Use Of Tracer Techniques For The Study Of Biogeochemical Cycles

During the twenty years the authors have been associated with the field of radiation ecology, there has been a diversified and increasing use of radionuclides in applied and basic biological research. Prior to the advent of the atomic age in the 1940s the use of radionuclides as tracers was initiated, and following that period one observed a dramatically increased use in many disciplines. Concurrent with this increase there appeared many books and articles on radionuclide tech niques useful to biologists in general. Although only a few ecological applications were evident in these early years, ecologists were quick to see the opportunities available in their field. In the United States, major centers for such activities included Oak Ridge National Laboratory and the U. S. Atomic Energy Com mission's Savannah River Plant. At Oak Ridge National Laboratory Dr. Stanley I. Auerbach, director of ecological activities, encouraged with remarkable suc cess the use of tracers by his associates. Dr. Eugene P. Odum had the foresight to see that radionuclide tracers provided the means to solve many problems of interest to ecologists. Consequently, his research included some unique radio tracer applications at the Savannah River Plant. In addition he encouraged others involved in ecological activities at the Savannah River Plant to do likewise. Ecologists such as Dr. Robert C. Pendleton at the U. S. Atomic Energy Com mission's Hanford Works applied radionuclides in their research. To these early investigators and to those who followed we owe the oppportunity to write this book.

This book takes an in-depth look at the theory and methods inherent in the tracing of riverine sediments. Examined tracers include multi-elemental concentration data, fallout radionuclides (e.g., 210Pb, 137Cs, 7Be), radiogenic isotopes (particularly those of Pb, Sr, and Nd), and novel (“non-traditional”) stable isotopes (e.g., Cd, Cu, Hg, and Zn), the latter of which owe their application to recent advances in analytical chemistry. The intended goal is not to replace more ‘traditional’ analyses of the riverine sediment system, but to show how tracer/fingerprinting studies can be used to gain insights into system functions that would not otherwise be possible. The text, then, provides researchers and catchment managers with a summary of the strengths and limitations of the examined techniques in terms of their temporal and spatial resolution, data requirements, and the uncertainties in the generated results. The use of environmental tracers has increased significantly during the past decade because it has become clear that documentation of sediment and sediment-associated contaminant provenance and dispersal is essential to mitigate their potentially harmful effects on aquatic ecosystems. Moreover, the use of monitoring programs to determine the source of sediments to a water body has proven to be a costly, labor intensive, long-term process with a spatial resolution that is limited by the number of monitoring sites that can be effectively maintained. Alternative approaches, including the identification and analysis of eroded upland areas and the use of distributed modeling routines also have proven problematic. The application of tracers within riverine environments has evolved such that they focus on sediments from two general sources: upland areas and specific, localized, anthropogenic point sources. Of particular importance to the former is the development of geochemical fingerprinting methods that quantify sediment provenance (and to a much lesser degree, sediment-associated contaminants) at the catchment scale. These methods have largely developed independently of the use of tracers to document the source and dispersal pathways of contaminated particles from point-sources of anthropogenic pollution at the reach- to river corridor-scale. Future studies are likely to begin merging the strengths of both approaches while relying on multiple tracer types to address management and regulatory issues, particularly within the context of the rapidly developing field of environmental forensics.

This volume was first published in 1981. The history of man's use of arid lands is a sad record of deterioration of the natural resource base and of low and declining living standards for the 300 million people who live in them. One prerequisite to meeting the challenge of reversing the deterioration and of raising living standards is a sound knowledge of the natural ecosystems.