Table 1 Contributions of different metabolisms to depth-integrated dark DIC fixation rates in the eastern tropical Pacific Ocean

From: Minor contribution of ammonia oxidizers to inorganic carbon fixation in the ocean

Depth-integrated rates

Stn 5

Stn 7

Stn 10

Stn 12

Total measured dark DIC fixation (µmol m−2 d−1)

234

382

348

860

Ammonia-fuelled chemoautotrophy (µmol m−2 d−1)

58 (25%)

15 (4%)

48 (13%)

33 (4%)

Nitrite-fuelled chemoautotrophy (µmol m−2 d−1)

82 (35%)

76 (20%)

23 (6%)

57 (7%)

Sulfur-fuelled chemoautotrophy (µmol m−2 d−1)

24 (10%)

6 (2%)

20 (5%)

14 (2%)

Heterotrophic DIC fixation (µmol m−2 d−1)

95 (41%)

99 (26%)

107 (31%)

203 (24%)

All metabolisms (µmol m−2 d−1)

259 (111%)

196 (51%)

198 (56%)

308 (36%)

  1. Total and ammonia-fuelled dark DIC fixation rates were measured directly, whereas the contributions of other metabolisms were estimated. Estimates of nitrite-fuelled chemoautotrophy were based on measured nitrite oxidation rates and the average DIC fixation yield of nitrite oxidizer cultures (0.036; ref. 27). Heterotrophic DIC fixation rates were estimated as 10% of the measured heterotrophic production rates. Sulfur-fuelled chemoautotrophy was estimated from ammonia-fuelled chemoautotrophy values based on differences in the N:S stoichiometry of particulate organic matter (17:1; ref. 45) and differences between the DIC fixation yields of ammonia oxidizer (Fig. 5a) and sulfide oxidizer cultures (0.35; ref. 51). Percentages in parentheses show the estimated contribution of each metabolism to measured total dark DIC fixation rates.
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