FIG. 1.

Formation of As(V) in anoxic lake water samples amended with 1 mM As(III). Note that the time scales (x axis) vary between the four panels. (A) Samples supplemented with 5 mM NaNO₃ added as the terminal electron acceptor to both live and killed controls, plus a live control without NO₃⁻. Symbols: ○, live with nitrate; •, killed with nitrate; ▴, live without nitrate. (B) Samples amended with nitrate (○) or nitrite (□), and killed controls with nitrite (▪). (C) Live (○) and killed (•) controls amended with 5 mM Fe(III)-NTA. (D) Live (□) and killed (▪) controls amended with MnO₂. Symbols represent the means for three separately incubated water samples, and error bars indicate ± 1 standard deviation.