FIG. 5.

Summary of experiments from three locations. Columns and upper axis: relative contribution of anaerobic ammonium oxidation to N₂ production calculated from isotope pairing (black) or ¹⁵NH₄⁺ consumption (gray). Circles and lower axis: rate of N₂ production through coupled ammonium oxidation-nitrate reduction. Conditions for each experiment summarized next to each column include the sediment depth interval (centimeters), the combination of nitrate and ammonium added (n and N, nitrate; a and A, ammonium; uppercase, ¹⁵N labeled; lowercase, unlabeled), and the time of sampling at Skagerrak S9. Sediment from Skagerrak S6 and Aarhus Bay was sampled in autumn 2000.