Fe(II) biogeochemistry in a changing ocean

Iron is a trace element, essential for the development of organisms and has a great impact on the carbon cycle through the planktonic communities and their productivity. Soluble iron in its reduced form Fe(II) is the species mainly available by phytoplankton, unlike oxidized iron, Fe(III), of low solubility and strongly complexed with the organic compounds of the medium. Due to the pH, T and oxygen conditions of the marine environment, Fe(II) is thermodynamically unstable and tends to oxidize rapidly. The acidification of the medium favors the presence of Fe(II). In addition, organic matter plays an essential role in the cycle of Fe in the ocean. The presence of organic compounds can reduce Fe(III) to Fe(II) and also stabilize Fe(II) through complexation, being a pH-dependent process.

The main objective of the ATOPFe project is to investigate which mechanisms determine the presence of dissolved Fe(II) in the marine environment, and how they are affected by the ocean acidification, warming and the presence of organic matter. To get this objective, studies carried out in different oceanic regions are combined with laboratory studies, in order to respond, from the theoretical point of view of marine chemistry-physics, to those mechanisms that control the behavior of Fe(II) and that can explain the effect of ocean acidification on the biogeochemical cycle of iron and its interaction with phytoplankton.