Soil microbiota of Area 13 of the Nevada Test Site

The influence of two desert plants, Atriplex canescens and Eurotia lanata, on kind and abundance of soil microbiota was determined in soil samples collected from Area 13 of the Nevada Test Site. This study was part of a larger research program to elucidate the role of soil microorganisms on the biological availability and the mobility of soil-deposited plutonium. The fungi identified in the soil samples included Aspergillus, Penicillium, Rhizopus, Stachybotrys, stysanus, Circinella, Cheaetomium, and Fusarium. The numbers of bacteria and fungi were generally highest at the 2.5- to 5.0-cm soil depth at both the mound and the interspace sampling sites. The highest numbers of fungi were found around the mound. The relative abundance of Aspergillus increased with increasing distance from the plants, whereas that of Penicillium decreased. Dematiaceae and chaetomium, both cellulose decomposers, were highest in the 0- to 2.5-cm soil segment. The abundance and distribution of soil microorganisms capable of incorporating plutonium (and probably other radionuclides as well) around the plants investigated indicate that this may be a factor in the bioavailability and movement of plutonium in the edaphic system. 17 references, 1 figure, 27 tables