Fe(II) Kinetic Variability in Different Water Masses Across the Equatorial Pacific

Abstract

Iron(II) is a species of iron that is highly soluble in water, making it the most bioavailable form of iron to organisms living in the ocean. Iron is a vital micronutrient for various plankton species and can be the limiting nutrient in much of the open ocean. Fe(II) kinetics in the world’s oceans have been revisited in numerous studies but little has been done to quantify the oxidation rates of Fe(II) in natural waters. Understanding the rate at which Fe(II) is oxidized is essential for determining iron’s bioavailability. Oxygen concentration, temperature, and pH are just some of the variables that contribute to changes in oxidation rates of Fe(II) and they are all related to one another, further making it difficult to attribute a change in oxidation rate to a specific environmental condition. The oxidation rates at each station in the equatorial Pacific were within 0.1 μM/s of one another. The difference in oxidation rates and physical properties between the water masses sampled in this research was small. Although there was a slight difference in oxidation rate at each station, we are unable to conclude that pH or oxygen concentration is responsible for the change.