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A summary of experimental results on the degradation of trifluoroacetate is presented. Experiments were conducted with a variety of materials, including freshwater and estuarine sediments, sediments from an alkaline, hypersaline environment, and from agricultural soils. Results with several pure cultures of a diversity of bacteria with regard to their ability to degrade trifluoroacetate are also presented. INTRODUCTION The 3 pages of attached graphs refer to successful TFA (trifluoroacetate) experiments which were conducted during October, 1993 and March, 1994. The Searsville Lake 14CH4 data appeared in Visscher and others, 1994 but the TFA, difluoroacetate (DFA), monofluoroacetate (MFA), and acetate data have not been published. Neither have the March, 1994 data from the Palo Alto Marsh site (sulfate or nitrate as electron acceptors). For completeness, we have included the results from our 1994 paper in this summary. We have divided the summary results into four sections: sediment slurry experiments (table 1), small subcore experiments (table 2), experiments with bacterial cultures (table 3), and a fourth section on the effects of unlabeled TFA upon bacterial growth of some of the tested cultures. These tables indicate that most of our experiments have not noted the production of radiolabeled gases from 14C-TFA. SIGNIFICANT FINDINGS The degradation of 214C-TFA was observed to occur under methanogenic conditions (fig. 1), sulfate reducing conditions (fig. 2), but not under nitrate-respiring conditions (fig. 3). In this last case, degradation of TFA took place after all the nitrogen oxides were depleted. Aside from some minor production of 14CH4 observed with Mono Lake 1 sediments (table 2) as well as the earlier work conducted with San Francisco Bay saltmarsh and Searsville Lake material (table 1), and some fluoroform production in our Thiobacillus strain number ASN1 culture, we have not observed any further activity. REFERENCES Visscher, P.T., Culbertson, C.W., and Oremland, R.S. 1994: Degradation of trifluoroacetate in oxic and anoxic sediments. Nature, vol. 369, p. 729 731. TABLE I. SEDIMENT SLURRY EXPERIMENTS (20ml slurries in 57ml serum bottles; approximately 90% water by weight) < D.L. = Less than detection limit of thermal conductivity detector (~0.1u,moles/headspace) TMA = Trimethylamine TFA = Trifluoroacetate Numbers in parenthesis ( ) indicate standard deviation of triplicate sample 14C-TFA specific activity = 54uCi/^mol

Summary of research results on bacterial degradation of trifluoroacetate (TFA), November, 1994-May, 1995