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| Titel |
Clues for a standardised thermal-optical protocol for the assessment of organic and elemental carbon within ambient air particulate matter |
| VerfasserIn |
L. Chiappini, S. Verlhac, R. Aujay, W. Maenhaut, J. P. Putaud, J. Sciare, J. L. Jaffrezo, C. Liousse, C. Galy-Lacaux, L. Y. Alleman, P. Panteliadis, E. Leoz, O. Favez |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 6 ; Nr. 7, no. 6 (2014-06-10), S.1649-1661 |
| Datensatznummer |
250115814
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| Publikation (Nr.) |
 copernicus.org/amt-7-1649-2014.pdf |
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| Zusammenfassung |
| Along with some research networking programmes, the European Directive
2008/50/CE requires chemical speciation of fine aerosol (PM2.5),
including elemental (EC) and organic carbon (OC), at a few rural sites in
European countries. Meanwhile, the thermal-optical technique is considered by
the European and US networking agencies and normalisation bodies as a
reference method to quantify EC–OC collected on filters. Although commonly
used for many years, this technique still suffers from a lack of
information on the comparability of the different analytical protocols
(temperature protocols, type of optical correction) currently applied in the
laboratories. To better evaluate the EC–OC data set quality and related
uncertainties, the French National Reference Laboratory for Ambient Air
Quality Monitoring (LCSQA) organised an EC–OC comparison exercise for
French laboratories using different thermal-optical methods (five laboratories
only). While there is good agreement on total carbon (TC) measurements among
all participants, some differences can be observed on the EC / TC ratio, even
among laboratories using the same thermal protocol. These results led to
further tests on the influence of the optical correction: results obtained
from different European laboratories confirmed that there were higher
differences between OCTOT and OCTOR measured with
NIOSH 5040 in comparison to EUSAAR-2. Also, striking differences between
ECTOT / ECTOR ratios can be observed when comparing
results obtained for rural and urban samples, with ECTOT being
50% lower than ECTOR at rural sites whereas it is only
20% lower at urban sites. The PM chemical composition could explain
these differences but the way it influences the EC–OC measurement is not
clear and needs further investigation. Meanwhile, some additional tests seem
to indicate an influence of oven soiling on the EC–OC measurement data
quality. This highlights the necessity to follow the laser signal decrease
with time and its impact on measurements. Nevertheless, this should be
confirmed by further experiments, involving more samples and various
instruments, to enable statistical processing. All these results provide
insights to determine the quality of EC–OC analytical methods and may
contribute to the work toward establishing method standardisation. |
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