Power Plants

Soaps Synthetic Surfactants And Polymers

People Leader Clip Art

Soaps, surfactants and polymers are discussed together, following the discussion of petroleum, because most of the polymers and the surfactants in detergents are made mainly from chemicals derived from petroleum. Natural fats and oils are also used in the manufacture of surfactants (Figure 7-1). Soaps and surfactants contain segments of linear or lightly branched hydrocarbon chains that are, in the main, broken down to acetate up on metabolism by microorganisms in the environment. The...

Structure and Properties of Water

Chemical interactions in aqueous systems make up an important area of environmental chemistry, and the properties of water determine the behavior observed in solution. The water molecule is angular and, owing to the large difference in electronegativity of oxygen and hydrogen, quite polar. Consequently, water molecules will have strong electrostatic interactions with one another, and with dissolved ionic materials or other highly polar molecules. Because the electronegativity of oxygen is large...

Incoming Radiation from the

The discussion on the general circulation of the atmosphere in Chapter 2 presupposed that most of the heating of the earth's surface comes from solar radiation. The total solar energy reaching the surface of the earth each year is about 2 x 1021 kj (5 x 1020 kcal). Heat generated by radioactive processes in the earth and conduction from the core contribute 8 x 1017 kj (2 x 1017 kcal), and human activities contribute about 4 x 1017 kj (1017 kcal) per year. This means that less than 0.1 of the...

Introduction

Some 90 naturally occurring elements exist in the environment, each with its own chemistry. Those elements present in high abundance determine the nature of the environment as a whole through the properties and behavior of themselves or their compounds. These, and some of lesser abundance, have important biological roles. This chapter will consider how the chemistry of some of the most important elements relates to the properties of the environment and to biological effects. The elements...

Solid Waste Disposal And Recycling

Rotary Kiln Incinerator

Safe disposal of solid wastes is a serious problem. With our culture, which generates ever larger amounts of disposable materials and an increasing population density, we can no longer simply throw things away. If we discard them on land, they must be buried for aesthetic, safety, and health reasons. Even this is not enough, because toxic materials can be dissolved and enter the groundwater. Consequently, disposal site construction that minimizes leaching and includes elaborate leachate...

The Catalytic Converter

Catalytic Converters With Zeolite

2HC + CO + 2NO* + (3x02) 3C02 + H20 + N2 2HC + CO + 3O2 3CO2 + H2O FIGURE 6-14 Cutaway view of an automotive catalytic converter. The honeycomb (enlarged, bottom left) contains 300-4000 square channels per square inch on which the metal catalysts are coated. Emissions pass through these channels and react on the catalyst surface. Provided by R. J. Farrauto, Engelhard Corp., NJ. FIGURE 6-14 Cutaway view of an automotive catalytic converter. The honeycomb (enlarged, bottom left) contains 300-4000...

Phosphorus Fertilizers And Eutrophication

Eutrophication Fertilizers

In solution, the mono- and dihydrogen phosphate ions, HPO4 and H2PO4 are the predominant forms of phosphate at the usual pH values (since H3PO4 is a strong acid), and it is in these forms that phosphate is taken up by organisms. The orthophosphate ion PO3 will exist in significant concentration in solution only at very high pH values. Polyphosphates can be formed from the heat-induced condensation polymerization of simple orthophosphate units, for example, which occurs readily with pure...

Sea Otters and Other Marine Mammals

Effects Oil Spills Mammals

Marine animals (like sea otters are very susceptible to the toxic effects of the oil mainly because they spend most of their time in the sea, swimming and surfacing through the oil. Exxon expended 8 million dollars for the helicopter capture of 357 otters ( 80,000 per otter ), of which 234 survived. Many of the captured otters were not oiled or were only slightly oiled. Those that survived were cleaned and released, 45 with surgically implanted radio monitors. Only 22 of those with radio...

General Circulation Of The Atmosphere

Only very general patterns of atmospheric movement are within the scope of this chapter, where they are pertinent because we are interested in discussing general movements of pollutants and other constituents of the atmosphere. Atmospheric circulation will thus be considered in an extremely simplified manner. Books on meteorology, such as the ones given in the Additional Reading at the end of this chapter, may be consulted for further details. There are two major reasons for the existence of a...

Hydrocarbons and Other Emissions from Automobiles

Engine Out Emissions Lambda

The automobile is a major nonnatural source of hydrocarbons in the atmosphere. The photochemical reactions of its gasoline and exhaust gases is an important source of an array of atmospheric oxidants that cause eye irritation and other problems for animals and plants (Section 5.3). Automotive air pollution is caused by the evaporation of gasoline or by tailpipe emissions. Gasoline evaporation occurs during the filling of the gas tank, and by the heating and cooling the automobile, as a result...

Summary of Photochemical Smog

Photochemical Smog Reactions

Only a very small portion of the hundreds of reactions possible in polluted atmospheres have been presented, but these are representative of the types of mechanism being considered to account for photoinitiation, oxidation of NO and VOCs, and formation of noxious products associated with photochemical smog. Figure 5-12 shows a computer integration of the differential kinetic rate 45The oxidation of HOSO2. to H2SO4 in the troposphere is not simply the addition of another .OH radical. Rather, it...

Effluents from Nuclear Power Plants

A nuclear power plant is obviously not a source of greenhouse gases. If a 1000-MWe nuclear power plant is substituted for a coal-fired plant of the same size, the annual production of such gases is reduced by approximately the following amounts, depending on the composition of the coal and the type of pollution control equipment installed about 7 million tons of C02, about 100,000 tons of S02, about 25,000 tons of N0*, and about 1500 tons of particulates. In addition, there would be about 1...

Radon in the Air in Mines and Buildings

Adirondack Fire Tower

When it was observed in the 1920s that uranium miners suffered from a relatively high incidence of lung cancer, the trend was at first attributed to radon in the air in the mines. Later it was shown that the effect is caused not by radon itself, but by its two short-lived a-emitting daughters, 218Po (3.10 m) and 214Po (163.7 s).6 Thus, radon is really the carrier for its nonvolatile progeny, and because of its half-life of almost 4 days it can, once airborne, travel a considerable distance from...

Carbonic Acid

Carbonate Speciation Curve

The most important environmental acid is carbonic acid, which is produced in natural waters by the dissolution of CO2 gas. The dissolution of gaseous CO2 is comparatively slow the average lifetime of a CO2 molecule in the atmosphere is about seven years. The air-solution transfer process may be catalyzed by the enzyme carbonic anhydrase in waters containing biological materials. When CO2 enters solution, two steps are actually involved CO2(aq) + H2O H2CO3(aq) (9-18) The species CO2(aq)...

The Earths Crust

Current theories consider the earth to have formed from condensation of dust and gas in space. Gravitational and radiochemical heating melted the aggregated solids, and as the planet cooled, partial solidification and separation of materials took place. The present structure of the earth consists of a largely molten core composed chiefly of iron and nickel, surrounded by lighter rocks. The outer few miles, the crust, is the only portion of the earth that is accessible, and is the source of most...

The Greenhouse Effect

The present average temperature T of the earth's surface, taken at any one time over the whole surface of the earth, is close to 15 C (288 K). Thus, even though the temperature varies with time and place, the earth's surface must therefore radiate much like a blackbody at 15 C. Figure 3-5 shows the intensity of emission I( ) for blackbodies at 255 and 288 K. The wavelength for maximum radiation intensity is about 10 m in this temperature range, that is, in the infrared region of the spectrum....

Polychlorinated Cyclodienes

Plasty Technique

A series of bicyclic insecticides, mirex, chlordane, heptachlor, aldrin, and dieldrin, can be synthesized by the Diels-Alder addition of hexachlorocyclo-pentadiene to olefins, as follows The preparation of these compounds is shown in reactions (8-43) and (8-44). It is possible to use the Diels-Alder reaction to prepare a whole series of potential insecticides simply by varying the diene and olefin. Mirex, another insecticide, is prepared by the aluminum chloride catalyzed cyclodimerization of...

Uncatalyzed Ozone Destruction

Beer Lambert Ozone

5.2.3.1 Ozone in a Clean Stratosphere Below 100 km into the midmesosphere region, the three-body recombination of O atoms, reaction (5-21), becomes potentially important because of the increasing total third-body pressure. However, the O2 concentration is also increasing as we go to lower altitudes, increasingly leading to absorption of the solar radiation below 243 nm. Photodissociation of O2 is decreased, lowering the O atom concentration. Since the rate of reaction (5-21) varies as the...

Tin and Lead

Anorexia Organ Damage

Tin and lead are the last two members of the carbon family but, in keeping with the general tendency for metallic character to increase with atomic number in a family, they show typical metallic properties. However, they have comparatively weak electropositive characteristics and strong electron acceptor properties. Bonds to nonmetals such as carbon have considerable covalent character and make up an important aspect of their chemistry. Both tin and lead form compounds in which they have the...

Nitrogen Oxides N0X in the Absence of Volatile Organic Compounds VOCs

As pointed out in Section 6.7, the main anthropogenic sources of nitrogen oxides in a polluted atmosphere are mobile and stationary petroleum and coal combustion chambers, where inside temperatures and pressures are high enough for the fixation of nitrogen to occur, (NO* represents a mixture of oxides of nitrogen mainly NO and NO2) and where quenching to low temperatures outside the chambers is rapid enough to prevent the thermodynamically favored back-reaction (dissociation) from occurring....

Exercises

What weight of water would have to evaporate from 1 m3 of water to produce a temperature decrease of 1 degree celsius How much energy would be released to the atmosphere when this vapor condensed 9.2. What would be the temperature decrease required in 1 M3 of water to increase the temperature of an equal volume of air by 1 degree celsius Assume 25 C where the density of air is 1.1843 x 10 3 g ml, and no evaporation. 9.3. Henry's law constant for 02 in water at 25 C is 1.28x 10 3 mole...

Sulfur And The Sulfur Cycle

Sulfur Cycle

Sulfur is an important, relatively abundant, essential element. As is true of many elements, it takes part in a biogeochemical cycle discussed shortly. It is a major component of air pollution, particularly in industrialized areas, although natural sources of sulfur also contribute. Several oxidation states are encountered in environmental systems the most stable under aerobic conditions is S(VI) as in SO3 and sulfates. The reduced form S(-II) is encountered in organic sulfides, including some...

Properties And Reactions Of Atomic Nuclei Radioactivity And Ionizing Radiation

The physical properties, chemical reactions, toxicity, carcinogenicity, and other properties of an element or compound present in the environment and discussed in the preceding chapters are determined by the electronic configuration of the atom, ion, or molecule of interest. Except for the fact that the number of electrons in an atom is determined by the number of protons in its nucleus, there is generally no need to give further consideration to the nucleus when dealing with the basic...

Pressurized Water Reactor Power Plants

Pressurized Water Reactor Eccs

First developed for the propulsion of submarines and other naval vessels, PWRs are much more compact than the graphite-moderated reactors used in the nuclear weapons program during World War II.31 The PWR type of reactor was also a logical choice for central power stations because its compactness made possible the use of relatively small containment buildings and because the electric utilities were experienced in the use of liquid water and steam in their fossil-fueled power stations.32 In...

Oxidationreduction Processes

Pourbaix Diagram For Sulfur

The oxidation state of an atom in a molecule is a concept helpful in keeping account of electrons. In many cases it is an indication of the number of electrons involved in bonding, but this is not always true and the oxidation state (or oxidation number) need not have any physical meaning. The oxidation state is equivalent to the charge on a positive or negative ion in an ionic substance, while for a covalent compound it is arrived at arbitrarily by assigning the electrons in a bond to the most...

Computer Models

We have seen in Table 2-2 that humans are presently contributing a large amount of particulate matter, and, certainly, aerosols, to the atmosphere. If this material, like that emitted by volcanoes, can contribute to a cooling of the earth, presumably by increasing the earth's albedo, then this may partially mitigate the effects from the simultaneous C02 emissions by humans. We have definitely been increasing both the carbon dioxide and the particle and aerosol content of the atmosphere, and...

Zinc Cadmium and Mercury

Zinc, cadmium, and mercury make up one family of the periodic table. These three elements are representative metals possessing two valence electrons. Their position in the periodic classification immediately follows the transition series, and in keeping with the usual periodic trends, they have comparatively high electronegativity values for metallic elements and form bonds with non-metals of significant covalent character. The covalent properties are emphasized on going down the family from...

Haloorganics And Pesticides

Haloorganic compounds have many uses, such as pharmaceutical agents, fibers, building materials, agricultural chemicals, solvents, and cleaning agents. Many of these compounds are inexpensive to manufacture and are used in large quantities. Many were manufactured and deliberately distributed in the environment as pesticides to control plant and insect pests. Some were allowed to be released in the environment because their long-term toxicity and environmental hazards were not understood. Yet...

Coal Gasification

The gasification of coal was carried out extensively from about 1820 to 1920 for the production of coal gas, which was used for lighting (gaslights) and energy in the United States and elsewhere. However the discovery of abundant natural gas in the 1950s and the construction of pipelines to deliver the gas from the southern United States to the northeastern and western states resulted in the shift to the cleaner, cheaper natural gas as a fuel. As a consequence, the production of coal gas ceased...

Symbols and Abbreviations

Note Some of these symbols have other meanings when used in specific contexts other symbols that are used only in specific contexts may not be Earth's albedo reflectivity also Beer-Lambert proportionality constant also Extinction coefficient also efficiency of a fuel cell Wavelength also nuclear decay constant Orbital angular momentum quantum number along internuclear axis Frequency also kinetic rate also symbol for electron neutrino Absorption cross section, also nuclear reaction cross section...

Wastewater Treatment

Clean water is a vital commodity, and usage is now so extensive that waste-waters must be repurified to avoid destruction of aquatic ecosystems and because, often, the water will be reused. Industrial wastewater may require specialized treatment that depends on the contaminants, while treatment of domestic waste (sewage) involves more general procedures. A great deal of water is used for cooling purposes. Such water, if discharged back to freshwater systems, could lead to so-called thermal...

Absorption of Light

The rather simple example just presented can be used to point out one of the basic principles of photochemistry (the Grotthus-Draper law, first formulated early in the nineteenth century) for light to be effective in producing photochemical transformations, not only must the photon possess sufficient energy to initiate the reaction, it must also be absorbed. Thus, even though we see from equation (4-5) that a 243-nm photon possesses enough energy to break the oxygen bond, in fact oxygen is not...

Designation of Spectroscopic States

The recipes briefly summarized here are used in arriving at atomic and molecular state (energy) descriptions. The reader is referred to standard textbooks of quantum mechanics and spectroscopy, some of which are given in the Additional Reading, for the mathematical formulations of these principles. The state of the electron in the hydrogen atom or hydrogen-like ion (e.g., He+ and Li2+, each containing only one electron) is specified by the three quantum numbers n, i, and mi. The principal...

Integrated Pest Management

The present strategy is to manage the insect pests by use of all possible techniques in an integrated program rather than by relying on a single approach. The goal is to minimize the use of synthetic pesticides and related agents while maintaining crop yield, quality, and profitability. This strategy limits the buildup of pesticides in the environment, the presence of pesticide residues on fruit and vegetables, and the development of resistant insect strains. More emphasis is placed on the use...

Environmental Degradation

The organophosphorus insecticides undergo a very rapid hydrolysis in the environment. There is no buildup of residues however, frequent application of the pesticide is required. In the typical hydrolytic process given in reaction (8-67), the nitro group of parathion is reduced by soil microorganisms to give the nontoxic aminoparathion, which is stable and remains bound to the soil. It is not known whether this inactive form of parathion constitutes an environmental problem. Organophosphorus...

Types of Application

The many environmental applications of naturally occurring nuclides can be separated into three categories. The first category is the well-known use of isotopes as tracers. An example is measurement of the ratio of radiogenic, stable 87Sr to stable 86 Sr to trace the source of groundwater and its path in an aquifer. Another is the use of cosmogenic 7Be (53.28 d) as a tracer for river sediment and its resuspension. The second category includes the study of chemical and physical processes...

Isotope Fractionation

Because isotope fractionation (Section 13.2.2.1) is very small, except for XH and 2H, any effect on the normal chemical behavior of an element is usually ignored. However, when a change in the ratio of two isotopes occurs in some process in the environment, the change can be used to obtain very valuable information about the environment, especially the paleoenvironment. Extremely small changes in the abundance ratio of two isotopes of an element can be measured very accurately by mass...

El zAEl p Ve y1332

Negatron emission occurs when there is a transition between a discrete energy level in the emitting nucleus (zEl) and a discrete energy level in the product nucleus (z+1El). The difference between the two levels is fixed and determines the energy available to the negatrons. When many nuclei undergo a given transition, the negatrons are not monoenergetic but have energies between zero and the maximum available and, thereby, fail to conserve energy. They have a characteristic, continuous energy...

High Level Dose

Nonlinear Threshold Dose Response Curve

There is no single value for absorbed dose that marks a sharp cutoff between a high-level and a low-level dose of ionizing radiation.69 For each harmful health 69Sometimes an absorbed dose above about 1 Gy is referred to as a high-level dose. The U.S. Nuclear Regulatory Commission refers to a High Radiation Area as one in which an individual effect, there is a range of values of dose within which the severity or the number of occurrences of the effect correlates with the dose in a statistically...

Mechanism of Action of DDT and DDT Analogues as Pesticides

Insects sprayed with DDT exhibit hyperactivity and convulsions consistent with the disruption of the nervous system by DDT. Many theories have been suggested for the toxic effect of DDT, and the exact mechanism is not known. A theory that appears to be plausible and has some experimental basis suggests that the DDT molecules are of the correct size to be trapped in the pores of the nerve membranes, which are thus distorted, allowing sodium ions to leak through and depolarize the nerve cell so...

Resistance The Bugs Fight Back

1908 1940 1950 1960 1970 1980 1990 Year FIGURE 8-6 Chronological increase in the number of insect and mite species resistant to at least one type of insecticide (total), and species resistant to each of the five principal classes of insecticides. Not discussed in this chapter were polychlorinated cyclodiene (cyctodienes), pyreth-rums (pyrethroid), and carbamates. From G. P. Georghiou, in Managing Riointance to Agrochem-icals, ACS symposium series 421, p. 20. American Chemical Society,...

Chronic Toxicity of DDT and Related Compounds

Reproductive Toxicity Example

The large-scale use of DDT as an insecticide entailed the release of large amounts into the environment, where it and its degradation products persist for decades. These compounds are so volatile that, like PCBs, they were spread worldwide in small amounts by the global winds. Yet while the use of DDT was increasing, it was noted that there was a decrease in many species, especially those at the end of food chains, on earth. These included especially eagles, hawks, and falcons, birds that feed...

Other Chloroorganic Pesticides 891 Lindane 8911 Synthesis

Lindane, the 7-isomer of 1,2,3,4,5,6-hexachlorocyclohexane, is prepared by the photochemical initiated addition of chlorine to benzene, as shown in reaction (8-40). In this reaction four of the eight possible isomers of 1,2,3,4,5,6-hexachlorocy-clohexane, are formed in appreciable amounts. These isomers differ in the relative orientations of the chloro substituents. Axial (a) groups are perpendicular to the cyclohexane ring and are labeled in the a-isomer in reaction (840). Equatorial groups...

Waste Disposal

The environmental system consists of a very large amount of material about 5 x 1018 kg of air and about 1.5 x 1018m3 of water. In principle, comparatively large amounts of other materials can be dispersed in these, and consequently both the atmosphere and water bodies have long been used for disposal of wastes. This is sometimes done directly, and sometimes after partial degradation such as by incineration. In part, such disposal is based on the principle of...

About The Authors

Bailey is an inorganic chemist whose research involves the synthesis of metal ion complexes and their spectroscopic and electrochemical behavior and structures in a variety of media. He became interested in environmental problems as a result of being asked about the complexing of metal ions in natural waters and sediments, and to provide assistance in explaining the chemistry involved in a proposed method for scrubbing stack gases. With this interest, he joined with other...

Nuclear Fuel Requirements

A fission rate of 3.1 x 1010 fissions per second will provide 1W of power (thermal). For a power plant with a thermal output of 3000 MWt as heat or an electrical output of about 1000 MWe of electricity the number of 235U nuclei that must be fissioned per second is 9.3 x 1019.30 This corresponds to the fissioning of 3.1 kg of 235U per day. Uranium in spent fuel contains about 0.8 w 235U. 29Zircaloys are alloys of zirconium and tin with minor constituents. 30MWe indicates the rate at which...

Pourbaix Diagram Inox

Pourbaix Diagram Magnetite

Iron is a common and important element environmentally. It forms two oxidation states in nature, Fe II and Fe III . The latter is of greater importance. In water solution, Fe III forms a strongly hydrated ion in which the water molecules are bonded to the iron by coordinate, largely covalent bonds to give the species Fe H20 6 3 . The shift of electron density to the iron and out of the 0H bonds of the coordinated water molecules makes their protons acidic and results in dissociation equilibria...

Complexing in Natural Systems

Most natural water systems contain an excess of Ca(II) compared with the available strong ligands. Consequently, although calcium complexes are rather weak, the amount of ligand left over to complex with trace metals is often small, perhaps often negligible. In some situations, however, complex formation is believed to be important in natural waters for example, when the concentration of dissolved metal ions is higher than expected in the solubiliza-tion of metal ions for transport in soils and...

Colloidal Material

Although we have been discussing concentrations of dissolved substances, a good deal of material may be present in water as suspended particles. If the particles are small enough, they may pass through filters and travel in aqueous systems very much like material in true solution. Such suspensions of small particles are called colloids. Typically, colloids are particles in the size range of 1-10 m, although some suspended material in natural water systems may be larger than this. Mineral...

Alkaline Earth Metals Beryllium Magnesium Calcium Strontium and Barium

Magnesium and calcium ions are extremely common in natural water systems, with calcium carbonate (limestone) and dolomite CaMg(CO3)2 being two widespread natural sources. Solubility in water is influenced by pH and CO2 content. The two ions are responsible for the hardness of water, which manifests itself by precipitation with soaps, the calcium carbonate deposits that form when water is heated (boiler scale), and so on. For many purposes (washing, waters for certain heat exchange processes),...

Sources Used in Nuclear Medicine

In nuclear medicine, a radiopharmaceutical, also called an imaging agent or a tracer and containing a particular radionuclide in a specific chemical form, is administered orally or intravenously to a patient. Diagnostic imaging is the usual purpose but, less frequently, radiation therapy is performed.23 The radiation that is measured to obtain an image of an organ originates within the body rather than in an external source of x or y rays. Radionuclides suitable for diagnostic imaging decay by...

Catastrophic Oil Spills

Oil Tanker Ship Spill

FIGURE 6-5 The midsize oil tanker Ventiza, built in 1986. It is 247m (811 ft, or 2.7 U.S. football fields) long and 41.6 m (136 ft) wide. In 2000 the largest tanker in the world was the Jahre Viking, which is 458m (1504ft, or 5 U.S. football fields) long and 69m (266ft, or 0.89 U.S. football field) wide. From http www.rigos.com ventiza.html. Also see color insert. FIGURE 6-5 The midsize oil tanker Ventiza, built in 1986. It is 247m (811 ft, or 2.7 U.S. football fields) long and 41.6 m (136 ft)...

Biochemical Methods Of Insect Control

Insect Repellent Permission Form

The development of insect resistance has been an important factor prompting the search for methods of insect control that are not totally dependent on the use of pesticides. These methods are outlined briefly because their adoption by farmers will help both to minimize the amounts of synthetic pesticides in the environment and to slow the development of resistant strains of insects. It should be noted that the majority of U.S. farmers use synthetic pesticides, but the amounts used per acre have...

Offshore Wells

Oil Spill Colour Sunglasses

Leakage from offshore oil wells is responsible for only about 2 of the oil in the sea (Figure 6-2). Thus it is surprising that there is always major opposition from local communities when it is proposed to drill for oil along the East or West coasts of the United States. This mind-set is probably due to the images of the well that blew off Santa Barbara, California, in January 1969. This oil was pressurized by methane gas in the ground, and the pressure forced out the oil when the well was...

Water Cooled Graphite Moderated Reactor Power Plants

The first-ever nuclear power station (5 MWe) was built in the USSR and began operation in 1954. Its reactor was fueled with uranium metal (5 235U), moderated with graphite, and cooled with pressurized water that flowed through a primary loop and then through a heat exchanger to generate steam in a secondary loop. Later (in the 1970s), large boiling water, pressure tube, graphite-moderated high-power boiling channel reactors were built for both the production of Pu and the generation of power....

Materials Used for Building Construction

Buildings can provide some shielding from extraterrestrial radiation and from 7 radiation from rocks and soil outside the buildings. However, certain materials of construction (e.g., stone, especially granite), containing uranium or a high potassium content, can raise the dose of ionizing radiation received by the occupants of a building. In the 1950s it was shown that the concentration of radon could reach 1.1kBq m3 (30 pCi liter) in the air of a residence that was heated by radiant heating...

Coal Formation and Structure

Coal was probably the first of the fossil fuels to be used for energy. It was recognized as an energy source by the Chinese around 1100 b.c., while the ancient Greeks were probably the first of the western cultures to be aware of coal. The Romans reported that the flammable earth was being mined in Gaul when they captured that section of Europe. The first known coal mines in North America were operated by the Hopi Indians of Arizona some 200 years before Columbus. Coal occurs mainly in the...

Additional Reading

Duplessy, Climate and Geo-Sciences. A Challenge for Science and Society in the 21st Century. Kluwer Academic, Dordrecht, 1989. Boeker, E., and R. van Grondelle, Environmental Physics. Wiley, New York, 1995. Calder, N., The Weather Machine. How Our Weather Works and Why It Is Changing. Viking Press, New York, 1974. Gribbin, J., Forecasts, Famines and Freezes. Climate and Man's Future. Walker New York, 1976. Gribbin, J., Future Weather and the Greenhouse...

Hooch2n7ch2cooh

It coordinates as the anion, with an oxygen from each ionized carboxyl group and the two nitrogens being the donor atoms. (It may be added parenthetically that while EDTA is potentially hex-adentate, it may not be so in all its complexes. For example, a water molecule may occupy the sixth coordination site, leaving a carboxyl group free.) EDTA is widely used in analytical chemistry and for other purposes that call for the sequestration of metal ions in soluble...

Thorium and Actinium Series

Symbol used in the early studies of naturally occurring radioactivity is given in parentheses MsThj , mesothorium I RdTh , radiothorium Tn , thoron. 7 indicates low intensity 1-5 7 rays with intensity below 1 are not included. Where both a and are given, branched decay occurs. 90 Th 232 89 Ac 88 Ra 228' 87 Fr 86 Rn 85 At 84 Po 83 Bi 82 Pb 81 Tl FIGURE B-1 Thorium 4k series. The main sequence is indicated by arrows and a dash. Symbol used in the early studies of naturally occurring...

La nuclear fission power plants

The fission rate and, therefore, the power level in a reactor, is controlled by rods that can be moved in or out of the reactor core. These control rods contain an element having at least one stable isotope that is a neutron poison'' (i.e., an isotope with a high absorption cross section for thermal neutrons). Examples are cadmium (113Cd) and boron (10B) as boron carbide. When the rods are fully inserted, the reactor is shut down. The reactor can be shut down by an operator or automatically by...

Gas Cooled Graphite Moderated Reactor Power Plants

Gas-cooled (C02), graphite-moderated reactors (GCRs) using natural uranium and a magnesium alloy (Magnox) as cladding and advanced gas-cooled reactors (AGRs) using LEU fuel (U02) have been used in power plants in the United Kingdom for many years. These power plants, which generate steam, operate at higher temperatures than do LWRs. A different type of graphite-moderated, high-temperature, gas-cooled reactor, the HTGR, has been studied in Germany and in the United States for many years....

Boiling Water Reactor Power Plants

As the name implies, the water that removes the heat from the reactor core of the boiling water type of LWR is allowed to boil and generate steam directly within the core.34 The steam thus generated (at about 288 C and 10MPa) is used directly to drive the turbine. Steam is delivered to the turbine via a steam separator and a drier that removes the liquid from the water-steam mixture leaving the reactor. Volatile fission products that escape from any defective fuel rods are carried with the...

Types of Nuclear Power Reactor

Several types of nuclear fission reactor have been used as heat sources to generate steam in power plants. A power reactor may be identified in different ways. For example, it may be a thermal or a fast reactor, depending on the energy of the neutrons causing fission (see Chapter 13, Section 13.7.3). A thermal reactor is usually identified according to the neutron moderator used. If the moderator and coolant are different, both are specified. Table 14-8 lists characteristics used to identify...

Uranium and Thorium Ores

There are over 100 minerals that contain uranium. Only a few of these are found in deposits that are economically significant. The uranium content of an ore is expressed as a percentage of U3Os and is commonly in the range of 0.1-0.5 , although ores with much higher uranium content have been found. Examples of specific ores are uraninite, which varies in composition from UO2 to UO2 2UO3 or U3Os (known as pitchblende), and carnotite (K2O 2UO3 V2O5 xH2O), which, in the past (before 1943), was...

Cosmic Radiation

When cosmic radiation was discovered in 1912, it was believed to consist of penetrating, high-energy y rays which were, therefore, called cosmic rays. The radiation is now known to consist mainly of particles having energies in the range of 108 1019 eV. Although much has been learned about cosmic radiation, especially in recent years from data obtained by means of satellites and spacecraft, many mysteries remain. It is known that the sun is a varying source of cosmic radiation at the low end of...

Residence Times

Where dC dt rate of change in concentration. Inflow and outflow may include gain or loss through chemical reactions in addition to physical Residence Times for Some Elements in the Oceans2 Residence Times for Some Elements in the Oceans2 102 106 103 101 107 107 103 107 102 aSee S. M. Libes, An Introduction to Marine Biogeochemistry, Wiley, New York, 1992, p. 638, for a more complete list. aSee S. M. Libes, An Introduction to Marine Biogeochemistry, Wiley, New York, 1992, p. 638, for a more...

Composition Of Water Bodies

The composition of natural water bodies depends on gain and loss of solutes through both chemical reactions and physical processes. For the most part, solutes undergo a geological cycle in which materials entering solution as products of weathering reactions of rocks, volcanism, and so on are carried to the oceans where they undergo further reaction, are deposited in sediments, and eventually are reincorporated into new rocks, which may repeat the cycle. Obviously, these processes have a long...

Complex Stability and Lability

The formation of a complex ML n+ in solution is part of an equilibrium process that can be represented by a series of steps, each described by its own equilibrium constant (often called formation constant) M(H20)6 n+ + L M(H2 )5L n+ + H2O (9-53) M(H20)5L n+ + L M(H20)4L2 n+ + H2O (9-55) 2 M(H2O)5L + L 1 (The ligand L has been written as a neutral species for simplicity it may equally well be an anion.) The overall process is M(H2O)6f + + 6L ML6 b+ + 6H2O (9-57) and the overall equilibrium...

Metal Ligand Preferences

The various metals show differing complexation tendencies and preferences for donor atoms. Ions of the alkali metals (Li, Na, K, Rb, Cs) have little electron pair acceptor tendency, although in aqueous solution they are hydrated by predominantly ion-dipole interactions. This tendency is greater for the smaller ions, which also have the lowest energy orbitals and greatest covalency in their interactions. Complexing is weak for this family. The alkaline earth ions, especially Mg(II) and Ca(II),...

Coordination Number and Geometry

The number of donor atoms linked to a metal ion is the coordination number of the complex. The most common coordination number is 6, with the donor atoms lying at the corners of a regular or distorted octahedron as illustrated in Figure 9-16. A 4-coordinate, tetrahedral structure also is common, and a variety of other structures are found in specific examples. The coordination geometry (i.e., the arrangement of the donor atoms around the central metal ion), favored by a given element may vary...

Effects Of Temperature And Pressure On Equilibrium

Equilibrium constants vary with temperature and pressure in a way that can be predicted thermodynamically. The equilibrium constant is related to the standard free energy change of the process AGO -RT ln K AHO - TAS (9-33) where AG is the standard free energy change, T the absolute temperature, R the gas constant, AH the standard enthalpy change, and AS the standard entropy change, for the reaction. In simple terms, AH is a measure of the change in energy (e.g., bond energies and other...

General Behavior

The most useful definition of acids and bases in aqueous chemistry is the Bransted-Lowry definition an acid is a proton donor a base is a proton acceptor. This definition may be illustrated by an equation, Here, HCl is acting as the acid (proton donor) and H2O as the base (proton acceptor) as the reaction goes from left to right. Such reactions are very rapid and reversible, although, as here, the reaction may go very far to the right. It may be noted that if this reaction were reversed, H3O+...

Use Of Petroleum In The Internal Combustion Engine

One of the major uses of petroleum as an energy source is in the automobile internal combustion engine. Most automobiles are driven by a four-stroke-cycle piston engine (Figure 6-10). Gasoline is mixed with air in the carburetor and drawn into the cylinder on the first stroke. The oxygen-gasoline vapor mixture is compressed on the second stroke and ignited by the spark plug. The expanding gases formed by combustion then drive the piston down on the third stroke, the stroke that provides the...

Fate Of An Oil Spill

The dispersal of an oil spill is illustrated in Figure 6-7. When oil is spilled, the lower boiling fractions evaporate and dissolve rapidly, with the result that 25-50 of a crude oil spill is soon lost from the surface of the sea. The extent to which these processes occur is determined by the temperature of water and the intensity of wind and wave action. The residue of higher molecular weight hydrocarbons is slowly degraded by microorganisms. This process may be slow because the other...

Transportation

The major source of oil in the marine environment is spills resulting from crude oil transport. There are some 6000 oil tankers worldwide that transport crude oil, and these vessels are designed to ride low in the water when carrying a full load. After they unload their cargo they must take on seawater as ballast for their return trip to the oil fields. This ballast is pumped into holding ponds where the oil can be recovered. However, this ballast, along with the residual crude oil in their...

Natural Sources

A major oil seep, 3600 gal day, is at Coal Oil Point near Santa Barbara on the coast of southern California. This seep produces an extensive oil slick on the ocean and often results in tar accumulation on the shore. The oil also supports a community of marine microorganisms that metabolize these hydrocarbons. Most seeps produce less than 40 gal day and the environmental effect appears to be quite limited. The contribution of natural sources to the oil in the marine environment is 9 of...

The General Nature of Smog

In polluted lower regions of the troposphere, particularly in urban environments (see Section 3.4), copious quantities of chemical compounds are released into the atmosphere, leading to a number of complex photochemical reactions producing a variety of eye and throat irritants, aerosols and reduced visibility, and other irritating or destructive species manifesting themselves in the general category of photochemical smog. Unlike the notorious smogs (smoke plus fog) that were a part of London...

Reactions In The Upper Atmosphere 521 Nitrogen

We have seen that molecular nitrogen is the most prevalent species in the atmosphere. The reason that nitrogen is not so important photochemically is its large bond energy (7.373 eV, corresponding to a photon of wavelength X 169 nm), which limits its photodissociation chemistry to areas above the ozone layer. Molecular nitrogen absorbs only weakly between 169 and 200 nm, absorption in this region leading to a spin-forbidden excitation from ground-state N2 to the (3X+) excited state 1The...

Kinetics Of Photochemical Processes

The second principle of photochemistry, that absorption is a one-photon process, taken together with quantum theory, requires that each quantum that is absorbed bring about a change (excitation) in that one molecule. In essence, this may be considered to be a bimolecular process involving interaction of one photon and one molecule. What happens to the excitation energy, however, depends on the amount of energy absorbed and the nature of the excited molecule. For example, the excited molecule...

Kinetics Of Thermal Processes

Most chemical reactions are kjnetjeally complex. That is, they take place by means of a series of two or more consecutive steps rather than by means of a single encounter of the reacting species. Nevertheless, the overall reaction between, say, two reactants A and B can be represented by the generalized equation aA + bB cC + dD + (4-15) where the stoichiometry of the reaction is given by the coefficients a, b, c, d, The rate, v, is then given by the differential equation _ _idnA _ _idnB 1dnc...

Temperature Inversions

When pollutants are trapped for a long time over a city, it is usually because of a temperature inversion above the city. This may result in accumulations that can reach lethal proportions, at least for the sick and elderly. Temperature inversions occur when air at some elevation in the troposphere ceases to decrease smoothly in temperature with increasing altitude as is normal near the surface of the earth (see later Figure 3-20). At a temperature inversion, the air temperature increases with...

The Milankovitch Theory of Earths Orbital Variations

The Milankovitch theory attempts to account for the existence of Ice Ages at various intervals (see Figure 3-9). This theory makes use of the dependence of the insolation, the total solar radiation impinging on the earth in different latitudes, on a number of factors involving the earth's revolution around the sun. There is quite a bit of controversy about the particular latitudes at which such variations in insolation are most important, but most workers feel that changes in insolation at high...

General Comments

Climate is mainly effected by wind patterns over the earth's surface, and these changes in wind patterns are generally caused by changes in the earth's energy balance, as mediated, among other things, by changes in ocean currents and ocean temperatures. A well-known example is the El Nino Southern Oscillation (ENSO), the eastward (toward South America) expansion of a pool of warm water usually found in the western Pacific Ocean global temperatures generally rise during an ENSO. The average...

Climate History Of The Earth

Before trying to decide whether humans are actually succeeding in changing the earth's climate at present, we must consider what sorts of climate change occurred before humans evolved, and what climate changes occurred before the major industrialization of the twentieth century. It is, unfortunately, beyond the scope of this chapter to discuss the various methods of calculating average temperatures at different times in the past these methods are discussed in some of the references at the end...

Other Factors

The mean temperature of the earth's surface is certainly affected by the magnitude of the greenhouse effect, but it is also affected by the percentage of incoming solar radiation that is reflected back out to space, that is, by the earth's albedo. It has already been stated that approximately 30 of the incoming radiation is immediately reflected. This is an average value Table 3-1 shows the albedo of various major features on earth. Major changes in cloud cover, snow and ice, field and forest,...

Extent Of The Atmosphere And Its Temperature And Pressure Profile

Roughly 5.1 x 1018 kg of atmosphere is distributed over the 5.1 x 1014 m2 of the earth's surface. This means that atmospheric pressure at sea level is about 104kg m2, or 103 g cm2. This is approximately equivalent to one standard atmosphere of pressure (1013 mbar). Most of the atmosphere is fairly close to the surface of the earth. Fifty percent of the atmosphere is within 5 km (3 mi) of sea level, that is, at a height of somewhat more than 5 km above sea level, atmospheric pressure is 0.5 atm....

Particulate Constituents Of The Atmosphere

Table 2-1 does not include the particulate matter,'' dust, or, in general, the nongaseous matter that is usually present in the atmosphere. These are particles, which are 10 7 10 2 cm in radius, that is, from approximately molecular dimensions to sizes that settle fairly rapidly. Particulate matter in the atmosphere can be natural or man-made. Table 2-2 gives some estimates of the tonnage of particles with radii less than 2 x 10 3 cm (20 m) emitted to the atmosphere each year. Table 2-2...

Evidence and General Theory

Unfortunately, there is no agreement in the literature either on the composition or on the time of origin of the earth's original atmosphere. Evidence for the composition of the atmosphere at earlier times comes from a study of objects that were formed in contact with the atmosphere at those times. These objects may have changed since, but they still provide us with clues about the conditions existing when they were formed. The earliest such objects in existence are sedimentary rocks about 3 x...