4.5 Generating carbon — the legacy of volcanoes

What is the origin of the carbon within the carbon cycle? Figure 1.9 showed that the great
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3.3 The Earth's internal heat

The occurrence of both volcanoes and hot springs shows that the Earth's interior is hot, producing molten rock at temperatures up to 1250 °C, and also superheated steam. However, these phenomena are mainly confined to several narrow zones along the world's active plate boundaries. Many measurements have now been made of the amount of heat flowing from the Earth's interior. Outside the distinctive zones mentioned above, heat flow varies from 40–120 milliwatts per square metre (mW m−2
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2.3 Broadband spectra

The broadband spectrum is the spectrum over all the observed wavelength ranges. To plot the broadband spectrum of any object it is necessary to choose logarithmic axes.

  • Why is it necessary to use logarithmic axes?

  • Because both the spectral flux density, Fλ, and the wavelength vary by many powers of 10.

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3.3 The consensus conference concept

Consensus conferences were developed in the USA in the late 1970s. Originally called ‘consensus development conferences’, the National Institute of Health used these conferences as a means of fostering social acceptability of medical practices for which scientific expertise could not provide unequivocal answers to questions with a social dimension (Jørgensen, 1995). The success of consensus conferences in the USA meant that they were soon adopted in Europe. They have proved particularly
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7.5 Control measures

7.5.1 Control measures to avoid exposure

There are four main methods of exposure to chemicals:

  1. Inhalation – This is the main method of exposure to volatile solvents and gases.

  2. Skin absorption – Certain chemicals possess the ability to penetrate through pores of skin (for example, mercury compounds and hydr
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6.2 Chemicals (Hazard Information and Packaging for Supply) Regulations CHIP3

These regulations, which were first introduced in 1992, are known as CHIP1 and these were last revised in 2002 and called CHIP3. They are currently being revised again in 2005 to keep up with developments in the field of health and safety.

Figure 7

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Acknowledgements

The content acknowledged below is Proprietary (see terms and conditions). This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:

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3.5 A new life

There is a common belief that life begins at the moment of conception, i.e. when a sperm fuses with an egg. This is a step forward from past years, when life was alleged to start at the time of ‘quickening’, i.e. when a woman could feel her fetus moving inside her. However, both these opinions suffer from an underlying falsehood: that life ‘begins’ at all. Life is a continuum; gametes are produced by living parents, and fuse to produce new living individuals, but unfused gametes are n
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Learning outcomes

After completing this unit you should be able to:

  • Define and use, or recognize definitions and applications of, each of the terms printed in bold in the text.

  • Explain the scientific basis for the main methods of contraception. (Question 1)

  • List the factors affecting fertilization. (Questions 2 and 5)

  • Describe with the help of diagrams the early stages of embryonic development. (Question 3)

  • <
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3.4.7 Induced earthquakes

Some reservoirs cause earthquakes to occur. This is perhaps not so surprising, as earthquakes are caused by stress in rocks, and the addition of a large mass of water in a reservoir on top of the rocks at the Earth's surface stresses the rocks and can trigger an earthquake. Not all reservoirs induce earthquakes: it is in general only the larger reservoirs, or the deeper ones (over 100m deep), and only if the reservoir is built in an earthquake area, releasing stress already stored in t
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Introduction

We have seen that where precipitation reaches the ground, some runs off the surface into streams and rivers and some of it infiltrates, passing through the soil. Water that reaches the water table to become groundwater may eventually re-emerge at the surface as springs where the water table intersects the surface. Almost all streams and rivers have springs or seepages as their ultimate source, or are fed by them at various points along their courses.

This unit is from our archive and is
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3 Summary

Power output from wind turbines is proportional to the area swept by their blades, and to the cube of wind speed. The narrow range of useable wind speeds restricts the areas where wind energy can be exploited.

Wind power has great potential, but has three main drawbacks. Output depends on intermittent wind speeds, irregular distribution of suitable wind speeds, and occupancy of large areas of land.


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Except for third party materials and otherwise stated (see terms and conditions), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence

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1 Solar energy

The Sun will radiate energy until it ceases thermonuclear fusion, in around 5 billion years. The solar power that enters the Earth's system is 1.1 × 105TW (0.3 × 105 TW to atmospheric heating and 0.8 × 105 TW absorbed at the surface – Figure 1). This is equivalent to a global e
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3 Hot dry rock (HDR) fields

Heat flow through some parts of the continental crust can be well above normal locally because the underlying rocks contain abnormally high concentrations of uranium, thorium and potassium, which generate considerable heat. To add significantly to surface heat flow and thereby create high-temperature anomalies at shallow depths requires a large volume of such radioactive rocks. This condition is satisfied by some, but not all, granitic igneous intrusions, whose original magma became ch
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Learning outcomes

By the end of this unit you should be able to:

  • explain the principles that underlie the ability of geothermal energy to deliver useable energy;

  • outline the technologies that are used to harness the power of geothermal energy;

  • discuss the positive and negative aspects of geothermal energy in relation to natural and human aspects of the environment.


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6 Summary

Nuclear power generation results from fission of uranium isotopes when bombarded by neutrons. Conventional burner reactors require relatively scarce uranium-235, whereas fast breeder reactors (which have not yet been developed on any significant scale) would exploit more abundant uranium-238.

In the early 21st century over 400 nuclear — mainly burner — reactors produced 16% of global electricity demand.

The UK played a leading role in nuclear power developments during the 1950
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4.5 Geological criteria for safe radioactive waste disposal

Even in the best of circumstances, containers such as the one shown in Figure 19 will survive for only 100–1000 years, although the glass itself may inhibit the migration of radioactive isotopes for a further 1000 years. So, in view of the long decay times (Author(s): The Open University