Description: The abundance and types of microorganisms in leachate samples from the West Valley low-level radioactive waste disposal site were enumerated. This study was undertaken in support of the study conducted by Ecology and Environment, Inc., to assess the extent of radioactive gas emissions from the site. Total aerobic and anaerobic bacteria were enumerated as colony forming units (CFU) by dilution agar plate technique, and denitrifiers, sulfate-reducers and methanogens by the most probable number technique (MPN). Of the three trenches 3, 9, and 11 sampled, trench 11 contained the most number of organisms in the leachate. Concentrations of carbon-14 and tritium were highest in trench 11 leachate. Populations of aerobes and anaerobes in trench 9 leachate were one order of magnitude less than in trench 11 leachate while the methanogens were three orders of magnitude greater than in trench 11 leachate. The methane content from trench 9 was high due to the presence of a large number of methanogens; the gas in this trench also contained the most radioactivity. Trench 3 leachate contained the least number of microorganisms. Comparison of microbial populations in leachates sampled from trenches 3 and 9 during October 1978 and 1989 showed differences in the total number of microbial types. Variations in populations of the different types of organisms in the leachate reflect the changing nutrient conditions in the trenches. 14 refs., 3 figs., 4 tabs.
Date: October 1, 1990
Creator: Gillow, J.B. & Francis, A.J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department