Fig. 2.

Effect of formate on the production of organic acids and gases in anoxic fen soil microcosms at 15°C. Data are for formate (A), CO₂ (B), acetate (C), methane (D), propionate (E), and H₂ (F). In panel B, CO₂ in formate treatments represents the combined CO₂ from the bicarbonate pulses and CO₂ derived from the apparent conversion of formate to H₂ and CO₂. Symbols: empty symbols, unsupplemented controls; gray symbols, [¹²C]formate treatments; black symbols, [¹³C]formate treatments. Insets show cumulative gas concentrations. Values are the means of triplicate microcosms, and the error bars indicate standard deviations.