Determination of the Carbon Content of Airborne Fungal Spores

Abstract

Airborne fungal spores contribute potentially to the organic carbon of the atmospheric aerosol, mainly in the "coarse aerosol" size range 2.5-10 microm aerodynamic equivalent diameter (aed). Here, we report about a procedure to determine the organic carbon content of fungal spores frequently observed in the atmosphere. Furthermore, we apply a new (carbon/individual) factor to quantify the amount of fungal-spores-derived organic carbon in aerosol collected at a mountain site in Austria. Spores of representatives of Cladosporium sp., Aspergillus sp., Penicillium sp., and Alternaria sp., the four predominant airborne genera, were analyzed for their carbon content using two different analytical procedures. The result was an average carbon content of 13 pg C/spore (RSD, 46%), or expressed as a carbon-per-volume ratio, 0.38 pg C/microm3 (RSD, 30%). These values are comparable to conversion factors for bacteria and some representatives of the zooplankton. Because biopolymers are suspected of interfering with elemental carbon determination by thermal methods, the amount of "fungal carbon" that might be erroneously mistaken for soot carbon was determined using the "two-step combustion" method of Cachier et al. and termed as "apparent elemental carbon" (AEC). This fraction amounted to up to 46% of the initial fungal carbon content. Although the aerosol samples were collected in March under wintry conditions, the organic carbon from fungal spores amounted to 2.9-5.4% of organic carbon in the "coarse mode" size fraction.

Polar organic compounds in rural PM<sub>2.5</sub> aerosols from K-puszta, Hungary, during a 2003 summer field campaign: Sources and diel variations

“…The remaining part of the organic compounds that were insoluble in methanol or not amenable to GC/MS analysis constitute a significant fraction of the unidentified organic material. The latter fraction likely includes humic-like substances, which are known to be significant at K-puszta (Zappoli et al, 1999), as well as biological structures, such as fragments or constituents of fungi, pollen, algae, bacteria, leaves and insects (MatthiasMaser and Jaenicke, 1995;Bauer et al, 2002a;Bauer et al, 2002b). Because a major fraction of the OC consists of large biomacromolecules such as proteins (Miguel et al, 1999), cellulose (Puxbaum and Tenze-Kunit, 2003) and phospholipids (Womiloju et al, 2003), which are embedded in biomembrane structures, techniques such as GC/MS cannot be expected to explain more than a small fraction of the organic aerosol mass.…”

Characterization of Ambient PM10 Bioaerosols in a California Agricultural Town

“…This is consistent with fungal spore fractions of 0.4-64% and 4-22% in PM 10 and PM 2.5 OC, respectively, reported in previous studies (see Table 7). Using the conversion factor of 13 pg C/spore by Bauer et al (2002b) would underestimate the fungal spore OC to total OC ratio by 46%. This is expected since fungal spore OC content should be size dependent, and larger fungal spores (58 µm 3 /spore) were found in this study (Table 4) compared to 34 µm 3 /spore by Bauer et al (2002b).…”

Better constraints on sources of carbonaceous aerosols using a combined <sup>14</sup>C – macro tracer analysis in a European rural background site

“…To calculate the concentration of POC bio in fine particles (PM 2.5 ) the content of OC from a single spore was assumed constant and equal to 5.2 pg C spore −1 (k 4 in Eq. 5), corresponding to the lower bound reported for PM 10 aerosol (Bauer et al, 2002). The contribution of primary biogenic carbon was then calculated according to Eq.…”