THE DEEP ATLANTIC OCEAN
161
Table 5.4
In situ measurements of sediment community oxygen consumption (SCOC) in the Atlantic ocean 1
Station
Water depth (m)
SCOC
ml O 2 m −2 h −1
mmol O 2 m −2 h −1
Reference
WESTERN ATLANTIC
Gayhead–Bermuda Transect
1850
0.50
22.8
Smith and Teal (1973)
2200
0.46
20.5
Smith (1978)
2750
0.35
15.6
Smith (1978)
3000
0.20
8.9
Smith (1978)
3650
0.21
9.4
Smith (1978)
4670
0.09
4.0
Smith (1978)
4830
0.04
1.8
Smith (1978)
5080
0.07
3.1
Smith (1978)
5200
0.02
0.9
Smith (1978)
Mid Atlantic Bight
2159
1.17 2
52.41 2
Hales et al. (1994)
4236
0.69
30.82
Hales et al. (1994)
4501
0.54
23.97
Hales et al. (1994)
5210
0.31
13.70
Hales et al. (1994)
5380
0.33
14.84
Hales et al. (1994)
North of Blake Plateau
1345
1.31
58.5
Hinga et al. (1979)
Florida Strait
675
2.95
131.7
Smith and Hinga (1983)
Tongue of the Ocean
2000
3.10
138.4
Smith and Hinga (1983)
Bermuda (BATS)
4400
0.28
12.5
Sayles et al. (1994)
EASTERN ATLANTIC
Rockall Trough
2280
1.50 3
67 3
Patching et al. (1986)
Porcupine Seabight
2000
2.12 3
94.58 3
Lampitt et al. (1995)
Porcupine Abyssal Plain
4980
1.39 3
62.00 3
Patching et al. (1986)
4000
0.66 3
29.75 3
Lampitt et al. (1995)
BIOTRANS
4590
0.40 (April 88)
17.9
Pfannkuche (1992)
4590
0.86 (July 86)
38.4
Pfannkuche (1992)
4590
0.81 (Aug 89)
36.3
Pfannkuche (1992)
Gulf of Guinea
278
3.93
175.5
Hinga et al. (1979)
4000
0.65
29.0
Hinga et al. (1979)
1 All measurements are based on grab respirometry unless indicated otherwise.
2 Porewater oxygen profiles made in situ by microelectrodes.
3 Suspended core methods.
than those observed in shallow water. Compilation of
mixing-coefficient data from sites in the Northwest,
Northeast and South Atlantic suggest several patterns
that bear further investigation. The D b data from
the Northwest Atlantic show an exponential decline
with water depth (r
2 = 0.634) which is not evident in
the Northeast Atlantic (Fig. 5.8A), where maximal
D b values were observed on the lower rise in the
Cape Verde and Porcupine Seabight regions. The South
Atlantic may exhibit lower mixing than the North
Atlantic, but the data are few. Latitude appears to have
little influence on mixing as estimated from D b values
(Fig. 5.8B).
Recent estimates of diffusive mixing coefficients
made in more dynamic environments with
234 Th, a
shorter-lived radiotracer (24-d half-life), are much
161
Table 5.4
In situ measurements of sediment community oxygen consumption (SCOC) in the Atlantic ocean 1
Station
Water depth (m)
SCOC
ml O 2 m −2 h −1
mmol O 2 m −2 h −1
Reference
WESTERN ATLANTIC
Gayhead–Bermuda Transect
1850
0.50
22.8
Smith and Teal (1973)
2200
0.46
20.5
Smith (1978)
2750
0.35
15.6
Smith (1978)
3000
0.20
8.9
Smith (1978)
3650
0.21
9.4
Smith (1978)
4670
0.09
4.0
Smith (1978)
4830
0.04
1.8
Smith (1978)
5080
0.07
3.1
Smith (1978)
5200
0.02
0.9
Smith (1978)
Mid Atlantic Bight
2159
1.17 2
52.41 2
Hales et al. (1994)
4236
0.69
30.82
Hales et al. (1994)
4501
0.54
23.97
Hales et al. (1994)
5210
0.31
13.70
Hales et al. (1994)
5380
0.33
14.84
Hales et al. (1994)
North of Blake Plateau
1345
1.31
58.5
Hinga et al. (1979)
Florida Strait
675
2.95
131.7
Smith and Hinga (1983)
Tongue of the Ocean
2000
3.10
138.4
Smith and Hinga (1983)
Bermuda (BATS)
4400
0.28
12.5
Sayles et al. (1994)
EASTERN ATLANTIC
Rockall Trough
2280
1.50 3
67 3
Patching et al. (1986)
Porcupine Seabight
2000
2.12 3
94.58 3
Lampitt et al. (1995)
Porcupine Abyssal Plain
4980
1.39 3
62.00 3
Patching et al. (1986)
4000
0.66 3
29.75 3
Lampitt et al. (1995)
BIOTRANS
4590
0.40 (April 88)
17.9
Pfannkuche (1992)
4590
0.86 (July 86)
38.4
Pfannkuche (1992)
4590
0.81 (Aug 89)
36.3
Pfannkuche (1992)
Gulf of Guinea
278
3.93
175.5
Hinga et al. (1979)
4000
0.65
29.0
Hinga et al. (1979)
1 All measurements are based on grab respirometry unless indicated otherwise.
2 Porewater oxygen profiles made in situ by microelectrodes.
3 Suspended core methods.
than those observed in shallow water. Compilation of
mixing-coefficient data from sites in the Northwest,
Northeast and South Atlantic suggest several patterns
that bear further investigation. The D b data from
the Northwest Atlantic show an exponential decline
with water depth (r
2 = 0.634) which is not evident in
the Northeast Atlantic (Fig. 5.8A), where maximal
D b values were observed on the lower rise in the
Cape Verde and Porcupine Seabight regions. The South
Atlantic may exhibit lower mixing than the North
Atlantic, but the data are few. Latitude appears to have
little influence on mixing as estimated from D b values
(Fig. 5.8B).
Recent estimates of diffusive mixing coefficients
made in more dynamic environments with
234 Th, a
shorter-lived radiotracer (24-d half-life), are much