Combining voltammetric and mass spectrometric data to evaluate iron organic speciation in subsurface coastal seawater samples of the Ross sea (Antarctica)

Abstract

Iron (Fe) is the most important trace element in the ocean, as it is required by phytoplankton for photosynthesis and nitrate assimilation. Iron speciation is important to better understand the biogeochemical cycle and availability of this micronutrient, in particular in the Southern Ocean. Dissolved Fe (dFe) concentration and speciation were determined in 24 coastal subsurface seawater samples collected in the western Ross sea (Antarctica) during the austral summer 2017 as part of the CELEBeR (CDW Effects on glacial mElting and on Bulk of Fe in the Western Ross sea) project. ICP-DRC-MS was used for dFe determination, whereas CLE-AdSV was used to obtain the concentration of complexed and free dFe, of the ligands, and the values of the stability constants of the complexes. Dissolved Fe values ranged from 0.4 to 2.5 nM and conditional stability constant (logK’Fe’L) from 13.0 to 15.0, highlighting the presence of Fe-binding organic complexes of different stabilities. Principal component analysis (PCA) allowed us to point out that Terra Nova Bay and the neighboring area of Aviator and Mariner Glaciers were different in terms of chemical, physical, and biological parameters. A qualitative investigation on the nature of the organic ligands was carried out by HPLC–ESI–MS/MS. Results showed that siderophores represented a heterogeneous class of organic ligands pool.

Biosynthesis of the proteins containing neurotoxinβ-N-methylamino-L-alanine in marine diatoms

“…Harmful algal blooms formed by diatoms showed that the supply of iron (Fe) played a critical role in the development of extensive diatom blooms in coastal upwelling regimes (Bruland et al 2001). In addition, Fe, as a micronutrient required for phytoplankton growth, contributed to the marine primary productivity and carbon export (Vivado et al 2022). However, the concentration of Fe in seawater, especially in surface seawater was very low (Hogle et al 2018), and Fe deficiency in seawater limited the photosynthesis and growth of phytoplankton, resulting in insufficient utilization of nitrogen (Bruland et al 2001).…”