 |
| Titel |
Chirality and the origin of atmospheric humic-like substances |
| VerfasserIn |
I. Salma, T. Mészáros, W. Maenhaut, E. Vass, Z. Majer |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 3 ; Nr. 10, no. 3 (2010-02-05), S.1315-1327 |
| Datensatznummer |
250008045
|
| Publikation (Nr.) |
 copernicus.org/acp-10-1315-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| Aerosol water extracts and atmospheric humic-like substances (HULIS)
obtained from PM2.5-fraction aerosol samples collected in a
rural/continental background environment and in an urban environment
in spring and summer, and at a tropical site that was heavily
impacted by biomass burning were studied. HULIS was obtained as the
water-soluble, methanol-elutable material isolated from a
solid-phase extraction procedure. The mean organic matter-to-organic
carbon mass conversion factor and the standard deviation of
2.04±0.06 were derived for HULIS from biomass burning. Mean
atmospheric concentrations of HULIS for the rural and urban
environments and for the biomass burning during daylight periods and
nights, were 1.65, 2.2, 43, and 60 μg m−3,
respectively. This and other abundances indicate that intense
emission sources and/or formation mechanisms of HULIS operate in
biomass burning. Mean contributions of C in HULIS (HULIS-C) to
water-soluble organic carbon (WSOC) were 35, 48, 63, and 76%,
respectively, for the sample set listed. HULIS-C is the major
component of the WSOC in tropical biomass burning. The data also
suggest that HULIS most likely do not share common origin in the
three environments studied. Differentiation among the possible
formation processes was attempted by investigating the optical
activity of HULIS through their (electronic and vibrational)
circular dichroism properties. The urban HULIS did not show optical
activity, which is in line with the concept of their major airborne
formation from anthropogenic aromatics. The rural HULIS revealed
weak optical activity, which may be associated with one of their
important formation pathways by photo-oxidation and oligomerisation,
i.e., with the formation from chiral biogenic precursors with one
of the enantiomers slightly enriched. The The biomass burning of HULIS
exhibited a strong effect in the vibrational circular dichroism as a
clear distinction from the other two types. This was related to the
contribution of the thermal degradation products of lignins and
cellulose. The biomass burning of HULIS resemble Suwannee River
Fulvic Acid standard more closely in some aspects than the urban and
rural types of HULIS, which may be related to their common origin
from plant material. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|