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Books > Earth & environment > Earth sciences > The hydrosphere > Oceanography (seas)
Over million-year timescales, the geologic cycling of carbon controls long-term climate and the oxidation of Earth's surface. Inferences about the carbon cycle can be made from time series of carbon isotopic ratios measured from sedimentary rocks. The foundational assumption for carbon isotope chemostratigraphy is that carbon isotope values reflect dissolved inorganic carbon in a well-mixed ocean in equilibrium with the atmosphere. However, when applied to shallow-water platform environments, where most ancient carbonates preserved in the geological record formed, recent research has documented the importance of considering both local variability in surface water chemistry and diagenesis. These findings demonstrate that carbon isotope chemostratigraphy of platform carbonate rarely represent the average carbonate sink or directly records changes in the composition of global seawater. Understanding what causes local variability in shallow-water settings, and what this variability might reveal about global boundary conditions, are vital questions for the next generation of carbon isotope chemostratigraphers.
This textbook provides an introduction to turbulent motion occurring naturally in the ocean on scales ranging from millimetres to hundreds of kilometres. It describes turbulence in the mixed boundary layers at the sea surface and seabed, turbulent motion in the density-stratified water between, and the energy sources that support and sustain ocean mixing. Little prior knowledge of physical oceanography is assumed. The text is supported by numerous figures, extensive further reading lists, and more than 50 exercises that are graded in difficulty. Detailed solutions to the exercises are available to instructors online at www.cambridge.org/9780521859486. This textbook is intended for undergraduate courses in physical oceanography, and all students interested in multidisciplinary aspects of how the ocean works, from the shoreline to the deep abyssal plains. It also forms a useful lead-in to the author's more advanced graduate textbook, The Turbulent Ocean (Cambridge University Press, 2005).
Fate and Impact of Microplastics in Marine Ecosystems: From the Coastline to the Open Sea brings together highlights from the conference proceedings for MICRO 2016: Fate and Impact of Microplastics in Marine Ecosystems: From the Coastline to the Open Sea. While the presence of microplastics in ecosystems has been reported in the scientific literature since the 1970's, many pressing questions regarding their impacts remain unresolved. This short format title draws from the shared scientific and technical material and summarizes the current research and future outlook.
Written by a group of international experts in their field, this book is a review of Lagrangian observation, analysis and assimilation methods in physical and biological oceanography. This multidisciplinary text presents new results on nonlinear analysis of Lagrangian dynamics, the prediction of particle trajectories, and Lagrangian stochastic models. It includes historical information, up-to-date developments, and speculation on future developments in Lagrangian-based observations, analysis, and modeling of physical and biological systems. Containing contributions from experimentalists, theoreticians, and modellers in the fields of physical oceanography, marine biology, mathematics, and meteorology, this book will be of great interest to researchers and graduate students looking for both practical applications and information on the theory of transport and dispersion in physical systems, biological modelling, and data assimilation.
The Biology of Particles in Aquatic Systems, Second Edition presents the latest information on particulate and dissolved matter found in aquatic habitats ranging from small streams to oceans. Only by studying this matter can we gain an understanding of the functioning of aquatic ecosystems and thus be able to predict changes that may occur as these systems become stressed. Updated and extensively revised, this new edition covers such topics as classification of particulate and dissolved matter, origin and formation of particles aquatic systems, factors affecting particle aggregation, methods for capturing particles by benthic and planktonic animals, and the use of particulate and dissolved organic matter as food.
This book is the first comprehensive introduction to the theory of equatorially-confined waves and currents in the ocean. Among the topics treated are inertial and shear instabilities, wave generation by coastal reflection, semiannual and annual cycles in the tropic sea, transient equatorial waves, vertically-propagating beams, equatorial Ekman layers, the Yoshida jet model, generation of coastal Kelvin waves from equatorial waves by reflection, Rossby solitary waves, and Kelvin frontogenesis. A series of appendices on midlatitude theories for waves, jets and wave reflections add further material to assist the reader in understanding the differences between the same phenomenon in the equatorial zone versus higher latitudes.
Ancient iron formations - iron and silica-rich chemical sedimentary rocks that formed throughout the Precambrian eons - provide a significant part of the evidence for the modern scientific understanding of palaeoenvironmental conditions in Archaean (4.0-2.5 billion years ago) and Proterozoic (2.5-0.539 billion years ago) times. Despite controversies regarding their formation mechanisms, iron formations are a testament to the influence of the Precambrian biosphere on early ocean chemistry. As many iron formations are pure chemical sediments that reflect the composition of the waters from which they precipitated, they can also serve as nuanced geochemical archives for the study of ancient marine temperatures, redox states, and elemental cycling, if proper care is taken to understand their sedimentological context.
Modeling and prediction of oceanographic phenomena and climate is based on the integration of dynamic equations. The Equations of Oceanic Motions derives and systematically classifies the most common dynamic equations used in physical oceanography, from large scale thermohaline circulations to those governing small scale motions and turbulence. After establishing the basic dynamical equations that describe all oceanic motions, M??ller then derives approximate equations, emphasizing the assumptions made and physical processes eliminated. He distinguishes between geometric, thermodynamic and dynamic approximations and between the acoustic, gravity, vortical and temperature-salinity modes of motion. Basic concepts and formulae of equilibrium thermodynamics, vector and tensor calculus, curvilinear coordinate systems, and the kinematics of fluid motion and wave propagation are covered in appendices. Providing the basic theoretical background for graduate students and researchers of physical oceanography and climate science, this book will serve as both a comprehensive text and an essential reference.
Molybdenum (Mo) is a widely used trace metal for investigating redox conditions. However, unanswered questions remain that concentration and bulk isotopic analysis cannot specially answer. Improvements can be made by combining new geochemical techniques to traditional methods of Mo analysis. In this Element, we propose a refinement of Mo geochemistry within aquatic systems, ancient rocks, and modern sediments through molecular geochemistry (systematically combining concentration, isotope ratio, elemental mapping, and speciation analyses). Specifically, to intermediate sulfide concentrations governing Mo behavior below the 'switch-point' and dominant sequestration pathways in low oxygen conditions. The aim of this work is to 1) aid and improve the breadth of Mo paleoproxy interpretations by considering Mo speciation and 2) address outstanding research gaps concerning Mo systematics (cycling, partitioning, sequestration, etc.). The Mo paleoproxy has potential to solve ever complex research questions. By using molecular geochemical recommendations, improved Mo paleoproxy interpretations and reconstruction can be achieved.
Lithium isotopes are a relatively novel tracer of present and past silicate weathering processes. Given that silicate weathering is the primary long-term method by which CO2 is removed from the atmosphere, Li isotope research is going through an exciting phase. We show the weathering processes that fractionate dissolved and sedimentary Li isotope ratios, focusing on weathering intensity and clay formation. We then discuss the carbonate and silicate archive potential of past seawater 7Li. These archives have been used to examine Li isotope changes across both short and long timescales. The former can demonstrate the rates at which the climate is stabilised from perturbations via weathering, a fundamental piece of the puzzle of the long-term carbon cycle.
In the modern marine environment, barium isotope ( 138Ba) variations are primarily driven by barite cycling-barite incorporates 'light' Ba isotopes from solution, rendering the residual Ba reservoir enriched in 'heavy' Ba isotopes by a complementary amount. Since the processes of barite precipitation and dissolution are vertically segregated and spatially heterogeneous, barite cycling drives systematic variations in the barium isotope composition of seawater and sediments. This Element examines these variations; evaluates their global, regional, local, and geological controls; and, explores how 138Ba can be exploited to constrain the origin of enigmatic sedimentary sulfates and to study marine biogeochemistry over Earth's history.
Geophysical fluid dynamics examines the dynamics of stratified and turbulent motion of fluids in the ocean and outer core, and of gases in the atmosphere. This book explains key notions and fundamental processes of the dynamics of large- and medium-scale atmospheric and oceanic motions from the unifying viewpoint of the rotating shallow water model. The model plays a distinguished role in geophysical fluid dynamics. It has been used for about a century for conceptual understanding of various phenomena, for elaboration of approaches and methods to be used later in more complete models, for development and testing of numerical codes, and for many other purposes. In spite of its simplicity, the model grasps essential features of the complete "primitive equations" models, being their vertically averaged version, and gives an intuitive representation and clear vision of principal dynamical processes. This book is a combination of a course on geophysical fluid dynamics (Part 1), with explanations and illustrations of fundamentals, and problems, as well as a more advanced treatise of a range of principal dynamical phenomena (Part 2), including recently arisen approaches and applications (Part 3). Mathematics and physics underlying dynamical phenomena are explained, with necessary demonstrations. Yet, an important goal of the book is to develop the reader's physical intuition and qualitative insights.
In one form or another, iron speciation has had a long history as a paleoredox proxy. The technique has been refined considerably over the years, and the most recent scheme is unique in its potential to distinguish three major oceanic redox states - oxygenated, ferruginous and euxinic. This Element covers the theory behind the proxy, methods involved in applying the technique, and potential complications in interpreting Fe speciation data. A series of case studies are also provided, which highlight how more advanced consideration of the data, often in concert with other techniques, can provide unprecedented insight into the redox state of ancient oceans.
Paleosols formed in direct contact with the Earth's atmosphere, so they can record the composition of the atmosphere through weathering processes and products. Herein we critically review a variety of different approaches for reconstructing atmospheric O2 and CO2 over the past three billion years. Paleosols indicate relatively low CO2 over that time, requiring additional greenhouse forcing to overcome the 'faint young Sun' paradox in the Archean and Mesoproterozoic, as well as low O2 levels until the Neoproterozoic. Emerging techniques will revise the history of Earth's atmosphere further and may provide a window into atmospheric evolution on other planets.
The stable chromium (Cr) isotope system has emerged over the past decade as a new tool to track changes in the amount of oxygen in earth's ocean-atmosphere system. Much of the initial foundation for using Cr isotopes ( 53Cr) as a paleoredox proxy has required recent revision. However, the basic idea behind using Cr isotopes as redox tracers is straightforward-the largest isotope fractionations are redox-dependent and occur during partial reduction of Cr(VI). As such, Cr isotopic signatures can provide novel insights into Cr redox cycling in both marine and terrestrial settings. Critically, the Cr isotope system-unlike many other trace metal proxies-can respond to short-term redox perturbations (e.g., on timescales characteristic of Pleistocene glacial-interglacial cycles). The Cr isotope system can also be used to probe the earth's long-term atmospheric oxygenation, pointing towards low but likely dynamic oxygen levels for the majority of Earth's history.
Nitrogen is an essential nutrient for life, and its sources and cycling have varied over earth history. Stable isotope ratios of nitrogen compounds (expressed as 15N, in 0/00) are preserved in the sedimentary record and track these changes, providing important insights into associated biogeochemical feedbacks. Here we review the use of nitrogen stable isotope geochemistry in unravelling the evolution of the global N cycle in deep time. We highlight difficulties with preservation, unambiguous interpretations, and local versus global effects. We end with several case studies illustrating how depositional and stratigraphic context is crucial in reliably interpreting 15N records in ancient marine sediments, both in ancient anoxic (Archean) and more recent well oxygenated (Phanerozoic) environments.
Reconstruction of ocean paleoproductivity and paleochemistry is paramount to understanding global biogeochemical cycles such as the carbon, oxygen and sulfur cycles and the responses of these cycles to changes in climate and tectonics. Paleo-reconstruction involves the application of various tracers that record seawater compositions, which in turn may be used to infer oceanic processes. Several important tracers are incorporated into pelagic barite, an authigenic mineral that forms in the water column. Here we summarize the utility of pelagic barite for the reconstruction of export production and as a recorder of seawater S, O, Sr, Ca and Ba.
Diverse and abundant lipid biomarker assemblages have been reported from a variety of Proterozoic marine environments from the careful analysis of well-preserved rocks and oils. These molecular biosignatures have provided unique insights into the communities and the environmental conditions which characterized the Proterozoic marine biosphere. We summarize some of the major temporal patterns evident in Proterozoic lipid biomarkers found to date, whilst emphasizing the scale of local heterogeneity found within Neoproterozoic oceans from region to region, and their relationship with the evolving ecological, climatic and ocean/atmospheric redox conditions. Short commentaries on a selection of papers published from the last 15 years of biomarker literature are given. The focus here is on key studies, highlighted for further reading, which have helped to better constrain the timing of the ecological expansion of eukaryotes in Proterozoic oceans or which have impacted on our knowledge of the biological sources of Proterozoic biomarkers.
"Understanding Sea-Level Rise and Variability" identifies the major impacts of sea-level rise, presents up-to-date assessments of past sea-level change, thoroughly explores all of the factors contributing to sea-level rise, and explores how sea-level extreme events might change. It identifies what is known in each area and what research and observations are required to reduce the uncertainties in our understanding of sea-level rise so that more reliable future projections can be made. A synthesis of findings provides a concise summary of past, present and future sea-level rise and its impacts on society. Key Features: Book includes contributions from a range of international sea level experts Multidisciplinary Four color throughout Describes the limits of our understanding of this crucial issue as well as pointing to directions for future research The book is for everyone interested in sea-level rise and its impacts, including policy makers, research funders, scientists, students, coastal managers and engineers. Additional resources for this book can be found at: http: //www.wiley.com/go/church/sealevel.
The use of the trace element content of sedimentary pyrite as a proxy for the trace element composition of past oceans has recently emerged. The pyrite proxy has several potential advantages over bulk sample analysis: preservation through metamorphism; little dilution during analysis (samples are ablated not dissolved, allowing for the less abundant elements commonly held in the sulfide fraction to be investigated as proxies); accurate measurement of several elements simultaneously; the ability to screen sediments for hydrothermal overprint; and the technique can give information regarding trace element availably at multiple stages of diagenesis. Because of these multiple strengths, the pyrite trace element proxy is a valuable potential addition to the paleo-ocean chemistry tool kit.
Vanadium isotope ratios (51V/50V) have potential to provide information about changes in past ocean oxygen contents. In particular, V isotopes may find utility in tracing variations at non-zero oxygen concentrations because the redox couple that controls V elemental and isotopic abundances in seawater (vanadate-vanadyl) appears to operate around 10M O2. This characteristic sets V isotopes apart from many other metal isotope redox proxies that require more reducing conditions to register significant changes in their isotope budgets. The oxygen abundance sensitivity range of V isotopes suggests that this paleoproxy could be particularly useful in tracing marine oxygenation changes throughout the Phanerozoic and potentially beyond. |
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