by Joni Marzalik, Tim Gilles, Scott Filer, and Monica TischlerMicroorganisms are important in nutrient cycling and in determining the inorganic composition of soils (Fenchel and Blackburn 1979). The use of radioactive tracers to study the breakdown of forest litter was initiated in the 1950's and 1960's as a result of international concern with radioactive fallout, focusing on the movement of radionuclides from the soil and into the food chain (Olson and Crossley 1963, Nelson and Evans 1969, Nelson 1971). These pioneering studies showed that microorganisms are important in the immobilization of radionuclide transport, and the movement of different radionuclides from the microves into their predators and then subsequently into higher organisms and plants (Auerbach, et al, 1963, 1964, 1967, Reichle and Crossley 1967, 1969, Reichle et al. 1970, 1971). Current research on radionuclides focuses on mobilization of plutonium by microorganisms.
With these early studies and the current conflicting information on the effects of soil microorganisms on radionuclides in mind, we are in the process of subjecting soil cores from a farming region in the Chernobyl area of the Ukraine to various treatments designed to stimulate or inhibit different bacterial populations. We will determine how these treatments affect both the mobilizaiton and the oxidation states of the readionuclides in the columns. We will also analyze the effects of the treatments on the leaching of the radionuclides from the soil. These studies will aid in modeling the migration of radionuclides through the soil and groundwater in the Chernobyl area. Using basic microbial ecology techniques and analytical equipment in collaboration with Argonne National Laboratory, these experiments will address some of the fundamental discrepancies in the literature concerning the role of microorganisms in the mobilization and leaching of radionuclides from soils.
This research measured a variety of physical, chemical, and biological characteristics in three different wetland sites in Greene Valley Forest Preserve, DuPage County, Illinois in an attempt to better understand the properties of these areas. The sites, two artificial and one natural, were surveyed for the course of one growing season, from February to November 1996. In July 1996, a significant flood event occurred which disrupted baseline readings of the two artificial riparian sites. Ongoing measurements indicated these two sites returned to their original baselines, in all tested parameters, before the end of the growing season. We present these results which illustrate the differences in characteristics between the two artificial wetlands and demonstrate their ability to recover from major flood events. It is hoped that an understanding of the dynamics of these areas will help in the formulation of sustainable management strategies for this type of watershed.