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| Titel |
A novel firn/ice-core melter system for semi-continuous extraction of PAHs and continuous ICP-QMS trace element analysis |
| VerfasserIn |
J. Gabrieli, P. Vallelonga, W. Cairn, G. Cozzi, F. Decet, M. Schwikowski, M. Sigl, C. Boutron, C. Barbante |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250026343
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| Zusammenfassung |
| A new melting device for on-line decontamination and continuous analysis of firn/ice cores
was used to analyse an alpine firn/ice core drilled at Colle Gnifetti (M. Rosa, 4450 m a.s.l.),
covering a time period of 10,000 years. Melt water from inner part of ice core section was
pumped to an ICP-QMS and a conductivity micro-cell for trace elements and continuous
conductivity measurements, respectively. Melt water from the outer section was extracted
on-line by solid-phase cartridges for semi-continuous Polycyclic Aromatic Hydrocarbons
(PAHs) analysis. High resolution profiles of 24 elements were obtained. Pronounced seasonal
variations were observed for both crustal (eg. Mg, Al) and anthropogenically enriched (eg.
Cd, Pb) elements, with higher concentrations during summer. While the long-term profiles of
crustal trace elements didn’t show significant variations, for anthropogenic enriched
metals a widespread increase is reported from 18th century, reflecting changing
emissions.
Very few works regarding PAHs determination in snow and ice samples are present in the
literature. As for polar environments, PAHs have only been sampled and analyzed in shallow
Greenland snow. To our knowledge, no PAHs profiles have been published for firn/ice in the
Alps. The concentrations of 12 PAHs were determined by HPLC-FD, obtaining detailed
profiles for the last three centuries.
Before 1875 the PAHs levels were very low: the pre-1750’s PAHs concentrations were
assumed to be the background level. ΣPAHs in the 1945-1955 ten-years period were 10 times
higher than background values with ΣPAHs* (heaviest compounds) about 40-50 times
higher. From 1900, PAHs concentrations increased exponentially, reaching a maximum in
1920. From the mid-1930s PAHs rapidly doubled reaching maximum concentrations from
1940 to 1950. Concentrations of the heaviest ΣPAHs* decreased by a factor 5 from 1950 to
1975 while for total ΣPAHs the concentrations halved. From 1975 to 2003, ΣPAHs rose
again to almost 1910 values. If the general PAHs trends are strongly correlated with
anthropogenic emission variation, the fine shape of the profile can be influenced by several
other parameters. This trend does not seem to be completed and further increases may occur
in coming years. The PAHs pattern is normally dominated by phenantrene, fluoranthene and
pyrene, which represent 60-80% of the total. The different behaviour of light and
heavy PAH profiles reflects the chemical features of single compounds. For light
compounds, which are relatively volatile, climatic variables affecting transport and
deposition processes may influence concentrations more than anthropogenic emissions. |
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