Particulate and phytoplankton absorption during POLARSTERN cruises ANT-XXVI/3 and ANT-XXVIII/3

The euphotic depth (Zeu) is a key parameter in modelling primary production (PP) using satellite ocean colour. However, evaluations of satellite Zeu products are scarce. The objective of this paper is to investigate existing approaches and sensors to estimate Zeu from satellite and to evaluate how different Zeu products might affect the estimation of PP in the Southern Ocean (SO). Euphotic depth was derived from MODIS and SeaWiFS products of (i) surface chlorophyll-a (Zeu-Chla) and (ii) inherent optical properties (Zeu-IOP). They were compared with in situ measurements of Zeu from different regions of the SO. Both approaches and sensors are robust to retrieve Zeu, although the best results were obtained using the IOP approach and SeaWiFS data, with an average percentage of error (E) of 25.43% and mean absolute error (MAE) of 0.10 m (log scale). Nevertheless, differences in the spatial distribution of Zeu-Chla and Zeu-IOP for both sensors were found as large as 30% over specific regions. These differences were also observed in PP. On average, PP based on Zeu-Chla was 8% higher than PP based on Zeu-IOP, but it was up to 30% higher south of 60°S. Satellite phytoplankton absorption coefficients (aph) derived by the Quasi-Analytical Algorithm at different wavelengths were also validated and the results showed that MODIS aph are generally more robust than SeaWiFS. Thus, MODIS aph should be preferred in PP models based on aph in the SO. Further, we reinforce the importance of investigating the spatial differences between satellite products, which might not be detected by the validation with in situ measurements due to the insufficient amount and uneven distribution of the data.

(Table 1) Composition of paraffin hydrocarbons at DSDP Site 56-434

Geochemical investigation of 18 samples of sediments from Site 434 involved determining the content of organic carbon, of bitumoid A (The chloroform A-chl and alcohol-benzene A-alb extracts) and its various fractions, and of individual hydrocarbons as well as the structural group composition of resins. We identified certain samples that differed sharply from the rest by their increased bitumen content and relatively low molecular hydrocarbons and by the fact that their resinous components were more neutral and aliphatic in composition. The distribution of bitumoid and its components seems to reflect migration processes in operation during the early stages of the transformation of organic matter.

Virgilio. Geórgicas. Ed. Bil. Introd., trad. y notas de Alejandro Bekes. Ilustrac. de Dolores Tamaño. Col. Griegos y Latinos. Bs. As., Losada, 2007. 334 pp.

Fil: Gassull, María José. Universidad Nacional de Cuyo

Verstraete, M.; Mannina de Gamero, L.; Catana, M. R.; Gabrielidis de Luna, A.; Rodríguez, A.; El Concepto del hombre, Exégesis e interpretación del De Anima de Aristóteles y su proyección contemporánea. Ediciones Propedéutica, Mendoza, 1985, 316 págs.

Fil: Diario Los Andes (Mendoza, Argentina).

Carrillo Narváez. La trayectoria del pensamiento filosófico en Latinoamérica. Quito, Editorial Casa de la Cultura Ecuatoriana, 1959, 334 p.

Fil: Torchia Estrada, Juan Carlos.

León Solís, Leonardo. Plebeyos y patricios en Chile colonial, 1750-1772. La gesta innoble. Santiago de Chile: Editorial Universitaria, 2015, 334 páginas. ISBN: 978-956-11-2459-2.

Fil: Bonnassiolle Cortés, Marcelo. Universidad de Santiago de Chile