Iron isotopes can be used as a tool in oceanography
Washington: A new research, involving scientists from the National Oceanography Centre, Southampton (NOCS), has highlighted the potential utility of iron isotopes for addressing important questions in ocean science.
Pore-fluid iron isotope measurements have so far been restricted to the continental shelves where the supply of carbon is typically high and dissimilatory iron reduction is extensive, precluding comparisons with low-carbon, deep-water environments.
William Homoky, who is a research student at the University of Southampton's School of Ocean and Earth Sciences based at NOCS, and his colleagues have helped fill this gap be measuring iron isotopes in pore fluids from both the Eel River shelf on the northern California margin (120 m water depth), and deep-sea sediments from the Southern Ocean around the Crozet Island Plateau (3000 m water depth), about 1400 miles southeast of South Africa.
"We are excited by our findings not only because they represent the first measurements of their kind, but because they are telling us something important about iron cycling processes in the deep-sea, which can inform future iron isotope investigations in ancient rocks and the modern oceans," said Homoky.
They found that the composition of iron isotopes in the pore fluids reflects the different extent of sedimentary iron recycling between the two sites.
Specifically, the pore-fluid iron isotope compositions reflect the extent of iron recycling during early diagenesis, which is driven by organic carbon inputs from the overlying water column.
The researchers believe that iron isotope processing in carbon-limited environments, such as the deep-sea, is important and that it should help future interpretations of the rock record.
"Additionally, the unique isotopic fingerprint of pore fluid iron in continental shelf settings is confirmed, highlighting the potential for iron isotopes to trace the inputs of continental shelf-derived iron in seawater," according to the researchers.
Current thesis research aims to improve our understanding of iron cycling between sediments and seawater and compares the affects of contrasting sediment geochemistry on iron flux generating processes.
"In the future, I would like to examine processes of sedimentary iron cycling in the high-latitudes, where sediments are subject to enhanced rates of environmental change due to changing climate in these regions," said Homoky.