environmental biochemistry. A related area, toxicological chemistry, is the chemistry of toxic substances with emphasis upon their interactions with biologic tissue and living organisms. 2 Toxicological chemistry, which is discussed in detail in Chapters 22 and 23, deals with the chemical nature and reactions of toxic sub stances and involves their origins, uses, and chemical aspects of exposure, fates, and 1.3. WATER, AIR, EARTH, LIFE, AND TECHNOLOGY In light of the above definitions, it is now possible to consider environmental chemistry from the viewpoint of the interactions among water, air, earth, life, and the anthrosphere outlined in Figure 1. 1. These five environmental"spheres"and the interrelationships among them are summarized in this section. In addition, the cha ters in which each of these topics is discussed in greater detail are designated here water and the hydrosphere Water, with a deceptively simple chemical formula of H,O, is a vitally important substance in all parts of the environment. Water covers about 70% of Earth's surface. It occurs in all spheres of the environment-in the oceans as a vast reservoir of saltwater. on land as surface water in lakes and rivers. underground as groundwater, in the atmosphere as water vapor, in the polar icecaps as solid ice, and in many segments of the anthrosphere such as in boilers or municipal water distribution systems. Water is an essential part of all living systems and is the medium from which life evolved and in which life exists Energy and matter are carried through various spheres of the environment 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. The accompanying release of latent heat provides a large fraction of the energy that is transported from equatorial regions toward Earths poles and owers massive storms Water is obviously an important topic in environmental sciences. Its environ- mental chemistry is discussed in detail in Chapters 3-8 Air and the atmosphere The atmosphere is a protective blanket which nurtures life on the Earth and protects it from the hostile environment of outer space. It is the source of carbon dioxide for plant photosynthesis and of oxygen for respiration. It provides the itrogen that nitrogen-fixing bacteria and ammonia-manufacturing industrial plants use to produce chemically-bound nitrogen, an essential component of life molecules As a basic part of the hydrologic cycle( Chapter 3, Figure 3. 1), the atmospher transports water from the oceans to land thus acting as the condenser in a vast solar powered still. The atmosphere serves a vital protective function, absorbing harmful ultraviolet radiation from the sun and stabilizing Earth's temperature C 2000 CRC Press llcenvironmental biochemistry. A related area, toxicological chemistry, is the chemistry of toxic substances with emphasis upon their interactions with biologic tissue and living organisms. 2 Toxicological chemistry, which is discussed in detail in Chapters 22 and 23, deals with the chemical nature and reactions of toxic sub￾stances and involves their origins, uses, and chemical aspects of exposure, fates, and disposal. 1.3. WATER, AIR, EARTH, LIFE, AND TECHNOLOGY In light of the above definitions, it is now possible to consider environmental chemistry from the viewpoint of the interactions among water, air, earth, life, and the anthrosphere outlined in Figure 1.1. These five environmental “spheres” and the interrelationships among them are summarized in this section. In addition, the chap￾ters in which each of these topics is discussed in greater detail are designated here. Water and the Hydrosphere Water, with a deceptively simple chemical formula of H2O, is a vitally important substance in all parts of the environment. Water covers about 70% of Earth’s surface. It occurs in all spheres of the environment—in the oceans as a vast reservoir of saltwater, on land as surface water in lakes and rivers, underground as groundwater, in the atmosphere as water vapor, in the polar icecaps as solid ice, and in many segments of the anthrosphere such as in boilers or municipal water distribution systems. Water is an essential part of all living systems and is the medium from which life evolved and in which life exists. Energy and matter are carried through various spheres of the environment 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. The accompanying release of latent heat provides a large fraction of the energy that is transported from equatorial regions toward Earth’s poles and powers massive storms. Water is obviously an important topic in environmental sciences. Its environ￾mental chemistry is discussed in detail in Chapters 3-8. Air and the Atmosphere The atmosphere is a protective blanket which nurtures life on the Earth and protects it from the hostile environment of outer space. It is the source of carbon dioxide for plant photosynthesis and of oxygen for respiration. It provides the nitrogen that nitrogen-fixing bacteria and ammonia-manufacturing industrial plants use to produce chemically-bound nitrogen, an essential component of life molecules. As a basic part of the hydrologic cycle (Chapter 3, Figure 3.1), the atmosphere transports water from the oceans to land, thus acting as the condenser in a vast solar￾powered still. The atmosphere serves a vital protective function, absorbing harmful ultraviolet radiation from the sun and stabilizing Earth’s temperature. © 2000 CRC Press LLC