Microbial competition for iron determines its availability to the ferrous wheel.

Iron plays a pivotal role in regulating ocean primary productivity. Iron is supplied from diverse sources such as the atmosphere and the geosphere, and hence iron biogeochemical research has focused on identifying and quantifying such sources of "new" iron. However, the recycling of this new iron fuels up to 90% of the productivity in vast oceanic regions.

Critical evaluation of a seaFAST system for the analysis of trace metals in marine samples.

A seawater preconcentration system (seaFAST) with offline sector-field inductively coupled plasma mass spectrometry (SF-ICP-MS) detection was critically evaluated for ultra-low trace elemental analysis of Southern Ocean samples over a four-year period (2015-2018). The commercially available system employs two Nobias PA1 resin columns for buffer cleaning and sample preconcentration, allowing salt matrix removal with simultaneous extraction of a range of trace elements. With a primary focus on method simplicity and practicality, a range of experimental parameters relevant to oceanographic analysis were considered, including reduction of blank levels (over weeks and years), instrument conditioning, extraction efficiencies over different pH ranges (5.