Depositional Age of a Fossil Whale Bone from São Paulo Ridge,South Atlantic Ocean,Based on Os Isotope Stratigraphy of a Ferromanganese Crust

Whale carcasses (whale falls) deposited on the deep seafloor are associated with a distinctive biotic community. A fossil whale bone recovered from São Paulo Ridge, South Atlantic Ocean, during cruise YK13–04 Leg 1 of R/V Yokosuka was covered by a ferromanganese (Fe–Mn) crust approximately 9 mm thick. Here, we report an age constraint for this fossil bone on the basis of Os isotopic stratigraphy (¹⁸⁷Os/¹⁸⁸Os ratio) of the Fe–Mn crust. Major‐ and trace‐element compositions of the crust are similar to those of Fe–Mn crusts of predominantly hydrogenous origin. Rare earth element concentrations in samples of the crust, normalized with respect to Post‐Archean average Australian Shale, exhibit flat patterns with positive Ce and negative Y anomalies. These results indicate that the Fe–Mn crust consists predominantly of hydrogenous components and that it preserves the Os isotope composition of seawater at the time of its deposition. ¹⁸⁷Os/¹⁸⁸Os ratios of three Fe–Mn crust samples increased from 0.904 to 1.068 in ascending stratigraphic order. The value of 1.068 from the surface slice (0–3 mm depth in the crust) was identical to that of present‐day seawater within error (~1.06). The value of 0.904 from the basal slice (6–9 mm) equaled seawater values from ca. 4–5 Ma. Because it is unknown how long the bone lay on the seafloor before the Fe–Mn crust was deposited, the Os stratigraphic age of ca. 5 Ma is a minimum age of the fossil. This is the first application, to our knowledge, of marine Os isotope stratigraphy for determining the age of a fossil whale bone. Such data may offer valuable insights into the evolution of the whale‐fall biotic community.     

Theoretical Studies of the Parameterization of the Non-Neutral Surface Boundary Layer

The parameterization of the non-neutral atmospheric surface layer has been reexamined using the basic principles of small-scale energetics and thermodynamics. On the basis of this more complete treatment, the K- parameterization has been reformulated. It is found that the linear regression laws between fluxes and driving gradient forces of the turbulent heat and humidity exchanges in the surface layer can be derived in a much more comprehensive manner than by using the commonly used K-theory. With respect to stationary conditions and in the context of similarity concepts, a system of algebraic equations has been formulated which provides reasonable estimates of the distributions of the dimension-less rates of viscous energy dissipation as well as turbulent kinetic and thermal-diffusive energy transport as functions of the variable z/L. Quantitative calculations have been performed using the scaling height formulations of Takeuchi and Yokoyama, Prandtl, and von Kármán as closure conditions of the equations.     

Wechselwirkungsreaktionen Untertagedeponie-relevanter chemisch-toxischer Abfälle mit hochsalinaren Lösungen

The complex reactions between high saline solutions and toxic chemical wastes were investigated by means of laboratory experiments and geochemical modelling. The specific boundary conditions of an underground repository in salt formations were taken into account. In order to determine the chemical equilibrium compositions of the resulting solutions a new leaching procedure was developed and successfully employed with several toxic wastes. The results for a fly ash waste stemming from a glass smelting furnace are given in detail. Zinc and cadmium are the two most prominent heavy metals, that accumulate significantly in the leachates. In order to gain an insight into the complex dissolution and precipitation processes in such multi-component systems, geochemical modelling was performed using the program code EQ3/6 and the Pitzer formalism for calculating the activity coefficients. The thermodynamic database used was extended and Pitzer coefficients for Zn and Cd in high saline solutions were derived from literature data and added to the database. The results of the geochemical modelling of the investigated reactions were in good agreement with the experimental data. On this basis the maximum concentrations that can be leached from the investigated fly ash into a Mg-rich saline solution, that is typical for a salt repository in Northern Germany, are predicted to be 0,181 mol/kg H₂O zinc and 0,00317 mol/kg H₂O cadmium, respectively.