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Alkenone-based temperature patterns along the eastern South Pacific Coastal Ocean: the effect of upwelling and advection on the sedimentary alkenone unsaturation-index (U37K')
1Graduate Program in Oceanography, Department of Oceanography, University of Concepción, Concepción, Chile
2Department of Oceanography and Center for Oceanographic Research in the eastern South Pacific (FONDAP-COPAS), University of Concepción, Concepción, Chile
3Department of Environmental Chemistry, Faculty of Sciences, Universidad Católica de la Santísima Concepción, Concepción, Chile
4Instituto de Biología Marina, Universidad Austral de Chile, Valdivia, Chile
5MARUM Center for Marine Environmental Sciences, Bremen University, Bremen, Germany
Abstract. We report that the sedimentary record of alkenone unsaturation-index (U37K') in the eastern South Pacific displays a wide range of temperatures, in response to sea surface temperature (SST), as well as nutrient concentrations. The U37K' inshore-offshore trend shows low-correlation with SSTs at many transitional sites (50–200 km offshore), and in one oligotrophic coastal site (~20° S). In contrast, in open-ocean sites SSTs play the expected dominant role. The latitudinal trend shows that nitrate, phosphate and/or temperature affect distinctively the U37K', suggesting progressive high-impacts in areas with permanent nutrient-stress conditions (~20° S), which is consistent with previous experiments. In contrast, this impact is slightly and not observable in transitional and open-ocean areas, respectively, where the coupling between offshore propagation of mesoscale eddies and upwelling filaments supply additional chlorophyll/nutrient. This study is a first field approximation to the impacts of thermal/non-thermal factors over the unsaturation-index in eastern Boundary Current systems, which would help in future temperature reconstructions.
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Citation: Placencia, J. A., Garcés-Vargas, J., Lange, C. B., and Hebbeln, D.: Alkenone-based temperature patterns along the eastern South Pacific Coastal Ocean: the effect of upwelling and advection on the sedimentary alkenone unsaturation-index (U37K'), Biogeosciences Discuss., 7, 545-564, 2010. Bibtex EndNote Reference Manager
