Icebergs as sources of trace metals to the ocean: which impact?

Science Highlights

18 October 2021

Earth’s Ice Sheets are known to release significant quantities of lithogenic particles into the ocean every year, but how does this material affect trace metal availability in the ocean? Combining results from GEOTRACES cruise GN05 at the ‘79° N Glacier’ with inshore work in Greenland and the Western Antarctic Peninsula, Krause et colleagues (2021, see reference below), present trends in dissolved iron, cobalt, nickel and copper across the glacier-to-ocean salinity gradient. Elevated signals of all metals are associated with glacier runoff, although ~98% of dissolved iron supplied from freshwater is rapidly returned to particulate phases. Curiously, dissolved iron concentrations in particular appeared to be strongly buffered in inshore waters throughout spring and summer, which means lateral fluxes from fjord over-turning may be a key driver of lateral trace element export year-round.

Figure: Field locations and sample collection points: Trace metal concentrations across the salinity gradient were sampled at 8 sites spanning Greenland and the Western Antarctic Peninsula.

Reference:

Krause, J., Hopwood, M. J., Höfer, J., Krisch, S., Achterberg, E. P., Alarcón, E., Carroll, D., González, H. E., Juul-Pedersen, T., Liu, T., Lodeiro, P., Meire, L., Rosing, M. T. (2021). Trace Element (Fe, Co, Ni and Cu) Dynamics Across the Salinity Gradient in Arctic and Antarctic Glacier Fjords. Frontiers in Earth Science, 9, 878. https://doi.org/10.3389/feart.2021.725279

Latest highlights

Mercury content and isotopes in bird’s guano: a window to reconstruct past climates

By analysing peat cores, Chuxian Li and her colleagues have shown how populations of nesting seabirds have fluctuated on a sub-Antarctic Island over the last 8,000 years.

Contraction of North Atlantic Deep Water during glacial times: a paradigm called into question

Blaser and co-authors propose a new distribution of deep-water masses in the Atlantic Ocean during the Last Glacial Maximum and the Heinrich Stadial..

Authigenic radiogenic neodymium isotope composition traces millennial-scale overturning circulation variability in the Arabian Sea

The neodymium isotopic signature of the sediment authigenic fraction is, a priori, a valuable proxy for reconstructing deep-water mass trajectories…

Magmatic activity at the Carlsberg Ridge in the Indian Ocean triggered by glacial sea-level variation

De and colleagues provide a high-resolution record of magmatic input and associated hydrothermal activity over the past 49 kyr from a core recovered from a magmatic segment of the slow-spreading Carlsberg Ridge in the Indian Ocean.

Rechercher