Fig. 1

Chemistry data from the incubation experiments. The pictures show a anoxic cores on the first day of incubation; b anoxic cores turned oxic after 21 days of incubation; c intermediate cores on the first day of incubation (first three from left side) and anoxic cores on the first day of incubation; and d intermediate cores turned oxic after 21 days of incubation (first three from left side) and oxic control cores maintained oxic after 21 days of incubation. Measurements of chemistry from the water phase are shown on the left e PO₄ ³⁻, g NO₂ ⁻ + NO₃ ⁻, i Fe²⁺, j Fe³⁺, and l SO₄ ^{2 −} (symbols: black circles, oxic control; black squares, anoxic control; white circles, oxic-to-anoxic; white squares, anoxic-to-oxic; and white diamonds, intermediate-to-oxic); pore-water chemistry from the top 1-cm-sliced sediment are on the right f PO₄ ³⁻, h NO₂ ⁻ + NO₃ ⁻, k total iron (Fe_tot), and m SO₄ ²⁻ (black bars denote zero time point measurements from the field and white bars denote measurements at the end of the incubation experiment). All values are averages of triplicates ±1 SD, except water and sediment anoxic-to-oxic (n = 2) and sediment anoxic-to-oxic (n = 2)