Water chemistry from the North Atlantic Bloom Experiment

The carbon export rate from the upper 35 m for the entire NABE study period (24 April to 1 June) was 39 mmol/m**2 day. This value divided by the averaged productivity for the entire study (86 mmol N/m**2 day) gave an F-ratio of 0.45. Concentrations of Cu, Fe, Ni, Pb and Zn were determined in water samples provided by JGOFS NABE scientists involved with primary productivity measurements.

Although little contamination was observed for Cu, Ni and Pb, relatively large amounts of Zn (10 nmol/kg) were found in some cases. In subsequent studies it was learned that this quantity of Zn can depress productivity rates by 25%. North Atlantic dissolved Fe concentrations were similar to those occurring in the Pacific (surface = 0.07; deep = 0.5-0.6 nmolP/kg).

Although no evidence of Fe deficiency was found in enrichment experiments, the addition of nmol amounts of Fe did increase CO2 uptake and POC formation by factors of 1.3-1.7. In this region, most of the phytoplankton's Fe requirement is probably met via the lateral transport of Fe from distant continental margins.