Chemistry of Iron in Different Marine Environments and the Binding of Iron, Copper, Manganese and Aluminum with Particles in a Microcosm System

• Main Author: Hong, Huasheng
• Format: Text
• Language: unknown
• Published: DigitalCommons@URI 1984
• Subjects: Northwest Atlantic
• Online Access: https://digitalcommons.uri.edu/oa_diss/1468; https://doi.org/10.23860/diss-hong-huasheng-1984; https://digitalcommons.uri.edu/context/oa_diss/article/2483/viewcontent/diss_hong_huasheng_1984.pdf

The different chemical forms of iron are an important factor in the marine biochemistry and geochemistry of this element. In this study, the forms and distribution of iron were investigated along a horizontal salinity gradient in the Connecticut River estuary in July 1981, and at a vertical profile in the Slope Water region of the Northwest Atlantic Ocean in September 1981. The redox state of iron was investigated in the offshore water of Peru in January 1984. Since the particulate phase is an important form of iron and other trace metals, the binding of iron, copper, manganese and aluminum with the particles collected in a microcosm were investigated in the summer of 1983. Chemical models, including a dissolved iron solubility model, an iron speciation model, and an adsorption model, were examined using the experimental data obtained in the field to gain a better understanding of the factors that control the behavior of iron in the marine environment. In the Connecticut River estuary, 80-90% of iron was in the particulate form and followed closely the transport of the total suspended matter. The decrease of the 0.1 to 0.4 μm fraction iron with salinity corresponded to the increase of the particulate iron fraction. Total iron in the Connecticut River estuary appeared to be conservative due to the short residence time of the water not allowing the particles to be removed from the water column. A substantial amount of the "dissolved" iron (0.1 μm filter) in the low salinity region was actually fine colloidal particles. The "dissolved" iron approached the true dissolved value calculated from a solubility model as the salinity increased. In a Slope Water station, the concentration of total iron was 1-3 nmol/kg near the surface, increasing to 6-9 nmol/kg in the 02 minimum zone and then increasing to 12 nmol/kg above the seafloor. Three different pore size filters retained almost the same amounts of particulate iron (50-60% of the total) except near the bottom nepheloid layer (80% of the total). Results showed that ...