Naslov
Organic matter in atmospheric aerosols over Zagreb: seasonal variation and characterisation of physicochemical properties

Autori
Vidović, Kristijan ; Frka, Sanja ; Orlović-Leko, Palma

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Protection of Cultural Heritage from Natural and Man-made Disasters / Krstić, Dragica ; Marasović, Nela ; Zajec Jasenka - Zagreb : National and University Library in Zagreb, 2014, 116-118

Skup
Protection of Cultural Heritage from Natural and Man-made Disasters

Mjesto i datum
Zagreb, Hrvatska, 08.05.2014. - 10.05.2014

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
aerosols ; organic matter ; surfactants ; black crust ; Zagreb cathedral

Sažetak
Aerosols are important atmospheric constituents due to of their impact on global climate and air quality. According to the Intergovernmental Panel on Climate Change, aerosols have been the most important atmospheric cooling component in the industrial period (IPCC, 2007). Aerosol particles affect climate directly by scattering and absorbing solar radiation and indirectly by acting as cloud condensation nuclei (CCN), thus influencing cloud droplet size distribution, cloud albedo and lifetime (Kaufman et al., 2002). The airborne solid and liquid particles in the nanometer to micrometer size range influence the energy balance of the Earth, the hydrological cycle, atmospheric circulation, and the abundance of greenhouse and reactive trace gases. The primary parameters that determine the environmental effects of aerosol particles are their concentration, size, structure, and chemical composition. These parameters, however, are spatially and temporally highly variable (Pöschl, 2005). Particles are removed from the atmosphere by two mechanisms: deposition at the Earth’s surface (dry deposition) and incorporation into cloud droplets during the formation of precipitation (wet deposition). Dry deposition is relevant with respect to local air quality, and the soiling of buildings and cultural monuments. Diesel particulate material is very effective at soiling the urban fabric. Particle from this source are small, sticky and extremely black entities and have become the principal contemporary cause of the blackening of buildings. Sandstone accumulated soot very effectively and the rain will not wash it out. On the other hand, limestone can be cleaned by the rain and soot collets on sheltered surface (Brimblecombe, 1996). Organic particles are either emitted directly into the atmosphere by fossil fuel or biomass combustion thus forming primary organic aerosols or are formed by gas-to-particle conversion from gaseous precursors leading to secondary organic aerosols (Kanakidou et al. 2005). A large part of the organic compounds (up to 75% of the total organics) from aerosol can be recovered in a water soluble fraction (WSOC). Chemical aging and oxidative transformation of organic aerosol components generally increases the number of functional groups and thus increases solubility of organic molecules. Polycarboxylic acids constitute a considerable portion of the polar fraction of diesel particulate matter directly extracted from a bus exhaust. Also, an important number of benzenepolycarboxylic acids were identified as major components of a polar fraction in the black crust from historic monuments. Namely, black crusts are repositories of urban aerosols, as the monument surfaces passively entrap particulates in a gypsum matrix and, to some extend, the compounds were preserved (Hermosin and Saiz-Jimenez, 2013). The most reactive part of the WSOC fraction of atmospheric aerosols is surface active arranging itself into organic films at the gas-aerosol interface (Orlović-Leko et al2010 ; Frka et al., 2012). Surface active substances (SAS) with long hydrocarbon chains and a polars groups play an essential role in the control of atmospheric processes. These films can depress surface tension of atmospheric aerosols, leading to enhanced cloud nuclei formation. Surface films can change the physicochemical properties of humid aerosol particle and may hinder the transport of trace gases and water vapor through the interface (Seidl, 2000). The present study describes results by specific focusing on the seasonal variability of surfactant properties of the ambient aerosol WSOC fraction (PM < 10 μm) collected during one year (2011-2012) in urban area of Zagreb. The qualitative and quantitative characterization of SAS in investigated samples was evaluated bycomparison with selected model substances as well as with those of naturally isolated humus-like material (polymeric nature) applying electrochemical methods. Dissolved organic carbon (DOC) and particulate organic carbon (POC) were determined as additional parameters for characterization of organic matter in aerosols samples, what is of special interest for understanding the pertaining physicochemical processes in the atmosphere.

Izvorni jezik
Engleski

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