398
Chemical Oceanography, 4th Edition
the oxygen changes, giving ΔC/ ΔO 2 = –0.72. The slightly lower ratios than those predicted
from the Redfield model have been attributed to the predominant production of diatoms
that have high concentrations of lipids. These results suggest the following stoichiometry
(Steinberg, Millero, and Zhu, 1998):
90CO 2 + 104H 2 O + 14HNO 3 + H 3 PO 4 + 18SiO 2
→ (CH 2 O) 76 (CH 2 ) 14 NH 3 ) 14 (H 3 PO 4 )(SiO 2 ) 18 + 125O 2
for the production of phytoplankton in the iron- enriched patch.
The results of these experiments should lead to a better understanding of the interactions between the effect of nutrients and metals on the growth of phytoplankton and the
resultant grazing of zooplankton. The issue of whether Fe additions can sequester substantial quantities of atmospheric CO 2 will lead to further debates. The IRONEX experiments, however, demonstrated that open ocean manipulative experiments are possible,
and ecological studies in the open ocean are no longer limited to passive observations.
This will change significantly the way geochemical and ecological studies are performed
in the ocean.
9.2.4 SOFeX Study
During the 2002 austral summer, two in situ, mesoscale iron fertilization experiments were
conducted (Coale et al., 2004) in two distinct silicic acid regimes of the Southern Ocean
(SOFeX) (see Figure 9.27). The properties of the surface waters on the transit from the south
and back are shown in Figure 9.28. The concentration of the nutrients and carbon dioxide
parameters all increase from the north to the south. This is due to the outcropping of
deep waters rich in nutrients and CO 2 . The silica concentrations are quite low in the north
and increase in the south. The iron was added to the low Si(OH) 4 concentrations of the
24:00
23:00
22:00
21:00
20:00
0.0
0.5
Fluorescence (V)
pCO
2 (ppm dry molar volume)
1.0
1.5
520
500
480
460
440
540
2.0
12
10
8
6
4
Nitrate
Fluorescence
pCO 2
Nitrate (µM)
GMT
Figure 9.26
The values of pCO 2 , NO 3
– , and fluorescence across the iron- enriched waters during the IRONEX II study, specifically Transect 3, Day 154 (1996).
Chemical Oceanography, 4th Edition
the oxygen changes, giving ΔC/ ΔO 2 = –0.72. The slightly lower ratios than those predicted
from the Redfield model have been attributed to the predominant production of diatoms
that have high concentrations of lipids. These results suggest the following stoichiometry
(Steinberg, Millero, and Zhu, 1998):
90CO 2 + 104H 2 O + 14HNO 3 + H 3 PO 4 + 18SiO 2
→ (CH 2 O) 76 (CH 2 ) 14 NH 3 ) 14 (H 3 PO 4 )(SiO 2 ) 18 + 125O 2
for the production of phytoplankton in the iron- enriched patch.
The results of these experiments should lead to a better understanding of the interactions between the effect of nutrients and metals on the growth of phytoplankton and the
resultant grazing of zooplankton. The issue of whether Fe additions can sequester substantial quantities of atmospheric CO 2 will lead to further debates. The IRONEX experiments, however, demonstrated that open ocean manipulative experiments are possible,
and ecological studies in the open ocean are no longer limited to passive observations.
This will change significantly the way geochemical and ecological studies are performed
in the ocean.
9.2.4 SOFeX Study
During the 2002 austral summer, two in situ, mesoscale iron fertilization experiments were
conducted (Coale et al., 2004) in two distinct silicic acid regimes of the Southern Ocean
(SOFeX) (see Figure 9.27). The properties of the surface waters on the transit from the south
and back are shown in Figure 9.28. The concentration of the nutrients and carbon dioxide
parameters all increase from the north to the south. This is due to the outcropping of
deep waters rich in nutrients and CO 2 . The silica concentrations are quite low in the north
and increase in the south. The iron was added to the low Si(OH) 4 concentrations of the
24:00
23:00
22:00
21:00
20:00
0.0
0.5
Fluorescence (V)
pCO
2 (ppm dry molar volume)
1.0
1.5
520
500
480
460
440
540
2.0
12
10
8
6
4
Nitrate
Fluorescence
pCO 2
Nitrate (µM)
GMT
Figure 9.26
The values of pCO 2 , NO 3
– , and fluorescence across the iron- enriched waters during the IRONEX II study, specifically Transect 3, Day 154 (1996).