333
9.4
Carbonate Reservoir Sizes and Fluxes Between Particulate and Dissolved Reservoirs
Table 9.7 Carbon fluxes from deep-sea sediments (below 1000 m water depth) in 10
12 mol yr
1 estimated by using different
parameters. Global estimations of regional data compilations are made by multiplication with surface area factors.
efficient in terms of CaCO 3 dissolution than higher
estimates of up to 31.6 cm
-2
yr
-1
(derived from
Wenzhöfer & Glud 2002). This is in contradiction
with studies of Reimers et al. (1992) and Hammond
et al. (1996) who predict that mineralization and
carbonate dissolution contribute about one half
each to the total dissolved carbon (DIC) or alkalinity fluxes. This 1:1 relationship obviously proves
true only for higher mineralization rates (Fig. 9.9).
Nevertheless, in combination with Archer’s
results from the non-respiratory dissolution runs
(7-34 · 10
12
mol yr
-1
) the global CaCO 3 -dissolution
flux may range between 22 to 81 · 10
12
mol yr
-1
(Hensen et al. 2003). On the one hand, it confirms
Archer’s results based on a number of newly
obtained in situ measurements from different deepsea locations, and, on the other hand, it suggests
that calcite dissolution fluxes to the seafloor that
even Archer’s maximum estimation of 54 · 10
12
mol
yr
-1
might be even an underestimation, if higher
benthic mineralization rates as derived from
Christensen (2000) and Wenzhöfer and Glud (2002)
prove true (compare with Milliman’s estimate).
A compilation of recent data on carbon re-flux
from deep-sea sediments is provided in Table 9.7.
Four flux categories are given in Table 9.7: The
CO 2 produced due to oxic respiration, calcite
dissolution, the alkalinity as a sum parameter for
calcium carbonate dissolution and CO 2 from oxic
respiration, and, hitherto neglected in the discussion, the dissolved organic carbon (DOC).
It is very interesting to note that many of the
more recently obtained calculations agree very
much with those of Berelson et al. (1994) who
calculated the benthic alkalinity input to the deep
ocean for the Pacific and the Indo-Pacific (Table
9.7). They suggested that most of the carbonate
dissolution in the deep ocean (Fig. 9.5) occurs
within the sediments (85 %). The extension of
their results from Pacific and Indian Ocean to the
Atlantic Ocean leading to 120 · 10
12
mol yr
-1
of
global dissolved carbon fluxes from sediments
may, however, be critical because of the completely different deep-water conditions in the IndoPacific and the Atlantic. Deep ocean waters in the
Indian and Pacific Oceans are known to be much
older and depleted in CO 3
2implying that a much
higher proportion of calcite dissolution contributes to the total alkalinity input there.
However, despite this problem of different bottomP a ra m eter
Are a
F lu x
S o u rc e
Re sp ira to ry C O 2
1
G lo b a l
40
afte r Ja hnke (19 9 6 )
6 1
a fte r C hriste ns e n (2 0 0 0 )
60 -7 5
W e nzhöfe r a nd G lud (2 0 0 2)
43
S e ite r e t a l. (2 0 0 5)
C a lcite D isso lutio n G lo b a l
27 -5 4
A rche r (1 9 9 6b )
G lo b a l
22 -8 1
He nse n e t a l. (2 00 3 )
G lo b a l
13
M illim an (1 99 9 )
A lka linity / TC O 2
P a cific
55
B e re lso n e t a l (1 9 94 )
Ind o -P a cific
91
B e re lso n e t a l (1 9 94 )
2
10 0
afte r B e re lso n et a l (1 9 94 )
12 0
afte r B e re lso n et a l (1 9 94 )
2
12 0
M a cke nzie e t al. (1 9 9 3 )
1 0 0
S um m a ry, this stud y
D O C
A tla ntic
3
4
O tto (1 99 6 )
G lo b a l
3
1 8
O tto (1 9 9 6 )
Tota l C
G lo b a l
12 0
S um m a ry, this study
1 Es timated as ox ic res piration of organic matter.
2 Us ing data of Broec ker and Peng (1987).
3 Inc luding w ater depth abov e 1000 m.
G lo b a l
9.4
Carbonate Reservoir Sizes and Fluxes Between Particulate and Dissolved Reservoirs
Table 9.7 Carbon fluxes from deep-sea sediments (below 1000 m water depth) in 10
12 mol yr
1 estimated by using different
parameters. Global estimations of regional data compilations are made by multiplication with surface area factors.
efficient in terms of CaCO 3 dissolution than higher
estimates of up to 31.6 cm
-2
yr
-1
(derived from
Wenzhöfer & Glud 2002). This is in contradiction
with studies of Reimers et al. (1992) and Hammond
et al. (1996) who predict that mineralization and
carbonate dissolution contribute about one half
each to the total dissolved carbon (DIC) or alkalinity fluxes. This 1:1 relationship obviously proves
true only for higher mineralization rates (Fig. 9.9).
Nevertheless, in combination with Archer’s
results from the non-respiratory dissolution runs
(7-34 · 10
12
mol yr
-1
) the global CaCO 3 -dissolution
flux may range between 22 to 81 · 10
12
mol yr
-1
(Hensen et al. 2003). On the one hand, it confirms
Archer’s results based on a number of newly
obtained in situ measurements from different deepsea locations, and, on the other hand, it suggests
that calcite dissolution fluxes to the seafloor that
even Archer’s maximum estimation of 54 · 10
12
mol
yr
-1
might be even an underestimation, if higher
benthic mineralization rates as derived from
Christensen (2000) and Wenzhöfer and Glud (2002)
prove true (compare with Milliman’s estimate).
A compilation of recent data on carbon re-flux
from deep-sea sediments is provided in Table 9.7.
Four flux categories are given in Table 9.7: The
CO 2 produced due to oxic respiration, calcite
dissolution, the alkalinity as a sum parameter for
calcium carbonate dissolution and CO 2 from oxic
respiration, and, hitherto neglected in the discussion, the dissolved organic carbon (DOC).
It is very interesting to note that many of the
more recently obtained calculations agree very
much with those of Berelson et al. (1994) who
calculated the benthic alkalinity input to the deep
ocean for the Pacific and the Indo-Pacific (Table
9.7). They suggested that most of the carbonate
dissolution in the deep ocean (Fig. 9.5) occurs
within the sediments (85 %). The extension of
their results from Pacific and Indian Ocean to the
Atlantic Ocean leading to 120 · 10
12
mol yr
-1
of
global dissolved carbon fluxes from sediments
may, however, be critical because of the completely different deep-water conditions in the IndoPacific and the Atlantic. Deep ocean waters in the
Indian and Pacific Oceans are known to be much
older and depleted in CO 3
2implying that a much
higher proportion of calcite dissolution contributes to the total alkalinity input there.
However, despite this problem of different bottomP a ra m eter
Are a
F lu x
S o u rc e
Re sp ira to ry C O 2
1
G lo b a l
40
afte r Ja hnke (19 9 6 )
6 1
a fte r C hriste ns e n (2 0 0 0 )
60 -7 5
W e nzhöfe r a nd G lud (2 0 0 2)
43
S e ite r e t a l. (2 0 0 5)
C a lcite D isso lutio n G lo b a l
27 -5 4
A rche r (1 9 9 6b )
G lo b a l
22 -8 1
He nse n e t a l. (2 00 3 )
G lo b a l
13
M illim an (1 99 9 )
A lka linity / TC O 2
P a cific
55
B e re lso n e t a l (1 9 94 )
Ind o -P a cific
91
B e re lso n e t a l (1 9 94 )
2
10 0
afte r B e re lso n et a l (1 9 94 )
12 0
afte r B e re lso n et a l (1 9 94 )
2
12 0
M a cke nzie e t al. (1 9 9 3 )
1 0 0
S um m a ry, this stud y
D O C
A tla ntic
3
4
O tto (1 99 6 )
G lo b a l
3
1 8
O tto (1 9 9 6 )
Tota l C
G lo b a l
12 0
S um m a ry, this study
1 Es timated as ox ic res piration of organic matter.
2 Us ing data of Broec ker and Peng (1987).
3 Inc luding w ater depth abov e 1000 m.
G lo b a l