This unique addition to reference literature provides an introduction to the major concepts and contemporary issues that are essential for students of environmental science and environmental studies to know. With over 200 entries authored by world-class names like Anthony Brazel, John Day and Edward Keller, this text is divided into six sections: Environmental Science, Environments, Paradigms & Concepts, Processes & Dynamics, Scales & Techniques, and Environmental Issues.
Radioactive isotopes have been used to measure rates of sedimentation, water movement, and photosynthesis. The half-life of isotopes can vary dramatically. For example, 232Th has a half-life of 14 billion years (nearly the age of the universe!) while that of 131I is about 0.02 years. By knowing this and the relative proportions of different daughter products, different processes can be dated. There is a group of primordial radionuclides, which are left over from the beginning of the universe and that are very long-lived. Included in this group are nuclides of U, Pa, Th, Ac, Ra, Rn, Fr, Po, Bi, Pb, and Tl. Although these isotopes are long-lived, the daughter products in the decay chains most often have shorter half-lives and are sometimes ...