Several hypotheses exist on the sources and decay rates of iron-binding organic ligands. Ligand concentrations vary between ~0.2 to ~10 nM and sources and sinks are thought to be active production by iron-stressed cells, release from organic debris, photochemistry and bacterial degradation. The role of these processes can now be put to the test with by combining three-dimensional modelling with observed ligand distributions. As the concentration of ligands influences the solubility of iron, a variable ligand distribution may feed back on the cycling of iron. Here we show first sensitivity studies on the effect of different assumptions on sources and sinks of iron-binding ligands on iron cycling and residence time in a global biogeochemical model, and compare the results to a model where ligand concentrations are held constant, as is often done. We also compare the resulting ligand distribution with a compilation of ligand measurements. Despite the heterogenous nature of the compiled data that includes very different opproaches to measure iron complexing capacity, some trends on deep ligand profiles and their interbasin variability begin to emerge.