 |
| Titel |
Geochemical perspectives from a new aerosol chemical mass closure |
| VerfasserIn |
B. Guinot, H. Cachier, K. Oikonomou |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 7, no. 6 ; Nr. 7, no. 6 (2007-03-27), S.1657-1670 |
| Datensatznummer |
250004836
|
| Publikation (Nr.) |
 copernicus.org/acp-7-1657-2007.pdf |
|
|
|
|
|
| Zusammenfassung |
| The aerosol chemical mass closure is revisited and a simple and inexpensive
methodology is proposed. This methodology relies on data obtained for
aerosol mass, and concentration of the major ions and the two main carbon
components, the organic carbon (OC) and the black carbon (BC). Atmospheric
particles are separated into coarse (AD>2 μm) and fine (AD<2 μm)
fractions and are treated separately. For the coarse fraction the
carbonaceous component is minor and assumption is made for the conversion
factor k of OC-to-POM (Particulate Organic Matter) which
is fixed to the value of 1.8 accounting for secondary species. The coarse
soluble calcium is shown to display a correlation (regression
coefficient f, y axis intercept b) with
the missing mass. Conversely, the fine fraction is dominated by organic
species and assumption is made for dust which is assumed to have the same
f factor as the coarse mode dust. The fine mode mass
obtained from chemical analyses is then adjusted to the actual weighed mass
by tuning the k conversion factor. The k
coefficient is kept different in the two modes due to the expected different
origins of the organic particles. Using the f and k coefficient obtained
from the data set, the mass closure is reached for each individual sample
with an undetermined fraction less than 10%. The procedure has been
applied to different urban and peri-urban environments in Europe and in
Beijing and its efficiency and uncertainties on f and
k values are discussed. The f and
k coefficients are shown to offer consistent geochemical
indications on aerosol origin and transformations. f
allows to retrieve dust mass and its value accounting for Ca abundance in
dust at the site of investigation may serve as an indicator of dust origin
and aerosol interactions with anthropogenic acids. f values were found to
vary in the 0.08–0.12 range in European urban areas, and a broader range in
Beijing (0.01–0.16). As expected, k appears to be a
relevant proxy for particle origin and ageing and varies in the 1.4–1.8
range. For Beijing, k exhibits high values of about 1.7 in
winter and summer. Winter values suggest that fresh coal aerosol might be
responsible for such a high k value, which was not taken
into account in previous works. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|