Seasonal variations in surface metabolite composition of Fucus vesiculosus and Fucus serratus sampled at outer Kiel Fjord (August 2012 - July 2013)

The chemical composition of surface associated metabolites of two Fucus species (Fucus vesiculosus and Fucus serratus) was analysed by means of gas chromatography-mass spectrometry (GC-MS) to describe temporal patterns in chemical surface composition. Method: The two perennial brown macroalgae F. vesiculosus and F. serratus were sampled monthly at Bülk, outer Kiel Fjord, Germany (54°27'21 N / 10°11'57 E) over an entire year (August 2012 - July 2013). Per month and species six non-fertile Fucus individuals were collected from mixed stands at a depth of 0.5 m under mid water level. For surface extraction approx. 50 g of the upper 5-10 cm apical thalli tips were cut off per species. The surface extraction of Fucus was performed according to the protocol of de Nys and co-workers (1998) with minor modifications (see Rickert et al. 2015). GC/EI-MS measurements were performed with a Waters GCT premier (Waters, Manchester, UK) coupled to an Agilent 6890N GC equipped with a DB-5 ms 30 m column (0.25 mm internal diameter, 0.25 mM film thickness, Agilent, USA). The inlet temperature was maintained at 250°C and samples were injected in split 10 mode. He carrier gas flow was adjusted to 1 ml min-1. Alkanes were used for referencing of retention times. For further details (GC-MS sample preparation and analysis) see the related publication (Rickert et al. submitted to PLOS ONE).

(Table 1) Stable isotope ratios of Globigerinoides ruber and pore water, and Cl measurement at ODP Hole 133-817C

The oxygen isotopic composition of pore waters squeezed from sediments in Hole 817C co-varies with the oxygen isotopic composition of Globigerinoides ruber below 8 mbsf. The magnitude of the variation in the pore water d18O is approximately 30% of the variation in the foraminifers. Overall, the d18O of the pore waters increases down the core, a trend that is also present in the Cl- concentrations. The variations in the d18O of pore waters may be the result of either of two phenomena. First, these may reflect original variations in the waters, the magnitude of which has been subsequently reduced by process of diffusion. Second, these may reflect recrystallization of the precursor sediment and isotopic exchange between the fluids and the recrystallized sediment. At the moment data are not available to ascertain which process is responsible although the correlation between the Cl- and the d18O data suggests that these values reflect the original composition modified by diffusion.

Reconstructions of eolian dust accumulation in northwest African margin sediments

Reconstructions of eolian dust accumulation in northwest African margin sediments provide important continuous records of past changes in atmospheric circulation and aridity in the region. Existing records indicate dramatic changes in North African dust emissions over the last 20 ka, but the limited spatial extent of these records and the lack of high-resolution flux data do not allow us to determine whether changes in dust deposition occurred with similar timing, magnitude and abruptness throughout northwest Africa. Here we present new records from a meridional transect of cores stretching from 31°N to 19°N along the northwest African margin. By combining grain size endmember modeling with 230Th-normalized fluxes for the first time, we are able to document spatial and temporal changes in dust deposition under the North African dust plume throughout the last 20 ka. Our results provide quantitative estimates of the magnitude of dust flux changes associated with Heinrich Stadial 1, the Younger Dryas, and the African Humid Period (AHP; ~11.7-5 ka), offering robust targets for model-based estimates of the climatic and biogeochemical impacts of past changes in North African dust emissions. Our data suggest that dust fluxes between 8 and 6 ka were a factor of ~5 lower than average fluxes during the last 2 ka. Using a simple model to estimate the effects of bioturbation on dust input signals, we find that our data are consistent with abrupt, synchronous changes in dust fluxes in all cores at the beginning and end of the AHP. The mean ages of these transitions are 11.8±0.2 ka (1Sigma) and 4.9±0.2 ka, respectively.

Clay mineralogy of South Atlantic surface sediments

Surface samples, mostly from abyssal sediments of the South Atlantic, from parts of the equatorial Atlantic, and of the Antarctic Ocean, were investigated for clay content and clay mineral composition. Maps of relative clay mineral content were compiled, which improve previous maps by showing more details, especially at high latitudes. Large-scale relations regarding the origin and transport paths of detrital clay are revealed. High smectite concentrations are observed in abyssal regions, primarily derived from southernmost South America and from minor sources in Southwest Africa. Near submarine volcanoes of the Antarctic Ocean (South Sandwich, Bouvet Island) smectite contents exhibit distinct maxima, which is ascribed to the weathering of altered basalts and volcanic glasses. The illite distribution can be subdivided into five major zones including two maxima revealing both South African and Antarctic sources. A particularly high amount of Mg- and Fe-rich illites are observed close to East Antarctica. They are derived from biotite-bearing crystalline rocks and transported to the west by the East Antarctic Coastal Current. Chiorite and well-crystallized dioctaedral illite are typical minerals enriched within the Subantarctic and Polarfrontal-Zone but of minor importance off East Antarctica. Kaolinite dominates the clay mineral assemblage at low latitudes, where the continental source rocks (West Africa, Brazil) are mainly affected by intensive chemical weathering. Surprisingly, a slight increase of kaolinite is observed in the Enderby Basin and near the Filchner-Ronne Ice shelf. The investigated area can be subdivided into ten, large-scale clay facies zones with characteristic possible source regions and transport paths. Clay mineral assemblages of the largest part of the South Atlantic, especially of the western basins are dominated by chlorite and illite derived from the Antarctic Peninsula and southernmost South America and supported by advection within the Circumantarctic Deep Water flow. In contrast, the East Antarctic provinces are relatively small. Assemblages of the eastern basins north of 30°S are strongly influenced by African sources, controlled by weathering regimes on land and by a complex interaction of wind, river and deep ocean transport. The strong gradient in clay mineral composition at the Brazilian slope indicate a relatively low contribution of tropically derived assemblages to the western basins.

Enviromagnetic, major element, and grain-size analyses of surface sediment samples along the continental margin between East Brazil and Patagonia

Continental margin sediments of SE South America originate from various terrestrial sources, each conveying specific magnetic and element signatures. Here, we aim to identify the sources and transport characteristics of shelf and slope sediments deposited between East Brazil and Patagonia (20°-48°S) using enviromagnetic, major element, and grain-size data. A set of five source-indicative parameters (i.e., chi-fd%, ARM/IRM, S0.3T, SIRM/Fe and Fe/K) of 25 surface samples (16-1805 m water depth) was analyzed by fuzzy c-means clustering and non-linear mapping to depict and unmix sediment-province characteristics. This multivariate approach yields three regionally coherent sediment provinces with petrologically and climatically distinct source regions. The southernmost province is entirely restricted to the slope off the Argentinean Pampas and has been identified as relict Andean-sourced sands with coarse unaltered magnetite. The direct transport to the slope was enabled by Rio Colorado and Rio Negro meltwaters during glacial and deglacial phases of low sea level. The adjacent shelf province consists of coastal loessoidal sands (highest hematite and goethite proportions) delivered from the Argentinean Pampas by wave erosion and westerly winds. The northernmost province includes the Plata mudbelt and Rio Grande Cone. It contains tropically weathered clayey silts from the La Plata Drainage Basin with pronounced proportions of fine magnetite, which were distributed up to ~24° S by the Brazilian Coastal Current and admixed to coarser relict sediments of Pampean loessoidal origin. Grain-size analyses of all samples showed that sediment fractionation during transport and deposition had little impact on magnetic and element source characteristics. This study corroborates the high potential of the chosen approach to access sediment origin in regions with contrasting sediment sources, complex transport dynamics, and large grain-size variability.

Looking for Determinants of Ontological Security in the Spain of the Crisis

The concept of ontological security has a remarkable echo in the current sociology to describe emotional status of men of late modernity. However, the concept created by Giddens in the eighties has been little used in empirical research covering various sources of risk or uncertainty. In this paper, a scale for ontological security is proposed. To do this, we start from the results of a research focused on the relationship between risk, uncertainty and vulnerability in the context of the economic crisis in Spain. These results were produced through nine focus groups and a telephone survey with standardized questionnaire applied to a national sample of 2,408 individuals over 18 years. This work is divided into three main sections. In the fi rst, a scale has been built from the results of the application of different items present in the questionnaire used. The second part explores the relationships of the scale obtained with the variables further approximate the emotional dimensions of individuals. The third part observes the variables that contribute to changes in the scale: These variables show the structural feature of the ontological security.

Maria de Fátima Sousa Silva, Ensaios sobre Eurípides, Lisboa, Livros Cotovia, 2005, 404 pp. [ISBN 972-795-133-3]

Resumo indisponível.

La jerarquía normativa en la interpretación del artículo 133 de la Constitución Política de los Estados Unidos Mexicanos

La perspectiva constitucional sobre la jerarquía normativa de las fuentes de derecho en el sistema jurídico mexicano, ha suscitado muy interesantes y variadas controversias que han llegado hasta la emisión de criterios, tanto jurisprudenciales como no jurisprudenciales, por la Suprema Corte de Justicia de la Nación. En correspondencia con ello y la necesidad que en la academia existe para aclarar a los estudiantes de derecho, de qué manera puede interpretarse la disposición constitucional que por excelencia refiere dicha temática, se presenta una propuesta de exégesis del Artículo 133 de la Constitución Política de los Estados Unidos Mexicanos, a la luz de una investigación cualitativa sustentada explícitamente en una epistemología orientada a producir conocimiento basada en la coherencia paradigmática de las posturas existentes en el ámbito del principio de supremacía constitucional y la jerarquización normativa y en la inteligencia de que no se pretende establecer reglas fijas e inmutables, sino por el contrario, se trata de una construcción donde las ideas, conjeturas, puntos de vista y reflexiones estén en constante y estrecha relación con el contexto y con los contenidos de la producción teórica sobre el tema.