Fig. 6: Changes in iron-mediated organo-mineral interactions (FeOMIs) following land use change.

a In pristine mangroves, FeOMIs are primarily governed by the association between organic matter and poorly crystalline iron oxides, mainly through co-precipitation, which effectively immobilizes organic carbon. b As mangroves are converted to shrimp ponds the more oxidative environment leads to an increase in crystalline iron oxides. These crystalline forms of iron oxides are less efficient at immobilizing organic matter, as they predominantly rely on adsorption. c Following conversion to pasture, the geochemical environment undergoes strong oxidation coupled to acidification. This causes the dissolution of iron oxides, leading to the massive release of Fe-bound OC. Figure adapted from BioRender (Gomes Viana, D. 2024 https://BioRender.com/m14f407). and adapted and modified from Integration and Application Network (ian.umces.edu/media-library), licensed under Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) https://creativecommons.org/licenses/by-sa/4.0/. This adapted figure is distributed under the same license (CC BY-SA 4.0).