393
Primary Production in the Oceans
were performed. Surface water iron, nitrate, fCO 2 , and fluorescence were also performed
on transits between stations (Sakamoto et al., 1998; Millero et al., 1998). The surface values
of temperature, nitrate, and fCO 2 around the islands showed the strong upwelling that
occurs off the western coast (see Figure 9.23).
The nitrate concentrations around the islands were greater than 10 μM at the surface.
Chlorophyll concentrations and rates of primary production were significantly elevated at
stations downstream when compared to upstream. Iron was not detected (<0.2 nM) with
the surface mapping system on transits upstream of the islands. Iron concentrations as
high as 1.3 nM were detected on a transect from 1°30′ S to 0° along 91°45′ W. The areas with
elevated iron concentrations are within 10 km of Isla Isabella. These high concentrations
appeared to be associated with upwelled water that had higher salinity and lower temperature than the surrounding surface water masses. Elevated chlorophyll fluorescence signals
were also associated with the high iron concentrations. Even higher iron concentrations
Table 9.6
Maximum Changes in Chemical Parameters
Observed during the Last Occupation of the
North Patch and the South Patch during
the SOFeX Study
North Patch
Day 39
South Patch
Day 20
NO 3 (μmol kg –1 )
–1.4 ± 0.1
–3.5 ± 0.1
PO 4 (μmol kg –1 )
–0.09 ± 0.02
–0.21 ± 0.02
Si(OH) 4 (μmol kg –1 )
–1.1 ± 0.1
−4.0 ± 0.1
NTA (μmol kg –1 )
0 ± 4
0 ± 4
NTCO 2 (μmol kg –1 )
14 ± 4
–23 ± 4
pH sws (25°C)
0.032 ± 0.01
0.057 ± 0.01
f CO 2 (μatm)
–26 ± 3
–36 ± 3
O 2 (μmol kg –1 )
23 ± 2
11 ± 2
Figure 9.21
Color satellite view showing the plume of high chlorophyll on the western coast of the Galapagos Islands.