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Identifier 000457352
Title Πτητικές οργανικές ενώσεις στην ατμόσφαιρα του Φινοκαλιά και επίδραση τους στον σχηματισμό και την επαύξηση των αιωρούμενων σωματιδίων
Alternative Title Volatile organic compounds in the atmosphere of Finokalia and their effect on the formation and growth of aerosol particles
Author Τζιτζικαλάκη, Ευαγγελία Ν
Thesis advisor Κανακίδου, Μαρία
Reviewer Μιχαλόπουλος, Νικόλαος
Περγαντής, Σπυρίδων
Σπύρος, Απόστολος
Πανδής, Σπυρίδων
Λιακάκου, Ελένη
Μπουγιατιώτη, Αικατερίνη
Abstract The impact of atmospheric aerosols on human health, ecosystems, visibility and the climate of our planet makes the understanding of the origin of particulate pollution in the atmosphere imperative. The secondary new particle formation (NPF) in the atmosphere from gaseous precursors is the dominant source of the total atmospheric particle number concentration. The exact mechanisms of new particle formation and growth are not fully understood, as they are highly regional since they are determined by meteorology and precursor abundance. Alkylamines and monoterpenes participate in new particle formation and growth. Alkylamines, due to their high basicity, have been identified as a major contributor to NPF by stabilizing the newly clusters formed during their NPF. Whereas, the oxidation products of monoterpenes that are of low volatility participate in the formation and growth processes of new particles. Measurements of amines in the atmospheric gas-phase are limited, mostly covering short time-periods and mainly cities, urban and suburban areas. Only a few studies were performed in rural and coastal environments, even less in the Eastern Mediterranean. Similarly to alkylamines, monoterpenes measurements in the Mediterranean are limited both temporally and regarding ecosystem coverage (mainly covering forested areas). Furthermore, even if tree species are responsible for the majority of monoterpene emissions to the atmosphere, the contribution of shrubs and phrygana vegetation, which are typical vegetation in our region, requires further investigation. For these reasons, atmospheric air samples were collected for the analysis of alkylamines and monoterpenes at the University of Crete station at Finokalia, at Lassithi (35o20΄N, 25o40΄E, 250 m a.s.l), a remote site on the northeast coast of the island of Crete. A total of 345 air monoterpene samples were collected in absorption tubes between 13 March 2014 and 20 April 2015. The samples were analyzed by a system comprising of a thermal desorber connected to a gas chromatography (GC) with a flame ionization detector (FID) system. A clear diurnal cycle of α-pinene was observed during spring and summer, typical for biogenic compounds, with a minimum around noon that reflected the intense photochemical loss. The most abundant monoterpene was p-cymene, for which, as for limonene, the highest mixing ratios were observed in spring and autumn, with maximum values during afternoon. The spring and autumn maxima could be attributed to the seasonality of vegetation at Finokalia. The green season at Finakalia starts in late autumn, when the phrygana vegetation grows due to rainfall, while temperature is still high at this time of year, as Finokalia is located in the south-eastern part of Europe. Factor analysis showed that limonene has different sources from α-pinene and pcymene that were grouped together, while none of the studied monoterpenes was associated with anthropogenic sources. Finally, the seasonalities of NPF events and monoterpenes show similarities, with a common maximum during spring, indicating that monoterpenes may contribute to the NPF process. The methodology available in the literature for atmospheric samples collection and subsequent analysis for detecting gas-phase alkylamines was optimized and standardized in this thesis. Samples were collected in the Eastern Mediterranean from January 2013 to July 2016 in suitably treated filters. Analysis was performed by a highperformance liquid chromatography (HPLC) triple quadrupole mass spectrometer (TSQ). A total of 358 samples were collected and analyzed. Dimethylamine (DΜΑ, (CH3)2NH) + ethylamine (EA, (C2 H5)NH2) and trimethylamine, (TMA, (CH3)3N) were observed to be the most abundant alkylamines throughout the whole period with mean mixing ratios of 7.8 ± 12.1 and 7.5 ± 12.4 ppt, respectively. Amines showed pronounced seasonal variability, with DMA + EA and TMA concentrations higher in winter. A factor analysis showed that the different amines have different sources, except for DMA + EA and diethylamine (DEA, (C2 H5)NH), which have common sources. TMA is attributed to marine sources, while triethylamine (TEA, (C2H5) 3N) is attributed to animal husbandry. None of the observed alkylamines was found to be associated with anthropogenic sources. Finally, while no correlation was found between the seasonality of alkylamines and that of NPF events, a clear similarity was found between the seasonality of nucleation mode particle number concentrations and alkylamine concentrations, indicating that amines may contribute to nucleation mode particles’ production. Finally, MALTE-BOX and ARCA box models were used to simulate NPF in the Eastern Mediterranean atmosphere, simulating the chemical and dynamic processes of aerosols in the atmosphere. In order to investigate the contribution of the studied VOCs to nucleation in our region, NPF events at Finokalia were identified from the particle number size distribution measurements. Using MALTE-BOX to simulate NPF observations at the subtropical environment of Finokalia, we were able to simulate, with good agreement, the observed NPF events during the selected time period. The parameterization used was significantly different from the one used for the boreal environment with the nucleation rates being much lower. This could be due to the contribution of unknown compounds in the new particle formation and growth processes. As far as the constituent in atmospheric NPF, monoterpenes seemed to play a key role in the mechanisms governing NPF phenomena. Simulations with the ARCA model show that DMA is the most effective precursor of NPF, while limonene has little contribution to it, and that the simulated NPF formation rates were found to be higher than those observed.
Language Greek
Subject Monoterpenes
New particle formation
Numerical simulations
Αlkylamines
Αλκυλαμίνες
Ανατολική Μεσόγειος
Αριθμητικές προσομοιώσεις
Μονοτερπένια
Σχηματισμός νέων σωματιδίων
Issue date 2023-07-28
Collection   School/Department--School of Sciences and Engineering--Department of Chemistry--Doctoral theses
  Type of Work--Doctoral theses
Permanent Link https://elocus.lib.uoc.gr//dlib/b/8/b/metadata-dlib-1689659951-593069-28158.tkl Bookmark and Share
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