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Paleo-reconstruction of the ocean acidification due to industrial era in tropical areas via boron isotope analysis of surface corals using MC-ICPMS.
Ocean Acidification due to anthropogenic release of carbon dioxide (CO2) to the atmosphere is today evaluated at about 0.1 pH-unit for surface waters for the last 200 years. This value was deduced from combined pH measurements over the last 30 years and models. The precise quantification of this running acidification and the prediction of its impact on marine ecosystems are major societal concerns since the level of this acidification could be multiplied by three before the end of this century. In order to better constrain this acidification, the PhD’s subject is to develop and apply the technique of reconstruction of paleo-pH based on boron isotopes in ancient surface corals (Porites, Acropora, etc.). Recent field and laboratory experiments, especially in the framework of a national project INSU entitled PHARE (collaboration LSCE, IRD-Noumea, IPG-Paris), highlighted the strong potential of this technique applied to tropical corals (porites sp.) to calculate a pH value with +/- 0.02 pH-unit of precision. Thus, the PhD’s works will focus on the application of the technique to surface coral samples collected from various tropical areas in the Pacific Ocean (New Caledonia, French Polynesia, Fiji islands, etc.) in order to quantify the evolution of this acidification since the beginning of the industrial era and to determine its impact on the ocean chemistry taking into account ocean dynamics in these areas. The isotopic composition of boron will be measured using new generation mass spectrometer MC-ICPMS. A multi-proxy analysis involving major and trace elements and oxygen and carbon isotopes will be also developed to complete the subject.
This PhD will be supervised by Eric Douville and Martine Paterne at the LSCE in Gif/Yvette (south of Paris) in collaboration with Guy Cabioch (IRD-Noumea) and Pascale Louvat (IPG-Paris). Its funding will start the 1st of October, 2009.
Student having a degree from the university or schools equivalent to French master II degree at the 1st of October, 2009 (Geochemistry, Climate, Environment, Sciences of the Earth).
Deadline: the 10th, April 2009 to give preliminary information useful for CEA (Curriculum Vitae). Supplementary information on the website
Contact : Eric Douville : Eric.Douville (at) lsce.ipsl.fr