Environmental Engineering Reference
In-Depth Information
Figure 7.
Vertical distribution of dark DIC assimilation relative to first depth of undetectable
O
2
on five dates.
3.6 Redoxcline's Chemoautotrophic Communities
The organisms responsible for chemoautotrophic carbon fixation are poorly
known. A portion of the observed DIC assimilation can be attributed to ana-
plerotic reactions that occur within all organisms [50] During 14 CARIACO
cruises, these reactions potentially amount to
7% (median; n = 32) of total
carbon production (NPP + BNP) in the upper 100m. However, in the redoxcline
only 1% of dark DIC assimilation can be derived anaplerotically (n = 137),
assuming that it accounts for as much as 10% of observed BNP. Furthermore,
addition of Hg
2
+
, formaldehyde or NaN
3
to incubations completely shuts down
dark
∼
14
C particle production (not presented). Clearly, biological assimilation
