Figure 2. Depth profiles for sulfate, ammonium, manganese (open circles), and iron (solid circles) in Site 999 interstitial waters. The fraction of bulk sediment composed of dispersed volcanic ash (shaded area) is plotted vs. depth on the ammonium profile to permit evaluation of the effect of ash alteration on pore-water ammonium concentrations. The arrow indicates mean ocean bottom-water sulfate concentration. The two symbols (open and solid) used in the sulfate profile reflect the incorporation of data from two holes at Site 999.