ALBERT

Description: The availability of dissolved iron (dFe) exerts an important control on primary production. Recent ocean observation programs have provided information on dFe in many parts of the ocean, but knowledge is still limited concerning the rates of processes that control the concentrations and cycling of dFe in the ocean and hence the role of dFe as a determinant of global primary production. We constructed a three-dimensional gridded dataset of oceanic dFe concentrations by using both observations and a simple model of the iron cycle, and estimated the difference of processes among the ocean basins in controlling the dFe distributions. A Green's function approach was used to integrate the observations and the model. The reproduced three-dimensional dFe distribution indicated that iron influx from aeolian dust and from shelf sediment were 7.6 Gmol yr and 4.4 Gmol yr in the Atlantic Ocean and 0.4 Gmol yr and 4.1 Gmol yr in the Pacific Ocean. The residence times were estimated to be 12.2 years in the Atlantic and 80.4 years in the Pacific. These estimates imply large differences in the cycling of dFe between the two ocean basins that would need to be taken into consideration when projecting future iron biogeochemical cycling under different climate change scenarios. Although there is some uncertainty in our estimates, global estimates of iron cycle characteristics based on this approach can be expected to enhance our understanding of the material cycle and hence of the current and future rates of marine primary production.