Fig. 3. Gas fluxes (sum of diffusion and ebullition) from the sediments. (a) CH₄ from the deep profundal, (b) CH₄ from the shallow profundal, (c) CO₂ from the deep profundal, (d) CO₂ from the shallow profundal, (e) N₂O from the deep profundal, and (f) N₂O from the shallow profundal sediments. The averages and standard error of the means are shown. Asterisks denote that increase in NO^-₃ or SO^2-₄ concentration affects gas fluxes in a statistically significant manner (***, P < 0.001).