Substantial intra-basin variation of the dissolved metal/phosphorus ratio in the different water masses of the Indian Ocean

Science Highlights

23 May 2013

The first simultaneous, full-depth, and basin-scale section-distribution of dissolved (D) aluminum (Al), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu),  zinc (Zn), cadmium (Cd), and lead (Pb) is reported in the Indian Ocean. In addition to widespread co-limitation for phytoplankton production by dissolved iron (DFe) and occurrence of redox-related processes, the authors observe an important variability of the dissolved metal/phosphorus ratio among the water masses within the Indian ocean (up to a factor of 300 between Arabian Surface waters and Lower Circumpolar Deep Water). The Cu/P, Zn/P, and Cd/P ratios are within the same order of magnitude for both phytoplankton and deep water, whereas the Mn/P, Fe/P, and Co/P ratios of phytoplankton can increase 100-fold or more compared to those in deep water. Such results are questioning the validity of using an “extended Redfield ratio” to trace metals. The consistent mechanism yielding these variations remains to be understood...

Meridional section distribution (~70°E) of the DMn/DAl ratio

Figure: Meridional section distribution (~70°E) of the DMn/DAl ratio.

Reference:

Thi Dieu Vu, H., Sohrin, Y. (2013) Diverse stoichiometry of dissolved trace metals in the Indian Ocean, Scientific Reports 3, DOI: 10.1038/srep01745

Latest highlights

Regional zinc cycling in the Indian Ocean

Chinni and his colleagues present dissolved zinc distributions across the Arabian Sea, Bay of Bengal and southern tropical Indian Ocean…

Contrasting organic carbon  remineralisation rates revealed by particulate excess barium in the North Pacific and South China Sea

Yuan and co-workers quantify organic carbon remineralisation in the twilight zone of the China Sea using particulate excess barium as a proxy…

Sedimentary controls on seawater nickel distributions and nickel isotope compositions: a two steps study

Nickel isotopic mass balance in the ocean stands among the less understood so far…

23 million years of productivity reconstructed in the Central Pacific Ocean using past and modern proxies

Using diverse geochemical proxies, Chu and colleagues analysed an iron–manganese crust to reconstruct central Pacific productivity over the past 23 million years.

Rechercher