Fig. 7.

Evolution of the TOC (green) and TIC (blue) concentrations in Interval 1 and 2 after initial injection with ${\text{NO}}_3^{-}$ only and pulse injection with H₂ (a Interval 1; pulse after 54 days) or acetate (b Interval 2; pulse after 70 days). Open markers indicate concentrations below detection limit, i.e. 0.4 mmol C L⁻¹ TIC. The error bars indicate the 95% confidence intervals