656 resultados para 181-1124
Resumo:
Stable isotope records were generated for a late Pliocene-early Pleistocene interval from Ocean Drilling Program (ODP) Site 1123 in the southwest Pacific (41°47 S, 171°30 W; 3290 m water depth). Based on these data, new revisions were made to the shipboard splice and composite section. The isotope records will be used to evaluate the influence of North Atlantic and Southern Ocean deepwater masses on water entering the Pacific in the Deep Western Boundary Current. Three holes were cored at Site 1123, yielding a complete composite section over approximately the last 4.7 m.y. A representative spliced record ("the splice") was developed aboard ship based on magnetic susceptibility, gamma ray attenuation bulk density, and percent reflectance data from the three adjacent holes (Carter, McCave, Richter, Carter, et al., 1999, doi:10.2973/odp.proc.ir.181.2000). No gaps in the sedimentary record were detected for the multiple-cored section of Site 1123. In addition to the isotope data, postcruise revisions to the splice and composite section based on stable isotope data are described here.
Resumo:
Approaches to quantify the organic carbon accumulation on a global scale generally do not consider the small-scale variability of sedimentary and oceanographic boundary conditions along continental margins. In this study, we present a new approach to regionalize the total organic carbon (TOC) content in surface sediments (<5 cm sediment depth). It is based on a compilation of more than 5500 single measurements from various sources. Global TOC distribution was determined by the application of a combined qualitative and quantitative-geostatistical method. Overall, 33 benthic TOC-based provinces were defined and used to process the global distribution pattern of the TOC content in surface sediments in a 1°x1° grid resolution. Regional dependencies of data points within each single province are expressed by modeled semi-variograms. Measured and estimated TOC values show good correlation, emphasizing the reasonable applicability of the method. The accumulation of organic carbon in marine surface sediments is a key parameter in the control of mineralization processes and the material exchange between the sediment and the ocean water. Our approach will help to improve global budgets of nutrient and carbon cycles.
Resumo:
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).