Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Railsback's Some Fundamentals of Mineralogy and Geochemistry Marine nutrient cycles IV: Iron Wind-borne particulate flux of Fe3+ Riverine particulate & colloidal flux of Fe3+ Oxidation in weathering Long-term geologic cycling with vast geologic reservoir of iron Particulate and sorbed Fe3+ Vast majority of oceanic iron takes this route and is irrelevant to biological processes Photochemical Dissolved reduction Fe2+ by siderophores Phyto(Fe-binding plankton ligands) produced by bacteria Re-oxidation Legend: Oxidized Fe (Fe3+) Reduced Fe (Fe2+) Sources: Barbeau (2006) etc. This is one of a series of pages presenting simple schematic cycles of nutrients in the oceans. The other pages are concerned with nitrogen, phosphorous, and silicon. Critical thoughts: Fe is useful to photosynthesizers only as Fe2+, which is very scarce in the ocean. Fe3+ is insoluble and settles readily in or on solids. The wind-borne flux of Fe is enhanced by barren land areas (e.g., deserts and peri-glacial environments) susceptible to erosion by wind. Differences from other cycles: Unlike N, P, and Si, Fe is not recycled at depth and so is not resupplied to surface waters by upwelling. Reduction, rather than oxidation, is required to make Fe available to photosynthesizers. Recycling of Fe from organisms is trivial compared to oceanic content of Fe. LBR SFMGNutrientCycles06 3/2009