The dissolved (D) trace metals zinc (Zn), cadmium (Cd), cobalt (Co), copper (Cu), iron
(Fe), manganese (Mn), nickel (Ni), titanium (Ti), lanthanum (La), yttrium (Y), and lead
(Pb) were analyzed via ICPMS in samples from the Ross Sea obtained during a cruise
between 20 December 2013 and 5 January 2014. The concentrations of DZn, DCd,
DCo, DCu, DFe, DMn, DNi, and DTi were significantly lower in the Antarctic surface
Water (AASW) compared to the other deeper water masses, indicating biological uptake
and possibly scavenging. In the AASW, DLa and DY were higher than in Winter Water
(WW). This can be explained by a spring source from ice melt followed by loss during
summer and autumn, probably due to passive adsorption. Dissolved Pb was low (16
pM) and no distinction between water masses was possible. Akin to the macro-nutrients
nitrate and silicate, the modified Circumpolar Deep Water (mCDW) shows elevated DCd
compared to the shelf water masses. Sea ice melt and ice sheet melt released DZn, DFe,
DMn, DNi, DY, DLa, and probably DPb into the Ross Sea. However, only DFe, DMn, DY
and DLa are transported into the Antarctic Circumpolar Current with the outflowing High
Salinity Shelf Water (HSSW). The bottom nepheloid layer (BNL) released DFe, as well as
DMn and DCu, into the HSSW whereas lateral transport from land formed a source of
DMn and DFe. One station in the Ross Sea Polynya was resampled after two weeks,
during which time the thickness of the BNL increased, with accompanying increases in
DFe and DMn near the seafloor. In the surface layer nutrients (including micro-nutrients)
were depleted further. The uptake slopes/stoichiometric ratios of DZn, DCd and DCo
versus phosphate indicated that the distribution of these metals is related to uptake as
well as the composition of the phytoplankton community. Estimated stoichiometric ratios
of Zn and Cd relative to P were higher at a station dominated by Phaeocystis antarctica
than at diatom-dominated stations, implying a higher utilization of these metals by
P. antarctica.
