Sediment metabolism in samples off Northwest Africa

Sediments off northwest Africa were assayed for activities of the respiratory electron transport system (ETS) and for primary amino nitrogen. ETS activities were used to compute respiratory oxygen consuption, carbon oxidation, and nitrate reduction rates. Activities were correlated with depth of the water column, and their longshore distribution resembled that of euphotic zone phytoplankton productivity. Protein concentrations were closely correlated with ETS activities. Carbon biomass was calculated from protein and compared with other computed values. The carbon oxidation rate accounted for 13 % of the region's primary production.

(Tables 1-15) Morphometric characteristics of the genus Hinia (Nassariidae, Gastropoda) in the Tertiary of northwest Germany

The genus Hinia is divided in 4 subgenera; other subgenera are not represented in the area studied. It was possible to find criteria for a better discrimination of the highly variable species H. (Hinia) schlotheimi and H. (Hinia) turbinella. The species "fuchsi" has been placed in the synonymy of H. (Hinia) turbinella. The species H. (Hinia) schlotheimi (BEYRICH) and H. (Telasco) schroederi (KAUTSKY) have been united under the name H. (Hinia) schlotheimi. The easily distinguishable species H. (Tritonella) tenuistriata and H. (Hinia) sulcata belong to two different genera. H. (Tritonella) cimbrica andersoni of the Viol- and Katzheide-Beds (Reinbek-stage) is separable from the population found in the Hemmoor-stage, it turned out to be a valuable guide subspecies for the Reinbek-stage. The species H. (Tritonella) serraticosta, H. (Tritonella) catulli, H. (Hinia) holsatica, and H. (Telasco) syltensis are all similar in respect to shape and ornamentation. Criteria have been found for a better discrimination of these species. The species contabulata, effusa and seminodifera described by SPEYER (1864), turned out to be contogenetic stages of H. (Tritonella) pygmaea. H. (Tritonella) cavata, previously described from the Tertiary of the North sea area, was proven to be absent from the area investigated. The forms described under that name, belong to H. (Tritonella) woodwardi.

Structural group composition of low-polarity organic matter dissolved in waters of the Northwest Indian Ocean and the Red Sea

Data on amounts of various functional groups, i.e. aldehyde, acid, ester, alcohol, thiol and aromatic groups in several fractions of low-polarity dissolved organic matter are presented. An assumption that this organic matter is part of the lipid fraction is not confirmed. Amount of aromatic compounds in waters of the Northwest Indian Ocean is estimated to be about 1000 times higher than quantity of aromatic hydrocarbons discharged into the ocean each year in petroleum and petroleum products.

Benthic foraminiferal fauna and isotope record in Holocene sediments of the northwest Indian Ocean

Historically, the Holocene has been considered an interval of relatively stable climate. However, recent studies from the northern Arabian Sea (Netherlands Indian Ocean Program 905) suggested high-amplitude climate shifts in the early and middle Holocene based on faunal and benthic isotopic proxy records. We examined benthic foraminiferal faunal and stable isotopic data from Ocean Drilling Program (ODP) Site 723 and total organic carbon data from ODP Site 724, Oman Margin (808 and 593 m water depths, respectively). At Site 723 the mid-Holocene shift in d18O values of infaunal benthic species Uvigerina peregrina (1.4 per mil) is 3 times larger than that of epifaunal benthic species Cibicides kullenbergi recorded at Site NIOP 905 off Somalia. However, none of the five other benthic species we measured at Hole 723A exhibits such a shift in d18O. We speculate that the late Holocene d18O decrease in U. peregrina represents species-specific changes in ecological habitat or food preference in response to changes in surface and deep ocean circulation. While the stable isotopic data do not appear to indicate a middle Holocene climatic shift, our total organic carbon and benthic faunal assemblage data do indicate that the early Holocene deep Arabian Sea was influenced by increased ventilation perhaps by North Atlantic Deep Water and/or Circumpolar Deep Water incursions into the Indian Ocean, leading to remineralization of organic matter and a relatively weak early Holocene oxygen minimum zone in the northwest Arabian Sea in spite of strong summer monsoon circulation.

Major and rare earth element composition of ODP Site 191-1179 sediments, northwest Pacific

Depth profiles of major element and rare earth element (REE) abundances in sediment samples (mainly siliceous ooze and clay) recovered from Holes 1179B and 1179C at Site 1179, Ocean Drilling Program Leg 191 (41.4°N, 159.6°E) were determined. The oxidation states of Mn and Ce were determined by X-ray absorption near-edge structure. Some geochemical indicators were tested, including the MnO/TiO2 ratios, a bivariate diagram of La/Ce vs. Al2O3/(Al2O3+Fe2O3), and other discrimination diagrams. The oxidation state of Mn is reduced Mn(II) in the depth profile below 0.60 meters below seafloor (mbsf), which is consistent with relatively low and high abundances of Mn in the sediments and pore waters, respectively. It is possible that the diagenetic effect on the oxidation state and abundance of Mn makes it difficult for the MnO/TiO2 ratio to reflect the depositional environment. The normalized ratio of La and Ce does not change very much with depth, suggesting that the diagenetic effect does not affect the REE signature in the sediments. On the diagram of La/Ce vs. Al2O3/(Al2O3+Fe2O3), the sediments studied here plot at the boundary of the pelagic and continental margin fields. This suggests that continental material has contributed to the sediment to some degree, even though Site 1179 is in a pelagic region of the northwestern Pacific Ocean, >1600 km from Japan.

Documentation of manganese nodules form the northwest Indian Ocean

Microscopic and electron probe examination of some manganese nodules show that they consist of segregations of manganese-iron oxides in an interstitial material almost free of manganese but rich in iron and silicates. The segregations are widely spaced in the volcanic cores of the nodules but become more abundant towards their outer crusts where they form the centres of linked polygons of interstitial materials. Most of the minor elements are concentrated in the segregations compared to the interstitial materials. It is suggested that the structures observed result partly from solution and reprecipitation of elements in the original volcanic cores of the nodules and partly from the replacement and coating of these cores by manganese-iron oxides precipitated from sea water.