POSTER Session 4

SPECTROPHOTOMETRIC MEASUREMENTS TO KNOW THE ROLE OF INDIVIDUAL ORGANIC LIGANDS ON THE Fe REDOX CHEMISTRY IN SEAWATER

To understand the role of organic ligands in the redox chemistry in seawater, the use of spectrophotometric measurements is indispensable. This technique allows us to identify them in seawater due to their optical fingerprints, identify their properties and, at the same time, measure the Fe(III) reduction to Fe(II) with the use of ferrozine. The presence of organic ligands in the ocean is coupled with trace metal chemistry. The organic ligands are included in a global pool of heterogeneous ligands and their role on the metal chemistry must be studied. Among all the trace metals, iron (Fe) is an essential element due to its vital role in primary production. In marine environments, Fe exists in two oxidation states Fe(II) and Fe(III). Although Fe(III) is not soluble, it can be found in solution due to the formation of complexes. On the other hand, Fe(II) can also be produced due to the Fe(III) reduction via reaction with some organic compounds making it more bioavailable for microorganisms. In the current study, the amino acid tryptophan, found in seawater from exudates of microalgae, can form complexes with metal ions, and its characteristic absorption band in the UV-visible spectrum at 280 nm can be used to detect it. These organic compounds affect the Fe(III) reduction in seawater. Therefore, the use of spectrophotometric techniques improves our knowledge of the Fe biogeochemical cycle through the characterization of organic ligands and their impact on Fe redox chemistry.

*Laura Suárez-Betancor, Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria (ULPGC), Spain, [email protected], https://orcid.org/0009-0009-9446-5733

David González-Santana, Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria (ULPGC), Spain, [email protected], https://orcid.org/0000-0001-8726-7768

Aridane G. González, Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria (ULPGC), Spain, [email protected], https://orcid.org/0000-0002-5637-8841

Melchor González-Dávila, Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria (ULPGC), Spain, [email protected]

J. Magdalena Santana-Casiano, Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de Las Palmas de Gran Canaria (ULPGC), Spain, [email protected]

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