Life in the Deep Sediments
Affect on Global Carbon
Budget
With new information on the
productivity and extent of the deep biosphere, the total amount of
organic
carbon tied up in the ocean has increased.
Parkes et al. 1994 estimated total carbon in the deep ocean sediments
at 1.5
t/ha. His estimate only included the top
500m of sediment. Extrapolated over the
ocean, this would represent about 10 percent of all living organic
carbon in
the surface biosphere. Whitman et al.
1998 expanded this estimate, claiming the total amount of prokaryotic
carbon
is 60-100% of the estimated total carbon in plants.
Furthermore, the earth's prokaryotes contain
about 10-fold more of phosphorous and nitrogen than do plants, and
represent
the largest pool of these nutrients in living organisms. Furthermore, it is estimated that 60%
of all bacteria live in the sea floor
(Whitman et al. 1998),. Total carbon
estimated by Whitman et al. 1998 was 3.5 x 10^30 cells.
This raises the importance of deep sediments
as a repository for carbon greatly.
Schippers et al. 2005 also estimated the total carbon in the
ocean to be
1.3 x 10^29 cells, an order of magnitude less than the Whitman et al. 1998
estimate. However, Schippers et al. 2005 used
data from CARD-FISH counts, which are often lower than traditional cell
counts.
The amount of total carbon is continually revised as more
information
becomes available