Unique winter dataset of particulate and dissolved cadmium in the Indian sector of the Southern Ocean

Cloete and collaborators (2021, see reference below) analysed particulate and dissolved cadmium (pCd and dCd respectively) at 7 stations in austral winter along a North South section between 41°S and 58°S, off South Africa. This heroic sampling effort and the subsequent analyses allowed these authors to establish that: 1) biological activity was still ongoing in winter although weaker than in summer; 2) biologically driven particulate Cd/P variations were observed along the section reflecting a stronger demand of Cd by diatoms in the Antarctic Zone compared to surface waters to the North; 3) the uptake of Cd is driven predominantly by the availability of dCd as well as a complex interplay involving dissolved iron (dFe), zinc (dZn) and manganese (dMn).

This last observation leads to distinct regional trends in Cd (vs phosphate, P) uptake and remineralization. The authors discuss the implications of the differential particulate Cd and P remineralization for the dCd to PO4 ratios in the upper water column. They also identify that in intermediate and deep waters, dCd distributions are largely the result of mixing between northward traveling waters of Antarctic origin (high dCd/dPO4 signatures) and southward traveling North Atlantic Deep Water (low dCd/dPO4 signature).

Figure: Particulate cadmium (pCd; black bars) and phosphorus (P; gray bars) normalized to profile maximum values (bottom axis) are plotted with absolute pCd:P ratios (red dots) to investigate potential differences in remineralization length scales. The plots show different trends in the pCd:P profiles, across the transect and with depth, reflecting variations in phytoplankton community structure, their Cd uptake characteristics and the relative remineralization length scales for pCd and P.

Reference:

Cloete R, Loock JC, van Horsten NR, Fietz S, Mtshali TN, Planquette H and Roychoudhury AN (2021) Winter Biogeochemical Cycling of Dissolved and Particulate Cadmium in the Indian Sector of the Southern Ocean (GEOTRACES GIpr07 Transect). Front. Mar. Sci. 8:656321. doi: 10.3389/fmars.2021.656321

Latest highlights

Science Highlights

Different fates of four poorly soluble trace elements in the Pacific Ocean

Zheng and co-authors present the full-depth distributions of aluminum, lead, manganese and copper in the western South Pacific.

24.11.2022

Science Highlights

Internal tides, energetic dynamical processes that generate particle nepheloids at different depths

In this study, Barbot and co-authors identified the sites where internal tides are responsible for sediment resuspension…

09.11.2022

Science Highlights

Greenland’s floating ice tongues, sources of dissolved lead to the Arctic

Using helium and neon as tracers for subglacial meltwater, Krisch and colleagues found that subglacial discharge is a source of dissolved lead.

Science Highlights

Debate on the dissolved nickel bioavailibility in surface waters

John and co-authors tackle one of the known paradoxes regarding trace metal cycles in the ocean…

08.11.2022

Rechercher