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Ricardo De Pol Holz, 2006-2008 Postdoctoral Scholar

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Ricardo De Pol Holz

Dr. De Pol-Holz arrived at the Woods Hole Oceanographic Institution (WHOI) in November of 2006, after completing his Ph.D. in Oceanography at the University of Concepcion, Chile. During his Ph.D. training, Dr. De Pol-Holz studied the biogeochemistry of nitrogen isotopes in the eastern South Pacific and used this information to asses the variability of the intensity of denitrification during the Late Quaternary. Dr. De Pol-Holz’s Ph.D. training provided him with a strong background in stable isotope analysis, nitrogen biogeochemistry and Paleoclimatology. At WHOI, Dr. De Pol-Holz seeks to become familiar with radiocarbon techniques, and to assess the past variability of intermediate water mass ventilation in the South Pacific. Dr. De Pol-Holz’s project at WHOI, in collaboration with faculty advisor Lloyd D. Keigwin, is to use paired radiocarbon analyses in benthic and planktonic foraminifera to investigate the deglacial changes in Antarctic Intermediate Water (AAIW) ventilation using cores from the Chile margin.

Dr. De Pol-Holz’s primary project is to use the radiocarbon data to determine the apparent ventilation age of a selected depth range in the eastern South Pacific. The N isotope information that he generated in his Ph.D. provided the evidence that during the last deglaciation, there was a collapse in the ventilation of the South Pacific subsurface (onset of the modern Oxygen Minimum Zone) which it has been associated with changes in intermediate water formation. The radiocarbon data that is being analyzed at WHOI constitutes the first attempt to directly assess the changes in AAIW near its formation zone west of the Drake Passage. Dr. De Pol-Holz hopes that the radiocarbon data will confirm the growing evidence of the existence of a deep and radiocarbon depleted water reservoir in the Pacific and that it was its ventilation and the spread of its signal to other basins by way of AAIW formation, the responsible mechanism for the deglacial increase in CO2 in the atmosphere.

Using stable isotope analysis on benthic foraminifera, Dr. De Pol-Holz will also try to identify hydrological changes that could have altered AAIW characteristics during the last glacial-interglacial transition (18,000-11,000 years ago). The methodology lies in the identification of peaks in abundance of selected species of benthic foraminifera like Uvegerina peregrina, Cibicidoides sp. and Bulimina sp. in several cores from intermediate depths along the Chilean margin. His preliminary results confirm the existence of such peaks, and the next step of stable isotope and radiocarbon analyses is about to begin.

CICOR sponsored Dr. De Pol-Holz’s travel to one national conference in 2006, an international research trip and an advanced course in 2007. The first was the American Geophysical Union fall conference in San Francisco, CA in December, 2006. Coming from a marine biological background, this conference was an important opportunity for Dr. De Pol-Holz to learn about the latest research in the broad field of Paleoclimatology and network with the leaders in this field.

The second trip was a research visit to the University of Bremen, Germany. This trip gave Dr. De Pol-Holz the opportunity to collect samples from a set of sediment cores along the Chile margin that were taken previously by the GeoB department. During this trip, Dr. De Pol-Holz was invited to give three public presentations of his previous and present work at the University of Bremen, the Alfred Wegener Institute in Bremerhaven and the ifM-Geomar Institute in Kiel.

Dr. De Pol-Holz will continue with his work on radiocarbon analysis of benthic foraminifera in the eastern South Pacificon as a co-PI on a project funded by the National Science Foundation.

In the last year (2006-2007), Dr. De Pol Holz has had one publication published, and one accepted:

De Pol-Holz, R., R. Robinson, D. Hebbeln, D. M. Sigman and O. Ulloa. Controls of sedimentary N isotopes along the Chile margin. 2007. Deep-Sea Res. II, accepted manuscript.

De Pol-Holz, R., O. Ulloa, F. Lamy, L. Dezileau, P. Sabatierr, D. Hebbeln. Late Quaternary variability of sedimentary nitrogen isotopes in the eastern South Pacific Ocean. 2007. Paleoceanography, 22, PA2207, doi:10.1029/2006PA001308.

De Pol-Holz, R., O. Ulloa, L. Dezileau, J. Kaiser, F. Lamy and D. Hebbeln. Melting of the Patagonian Ice Sheet and deglacial pertubations of the nitrogen cycle in the eastern South Pacific. 2006. Geophysical Research Letters, 33(4), L04704, doi:10.1029/2005GL024477.

Last updated: May 21, 2009

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