ACETATE AND PROPIONATE IN LANDFILL LEACHATES - IMPLICATIONS FOR THE RECOGNITION OF MICROBIOLOGICAL INFLUENCES ON THE COMPOSITION OF WATERS IN SEDIMENTARY SYSTEMS

Routine monitoring of landfill leachates provides information concerni ng aqueous systems in which anaerobic microbiological processes influe nce mater chemistry. Propionate and acetate are substrate and product, respectively, of metabolism by bacteria that have an obligate syntrop hic relationship with sulfate-reducing bacteria. The stoichiometry of the bacteriological metabolic reactions indicates a 1:1 molar proporti onality for acetate and propionate, This is observed for landfill leac hates, consistent with the known biological control on their organic a cid anion contents. Similar data for oil-field waters show the same 1: 1 molar proportionality for reservoirs where bacterial sulfate reducti on is known to take place, at temperatures up to about 95 degrees C, i n contrast to the 3:2 proportionality (acetic acid:propionic acid) obs erved in higher temperature systems. These observations suggest that 1 :1 molar proportionality for acetate and propionate may be characteris tic of natural systems where anaerobic bacterial activity occurs, incl uding bacterial sulfate reduction.