Figure 3: Porewater data from four selected cores.

The profiles of sulfate, ΣHS, TA, calcium and magnesium reveal a system out of steady state at three of the sites. Ammonium concentrations at these three sites show smooth profiles without any apparent kinks. We include porewater data from core 920GC to illustrate a steady-state system in the vicinity of the investigated active gas hydrate mound.