There are slight iron isotopic variations in the oceans relative to IRMM-014, which likely reflect variations in the biogeochemical cycling of iron within a given ocean basin. In the southeastern Atlantic, δFe values between -0.13 and +0.21‰ have been measured. In the north Atlantic,  δFe values between -1.35 and +0.80‰ have been measured. In the equatorial Pacific δFe values between -0.03 and +0.58‰ have been measured. The supply of aerosol iron particles to the ocean have an isotopic composition of approximately 0‰. Dissolved iron riverine input to the ocean is isotopically light relative to igneous rocks, with δFe values between -1 and 0‰.
Most modern marine sediments have δFe values similar to those of igneous δFe values. Marine ferromanganese nodules have δFe values between -0.8 and 0‰.