Scandium: a new oceanic tracer with surprising properties

29 June 2016

The first modern data set of dissolved scandium (Sc) in the open ocean is presented. Thanks to three GEOTRACES cruises, its distribution is compared between the different oceanic basins. This work also compares the reactivity of Sc with its trivalent periodic table group mates: yttrium (Y) and lanthanum (La) on the one hand, and aluminium (Al) and gallium (Ga) on the other hand.

These distributions and comparisons reveal that scandium is a hybrid-type metal with a residence time on the order of 1000 years. In addition, Sc displays similar particle reactivity to iron, which makes the authors suggest that Sc could help to constrain the non-biogenic part of the iron cycle.

16 Parkeretal l — **Figure:** Comparing the concentrations of elements from deep water in different ocean basins is a classic way to categorize their reactivity and understand something about how they cycle through the ocean. Scandium, yttrium and lanthanum all occupy the same column in the periodic table, meaning that they are likely to have similar reactivity. However, this figure shows that while yttrium and lanthanum have higher concentrations in the North Pacific deep water than in the North Atlantic, scandium has similar deep-water concentrations in both ocean basins. From this we conclude that scandium is more reactive than yttrium and lanthanum in the ocean, and that scandium is in fact similar to iron, an important element that perhaps can be better understood through its similarity to scandium. Please click on the figure to view it larger.

Reference:

Parker, C. E., Brown, M. T., & Bruland, K. W. (2016). Scandium in the open ocean: A comparison with other group 3 trivalent metals. Geophysical Research Letters, 43, 2758–2764. doi:10.1002/2016GL067827

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