Dissolved iron in the Southern Ocean (Atlantic sector)

Viral lysis and microzooplankton grazing of phytoplankton throughout the Southern Ocean

“…Nutrient concentrations in the WG were similar to those in the AAZ, with the exception of elevated silicate ($ 50 mmol L 21 ). Dissolved free iron concentrations were low over the entire transect, with concentrations never exceeding 0.5 nmol L 21 (Klunder et al 2011).…”

Diagnosing oceanic nutrient deficiency

“…Data on the distributions of the macronutrient elements N, P, Si [44,[62][63][64][65][66][67], the micronutrient elements Fe, Mn, Ni, Zn and Cd [64,[68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] and the non-nutrient element Al [67,85,86] were downloaded from the IDP2014 collection [20] and imported into a Matlab™ environment for analysis. For each sampling location and/or seawater volume/water mass, a ranking of the relative deficiencies of multiple nutrient elements was calculated by dividing observed dissolved concentrations by an assumed 'typical' stoichiometric ratio within newly formed organic (biological) material (figure 1) [11,18].…”

Impact of hydrothermalism on the ocean iron cycle

“…Indeed, a synthesis study suggests a significant number of ridge systems remain to be discovered in the Southern Ocean, pointing out that only eight sites have been recorded along the approximately 20 000 km ridge system around Antarctica [45]. Apart from one study near the Bouvet Triple junction [17], much of our understanding of the broader biogeochemical impacts of hydrothermal vents on the ocean Fe cycle comes from studies that have taken place in the Atlantic [20,21], Pacific [24] and Indian [46] Oceans. As discussed in §4a, it is important to consider how generalized these inferences are for ridges in the Southern Ocean, which we have demonstrated to be the main driver of the carbon cycle response.…”

“…A discrete set of observations finding elevated Fe close to hydrothermal systems [15] or distal anomalies in Fe linked to the noted hydrothermal tracer 3 He [16] provided initial indications of the importance of hydrothermal Fe. But it was the first large-scale GEOTRACES sections conducted as part of the international polar year that noted widespread Fe signals linked to noted hydrothermal sites in the Southern [17] and Arctic [18] Oceans. When a hydrothermal Fe source was added to an ocean biogeochemical model, it was found to have a large influence on interior-ocean Fe concentrations and improved the ability of the model to reproduce Fe observations [19].…”