ALBERT

Beschreibung / Inhaltsverzeichnis: Starting from a more general discussion of mechanisms controlling organic carbon deposition in marine environments and indicators useful for paleoenvironmental reconstructions, this study concentrates on detailed organic-geochemical and sedimentological investigations of late Cenozoic deep-sea sediments from (1) the Baffin Bay and the Labrador Sea (ODP-Leg 105), (2) the upwelling area off Northwest Africa (ODP-Leg 108), and (3) the Sea of Japan (ODP-Leg 128). Of major interest are shortas well as long-term changes in organic carbon accumulation during the past 20 m.y. As shown in the data from ODP-Legs 105, 108, and 128, sediments characterized by similar high organic carbon contents can be deposited in very different environments. Thus, simple total organic carbon data do not allow (i) to distinguish between different factors controlling organic carbon enrichment and (ii) to reconstruct the depositional history of these sediments. Data on both quantity and composition of the organic matter, however, provide important informations about the depositional environment and allow detailed reconstructions of the evolution of paleoclimate, paleoceanic circulation, and paleoproductivity in these areas. The results have significant implications for quantitative models of the mechanisms of climatic change. Furthermore, the data may also help to explain the formation of fossil black shales, i.e., hydrocarbon source rocks. (1) BAFFIN BAY AND LABRADOR SEA The Miocene to Quaternary sediments at Baffin Bay Site 645 are characterized by relatively high organic carbon contents, most of which range from 0.5% to almost 3%. This organic carbon enrichment was mainly controlled by increased supply .of terrigenous organic matter throughout the entire time interval. Two distinct maxima were identified: (i) a middle Miocene maximum, possibly reflecting a dense vegetation cover and fluvial sediment supply from adjacent islands, that decreased during late Miocene and early Pliocene time because of expansion of tundra vegetation due to global climatic deterioration; (ii) a late Pliocene-Pleistocene maximum possibly caused by glacial erosion and meltwater outwash. Significant amounts of marine organic carbon were accumulated in western Baffin Bay during middle Miocene time, indicating higher surface-water productivity (up to about 150 gC m -2 y-l) resulted from the inflow of cold and nutrient-rich Arctic water masses. The decrease in average surface-water productivity to values similar to those of the modern Baffin Bay was recorded during the late Miocene and was probably caused by the development of a seasonal sea-ice cover. At Labrador Sea Sites 646 and 647, organic carbon contents are low varying between 0.10% and 0.75%; the origin of most of the organic matter probably is marine. A major increase in organic carbon accumulation at Site 646 at about 7.2 Ma may indicate increased surface-water productivity triggered by the onset of the cold East-Greeniand Current system. Near 2.4 Ma, i.e., parallel to the development of major Northern Hemisphere Glaciation, accumulation rates of both organic carbon and biogenic opal decreased, suggesting a reduced surface-water productivity because of the development of dosed seasonal sea-ice cover in the northern Labrador Sea. The influence of varying sea-ice cover on surface-water productivity is also documented in the short-term glacial/interglacial fluctuations in organic carbon deposition at Sites 646 and 647. (2) UPWELLING AREAS OFF NORTHWEST AFRICA The upper Pliocene-Quaternary sediments at coastal-upwelling Site 658 are characterized by high organic carbon contents of 4%; the organic matter is a mixture of marine and terrigenous material with a dominance of the marine proportion. The upper Miocene to Quaternary pelagic sediments from close-by non-upwelling Sites 657 and 659, on the other hand, display low organic carbon values of less than 0.5%. Only in turbidites and slumps occasionally intercalated at the latter two sites, high organic carbon values of up to 3% occur. The high accumulation rates of marine organic carbon recorded at Site 658 reflect the high-productivity upwelling environment. Paleoproductivity varies between 100 and 400 gC m "2 y-1 during the past 3.6 m.y. and is clearly triggered by changes in global climate. However, there is no simple relationship between climate and organic carbon supply, i.e., it is not possble to postulate that productivity was generally higher at Site 658 during glacials than during interglacials or vice versa. Changes in the relative importance between upwelling activity (which was increased during glacial intervals) and fluvial nutrient supply (which was increased during interglacial intervals) may have caused the complex productivity record at Site 658. Most of the maximum productivity values, for example, were recorded at peak interglacials and at terminations indicating the importance of local fluvial nutrient supply at Site 658. Near 0.5 Ma, a long-term decrease in paleoproductivity occurs, probably indicating a decrease in fluvial nutrient supply and/or a change in nutrient "content of the upwelled waters. The former explanation is supported by the contemporaneous decrease in terrigenous organic carbon and (river-borne) clay supply suggesting an increase in long-term aridity in the Central Sahara. At Site 660, underneath the Northern Equatorial Divergence Zone, (marine) organic carbon values of up to 1.5% were recorded in upper Pliocene-Quaternary sediments. During the last 2.5 Ma, the glacial sediments are carbonate-lean and enriched in organic carbon probably caused by the influence of a carbonate-dissolving and oxygen-poor deep-water mass. (3) SEA OF JAPAN Based on preliminary results of organic-geochemical investigations, the Miocene to Quaternary sediments from ODP-Sites 798 (Oki Ridge) and 799 (Kita-Yamato-Trough) are characterized by high organic carbon contents of up to 6%; the organic matter is a mixture between marine and terrigenous material. Dominant mechanisms controlling (marine) organic carbon enrichments are probably high-surface water productivity and increased preservations rates under anoxic deep-water conditions. In the lower Pliocene sediments at Site 798 and the Miocene to Quaternary sediments at Site 799, rapid burial of organic carbon in turbidites may have occurred episodically. Distinct cycles of dark laminated sediments with organic carbon values of more than 5% and light bioturbated to homogenous sediments with lower organic carbon contents indicate dramatic shortterm paleoceanographic variations. More detailed records of accumulation rates of marine and terrigenous organic carbon and biogenic opal as well as a detailed oxygen isotope stratigraphy are required for a more precise reconstruction of the environmental history of the Sea of Japan through late Cenozoic time.

Beschreibung / Inhaltsverzeichnis: PREFACE There are problems, when applying statistical inference to the analysis of data, which are not readily solved by the inferential methods of the standard statistical techniques. One example is the computation of confidence intervals for variance components or for functions of variance components. Another example is the statistical inference on the random parameters of the mixed model of the standard statistical techniques or the inference on parameters of nonlinear models. Bayesian analysis gives answers to these problems. The advantage of the Bayesian approach is its conceptual simplicity. It is based on Bayes' theorem only. In general, the posterior distribution for the unknown parameters following from Bayes' theorem can be readily written down. The statistical inference is then solved by this distribution. Often the posterior distribution cannot be integrated analytically. However, this is not a serious drawback, since efficient methods exist for the numerical integration. The results of the standard statistical techniques concerning the linear models can also be derived by the Bayesian inference. These techniques may therefore be considered as special cases of the Bayesian analysis. Thus, the Bayesian inference is more general. Linear models and models closely related to linear models will be assumed for the analysis of the observations which contain the information on the unknown parameters of the models. The models, which are presented, are well suited for a variety of tasks connected with the evaluation of data. When applications are considered, data will be analyzed which have been taken to solve problems of surveying engineering. This does not mean, of course, that the applications are restricted to geodesy. Bayesian statistics may be applied wherever data need to be evaluated, for instance in geophysics. After an introduction the basic concepts of Bayesian inference are presented in Chapter 2. Bayes' theorem is derived and the introduction of prior information for the unknown parameters is discussed. Estimates of the unknown parameters, of confidence regions and the testing of hypotheses are derived and the predictive analysis is treated. Finally techniques for the numerical integration of the integrals are presented which have to be solved for the statistical inference. Chapter 3 introduces models to analyze data for the statistical inference on the unknown parameters and deals with special applications. First the linear model is presented with noninformative and informative priors for the unknown parameters. The agreement with the results of the standard statistical techniques is pointed out. Furthermore, the prediction of data and the linear model not of full rank are discussed. A method for identifying a model is presented and a less sensitive hypothesis test for the standard statistical techniques is derived. The Kalman-Bucy filter for estimating unknown parameters of linear dynamic systems is also given. Nonlinear models are introduced and as an example the fit of a straight line is treated. The resulting posterior distribution for the unknown parameters is analytically not tractable, so that numerical methods have to be applied for the statistical inference. In contrast to the standard statistical techniques, the Bayesian analysis for mixed models does not discriminate between fixed and random parameters, it distinguishes the parameters according to their prior information. The Bayesian inference on the parameters, which correspond to the random parameters of the mixed model of the standard statistical techniques, is therefore readily accomplished. Noninformafive priors of the variance and covariance components are derived for the linear model with unknown variance and covariance components. In addition, informative priors are given. Again, the resulting posterior distributions are analytically not tractable, so that numerical methods have to be applied for the Bayesian inference. The problem of classification is solved by applying the Bayes rule, i.e. the posterior expected loss computed by the predictive density function of the observations is minimized. Robust estimates of the standard statistical techniques, which are maximum likelihood type estimates, the so-called M-estimates, may also be derived by Bayesian inference. But this approach not only leads to the M-estimates, but also any inferential problem for the parameters may be solved. Finally, the reconstruction of digital images is discussed. Numerous methods exist for the analysis of digital images. The Bayesian approach unites some of them and gives them a common theoretical foundation. This is due to the flexibility by which prior information for the unknown parameters can be introduced. It is assumed that the reader has a basic knowledge of the standard statistical techniques. Whenever these results are needed, for easy reference the appropriate page of the book "Parameter Estimation and Hypothesis Testing in Linear Models" by the author (Koch 1988a) is cited. Of course, any other textbook on statistical techniques can serve this purpose. To easily recognize the end of an example or a proof, it is marked by a A or a t~, respectively. I want to thank all colleagues and students who contributed to this book. In particular, I thank Mr. Andreas Busch, Dipl.-Ing., for his suggestions. I also convey my thanks to Mrs. Karin Bauer, who prepared the copy of the book. The assistance of the Springer- Verlag in checking the English text is gratefully acknowledged. The responsibility of errors, of course, remains with the author.

Beschreibung / Inhaltsverzeichnis: Cellular growth is an important crystal growth process and offers an interesting example of natural pattern formation. The present work has been undertaken to study cellular growth, especially its pattern formation, both experimentally and numerically. In situ observations of faceted cellular growth clearly revealed cellular interactions in the array of cells. Cell tip splitting and loss of cells were observed to be the two main mechanisms for the adjustment of cell spacings during growth. For the first time, the true time-dependent faceted cellular growth has been modelled properly. The time evolution of faceted cellular growth has demonstrated the dynamical features of cellular growth processes. It was shown that the pattern formation was determined by cellular interactions in the array, either transient or persistent depending on the growth condition. The cellular structures were irregular when persistent interactions occurred, whereas relatively regular structures could be formed once the transient interactions had stopped. As a result of cellular interactions, a finite range of stable cell spacings was found under a given growth condition. Numerical experiments were carried out for k 〉 1 and k 〈 1 (where k is the solute partition coefficient), under a number of different growth conditions. It was found that these two cases were not symmetric as far as solute distribution is concerned; however the pattern formation behaviours were similar. For k 〉 1 shallow cells were retained, while for k 〈 1, the formation of liquid grooves along the cell boundary depended on the growth condition. The solute effect plays an important role in the cellular interactions in the array. The results were compared with experimental observations in thin film silicon single crystals. It is felt that a general behaviour of pattern formation is found and should be expected for other processes such as non-faceted cellular or eutectic growth. In addition, the solute flow in steady state cellular array growth was studied using the point source technique. Preliminary work was carried out to measure steady state non-faceted cell shapes. Heat flow in zone melting was studied numerically.

Beschreibung / Inhaltsverzeichnis: PREFACE This volume presents results from members of the Project 216 "Global Biological Events in Earth History" of the International Geological Correlation Programme (IGCP). The project, initiated by the elder editor (O.H.W.) within the framework of the International Palaeontological Association (IPA) in the late 70s, was officially established in 1984. Subsequently, it led to the first three conferences on Global Bio-Events, and their respective symposia volumes: 1) In G6ttingen, West Germany in 1986 (WaUiser, O. H., Ed., 1986, Global Bio-Events, Springer-Verlag); in Bilbao, Spain in 1987 (Lamolda, M. A., Kauffrnan, E. G., and Walliser, O. H., Eds., 1988, Paleontology and Evolution: Extinction Events; Rev. Espafiola de Paleont., n. extraord.); and in Boulder, Colorado, U.S.A. in 1988 (this volume). The next meeting, on Innovations and Revolutions in the Biosphere, is planned in Oxford, England in 1990, to be hosted by Martin Brasier. During the history of this project, the focus of our research has shifted significantly. Initial focus was on specific global mass extinctions (e.g. the Precambrian/Cambrian, Frasnian/Fammenian, Cretaceous/Tertiary, and Eocene/Oligocene events) to a broader treatment of Phanerozoic mass extinctions, their differences or unifying factors, and their causal mechanisms. Subsequent meetings have attempted to focus attention on a fuller spectrum of global bio-events in Earth history. The Boulder Conference, and this volume, although still strongly influenced by the excitement of mass extinction research, expresses these new trends in bioevent studies. The Boulder conference, held on May 16-23, 1988, focused on a broad spectrum of Abrupt Changes in the Global Biota. Over 100 participants from 13 nations attended this meeting, representing diverse disciplines of palaeobiology, palaeoclimatology, palaeoceanography, sedimentology, geochemistry, and a broad spectrum of the stratigraphic and geological sciences. Four days of talks were supplemented by field trips to the continental Cretaceous/Tertiary boundary in the Raton Basin, New Mexico, and to the Cenomanian/Turonian mass extinction interval exposed near Pueblo, Colorado. The Conference itself was characterized by a great diversity of approaches to bio-event research, and the phenomenon of mass extinction. In particular, interactive causes involving both extraterrestrial and earthbound (tectonic, oceanographic, climatic) forces were discussed, and each major Phanerozoic mass extinction was treated by specialists in the field. In addition, many presentations focused on the causal mechanism and patterns of bio-event development that were not restricted to mass extinction intervals, but which could cause regional to global biotic response at any time in Earth history. Thus, both the conference, and this volume, focus attention on climatic and oceanic perturbations from anoxia, advection, rapid thermal change, toxic chemical enrichment, and energy shock from impacts and giant tsunamis as forcing mechanism for regional to global bio-events. The delicate balance of perched ocean/ctimate~fe systems under typical warm equable non-glacial Phanerozoic conditions, and their susceptibility to shock from even small perturbations, was a philosophical theme that ran throughout the meeting. The case for extraterrestrial forcing of tectonic, volcanic, and biological events was greatly strengthened by new data presented at this conference, with special concern for the effects of small comet/meteorite impacts in the oceans, and their chemical/physical/biological signature which might be used, in the absence of shocked minerals, microspheres or trace metals, to identify extraterrestrial events associated with global and regional bio-events. The conference benefitted from the introduction of much new data at high levels of resolution, especially from poorly studied mass extinction intervals. Interactive discussions, and many new ideas characterized the meeting. The new scientific results of this meeting are exciting; they are reviewed in the Conference Report published in Episodes (1988, v. 11, n. 4, p. 289-292). Most of the key papers presented at the Boulder meeting appear in this volume. What lies ahead in bio-event research? Clearly, a great deal of excitement and an age of discovery. We have only touched the surface of this new and dynamic field. We are starting to comprehend the dynamics of global mass extinctions, integrating detailed geochemical, physical and biological data into scenarios of cause and effect. But in the years ahead lies the job of understanding the whole spectrum of regional bioevents preserved in the ancient record, and especially the application of this research to solutions of the critical problems inherent in global change and the modern biotic crisis. Future directions for research at this conference include the investigation and modeling of abrupt chemical and thermal shifts in the ocean, the effects of impacts at deep ocean sites, the documentation of successful survival strategies and repopulation patterns following biotic crises, the deep ocean record of bio-events, and focus on alternative forces other than impacting to account for mass extinction events. This volume introduces some of these new pathways in bio-event research.

Beschreibung / Inhaltsverzeichnis: PREFACE Following the economical and social development of the local communities, mountain regions of temperate climates are increasingly becoming the site of valuable infrastructures and important urban and industrial settlements. As the catastrophic events of last years in the European Alps have clearly shown, the vulnerability of these territories has correspondingly increased, in terms of both property damage and losses of human life. Until recently, the hydraulic scientific community has paid little attention to mountain watersheds, except perhaps during the period if the hydropower development. Nevertheless attention was then focused on problems and methodologies somewhat different from the issues of actual environmental concern. More recently, however, hydraulic engineers have joined their colleagues from forest and rural engineering, who have traditionally dealt with erosion control in mountain areas, to bring in their own methodology, already experienced in lowland rivers. At the same time, academic people focused an interest in some phenomena, like massive transport, which is typical of mountain environment. To bring together all these contributions and to make the state of the art of the mountain river science (oropotamology) and technology, an International Workshop was called at the University of Trent (Italy), on October 1989, under the sponsorship of Fluvial Hydraulic Section of the IAHR. Three main topics have been recognized as particularly relevant from the point of view of both research and professivnal people: a) Hydrodynamics of steep channels and local scale process; b) Sediment movement and sediment training, with special emphasis on massive transport; c) Particular features of sediment transport related to non-uniform grain-size. However, as it is the case in these circumstances, the contest of several contributions often spread over more than one topic. In the following Introduction to papers, the three topics were split into 11 Sections, each one devoted to a more particular aspect recurrently addressed during the discussion. The same paper, thus, may be mentioned in different Sections of the Introduction.

Beschreibung / Inhaltsverzeichnis: PREFACE This book represents the first attempt in three decades to marshall out available information on the regional geology of Africa for advanced undergraduates and beginning graduate students. Geologic education in African universities is severely hampered by the lack of a textbook on African regional geology. This situation is greatly exacerbated by the inability of most African universities to purchase reference books and maintain journal subscriptions. Besides, geologic information about Africa is so widely dispersed that a balanced and comprehensive course content on Africa is beyond the routine preparation of lecture notes by university teachers. Since geology is a universal subject and Africa is one of the largest landmasses on Earth with one of the longest continuous records of Earth history, there is no doubt that geologic education in other parts of the world will benefit from a comprehensive presentation of African geologic case histories. The scope of this text also addresses the need of the professional geologist, who may require some general or background information about an unfamiliar African geologic region or age interval. Africa occupies a central position in the world's mineral raw materials trade. Because of its enormous extent and great geologic age, the diversity and size of Africa's mineral endowment is unparalleled. Africa is the leading source of gold, diamond, uranium, and dominates the world's supply of strategic minerals such as chromium, manganese, cobalt, and platinum. Consequently, African nations from Algeria to Zimbabwe depend solely on mineral exports for economic survival. The geologic factors which govern economic mineral deposits are stressed in this text. The geological history of Africa spans 3.8 billion years, a record that is unique both in duration and continuity. Few other parts of our planet match the plethora of geologic phenomena and processes that are displayed in the African continent. From the various stages of crustal evolution decipherable from the Archean of southern Africa, through the plate tectonics scenarios in the ubiquitous Late Proterozoic-Early Paleozoic Pan-African mobile belts and in the Hercynian and Alpine orogenies of northwest Africa, to the East African Rift Valley, Africa is replete with excellent examples and problems for a course on regional tectonics. Teachers of igneous and metamorphic petrology can hardly ignore Africa's anorogenic magmatism (e.g.. layered ultramafic intrusives such as the Great Dyke and the Bushveld Complex; the Tete gabbro-anorthosite pluton; alkaline complexes; basaltic volcanism), or tantalizing highgrade metamorphic terranes such as the Limpopo belt, the Namaqua mobile belt, and the Mozambique belt. From the extensive Precambrian supracrustal sequences throughout the continent with enormous thicknesses of sedimentary rocks that have hardly been deformed or metamorphosed, to the stratigraphic evolution of Africa's present-day passive continental margin, there is a complete spectrum of facies models upon which to base a course on basin analysis and stratigraphy. To maintain its integrity a course on historical geology anywhere in the world must address the theory of Continental Drift beyond invoking past continuities between West Africa and South America. Past connections between West Africa and eastern North America must equally be explored, so also connections between northeast Africa and Arabia, and the paleogeography of southern Gondwana where Africa occupied centre stage. The Precambrian fossil record, the transitions from reptiles to the earliest mammals and dinosaurs, and the evolution of Man are among Africa's unique contributions to the history of life and the story of organic evolution. Although it lies today in the tropics Africa was the theatre of the Earth's most-spectacular glaciations. Even after the scene of continental glaciation had shifted to the northern continents only lately during the Pleistocene, Africa still witnessed spectacular climatic fluctuations during the Quaternary. Certainly students of archeology and paleoanthropology cannot overlook the Quaternary paleoenvironmental record of the Olduvai Gorge in Tanzania, the Lake Turkana basin in Kenya, the Nile valley, the Sahara, and southern Africa. But since African examples have already been cited in standard geologic textbook, I have often been asked why it has become necessary to revive the idea of a full-length textbook on African geology, 30 years after this idea was abandoned by the geologic community. My simple answer, as already stated, is that the wealth of available geologic information about Africa is so enormous and fascinating, but so diffuse, that an attempt must be made to assemble and pass on this knowledge.

Beschreibung / Inhaltsverzeichnis: PREFACE This monograph is a compendium of revised papers which were originally presented at the "Ron Mather Symposium on Four-Dimensional Geodesy", 28-31 March, 1989, held at the University of New South Wales, Sydney, Australia. The symposium had the enthusiastic support of the International Association of Geodesy and the Australian Academy of Sciences. The symposium served two purposes: to honour the achievements of the late Professor Ron S. Mather, the distinguished Australian geodesist who died in 1978, and to review and report on the latest developments in four-dimensional geodesy. Four-dimensional geodesy is a convenient term for those geodetic principles and techniques which yield position, gravity and their time variations. In the past geodesists have tended to think of the earth as a static body, save from occasional savage earthquakes or volcanic eruptions. So, why the need to coin the term "four-dimensional geodesy") Because it explicitly recognises that time is an integral part of understanding geodetic measurements. But let's first identify the scope of modern geodesy. Geodesy has traditionally been concerned with two separate, though closely related, topics: accurate positioning of objects on the earth's surface, and mapping the earth's external gravity field. These are still the fundamental tasks of geodesy, although the spheres of application have now extended into space. However, present and emerging geodetic measurement technologies for gravity field mapping and positioning are sensitive to defolTnations of the earth's surface and gravity field. Within the geodetic community, this new emphasis on accounting for the time-varying characteristics of position and gravity has fundamental principles; in particular the establishment and maintenance of appropriate global reference systems for geodesy. At the same time, there has been a growing recognition by the earth sciences in general of the important role of geodesy in studying earth deformations, as well as atmosphere and ocean dynamic phenomena. The geodetic measurements, for example, are taken over time scales of hours to decades, and occasionally to a century or longer. Though this is only a small part of the whole deformation spectrum, it is a very important one. Geodesy bridges the low frequency part of the spectrum available from geological observations, with the high frequency end observed from, for example, seismic instrumentation. It's role in atmospheric and oceanographic studies is as a unique, high precision remote sensing tool. The revolution in geodesy is not, however, restricted to the measurement technology only. It is true that without the advances of space geodesy and terrestrial metrology, the notion of four-dimensional geodesy is a rather academic one. These advances, which now reveal time-variable signals above the measurement noise level, have important implications for all geodetic activities. The geodetic activities we refer to can be identified as: experiment design and measurement processes; definition and maintenance of highly stabie geodetic reference systems; data analysis; and interpretation of position and gravity results. Ultra high precision measurements are of little use without sophisticated analysis tools to extract the small signals in the data. The interpretation of geodetic results will be in error if insufficient attention is paid to ensuring that the reference systems to which the results relate are themselves stable. Clearly four-dimensional geodesy is as much about concepts and principles, as about computers and geodetic equipment. This diversity is reflected in the papers selected for this book. They range over topics related to the modem measurement tools, the reduction and analysis techniques, to the interpretation of geodetic results within the context of problems currently being investigated in the earth sciences. We would like to thank the International Association of Geodesy and the Australian Academy of Sciences for sponsorship of the Symposium. Unisearch Ltd., the commercial arm of the University of New South Wales, was the managing agent, and staff members of the School of Surveying and of Unisearch Ltd. were involved in the organisation of the Symposium. We would like to gratefully acknowledge these excellent contributions. Let us express also our gratitude for the useful guidance which we received from Prof. K. Lambeck, A. Prof. A. Stolz and Dr. R. Coleman of the Scientific Advisory Committee and the continuous support given by Prof. E.W. Grafarend. Sincere thanks are due to the authors of the selected papers for agreeing to contribute to this Monograph, and for their positive cooperation during the production of this volume.

Beschreibung / Inhaltsverzeichnis: INTRODUCTION Ecometry concerns measurements and interpretation of ecological data and relationships between data. It deals with most matters involved in the scientific aspects of the representativity and information value of samples and does not, in fact, concern statistical methods. In particular, ecometry can be regarded as an approach to obtain so-called load models and load diagrammes (effect-dose-sensitivity diagrammes), which are one of the aims/final products in aquatic environmental consequence analysis (H~- kanson, 1990; all these terms will be explained later on). This publication is meant to demonstrate what can and cannot be done using ecometric approaches. It must be emphasized at the outset that the main intention here is not to provide new radioecological knowledge on how Cs-137 is dispersed in aquatic ecosystems after the Chernobyl accident and is taken up in fish, but to use Cs-137 as a type substance and pike as a biological indicator to go through methods which should also apply to other types of environmentally hazardous substances (it could just as well have been substance X in ecosystem Y). As a secondary effect, we may also learn something about Cs-137. Several terms and methods, which have not been used earlier in the aquatic environmental sciences, e.g., ecometric analysis and dynamic modelling using moderators, will be discussed and defined...

Beschreibung / Inhaltsverzeichnis: INTRODUCTION Humic substances, comprise a class of biogenic, coloured, organic substances that are ubiquitous in soil, sediment and water. Originally, the occurrence and nature of humic substances were regarded as issues of primarily academic interest. This situation is now rapidly changing, and studies of humics have gained recognition as important contributions to environmental science. In particular it has been shown that humic substances, in several different ways can interact with biologically active substances, thereby modifying their environmental impact. Whereas the history of soil humus studies goes back to the 19th century, the awareness of aquatic humus is more recent. The brownish colour that, in many surface waters, shows the presence of substantial amounts of humic substances, was long considered to be a harmless phenomenon that did not call for detailed investigations. Hnmic waters had few known toxic effects, and the refractory character of hnmic substances indicated the they played a peripheral role in most biochemical processes. In fact, it was not until the mid 70's that aquatic humus was brought into focus in environmental science. The event trigging this was the discovery of the interaction between humic substances and chlorine used for disinfection of drinking water. Toxic substances, such as chloroform, were detected in all chlorinated waters, and humic substances were identified as the main precursors. The role of humics in the mobilization and subsequent transport of trace elements in the environment was recognized for the first time in the early 80's. This role was considered to be of particular importance in connection with geologic storage of high-level radioactive waste. In water with "normal" concentration levels of humic compounds, the speciation of e.g. the trivalent actinides, would be entirely dominated by the complexation with these agents. The topics of this conference (Session 1 - Isolation, fractionation and characterization; Session 2 - Biological and chemical transformation and degradation; Session 3 - Complex formation and interactions with solids; Session 4 - Biological activity; and session 5 Halogenation of humic substances) were selected to represent areas of current environmental interest...

Beschreibung / Inhaltsverzeichnis: PREFACE The search for tin dates back to the earliest days of civilization. For about 40 years, world tin mining has oscillated at a level of 150,000-250,000 t Sn/year, with a mine output in 1989 of 210,000 t Sn (MCS 1990). This figure corresponds to a current annual value of about US$1.5 billion and places tin ninth on the metal market behind iron, gold, uranium, copper, zinc, silver, platinum and nickel. Tin deposits belong to the granite-related ore deposit spectrum which includes many metals vital to current and future technologies such as Cu, W, Mo, U, Nb, Ta, Ag, Au, Sb, Bi, As, Pb, Zn, REE, Be, Ga and Li. The granitic rocks associated with tin and tin-tungsten deposits have long been identified as a special group of granites, the so-called tin granites. These rocks provide a unique opportunity to study the magmatic and hydrothermal history of tin ore formation. Tin granites are more easily identifiable as parent rocks for tin (and tungsten) mineralization than is the case for other mineralized granitic rocks such as molybdenum and copper porphyries. The magmatic molybdenum and copper distribution patterns are more complex (control by sulfide solubilities), and commonly obliterated by fluid interaction. The relatively simple situation of tin granites provides therefore an invaluable opportunity to study some metallogenic aspects of magmatic-hydrothermal ore deposits in general. The present study attempts to develop a general metallogenic model for tin in identifying the essential or relevant processes in tin ore formation. The methodological principle is based, on an interplay between a background of some basic petrogenetic concepts and a number of specific local and regional data on tin deposits and tin provinces, with particular reference to those areas with which the author is most familiar with (Bolivia, SE Asia, Europe). This inductive approach condenses the many apparently specific complexities encountered in individual ore deposits to a few major processes of general importance. The inherent reductionism may have a personal bias which is probably inevitable in any simple and broad-scale picture ("Apr6s tout, la raison est bien I'esclave des passions"; Feyerabend 1979:210). The critical problem of the relevance of those factors chosen for our model can be judged by its degree of consistency and predictive capability for new and analogous cases...

Beschreibung / Inhaltsverzeichnis: The present study will provide an introduction into the biomechanics of trees and will give a critical survey of the phylogeny and the constructional principles of the tree habit. Since the trunk is considered the basic and crucial element of a tree, the analysis is largely restricted to a functional comparison of the stem anatomy of the various tree forms. It is based on the concept of constructional morphology, thus considering simultaneously the functional aspect and the ontogenetical and phylogenetical development of the various trunk types. The main questions to be answered in this study are; Why do trees exist? - Which are the constructional principles of tree trunks and when and in which group of plants do they appear? - How important are internal (phylogenetic) and external (functional, constructional) constraints? - What are the specific properties of the different constructional principles and does a correlation between trunk design and growth habit exist? - Is there a tendency in phylogeny to a better performance? The study does not (and cannot) intend to provide a detailed biophysical analysis of individual cases because experimental data on the mechanical properties of the structural elements of the different kinds of trees are still lacking. Instead, it will he the task to evaluate in a comprehensive and qualitative or semi-quantitative manner the available data of the morphology, anatomy and phylogeny of fossil and recent trees by using concepts of biomechanics and constructional morphology. Thus a somewhat holistic approach is used, which is becoming increasingly more acceptable today.

Beschreibung / Inhaltsverzeichnis: PREFACE The application of thermal analysis to earth science has a long history. This is evidenced by the extensive coverages by Mackenzie (1957, 1970), Langier-Kuzniarowa (1967), Schultze (1971), Liptay (t973), Smykatz- Kloss (1974), Todor (1976) and Heide (1982). The chief thermal method has been differential thermal analysis (DTA). Additionally, thermogravimetry (TG; Duval, 1963; Keattch, 1969; Earnest, 1988) and thermodilatometry (Schomburg & Strörr, 1984) have gained some importance. All these methods are still widely ltsed. But recently several new techniques have gained attention, such as thermomagnetometry, thermomechanical analysis and thermosonimetry. Improved equipment made possible the application of thermal methods to problems in thermodynamics and kinetics (e.g. by means of differential scanning calorimetry, DSC). This progress in the construction of new instruments as well as the combination of existing methods to enable simultaneous determinations (e.g. TG/DTA; TG/IR spectroscopy; DTA/mass spectrometry; DTA/microscopy; high-pressure DTA) have led to a resurgence in the use and application of thermal analysis in the earth sciences. Here the applications cover such diverse areas as the examination of individual minerals, mineral mixtures, rocks, soils, ceramics, cements, raw materials as well as their industrial evaluation, performance assessment and quality control. In the field of solid fossil fuels thermal determinations range from proximate analysis of inorganic constituents and the measurement of calorific values to the assessment of the environmental aspects of fly ashes and mineral residues. To support this tendency, the International Confederation for Thermal Analysis (ICTA) has recently founded a "Committee for Thermal Analysis in Geosciences". The aim of this committee shall be to discuss, improve and distribute the knowledge about the possibilities of solving geoscientific questions by means of thermal analytic methods...