A NEW MODEL FOR PEBBLE BEACH TRACER DISPERSAL

A series of eight tracer experiments were carried out over one year (1983) on a low energy, macro-tidal beach in South Wales, UK. Tracer movement was monitored and 30 pebbles adjacent to coloured tracer pebbles were measured. Measurements were of the A, B, and C axes, roundness, Maximum Projection Sphericity and Oblate-Prolate indices. Analysis shows that through time, the percentage rejection of these properties increased. It is theorised that the surface tracers are 'misfits' or 'rejects' which have not found their equilibrium position in the pebble facies.     

Subaerially exposed Late-Quaternary basinal shelf of the inner Mersin Bay,Eastern Mediterranean: Paleoenvironmental evidence

High-resolution seismic profiles and petrographic data from surface and subsurface sediment samples from Mersin Bay, together with lithologic data from boreholes, were used to determine the origin and distribution of the pre- or early-Holocene unconformities in Mersin Bay (eastern Mediterranean). Reflectors corresponding to unconformities separate the younger, unconsolidated, marine transgressive sediments (Holocene) from the underlying, relatively coarser, consolidated sediments (Plio-Pleistocene). These unconformities correspond mainly to the erosional and subaerially deposited or later subaerially weathered land surfaces. These unconformities are probably related to the latest Pleistocene or earliest Holocene sea-level low stands.     

The effect of copper pollution on mitochondrial degeneration

The authors describe the effect of copper pollution on the mitochondria from various areas of the Torpedo marmorata central nervous system. A high percentage of swollen mitochondria has been observed in neurons from animals experimentally exposed to high level of copper (4 ppm). The correlation with age pigment granules is discussed.     

An improved specific interaction model for seawater at 25°C and 1 atmosphere total pressure

Equations recently developed by Pitzer are applied to a seawater model on the assumption that only interactions between ions of opposite charge sign are significant. This model is shown to give good agreement with available experimental data for the osmotic coefficient and for the mean-ion activity coefficients of the major electrolyte components. The results are compared with the predictions of the ion-association model and with a number of models using the concept of specific ionic interaction. The relative merits of the various models are discussed. Pitzer's original equations are modified to enable the calculation of conventional single-ion activity coefficients. These values are compared with those obtained on the basis of alternative conventions and an encouraging measure of agreement is observed. It is concluded that the new model introduces a fluency into the specific interaction approach that should greatly facilitate the incorporation of trace components into future models.