Hydrosphere

4 Key excerpts on "Hydrosphere"

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  eBook - ePub

  Exploring Environmental Issues

  An Integrated Approach

  • David D. Kemp(Author)
  • 2004(Publication Date)
  • Routledge

    (Publisher)

  First, it provides and maintains the supply of oxygen required for life itself. Second, it controls the earth' s energy budget through such elements as the ozone layer and the greenhouse effect and, by means of its internal circulation, distributes heat and moisture across the earth' s surface. Thirdly, it has the capacity to dispose of waste material or pollutants generated by natural or human activity. Through ignorance of the mechanisms involved, or lack of concern for the consequences, society has interfered with all of these elements and created or intensified problems, many of which are now recognized as being of global concern (Kemp 1994). These include atmospheric pollution, acid precipitation, global warming and ozone depletion (see Chapters 10 and 11). Most of these issues have their roots in changes in the composition of the atmosphere, interference with the global energy budget or lack of understanding of the elements of the general circulation, either individually or in combination. Hydrosphere The Hydrosphere is that part of the environment that includes all of the water in and on the lithosphere and above it in the atmosphere. It is most obvious in oceans, seas, rivers and lakes, but the ground water in the rocks beneath the surface, the water vapour and water droplets in the atmosphere and the water contained in the living elements of the biosphere are also part of the Hydrosphere. The water in the Hydrosphere is very unevenly distributed. In some places it is abundant, in other places it is absent, and society spends much time, money and energy redistributing it. Some 97 per cent of the world' s water is in the oceans, while a further 2 per cent is in the form of ice and snow, and TABLE 2.3 THE PHYSICAL DISTRIBUTION OF THE WORLD' S WATER (%) Oceans 97.00 Fresh water of which 3.00 Snow and ice 77.09 Ground water 22.3 Lakes and rivers 0.53 Atmosphere 0.03 Living organisms 0.0016 Source: based on data in J.P. Peixoto and M

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  eBook - ePub

  Fundamentals of Hydrology

  • Tim Davie(Author)
  • 2019(Publication Date)
  • Routledge

    (Publisher)

  geomorphology ) and is rooted in a history of explaining the processes that lead to water moving around the earth and to try to understand spatial links between the processes. The engineering approach tends to be a little more practically based and looks towards finding solutions to problems posed by water moving (or not moving) around the earth. In reality there are huge areas of overlap between the two and it is often difficult to separate them, particularly when you enter into hydrological research. At an undergraduate level, however, the difference manifests itself through earth science hydrology being more descriptive (understanding processes) and engineering hydrology being more numerate (quantifying flows). Within the broad discipline of hydrology there are also areas of specialisation. For example, some hydrologists focus on groundwater and this specialised area is known as geohydrology or hydrogeology. In recent decades another area of specialisation has emerged; that of ecohydrology or hydroecology. This is the study of hydrology in relation to the natural aquatic environment (e.g. rivers and wetlands) and the important interdependence of water and ecosystems.

  The approach taken in this book is more towards the earth science side, a reflection of the authors’ training and interests, but it is inevitable that there is considerable crossover. There are parts of the book that describe numerical techniques of fundamental importance to any practising hydrologist from whatever background, and it is hoped that the book can be used by all undergraduate students of hydrology.

  Throughout the book there are highlighted case studies to illustrate different points made in the text. The case studies are drawn from research projects or different hydrological events around the world and are aimed at reinforcing the text elsewhere in the same chapter. Where appropriate, there are highlighted worked examples illustrating the use of a particular technique on a real data set.

  Importance of Water

  Water is the most common substance on the surface of the earth, with the oceans covering over 70 per cent of the planet. Water is one of the few substances that can be found in all three states (i.e. gas, liquid and solid) within the earth’s climatic range. The very presence of water in all three forms makes it possible for the earth to have a climate that is habitable for life forms: water acts as a climate ameliorator through the energy absorbed and released during transformation between the different phases. In addition to lessening climatic extremes the transformation of water between gas, liquid and solid phases is vital for the transfer of energy around the globe: moving energy from the equatorial regions towards the poles. The low viscosity of water makes it an extremely efficient transport agent, whether through international shipping or river and canal navigation. These characteristics can be described as the physical properties

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  eBook - ePub

  Environmental Plant Physiology

  Botanical Strategies for a Climate Smart Planet

  • Vir Singh(Author)
  • 2020(Publication Date)
  • CRC Press

    (Publisher)

  Water movement takes place along the water-potential gradient from soil to plants and then transpirational loss from the leaves of the plants. But how is this gradient established? It is the transpirational loss of water that establishes the water-potential gradient—a condition for water movement from soil to roots, to shoots, and to leaves. The water potential in the roots of a plant system is lower than that of the soil. This allows water movement from the soil to the plant roots. Water potential in the xylem of the shoot of the plants is further lowered than that in roots; thus, water moves from roots to shoots and subsequently to the atmosphere via leaves. In this way, water becomes available to the whole plant.

  WATER PLANET A CLIMATE-SMART PLANET

  The planet’s climate change is hidden in what is the largest component of it. That is, water, the most of the planet. The planet’s climate solutions are hidden in the largest component of the water. That is, oceans, the most of the water on the water planet. Covering about 71% of the earth’s surface, the oceans are home to a vast majority of living things of the planet. The waters outside the oceans and seas—lakes, rivers, rivulets, wetlands, etc.—are all vital sources of climate benevolence on the Living Planet.

  Waters of the earth are not just a resource to reckon with. They are a phenomenon in themselves. The hydrological cycle itself serves as a dominant factor of ecological integrity of the planet. The role of water in maintaining the ecological integrity also involves its role in holding the planet’s temperatures in an appropriate range. Water is integral to life as well as a medium of life (cells, organisms, ecosystems, the entire biosphere) that resists changes in temperatures. Previously in this chapter, we have discussed that water in organisms’ cells acts as a buffer, not allowing temperature changes beyond a range that is attributable to its high specific heat, or heat capacity. Water holds temperatures in a range soothing for the metabolic processes to keep going. In the same way, water in the ecosystems and in the entire biosphere acts as a buffer to resist temperature changes beyond a limit.

  The temperature-buffering role of water is on account of its very specific properties vital to life already discussed in this chapter. In our contemporary times, the processes of climate change, via global warming, are gradually strengthening, breaking the barrier of normal ranges of temperature fluctuations. The heat budget of the biosphere is being influenced to the extent that the water capacity to resist temperature change is being gradually overreached.

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  eBook - ePub

  Minerals, Metals and Sustainability

  Meeting Future Material Needs

  • WJ Rankin(Author)
  • 2011(Publication Date)
  • CSIRO PUBLISHING

    (Publisher)

  3     An introduction to Earth

  Earth is the third planet from the Sun and orbits at an average distance of 1.50 × 108 km. The atmosphere extends about 150 km above the surface of the Earth and consists of mainly nitrogen (78% by volume), oxygen (21% by volume) and argon (0.9% by volume). Other components include water vapour, carbon dioxide, hydrogen and the inert (noble) gases. Together, the atmosphere and the Earth constitute the Earth system . The Earth has a diameter of about 12 750 km and a mass of 6.0 × 1024 kg. The Earth consists of the biosphere, the Hydrosphere, the lithosphere, the mantle and the core. Its structure is illustrated in Figure 3.1 . The biosphere and Hydrosphere form a thin layer over the lithosphere and are not shown in the figure. From a utilitarian point of view, the biosphere, Hydrosphere and the upper part of the lithosphere, called the crust , are of most interest. The crust is the ultimate source of the inorganic materials and fossil fuels used by humans, and the source of the nutrients required by living matter. The biosphere and Hydrosphere are the sources of materials made from living matter and of our food.

  This chapter examines the nature of the crust, Hydrosphere and biosphere and considers some implications of the law of conservation of matter and the laws of thermodynamics for the Earth system. The emphasis on the biosphere and Hydrosphere provides the background and context required for an understanding of the principles of environmental sustainability discussed in Chapter 4 . The crust, as the source of minerals and rocks, is examined in greater detail in Chapter 5 .

  3.1   THE CRUST

  The crust is the outermost layer of the Earth and is broadly of two types. The crust under the oceans (oceanic crust ) is typically 6–7 km thick and has an average density of around 3.0 g mL-1 . The crust making up the continents (continental crust ) is typically 30–50 km thick and has an average density of about 2.7 g mL-1

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