, , 2016Huffman et al, 2012;Valsan et al, 2016), in urban aerosol Saari et al, 2015b;Yu et al, 2016), from composting centers (O'Connor et al, 2015b), at high altitude Gabey et al, 2013;Perring et al, 2015;Ziemba et al, 2016), and in many other environments (Healy et al, 2014;Li et al, 2016;O'Connor et al, 2015a). The same instrumentation has been utilized for a number of studies involving the built, or indoor, environment as well (Wu et al, 2016).…”