Fluorescent Bioaerosol Particle, Molecular Tracer, and Fungal Spore Concentrations during Dry and Rainy Periods in a Semi-Arid Forest

Abstract

<p><strong>Abstract.</strong> Bioaerosols pose risks to human health and agriculture and may influence the evolution of mixed-phase clouds and the hydrological cycle on local and regional scales. The availability and reliability of methods and data on the abundance and properties of atmospheric bioaerosols, however, are rather limited. Here we analyze and compare data from different real-time Ultraviolet Laser/Light Induced Fluorescence (UV-LIF) instruments with results from a culture-based spore sampler and offline molecular tracers for airborne fungal spores in a semi-arid forest in the Southern Rocky Mountains of Colorado. Commercial UV-APS (Ultraviolet Aerodynamic Particle Sizer) and WIBS-3 (Wideband Integrated Bioaerosol Sensor, Version 3) instruments with different excitation and emission wavelengths were utilized to measure fluorescent aerosol particles (FAP) during both dry weather conditions and periods heavily influenced by rain. Seven molecular tracers of bioaerosols were quantified by analysis of total suspended particle (TSP) high-volume filter samples using High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD). From the same measurement campaign Huffman et al. (2013) previously reported dramatic increases in total and fluorescence particle concentrations during and immediately after rainfall and also showed a strong relationship between the concentrations of FAP and ice nuclei (Huffman et al., 2013; Prenni et al., 2013). Here we investigate molecular tracers and show that during rainy periods the atmospheric concentrations of arabitol (35.2 ± 10.5 ng m<sup>−3</sup>) and mannitol (44.9 ± 13.8 ng m<sup>−3</sup>) were 3–4 times higher than during dry periods. During and after rain the correlations between FAP and tracer mass concentrations were also significantly improved. Fungal spore number concentrations on the order of 104 m<sup>−3</sup>, accounting for 2–4 % of TSP mass during dry periods and 17–23 % during rainy periods, were obtained from scaling the tracer measurements and from multiple analysis methods applied to the UV-LIF data. Endotoxin concentrations were also enhanced during rainy periods, but showed no correlation with FAP concentrations. Average mass concentrations of erythritol, levoglucosan, glucose, and (1→3)-β-D-glucan in TSP samples are reported separately for dry and rainy weather conditions. Overall, the results indicate that UV-LIF measurements can be used to infer fungal spore concentrations, but substantial development of instrumental and data analysis methods seems required for improved quantification.</p>

Real-time detection of airborne fluorescent bioparticles in Antarctica

“…We speculate that they may potentially represent either bacterial aggregates or larger dust particles containing uncharacterised bacteria. The fluorescence spectra do not generally follow those for bacteria or fungal spores observed in previous studies using the WIBS-3 instrument, which tend to fluoresce most strongly in FL1 (Gosselin et al, 2016;Hernandez et al, 2016;Crawford et al, 2015Crawford et al, , 2016. However, in laboratory experiments (using a WIBS-4A) Hernandez et al (2016) demonstrated that a small subset of certain large fungal spores such as the necrotrophic fungus, Botrytis, can fluoresce in all three channels.…”

“…This method has successfully been used to differentiate and identify fungal spores, bacteria and mineral dust classes at remote forests and mountain-top sites (Crawford et al, , 2015Gosselin et al, 2016;Whitehead et al, 2016). First the data to be clustered were filtered to remove particles with diameters smaller than 0.8 µm and all nonfluorescent particles to leave only fluorescent particles.…”

“…This instrument was designed to identify common bio-fluorophores and discriminate potentially harmful pathogenic bioaerosols from the background population. A full technical description of earlier and later versions of the instrument can be found in Kaye et al (2005), Foot et al (2008) and , while results from monitoring bioaerosols and analysis tools for identification of bioaerosols, mainly at remote sites, can be found in Crawford et al (2016Crawford et al ( , 2014, Gosselin et al (2016), Whitehead et al (2016), Ziemba et al (2016), Perring et al (2015), O'Connor et al (2015O'Connor et al ( , 2014, Robinson et al (2013), , and Gabey et al (2013Gabey et al ( , 2011Gabey et al ( , 2010. The instrument has an inlet flow of 2.35 L min −1 , the majority of which is filtered with a HEPA filter to remove all particles, such that the 0.23 L min −1 sample flow is sheathed in particle free air to constrain the aerosol into a controlled jet and to minimise contamination of the optics.…”

Global modeling of primary biological particle concentrations with the EMAC chemistry-climate model

“…The FBAP observations show a peak in the number distribution at about 1 -4 µm, irrespective of location or instrument. It has been previously suggested for several geographic locations that the UV-APS and WIBS FL3 channel may yield lower limit proxies for fungal spores, due in part to the large 20 number concentration of spores in this size range compared to other biological particles (Gosselin et al, 2016;Healy et al, 2014) .…”

Caracterização do aerossol biogênico primário na atmosfera da Região Metropolitana de São Paulo

“…Nesse trabalho, também deve ser considerado que o período com maior temperatura foi também quando ocorreu maior acúmulo de precipitação e maior umidade, o que também pode ser relacionado com a liberação de esporos na atmosfera (Haines et al, 2000;Burge et al, 2006;Burch & Levetin, 2002;Lacey, 1996;Li & Kendrick, 1995;Fischer et al, 2010;Webster & Weber, 2007) Predominantemente, maiores correlações são observadas entre os esporos de fungos (TS, AS, BS e UD) com arabitol e manitol, quando há precipitação (Figura C XIX) quando comparado com dias sem precipitação (Figura C XX) ou com todo o período amostrado (Figura C XXI). Uma maior concentração de esporos fúngicos durante períodos chuvosos, e um maior background de outras partículas contendo arabitol e manitol na sua composição durante períodos secos, poderia explicar essa diferença na correlação, como sugerido por Gosselin et al (2016). Essa poderia ser também a explicação para a falta de correlação entre os açúcares e o MS, uma vez que o MS apresenta maiores concentrações em períodos com baixa concentração de esporos fúngicos.…”