NOPR Collection:

Parent-Daughter equilibria in ocean arising out of disposal of solid radioactive wastes on the sea bed

Sat, 01 Mar 1986 00:00:00 GMT

Title: Parent-Daughter equilibria in ocean arising out of disposal of solid radioactive wastes on the sea bed Authors: Sarma, T P; Krishnamoorthy, T M Abstract: One dimension diffusion model, incorporating geochemical elimination and reflection at ocean boundaries, is employed to show the differences in spatial and temporal distribution of parent and daughter radionuclides, produced in situ, due to the discharge of solid radioactive wastes on to the sea bed. Concentration of daughter is generally lower than that of parent in deep waters. Short-lived daughters (relative to parent) reach spatial equilibrium with parent for finite periods whereas long-lived daughters attain only a fraction of the parent activity. However, when the dumping operation is assumed to be for infinite period, the relative ratio of concentration of daughter to parent would reach value 1 in surface waters irrespective of the halflives of the daughter and the magnitude of this ratio increases with increase in half-life of the daughter relative to the parent. This is the result of steep vertical gradient for the parent due to the small physical half-life and more or less uniform concentration of long-lived daughter. Geochemical elimination rate, when becomes significant in the overall removal processes, controls this differential spatial gradient of daughter and parent. However, the integrated activity of daughter over the entire depth is equal to or less than the parent activity. Page(s): 1-7

Numerical model for wind-driven circulation in the Bay of Bengal

Sat, 01 Mar 1986 00:00:00 GMT

Title: Numerical model for wind-driven circulation in the Bay of Bengal Authors: Bahulayan, N; Varadachari, V V R Abstract: Wind-driven circulation in the Bay of Bengal, generated by a southwest wind of constant speed (10 m.sec^-1) and direction (225ᵒTN), is presented. A non-linear hydrodynamic model is used for the simulation of circulation. Numerical experiments have shown that when a uniform wind stress in suddenly imposed over the sea surface, a steady circulation is generated after 50 h of numerical integration of model equations. The sensitivity of this model to bathymetry and coastal configuration is also discussed. The study shows that maximum current speed is observed near the coastal region as anticipated and it generally tends to follow the idealised bottom contours. Page(s): 8-12

Geochemistry of Ferromanganese Nodules from Different Areas in North Equatorial Pacific

Sat, 01 Mar 1986 00:00:00 GMT

Title: Geochemistry of Ferromanganese Nodules from Different Areas in North Equatorial Pacific Authors: Rajamanickam, G V; Roonwal, G S; Friedrich, G H Abstract: Among the analysed manganese nodules from VA-05/1, VA-08/1 and VA-13/2 areas, interelemental relationships, regardless of topography and morphology indicate a close alfmity among Mn, Ni, Cu, Cd and Zn distribution. Unlike the earlier reports, Co behaves sympathetically with both Mn and Fe. P follows Al rather than Ca. Ca stands independently. Hg does not show any association with the analysed elements whereas Cd is harmonic with Mn, As with Fe and Zn. VA-13/2 area samples show large variation in the metal values. Wider difference in Mn/Fe ratio of nodules from VA-13/2 area, compared to the nodules from other areas in the region is attributed to the observed topographic variability and the differences in the morphology of the nodules. The distinct contrasting relationship of Mn and its associates with Ca, Al and P suggest the clear divergence in the mode of incorporation as authigenic and lithogenic components. Higher concentrations of Hg, As and Cd and their relationships with other elements suggest the probability of their supply from many sources. The overall geochemical behaviour of these nodules suggests the domination of hydrogenous origin over the early diagenetic process. Page(s): 13-19

Geochemical studies of clays from red sediments of Visakhapatnam coast, east coast of India

Sat, 01 Mar 1986 00:00:00 GMT

Title: Geochemical studies of clays from red sediments of Visakhapatnam coast, east coast of India Authors: Rao, A T; Raman, C V Abstract: Red sediments, characterised by badland like topography, found along the Visakhapatnam - Bhimunipatnam coast and associated with khondalite hill ranges comprise 60-70% (quartz + heavies), 20% silt and 10% ferruginous clay. Kaolinite and illite proportions are dominant in the clays of the red sediments and compare fairly with the clays from the offshore region. The similar concentration of elements - K, Fe, Ti, Cr,Co, Ba, Sr and Pb - supports the clay input from the red sediments into the shelf region, Ti, V, Mn, Cr with Fe and Sr, Ba, Pb with K show positive relationship, which reflects alteration of detrital magnetite and ilmenite and orthoclase in the source rocks. Page(s): 20-23