Eutrophication of a partially enclosed estuarine mudflat

Some 130 years ago, a small estuary to the north of Dublin was partly cut off from the sea by a railway causeway. The mudflats that formed became an important feeding ground for wildfowl. In recent years the estuary has become subject to increasing organic pollution. Algal growth has increased and while the situation is not yet damaging to wildfowl, there is evidence that further increase in nutrients would cause undesirable extension of algal mats in the estuary.     

Spatial systems and structures. A model and a case studyRäumliche systeme und strukturen. Ein Modell und ein BeispielStructures et systèmes spatiaux. Un modèle et une application

World space appears to be divided into unequally stable wholes which we see as being structures produced by the combined action of natural systems, spatial gradients and open energetic systems. The latter are based on the inter play of population, information, resources and capital, acting through the means of production, and in interaction with the social structures which are reproduced by the system and in turn reproduce it — until they become inconsistent with it: these successive reproductions are factors of change.This model is applied, as an example, to Champagne (France).     

Parameterization of hemispheric heating and temperature variance fields in the lower troposphere

Summary Indirect observational estimates are obtained of the covariance of diabatic heating and temperature at 850 mb, and of the implied value of the Newtonian cooling coefficient, for winter and summer mean conditions over the Northern Hemisphere. Combining the Newtonian approximation for heating and the Austausch approximation for the horizontal transient eddy heat transport we obtain a simple formula for the variance of the temperature at 850 mb in terms of the climatological mean temperature field at that level. Hemispheric fields computed from this formula seem to be an acceptable first approximation to the observations     

The effect of prolonged X-ray irradiation on lithium tetraborate glass discs as used in X.R.F. analyses

Prolonged irradiation by X-rays of lithium tetraborate glass discs causes significant changes in countrates for certain elements e.g. Na and Mg decrease while Al, Si and P increase. This effect is probably due to surface diffusion in the glass as grinding away about 10 μm of the surface of the disc restores the countrates to their original levels. Although no change in countrates will ever be noticed on individual glass discs undergoing routine analyses, where irradiation time is only a minute or so, a close watch must be kept on any specimens that have been irradiated for more than a few tens of hours.     

Long-term changes in the rotation rate of the Earth

In the last decade, major advances in both observational and theoretical fields have taken place in our understanding of the rotation of the Earth. With the adoption of Atomic Time, the rotation rate can now be measured with unprecedented precision and independently of planetary or lunar motions. Information from earlier observations is also being recovered more accurately: independent analyses and new data from ancient eclipse observations have increased confidence in the controversial results obtained earlier. Perhaps the most outstanding development is the tentative measurement of the mean rotation rate in the remote geological past, made possible by the study of periodicities in the skeletal growth of fossil organisms.The improved data have exposed new geophysical problems and accentuated earlier ones. An unexplained acceleration of the Earth's rotation is confirmed by the re-examination of ancient eclipse records. In addition, Darwin's theory of tidal friction now has the arbitrariness of its time-scale replaced by data from modern astronomical observations so that, in spite of various theoretical refinements, it leads to the unacceptable prediction of a catastrophic period in the history of the Earth-Moon system in the mid-Precambrian. Information from the study of fossil growth increments can make a vital contribution in both these problems.The palaeontological data have been gathered mainly from corals and bivalves, although several other groups with accretionary skeletons provide a few figures and are potentially useful. The unexpected cosmogonic applications of these data have stimulated research into the physiological and particularly the ecological factors controlling incremental growth in these organisms, especially the bivalves. The main problems centre on the recording accuracy and the definition of the growth increments. The difficulty of eliminating irregular interference and of recovering geophysically useful measurements from the fossil record is discussed and we have tried to assess the reliability of the information already derived from this source.     

Topography and evolution of the East Pacific Rise between 5°S and 20°S

In the absence of convincing magnetic anomaly information, topographic profiles have been used to infer the tectonic history of the East Pacific Rise between 5°S and 20°S. Profiles projected at right angles to the rise crest show a sharp drop in elevation at roughly the same distance on either side of the crest. Profiles to the east of the rise also show a second topographic high at 95°W. Comparison of these profiles with empirical depth versus age curves for the North Pacific suggests that this rise, the Galapagos Rise, is the fossil East Pacific Rise which terminated close to 6 mybp by the spreading center jumping 900 km to the west. The extreme youthfulness of the present East Pacific Rise, the step structure of its flanks, and the similarity in age of the top of this step and the crest of the Galapagos Rise substantiate this interpretation. This jump coincided with a similar readjustment involving the Mathematicians ridge at 5° to 20°N and the opening of the Gulf of California.