AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Bioaerosols in the Eastern Mediterranean: Seasonal Variability and Nutrient Supply
ARNALDO NEGRON-MARTY, Chara Almpani, Giorgos Kouvarakis, Iordanis Magiopoulos, Paraskevi Pitta, Kostas Konstantinidis, Maria Kanakidou, Nikolaos Mihalopoulos, Athanasios Nenes, Georgia Institute of Technology
Abstract Number: 530 Working Group: Bioaerosols
Abstract Primary biological atmospheric particles (PBAP), also called bioaerosols, are ubiquitous in the atmosphere and potentially contribute to cloud formation [1], affect the hydrological cycle [2], public health [3], and nutrient supply to ocean ecosystems [4,5]. Critical towards understanding the role of PBAP on clouds and ecosystems is the quantitative understanding of their concentration and size. Little is known however about their prevalence and seasonal variability in part due to challenges in available techniques for PBAP detection [6,7]. Our study aims to speciate and quantify the concentration of coarse-mode PBAP at a remote marine ground site in the Eastern Mediterranean to help understand their importance as a supply of phosphorus (P) into the oligotrophic sea. Sampling took place twice a week over a year (May, 2016 – May, 2017) at the ACTRIS site of Finokalia, Crete and the University of Crete campus outside Heraklion, Crete. PBAP samples were collected with a modified wet-walled cyclone high volume bioaerosol sampler, SpinCon-II, which was operated for 8 hours per sample. During sampling, all PBAP above roughly 500nm diameter were collected in PBS, fixed in formalin, and subsequently analyzed using flow cytometry (FCM) and epifluorescence microscopy (EPM) using protocols developed by Negron et al., 2017 [8]. FCM results show PBAP concentrations up to 106 m-3 associated with African dust events, and around 105 m-3 associated with European air masses. Moreover, Heraklion FCM results shows consistently that daytime PBAP are up to tenfold higher than nighttime PBAP concentrations, suggesting that PBAP is introduced into the boundary layer from aloft, which is most effective during midday, and is lost continuously from dry deposition to the sea surface. The effect of environmental conditions (humidity, UV radiation levels, temperature) on the relative amounts of PBAP (bacteria, fungi, pollen, biological debris) and resulting nutrient (P) flux to the East Mediterranean Sea is computed and compared against model estimates [4].
References: [1] Hoose, et al., Env.Res.Lett., 2010; [2] Morris, et al., Global change biology, 2014; [3] Eduard et al., J Environ. Monit., 2012; [4] Myriokefalitakis, Stelios, et al., Biogeosciences, 2016; [5] Longo, et al., Geoph. Res.Let., 2014; [6] Jaenicke, R., Science, 2005; [7] DeLeon-Rodriguez et al., Proc.Nat.Acad.Sci., 2013; [8] Negron et al., in prep.