 |
| Titel |
Reconstruction of Aerosol Concentration and Composition from Glacier Ice Cores |
| VerfasserIn |
Alexander Vogel, Kaspar Dällenbach, Imad El-Haddad, Isabel Wendl, Anja Eichler, Margit Schwikowski |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250149936
|
| Publikation (Nr.) |
 EGU/EGU2017-14345.pdf |
|
|
|
|
|
| Zusammenfassung |
| Reconstruction of the concentration and composition of natural aerosol in an undisturbed
atmosphere enables the evaluation of the understanding of aerosol-climate effects, which is
currently based on highly uncertain emission inventories of the biosphere under pre-industrial
conditions. Understanding of the natural state of the pre-industrial atmosphere and evaluating
the atmospheric perturbations by anthropogenic emissions, and their potential feedbacks,
is essential for accurate model predictions of the future climate (Boucher et al.,
2013).
Here, we present a new approach for the chemical characterization of the organic
fraction preserved in cold-glacier ice cores. From this analysis historic trends of
atmospheric organic aerosols are reconstructed, allowing new insights on organic aerosol
composition and mass in the pre-industrial atmosphere, which can help to improve
climate models through evaluation of our current understanding of aerosol radiative
effects.
We present results from a proof-of-principal study, analyzing an 800 year ice core record
from the Lomonosovfonna glacier ice core, drilled in 2009 in Svalbard, Norway, using a
setup that has until then only been applied on offline measurements of aerosol filter extracts
(Dällenbach et al., 2016): The melted ice was nebulized and dried, such that aerosols
are formed from the soluble and insoluble organic and inorganic compounds that
are preserved in the ice. To improve the sensitivity, the aerosol stream was then
enriched by the application of an online aerosol concentrator, before the aerosol was
analyzed by electron ionization within a high resolution time-of-flight aerosol mass
spectrometer (HR-ToF-AMS). We were able to demonstrate that this setup is a quantitative
method toward nitrate and sulfate when internal inorganic standards of NH415NO3
and (NH4)234SO4 are added to the sample. Comparison between AMS and IC
measurements of nitrate and sulfate resulted in an excellent agreement. The analysis of the
organic fraction, however, was biased by a source of organic contamination, likely
introduced during sample storage. However, freshly prepared ice blanks showed no
significant source or organics, and the calibration with an organic surrogate standard
demonstrated that this technique is applicable for the analysis of newly prepared ice
samples.
Furthermore, we present first results of the method development towards organic molecular
tracer analysis using solid phase extraction and liquid-chromatography coupled to ultra-high
resolution mass spectrometry.
References:
Boucher, O., et al., Clouds and Aerosols: 7, in: Climate Change 2013: The Physical Science
Basis., Cambridge University Press, 571–658, 2013.
Dällenbach, K. R., et al., Atmos. Meas. Tech. 9, 23–39, 2016. |
|
|
|
|
|
|