Extraction and size distribution measurements of subpollen particles

Während der Blütezeit von Pflanzen ist Pollen ein wichtiger Bestandteil des atmosphärischen Aerosols. Obwohl die sexuelle Reproduktion von Pflanzen die Hauptfunktion von Pollen ist, kann er, einmal in die Luft gelangt, auch Einfluss auf die menschliche Gesundheit (z.B. Heuschnupfen) und Wolkenbildung haben. Allerdings ist die Konzentration von Pollen in der Atmosphäre zu gering, um Wolken merklich zu beeinflussen. Es ist jedoch bekannt, dass Pollenkörner vieler Spezies unter gewissen Bedingungen aufplatzen und neben anderem Material auch kleinere Partikel freisetzen, häufig Subpollen-Partikel (SPP) genannt. Diese SPP könnten sich in größere Anzahl in der Atmosphäre befinden und ihrerseits wieder einen Einfluss auf die Wolkenbildung haben. Um die Anzahlkonzentration von SPP in der Atmosphäre zu untersuchen, muss eine Methode gefunden werden um sie zu identifizieren. Bisher gibt es kein Instrument, welches in der Lage ist SPP in der Luft zu erkennen. In dieser Arbeit wurde eine Methode entwickelt, die es erlaubt Material aus Pollenkörner aufgrund von mechanischem Stress zu extrahieren. Dies wird mithilfe einer Schwingmühle gemacht, welche die Pollenwand aufbricht. Dadurch werden SPP freigesetzt. Diese Methode wurde auf fünf verschiedene Pollenspezies angewandt (Betula pendula, Phleum pratense, Poa pratensis, Corylus avellana, Artemisia vulgaris). Die Resultate zeigen, dass Pollenkörner von Betula, Phleum, Poa und Corylus sowohl lösliches als auch partikuläres Material besitzen, wohingegen Pollenkörner von Artemisia nur lösliche Substanzen enthalten. Weiters wurden die SPP vom löslichen Material getrennt, indem die Partikel reingewaschen wurden. Die Größenverteilung und Form der verschiedenen SPP wurde untersucht. Die SPP reichen von etwa 200 nm bis 2 µm und sind damit um bis zu 100-fach kleiner als die intakten Pollenkörner. Die Größenverteilungen zeigen leichte Unterschiede zwischen den Spezies. Beispielsweise besitzt Betula pendula die größten SPP, deren Form zudem am länglichsten sind. Aufgrund der kleineren Größe der SPP, verglichen mit Pollenkörnern, könnten sie sich weiter in der Atmosphäre verteilen und dort länger ausharren. Die Methode zur Extraktion der SPP, die in dieser Arbeit entwickelt wurde ist ein erster Schritt hin zur Entwicklung von Methoden zur Messung von SPP in der Atmosphäre.During the blooming season of plants, pollen is a persistent component of the atmospheric aerosol. Although sexual reproduction of plants is the main purpose of pollen, once airborne in the atmosphere, pollen grains can also impact human health (e.g. hay fever) and cloud formation. However, the concentration of pollen grains in the atmosphere is too low to strongly influence clouds. But it is known that many species of pollen rupture under certain conditions and release, amongst other material, smaller particles commonly referred to as subpollen particles (SPP). These SPP might exist in higher numbers in the atmosphere and could have an considerable effect on cloud formation as well. To investigate the number concentration of SPP in the atmosphere, a method needs to be found to identify them. So far, no instrument exists which is able to recognize them in the air. In this thesis, a method was developed to extract material from pollen grains by rupture due to mechanical stress. This is done by putting pollen in a Mixer Mill which breaks the pollen wall so that the SPP are released. This method is applied to five different pollen species (Betula pendula, Phleum pratense, Poa pratensis, Corylus avellana, Artemisia vulgaris). It was found that pollen grains of Betula, Phleum, Poa and Corylus contain both, soluble and particulate material, whereas those of Artemisia only contain soluble material. Furthermore, the SPP are separated from the soluble material by washing it off the particles. The size distribution and shape of the different SPP was investigated. The size of the SPP ranges from about 200 nm to 2 µm and therefore, are smaller than the entire intact pollen grains by a factor up to about 100. The size distributions show slight differences between species: For instance, Betula pendula possesses the biggest SPP which are also the most elongated in shape. Due to the smaller size of the SPP compared to pollen grains, they might disperse farther in the atmosphere and have longer lifetimes. The method to extract SPP that was developed in this thesis is a first step towards the development of methods to measure SPP in the atmosphere

A fluorescence approach for an online measurement technique of atmospheric microplastics

Microplastic particles in the atmosphere are regularly detected in urban areas as well as in very remote locations. Yet the sources, chemical transformation, transport, and abundance of airborne microplastics still remains largely unexplained. Therefore, their impact on health, weather and climate related processes lacks comprehensive understanding. Single particle detection presents a substantial challenge due to its time-consuming process and is conducted solely offline. To get more information about the distribution, fluxes and sources of microplastics in the atmosphere, a reliable and fast online measurement technique is of utmost importance. Here we demonstrate the use of autofluorescence of microplastic particles for their online detection with a high sensitivity towards different widely used polymers. We deploy online single particle fluorescence spectroscopy with a Wideband Integrated Bioaerosol Sensor WIBS 5/NEO (Droplet Measurement Technologies), which enables single particle fluorescence measurements at two excitation wavelengths (280 nm and 370 nm) and in two emission windows (310 – 400 nm and 420 – 650 nm). We investigated shredded (< 100 μm) everyday plastic products (drinking bottles, yogurt cups) and purchased pure powders of polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP). For that broad range of typical plastic products analyzed, we detected fluorescence on a single particle level using the WIBS. The online detection is possible even for particles smaller than 2 μm, with a remarkable detection efficiency of microplastic particles from a PET bottle as small as 1.2 μm with 95% effectivity. Comparison with biological aerosol reveals that microplastics can be distinguished from two abundant pollen species and investigation of the complete fluorescence excitation emission maps of all samples show that online identification of microplastics might be possible with fluorescence techniques if multiple channels are available

Synthesis and Biological Evaluation of Novel Alkyl-Imidazolyl Carbinols and their Esters: Potent Antimycotics

A novel series of imidazol-5-yl carbinols and their 4-chlorobenzoyl esters has been synthesized by the Grignard reaction and subsequent esterification. These compounds were screened for their antimicrobial activities in an agar diffusion assay. The compounds with C10 to C12-alkyl side chains displayed significant antimycotic activity