390
P. J. Worsfold . E. P. Achterberg· A. R. Bowie· R. Sandford· V. Cannizzaro· P. Gardolinski
Iron is an essential micronutrient for biological organisms and limits phytoplankton growth in certain high-nutrient, low-chlorophyll (HNLC) areas of the world's
oceans, which may have important implications for global carbon cycles. Such hypotheses have recently been tested in the under-productive waters of the equatorial Pacific
(Coale et al. 1996) and Southern Ocean (Boyd et al. 2000), where seeding an expanse
of surface water with low concentrations of dissolved Fe triggered a massive phytoplankton bloom, and resulted in a significant drawdown of surface water nitrate and
atmospheric CO 2 , The ongoing debate about the effect of Fe limitation on phytoplankton communities has highlighted how little is actually known about the complex marine speciation of Fe and uptake mechanisms for the growth of microorganisms. Similar mesoscale iron enrichment experiments are planned for different regions of the
HNLC Southern Ocean.
16.2.2
FI-CL Manifold for Iron
The manifold for the Fe monitor, shown in Fig. 16.5 (Bowie et al. 1998), utilizes the
luminol reaction (see Sect. 16.1.2) and a chelating microcolumn of 8-hydroxyquinoline (8-HQ) immobilized on a commercial hydrophilic vinyl co-polymer (Toyopearl
TSK gel, HW 75F, 32-63 micron fine, Toso Haas Co.). After Fe(III) reduction by sulphite
to the Fe(II) species, the 8-HQ resin extracts and preconcentrates the Fe from the sea
water sample as it flows through the column. Elution is then performed using a HCI
stream, which is mixed with the luminol reagent inside a quartz flow cell, emitting light
that is detected by a photomultiplier tube and the output sent to a flatbed chart recorder. The analytical figures of merit for this manifold are given in Table 16.1 and show
that it is suitable for the determination of Fe(II + III) in coastal and open ocean waters.
UHP water rinse
Acid wash
Sample
PumpS
1.5
Acetate buffer
I 0.2
PumpC
0.09 M Hel eluent
1.5
Luminol
1.5
mlmin-1
V2
8-HQ colu.mn
Waste
Chart
recorder
Fig. 16.5. Flow injection manifold with chemiluminescence detection for the determination of Fe(II + III)
in the marine environment
P. J. Worsfold . E. P. Achterberg· A. R. Bowie· R. Sandford· V. Cannizzaro· P. Gardolinski
Iron is an essential micronutrient for biological organisms and limits phytoplankton growth in certain high-nutrient, low-chlorophyll (HNLC) areas of the world's
oceans, which may have important implications for global carbon cycles. Such hypotheses have recently been tested in the under-productive waters of the equatorial Pacific
(Coale et al. 1996) and Southern Ocean (Boyd et al. 2000), where seeding an expanse
of surface water with low concentrations of dissolved Fe triggered a massive phytoplankton bloom, and resulted in a significant drawdown of surface water nitrate and
atmospheric CO 2 , The ongoing debate about the effect of Fe limitation on phytoplankton communities has highlighted how little is actually known about the complex marine speciation of Fe and uptake mechanisms for the growth of microorganisms. Similar mesoscale iron enrichment experiments are planned for different regions of the
HNLC Southern Ocean.
16.2.2
FI-CL Manifold for Iron
The manifold for the Fe monitor, shown in Fig. 16.5 (Bowie et al. 1998), utilizes the
luminol reaction (see Sect. 16.1.2) and a chelating microcolumn of 8-hydroxyquinoline (8-HQ) immobilized on a commercial hydrophilic vinyl co-polymer (Toyopearl
TSK gel, HW 75F, 32-63 micron fine, Toso Haas Co.). After Fe(III) reduction by sulphite
to the Fe(II) species, the 8-HQ resin extracts and preconcentrates the Fe from the sea
water sample as it flows through the column. Elution is then performed using a HCI
stream, which is mixed with the luminol reagent inside a quartz flow cell, emitting light
that is detected by a photomultiplier tube and the output sent to a flatbed chart recorder. The analytical figures of merit for this manifold are given in Table 16.1 and show
that it is suitable for the determination of Fe(II + III) in coastal and open ocean waters.
UHP water rinse
Acid wash
Sample
PumpS
1.5
Acetate buffer
I 0.2
PumpC
0.09 M Hel eluent
1.5
Luminol
1.5
mlmin-1
V2
8-HQ colu.mn
Waste
Chart
recorder
Fig. 16.5. Flow injection manifold with chemiluminescence detection for the determination of Fe(II + III)
in the marine environment