Carbon Isotope Techniques deals with the use of carbon isotopes in studies of plant, soil, and aquatic biology. Topics covered include photosynthesis/translocation studies in terrestrial ecosystems; carbon relationships of plant-microbial symbioses; microbe/plant/soil interactions; and environmental and aquatic toxicology. Stable carbon isotope ratios of natural materials are also considered. Comprised of 15 chapters, this book begins with an introduction to radiation-counting instruments used in measuring the radioactivity in soil and plant samples containing carbon-14. The discussion then turns to the basic methods of 14C use in plant science, highlighted by three examples of applications in the field of plant physiology and ecology. Subsequent chapters explore the use of carbon isotope techniques for analyzing the carbon relationships of plant-microbial symbioses; the interactions of microbes, plants, and soils; and the degradation of herbicides and organic xenobiotics. Carbon dating and bomb carbon are also described. The final section is devoted to the uses and procedures for 13C and 11C. This monograph is intended for advanced undergraduate or graduate students, as well as generalist scientists who have not previously used radioisotopes or stable isotopes in their research.