Midtvejskollokvium: Helle Astrid Kjær – Niels Bohr Institute - University of Copenhagen

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Niels Bohr Institute > Calendar > 2010 > Midtvejskollokvium: He...

Midtvejskollokvium: Helle Astrid Kjær

Continuous measurements of chemical impurities in ice cores


Supervisor:
Anders Svensson

Ice cores provide an archive to past climates. Measurements of ions deposited on the ice reveal changes in sea salt, terrestrial dust, volcanic eruptions, biosphere activity and anthropogenic combustions. My master project concerns continuous measurements of a new proxy, phosphate, in ice cores, with the purpose of increasing knowledge on the biosphere primary activity. Several chemical species have more than one source and different transport pathways can alter the amount and relative composition of the species, hence care must be taken when interpreting measurements. Phosphate can have different sources too. Over the last centuries human impact might have enhanced the concentration level and in glacial times sea level changes and ocean bioproductivity can have altered the phosphate cycle. The talk will be on how chemical proxies are measured in ice cores by continuous flow analysis (CFA) using fluorescence and absorption spectrometry methods, and by inductively coupled plasma mass spectrometry (ICP-MS). The interpretation of the different chemical impurities will be discussed and examples of records from Greenland and Antarctica will be shown. The first measurements of phosphate in a shallow firn core from Greenland will also be discussed.