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| Titel |
Composition, size distribution, optical properties, and radiative effects of laboratory-resuspended PM10 from geological dust of the Rome area, by electron microscopy and radiative transfer modelling |
| VerfasserIn |
A. Pietrodangelo, R. Salzano, C. Bassani, S. Pareti, C. Perrino |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 22 ; Nr. 15, no. 22 (2015-11-27), S.13177-13194 |
| Datensatznummer |
250120191
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| Publikation (Nr.) |
 copernicus.org/acp-15-13177-2015.pdf |
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| Zusammenfassung |
In this work, new information has been gained on the laboratory-resuspended
PM10 fraction from geological topsoil and outcropped rocks
representative of the Rome area (Latium).
Mineralogical composition, size distribution, optical properties and the
surface radiative forcing efficiency (RFE) of dust types representing the
compositional end members of this geological area have been addressed. A
multi-disciplinary approach was used, based on chamber resuspension of raw
materials and sampling of the PM10 fraction, to simulate field sampling
at dust source, scanning electron microscopy/X-ray energy-dispersive
microanalysis (SEM XEDS) of individual mineral particles, X-ray diffraction
(XRD) analysis of bulk dust samples, building of number and volume size
distribution (SD) from microanalysis data of mineral particles and fitting
to a log-normal curve, and radiative transfer modelling (RTM) to retrieve
optical properties and radiative effects of the compositional end-member
dust samples.
The mineralogical composition of Rome lithogenic PM10 varies between an
end-member dominated by silicate minerals (from volcanics lithotypes), and
one mostly composed of calcite (from travertine or limestones). Lithogenic
PM10 with intermediate composition derives mainly from siliciclastic
rocks or marlstones. Size and mineral species of PM10 particles of
silicate-dominated dust types are tuned mainly by rock weathering and, to
lesser extent, by debris formation or crystallization; chemical
precipitation of CaCO3 plays a major role in calcite-dominated types.
These differences are reflected in the diversity of volume distributions, either
within dust types or mineral species. Differences are also observed between
volume distributions of calcite from travertine (natural source; SD unimodal
at 5 μm a.d.) and from road dust (anthropic source; SD bimodal at 3.8
and 1.8 μm a.d.).
The volcanics and travertine dusts differently affect the single scattering
albedo (SSA) and the asymmetry parameter (g) in the visible (VIS) and near-infrared (NIR) regions. The downward component of the bottom-of-atmosphere
(BOA) solar irradiance simulated by RTM for an atmosphere where only
volcanics (or only travertine dust) composes the aerosol, shows that the volcanics contribution to the solar irradiance differs significantly from
that of travertine in the NIR region, while similar contributions are
modelled in the VIS. The RFE (−293 W m−2 for volcanics and −139 W m−2 for travertine, at 50° solar zenith angle) shows that
volcanics dust produces a stronger cooling effect at surface than
travertine, as expected for more absorbing aerosols. |
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