FIG. 3.

Sulfur isotope ratio profiles of pore water sulfate (A) and chromium-reducible sulfides (B). ⧫, AMD pond predredging; •, AMD pond postdredging; ▪, upper tidal slough; ▴, lower tidal slough. x axis uncertainties represent 2 standard errors of the mean (2 or 3 replicates), with the exception of the AMD pond predredging and upper tidal slough CRS values, where the uncertainties represent the largest value for 2 standard errors of the mean for IAEA standards obtained during analysis of these samples. y axis uncertainties reflect scales of homogenization of samples obtained from sediment coring. For reference, the δ³⁴S value of AMD sulfate is 1.14‰ ± 0.1‰, and the δ³⁴S value of seawater is ≈21‰.