ALBERT

Notes: SUMMARYA comparison is made between the void ratio and pressure relationships resulting from a laboratory consolidation test and a sedimentation-compression computation on a short core of calcareous mud or ooze of low plasticity. Geo-technical measurements of grain size, bulk density, Atterberg limits, water content, vane shear strength, pore-water salinity, and carbonate content are graphically related to depth in the core. Results of the laboratory consolidation test on this material differ markedly from the in-place relationship between void ratio, or water content, and the effective overburden pressure, or burial depth, shown by the sedimentation-compression curve. The previous maximum consolidation pressure, based on laboratory consolidation test data, is about 60 times greater than the computed in-place effective overburden pressure. An explanation for this difference would include the different magnitudes of time available for consolidation, cementation occurring in-place, and orientation of the constituents. It is suggested that results of the consolidation test on carbonate muds or oozes should be interpreted with caution for geological and engineering purposes.

Notes: Uranium occurs in corals at three sites: 1, in organic matter; 2, adsorbed on the surfaces of skeletal aragonite; and 3, in the aragonite lattice. Organic matter incorporates from sea water by chelation 40–70 ppm uranium; skeletal aragonite incorporates only 3 ppm. However, as the organic fraction is low (0·1%), its high concentration of uranium does not significantly affect the total concentration of uranium in the coral. A negligible concentration of uranium, 40–60 ppb, is adsorbed on skeletal aragonite from which it is readily leached or exchanged. This low concentration of adsorbed uranium (〈2% of the total uranium in skeletal aragonite) is related to the very small specific surface area (1·5–1·8 m2/g of the corals.

Notes: The objective of this study is to locate as closely as possible the sites of strontium, magnesium, sodium, and potassium in modern aragonitic corals, specifically whether these cations are adsorbed, or are substituted in the carbonate lattice or are incorporated in organic components. In addition to locating the sites of each of these four elements we wanted to find out quantitatively how much of each element occurs at each site. The experiments in this study are based on the dissolution rate of aragonite in distilled water and on the substitution of strontium and magnesium by calcium and sodium. Special attention has been given to the occurrence of strontium, magnesium, sodium, and potassium in the organic components of the corals.The main site for strontium in the corals is in the aragonite lattice. Twenty-five per cent of the total magnesium occurs in adsorbed sites and in organic compounds. The rest of the magnesium may be located in the aragonite lattice, but it is easily removed by repeated leaching or by replacement with calcium ions. Another possibility is that magnesium may occur in a dispersed mineral phase more soluble than aragonite because magnesium was released at a higher Mg to Ca ratio than is found in the solid coral; also because no local concentration of magnesium could be detected with an electron microprobe. About 12% of the total sodium is in adsorbed sites and is included in the organic compounds. The rest of the sodium might be in the lattice replacing calcium, but the low total exchange capacity is not enough to provide the needed charge balance. Another possibility is that sodium is located in a proposed mineral phase. Potassium is in adsorbed sites and incorporated in the organic compounds to an extent greater than all the other elements studied (30% of the total potassium), but again the evidence suggests that the remaining potassium is in a proposed mineral phase.Calcite is detected on the surfaces of aragonite corals after 5 months in the substitution experiment. The change of argonite to calcite took place after the inhibitor magnesium was exchanged from the surface sites and replaced by calcium.The organic compounds in corals contain small amounts of strontium, magnesium, sodium and potassium. Strontium is preferentially enriched in the organic compounds over magnesium.

Notes: SYNOPSIS. Paramecia immobilized on an agar surface were stimulated with pulses of 2–8 mamps/cm2 with intervals ranging from 1.0 to 1000 msec. High speed cine films (1500-6000 frames per second) of the animals' responses were analyzed to determine changes in body length and the effects on cilia and trichocysts. At current densities in the range of 1.0 mamp/cm2, rapid ciliary reversal occurred. Above this value the paramecia shortened. This body contraction can be very rapid, resulting in shortening to 95% of the body length in 0.95 msec. At all levels of stimulation, contraction of the body length occurred 1st anodally, then cathodally. Extensive trichocyst extrusion occurred 1st at the anode and later at the cathode at current densities greater than 5 mamp/cm2 in the agar. Results of this study indicate that the protoplasm of paramecia is capable of very fast contraction in response to electric stimulation and that the initial response is always anodal.