Molekularna karakterizacija lebdećih čestica slobodne troposfere sa Opservatorija Pico planine

Katja Džepina (Author), Claudio Mazzoleni (Author), Paulo Fialho (Author), Swarup China (Author), B. Zhang (Author), R. Chris Owen (Author), D. Helmig (Author), J. Hueber (Author), Sumit Kumar (Author), J. A. Perlinger (Author)

Abstract

Long-range transported free tropospheric aerosol was sampled at the PMO (38°28’15’’N, 28°24’14’’W; 2225 m amsl) on Pico Island of the Azores in the North Atlantic. Filter-collected aerosol during summer 2012 was analysed for organic and elemental carbon, and inorganic ions. The average aerosol ambient concentration was 0.9 µg m-3. Organic aerosol contributed the majority of mass (57%), followed by sulphate (21%) and nitrate (17%). Filter-collected aerosol was positively correlated with on-line aerosol measurements of black carbon, light scattering and number concentration. Water-soluble organic compounds (WSOC) from 9/24 and 9/25 samples collected during a pollution event were analysed with ultrahigh-resolution FT-ICR MS. FLEXPART analysis showed the air masses were very aged (>12 days). ~4000 molecular formulas were assigned to each of the mass spectra between m/z 100-1000. The majority of the assigned molecular formulas have unsaturated structures with CHO and CHNO elemental compositions. WSOC have an average O/C of ~0.45, relatively low compared to O/C of other aged aerosol, which might be the result of evaporation and fragmentation during long-range transport. The increase in aerosol loading during 9/24 was linked to biomass burning emissions from North America by FLEXPART and MODIS fire counts. This was confirmed with WSOC biomass burning markers and with the morphology and mixing state of particles as determined by SEM. The presence of markers characteristic of aqueous-phase reactions of biomass burning phenolic species suggests that the aerosol collected at Pico had undergone cloud processing. The air masses on 9/25 were more aged (~15 days) and influenced by marine emissions, as indicated by organosulphates and species characteristic for marine aerosol (e.g. fatty acids). The change in air masses for the two samples was corroborated by the changes in ozone, ethane, propane, morphology of particles, as well as by FLEXPART. In this presentation we will presents the first detailed molecular characterization of free tropospheric aged aerosol intercepted at the PMO.

Keywords

Atmospheric aerosol;Free troposphere;Mass spectrometry;Pico mountain observatory;

Data

Language:	Croatian
Year of publishing:	2017
Typology:	1.12 - Published Scientific Conference Contribution Abstract
Organization:	UNG - University of Nova Gorica
UDC:	54
COBISS:	64751107
Views:	1509
Downloads:	0
Average score:	0 (0 votes)
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Other data

Secondary language:	English
Secondary title:	Molecular characterization of free tropospheric aerosol at the Pico Mountain Observatory (PMO)
Secondary abstract:	Dalekosežno transportirane lebdeće atmosferske čestice (aerosoli) uzorkovane su u slobodnoj troposferi na Observatoriju Pico planine (Pico Mountain Observatory, PMO; 38°28’15’’N, 28°24’14’’W; 2225 m n.v.) na otoku Pico azorskog otočja u Sjevernom Atlantiku. Aerosoli su prikupljani na filterima u ljeto 2012. i njihov kemijski sastav određen je analizama organskog i elementarnog ugljika te anorganskih iona. Prosječna masena koncentracija bila im je 0.9 µg m-3, pri čemu su većinu mase činile organske tvari (57%), uz doprinose sulfata (21%) i nitrata (17%). Masene koncentracije aerosola bile su značajno korelirane sa kontinuiranim mjerenjima čađi, te njihovog raspršenja svjetlosti i brojčane koncentracije. Organske tvari topive u vodi (Water-Soluble Organic Compounds, WSOC) uzoraka prikupljenih 24. i 25. 09.(uzorci 9/24 i 9/25) tijekom perioda visokog zagađenja analizirani su upotrebom masene spektrometrije ultravisoke rezolucije (FT-ICR MS). Analiza sa FLEXPART modelom pokazala je kako su te zračne mase putovale do PMO vrlo dugo (>12 dana). U masenim spektrima uzoraka identificirano je ~4000 molekularnih formula (m/z 100-1000) i većina je imala nezasićenu strukturu sa elementarnim sastavom CHO i CHNO. WSOC imale su O/C ~0.45, relativno nisko u usporedbi sa O/C drugih aerosola koji su proveli dugo vrijeme u atmosferi, što je moguće rezultat isparavanja i fragmentacije u dalekosežnom transportu. Viša koncentraciji uzorka 9/24 povezana je FLEXPART-om i MODIS satelitom sa požarima u Sjevernoj Americi. To potvrđuju i markeri požara u prikupljenim WSOC i morfologija čestica određena SEM tehnikom. Prisustvo markera karakterističih za reakcije fenola iz požara u vodenoj fazi sugerira da su aerosoli prošli kroz procesiranje u oblacima. Značne mase uzorka 9/25 putovale su duže (~15 dana) i bile pod utjecajem morskih emisija, kako je indicirano detektiranim organosulfatima i tvarima karakterističnim za morske aerosole (npr. masne kiseline). Razlike u aerosolima u dva uzorka potvrđene su i promjenama u ozonu, etanu, propanu, morfologiji čestica, te sa FLEXPART-om. U ovoj prezentaciji prikazat će se prva detaljna molekularna karakterizacija dalekosežno transportiranih aerosola u slobodnoj troposferi uzorkovanih na PMO.
Secondary keywords:	atmospheric aerosol;free troposphere;mass spectrometry;Pico Mountain Observatory;
URN:	URN:SI:UNG
Pages:	Str. 63-64
ID:	12943111