FIG. 6.

(A) Vertical distribution of DAPI-stained total cells, Thio820 probe-hybridized Acidithiobacillus cells, ACD840 probe-hybridized Acidiphilium cells, and LF655 probe-hybridized Leptospirillum cells in the heavily corroded gypsum layer after a 1-year exposure to the sewer atmosphere. (B) Concentration profiles of O₂ and pH in the top 2,000 μm of the heavily corroded gypsum layer that was exposed to the H₂S atmosphere for 1 year. Stable total H₂S concentration profiles could not be determined in this study. The surface of corroded concrete is at a depth of 0 μm. Error bars represent the standard errors of duplicate measurements (A) and of triplicate measurements (B).