Table 1

Carbon balances and kinetic decay constants for DOM at different stages in seawater cultures with bacteria and glucose or glutamate as an initial substrate. The data are given as the mean ± ∣mean-replicate∣ of duplicate bottle incubations. Carbon balances were calculated at the end of each stage period, including remineralized % (i.e., the loss of TOC) and remaining % as DOC or POC relative to the initial TOC. The results of POC at Stage III were not available, because the difference between TOC and DOC were statistically insignificant or no measurement of TOC was made. The decay constants for DOC during each stage were calculated on the assumption of first-order decay kinetics.

Stage (days)Remineralized %Remaining %Decay constant (day−1)
DOCPOC
Glucose (208 ± 0 μM C)
I (0–2)78 ± 115 ± 07 ± 11.1 ± 0.0
II (2–7)87 ± 18 ± 16 ± 10.13 ± 0.03
III (7–365)95 ± 05 ± 00.0012 ± 0.0003
Glutamate (132 ± 2 μM C)
I (0–2)66 ± 513 ± 722 ± 21.1 ± 0.1
II (2–9)77 ± 210 ± 113 ± 10.14 ± 0.08
III (9–560)93 ± 17 ± 10.0023 ± 0.0003