Epoch, organic carbon and compounds at DSDP Holes 93-605 and 95-613

Twenty-four sediment samples from DSDP Holes 605 (Leg 93) and 613 (Leg 95) on the New Jersey continental rise were analyzed by pyrolysis-gas chromatography. Twelve of these samples were also analyzed by pyrolysis-gas chromatography/mass spectrometry. The degree of preservation of sediment organic matter, as determined by these techniques, helped to distinguish slumped sediments from sediments that have not moved from their original place of deposition. Total levels of pyrolyzable organic material, as determined from pyrolysis-gas chromatography, were low in sediments that were not slumped, indicating that the organic material is highly degraded. Nitrogen- and oxygen-containing compounds were the primary compounds detected by gas chromatography/mass spectrometry (GCMS) analysis of the pyrolyzate of non-slumped sediments. Smaller amounts of aromatic compounds and branched alkanes were also present in some of these samples. In contrast, slumped sediments showed larger amounts of pyrolyzable organic matter, as determined from pyrolysis-gas chromatography, and better preservation of alkyl chains in the sediment organic matter, as suggested by the presence of n-alkanes in GCMS analysis of the pyrolyzate. Better preservation of the organic matter in slumped sediments can be attributed to more moderate bioturbation by bottom-dwelling organisms at the original deposition site.

Hyperspectral downwelling irradiance during POLARSTERN cruise ANT-XXVI/1

A Monte Carlo based radiative transfer model has been developed for calculating the availability of solar radiation within the top 100 m of the ocean. The model is optimized for simulations of spatial high resolution downwelling irradiance Ed fluctuations that arise from the lensing effect of waves at the water surface. In a first step the accuracy of simulation results has been verified by measurements of the oceanic underwater light field and through intercomparison with an established radiative transfer model. Secondly the potential depth-impact of nonlinear shaped single waves, from capillary to swell waves, is assessed by considering the most favorable conditions for light focusing, i.e. monochromatic light at 490 nm, very clear oceanic water with a low chlorophyll a content of 0.1 mg/m**3 and high sun elevation. Finally light fields below irregular wave profiles accounting for realistic sea states were simulated. Our simulation results suggest that under open ocean conditions light flashes with 50% irradiance enhancements can appear down to 35 m depth, and light variability in the range of ±10% compared to the mean Ed is still possible in 100 m depth.

Quaternary benthic foraminifers from DSDP Sites 95-612 and 95-613

The Quaternary benthic foraminifers from Leg 95 Sites 612 and 613 were examined with respect to paleoceanographic trends. Data from the two sites indicate the presence of markedly different bottom-water masses, during both glacial and interglacial periods. The dominant interglacial species at Site 612 is Uvigerinct peregrina, which is barely present in corresponding intervals at Site 613. Dominant glacial species are Elphidium excavatum and Cassidulina reniforme at Site 612 and Epistominella takayanagii at Site 613.