Water, air, earth, life, and technology are strongly interconnected as shown in Figure 1.2, which, in a sense, summarizes and outlines the theme of the rest of this book. Traditionally, environmental science has been divided into the study of the atmosphere, the hydrosphere, the geosphere, and the biosphere.
However, for better or for worse, the environment in which all humans must live has been affected irreversibly by technology. Therefore, technology is considered strongly in this book within a separate environmental sphere called the anthrosphere in terms of how it affects the environment and in the ways by which, applied intelligently by those knowledgeable of environmental science, it can serve, rather than damage, this Earth upon which all living beings depend for their welfare and existence.
The strong interactions among living organisms and the various spheres of the abiotic (nonliving) environment are best described by cycles of matter that involve biological, chemical, and geological processes and phenomena. Such cycles are called biogeochemical cycles, and are discussed in more detail in Chapter 2 and elsewhere in this book.
In light of the above defi nitions, it is now possible to consider environmental chemistry from the viewpoint of the interactions among water, air, earth, life, and the anthrosphere as outlined in Figure 1.2. These fi ve environmental “spheres” and the interrelationships among them are summa-rized in this section. In addition, the chapters in which each of these topics is discussed in greater detail are designated here.
1.4.1 WATERANDTHE HYDROSPHERE
The hydrosphere contains the Earth’s water, a vitally important substance in all parts of the environ-ment. Water, the environmental chemistry of which is discussed in detail in Chapters 3 through 8, is an essential part of all living systems and is the medium from which life evolved and in which life exists. Water covers about 70% of the Earth’s surface. Over 97% of the Earth’s water is in oceans, and
Into the river
Out the door Up the stack
FIGURE 1.1 In the “bad old way” of doing things that prevailed until the mid-1900s, and even today in some places, wastes and by-products of chemical operations were commonly discarded to waterways, sent up stacks, or dumped in the geosphere, resulting in enormous environmental problems.
6 Environmental Chemistry
most of the remaining freshwater is in the form of ice. Therefore, only a relatively small percentage of the total water on Earth is actually involved with terrestrial, atmospheric, and biological processes.
Water plays a key role in many segments of the anthrosphere, such as in boilers or municipal water distribution systems. Energy and matter are carried through various spheres of the environ-ment by water. Water leaches soluble constituents from mineral matter and carries them to the ocean or leaves them as mineral deposits some distance from their sources. Water carries plant nutrients from soil into the bodies of plants by way of plant roots. Solar energy absorbed in the evaporation of ocean water is carried as latent heat and released inland. This process provides a large fraction of the energy that is transported from equatorial regions toward the Earth’s poles and that powers massive storms in the atmosphere.
1.4.2 AIRANDTHE ATMOSPHERE
The atmosphere is a thin protective blanket that nurtures life on Earth and protects it from the hos-tile environment of outer space by absorbing energy and damaging ultraviolet radiation from the sun and by moderating the Earth’s temperature to within a range conducive to life. It is the source of carbon dioxide for plant photosynthesis and of oxygen for respiration. It provides the elemental nitrogen that nitrogen-fi xing bacteria and ammonia-manufacturing industrial plants use to produce
Atmosphere Hydrosphere
Biosphere Geosphere
Anthrosphere
Precipitation, water vapor, hydrologic cycle, energy, CO2, O2
Biomass, nutrients, H2O, CO2, O2
Particulate mineral matter, H2S, CO2, H2O
Nutrients, organic matter
Energy, nitrogen CO
2, O
2
Water, salts Minerals, raw materials,
energy, wastes
Biopolymers, pesticides, toxicants, genetic engineering N
2, fixed N, CO
2, O
2, pollutants
Transportation, industrial water, raw materials, Water
vapor Ca
2+, HCO
– 3
FIGURE 1.2 Illustration of the close relationships among the air, water, and earth environments with each other and with living systems, as well as the tie-in with technology (the anthrosphere).
The Environment and Sustainability Science 7 chemically bound nitrogen, an essential component of life molecules. As a basic part of the hydro-logic cycle (Chapter 3, Figure 3.1), the atmosphere transports water from the oceans to land.
Atmospheric science deals with the movement of air masses in the atmosphere, atmospheric heat balance, and atmospheric chemical composition and reactions. Atmospheric chemistry is covered in Chapters 9 through 14 of this book.
1.4.3 EARTH, THE GEOSPHERE
The geosphere, discussed in general in Chapter 15, consists of the solid earth, including soil, which supports most plant life (Chapter 16). The geosphere is composed of a solid, iron-rich inner core, a molten outer core, mantle, and the crust. The crust, only 5–40 km thick, is a thin outer skin com-posed largely of lighter silicate-based minerals and is the most important part of the geosphere insofar as interactions with the other spheres of the environment are concerned. It is that part of the Earth upon which humans live and from which they extract most of their food, minerals, and fuels.
Geology is the science of the geosphere and is very important in considerations of the environ-ment. It pertains mostly to the solid mineral portions of the Earth’s crust. But it must also consider water, which is involved in weathering rocks and in producing mineral formations; the atmosphere and climate, which have profound effects on the geosphere and interchange matter and energy with it; and living systems, which largely exist on the geosphere and in turn have signifi cant effects on it.
Modern technology, for example, the ability to move massive quantities of dirt and rock around, has a profound infl uence on the geosphere.
1.4.4 LIFE, THE BIOSPHERE
All living entities on the Earth compose the biosphere. Living organisms and the aspects of the environment pertaining directly to them are called biotic, and other portions of the environment are abiotic. Biology is the science of life. It is based on biologically synthesized chemical species, many of which exist as large molecules called macromolecules. As living beings, the ultimate concern of humans with their environment is the interaction of the environment with life. Therefore, biological science is a key component of environmental science and environmental chemistry.
The role of life in environmental science is discussed in the following section and in numerous other parts of this book. The crucial effects of microorganisms on aquatic chemistry are covered in Chapter 6. Chapter 22 addresses biochemistry as it applies to the environment. The effects on living beings of toxic substances, many of which are environmental pollutants, are addressed in Chapters 23 and 24. Other chapters discuss aspects of the interaction of living systems with various parts of the environment.
1.4.5 TECHNOLOGYANDTHE ENVIRONMENT
Technology refers to the ways in which humans do and make things with materials and energy, that is, how they construct and operate the anthrosphere. Technology is the product of engineering based on science, which explains interrelated natural phenomena of energy, matter, time, and space.
Engineering applies science to provide the plans and means to achieve specifi c practical objectives.
Technology uses these plans to carry out desired objectives.
It is essential to consider technology, engineering, and industrial activities in studying environ-mental science because of the enormous infl uence that they have on the environment. Humans will use technology to provide the food, shelter, goods, and transportation that they need for their well-being and survival. The challenge is to integrate technology with considerations of the environment and ecology such that the two are mutually advantageous rather than in opposition to each other.
Technology, properly applied, is an enormously positive infl uence for environmental protection.
The most obvious such application is in air and water pollution control. As necessary as “end-of-pipe”
8 Environmental Chemistry measures are for the control of air and water pollution, it is much better to use technology in
manu-facturing processes to prevent the formation of pollutants. Technology is being used increasingly to develop highly effi cient processes of energy conversion, renewable energy resource utilization, and conversion of raw materials to fi nished goods with minimum generation of hazardous waste by-products. In the transportation area, properly applied technology in areas such as high-speed train transport can enormously increase the speed, energy effi ciency, and safety of means by which people and goods are moved.
Until very recently, technological advances were made largely without heed to environmental impacts. Now, however, the greatest technological challenge is to reconcile technology with envi-ronmental consequences. The survival of humankind and of the planet that supports it now requires that the established two-way interaction between science and technology become a three-way rela-tionship including environmental protection and emphasizing sustainability.
1.5 ECOLOGY, ECOTOXICOLOGY, AND THE BIOSPHERE