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| Titel |
A novel method for the detection of acidity in ice cores |
| VerfasserIn |
Helle Astrid Kjær, Paul Vallelonga, Anders Svensson |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087475
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| Publikation (Nr.) |
 EGU/EGU2014-1526.pdf |
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| Zusammenfassung |
| The pH of polar ice is important for the stability and mobility of impurities in ice cores and
can be strongly influenced by volcanic eruptions or anthropogenic emissions.
We present a simple optical method for continuous determination of acidity in ice cores
based on the absorption spectroscopy of two common pH-indicator dyes, bromophenol blue
and chlorophenol red. The method does not require calibration with CO2 and is simpler
than existing continuous flow analysis (CFA) methods for pH determination in ice
cores, offering a 10-90% peak response time of 45s and a combined uncertainty of
9%.
The method has been applied to sections of Greenland firn and Antarctic ice and
compared to standard techniques such as Electrical Conductivity Measurements (ECM),
conducted on the solid ice, and electrolytic conductivity of melted ice samples.
The acidity as detected in the Greenland NEGIS firn core (75.38N, 35.56W), show an
increasing trend up to the 1970’s that can be explained by deposition of anthropogenic SO42-
and NOX. The seasonal variability show highest acidity in winter (1900-1950 AD), but shifts
towards spring for the period 1950-2000 AD.
Conductivity and pH are found to be highly correlated in the Greenland NEGIS firn core
with all signals greater than 3Ïă variability being related to either volcanic eruptions or forest
fire activity. The method is ideal for finding the volcanic spikes in the firn than
conventional ECM and DEP, which require density corrections in firn. In contrast to the
NEGIS site, the Antarctic Roosevelt Island ice core (79.36S, 161.71W) features an
anti-correlation between conductivity and pH, most likely due to the influence of marine
salts. |
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