Nickel bioactive role in the oceans assessed by its isotopes

Although Nickel (Ni) is identified as a co-enzyme factor for the phytoplankton development, its role as bioactive element is controversial. Among others, the fact that Ni concentrations are never totally depleted in the surface waters remains an enigma. Lemaitre and her colleagues (2022, see reference below) realized the simultaneous analysis of the dissolved Ni isotopes and concentrations in waters collected in contrasting biogeochemical provinces as part of the GEOVIDE cruise (GA01), to which they added data extracted from the GEOTRACES IDP2021. Based on this data set, incubation results from the literature and a 3D modelling of the oceanic Ni cycle, reveal a strong biogeochemical divide with Ni isotope fractionation only occurring in low latitude surface waters. Indeed, in their new North Atlantic dataset, the lowest Ni concentrations (1.8-2.6 nmol/L) and highest δ60Ni (up to +1.67) are associated with low nitrate, south of the subarctic front (SAF), contrasting with stations at latitudes north of the SAF, where no clear Ni concentrations and isotopic variations are observed while they are richer in nitrates. The authors also evidence relationships with nitrogen isotope effects in the same samples that are suggestive of a link between Ni utilization, isotope fractionation and nitrogen fixation. This leads them to ask the exciting question of a possible nickel-nitrogen co-limitation in the low latitude ocean.

Figure: Nickel biogeochemical divide between high and low latitudes. a) Location of the GEOVIDE stations, superimposed on a map of the seasonal average nitrate (NO3) concentrations in surface waters. The subarctic front (SAF), displayed by the white dashed line, separates the low and high latitude stations (shown as circles and triangles respectively). b) Depth profiles of dissolved Ni concentrations and isotope composition (δ60Ni) at low (shown as circles) and high (shown as triangles) latitude stations. Low Ni concentrations in surface waters of low latitude stations are accompanied by significantly higher δ60Ni values.

Reference:

Lemaitre, N., Du, J., de Souza, G. F., Archer, C., & Vance, D. (2022). The essential bioactive role of nickel in the oceans: Evidence from nickel isotopes. Earth and Planetary Science Letters584, 117513. doi:10.1016/j.epsl.2022.117513

Latest highlights

MOTES: a new facility designed for trace element sampling in seawater

Zhang and a group of engineers and researchers from Shanghai and Qingdao are presenting a modular trace element sampling facility.

A thorough estimate of the hydrothermal plumes on neodymium concentration and isotope oceanic cycles

Basak and co-workers investigated the influence of particulate matter on neodymium distributions in the Southern East Pacific Rise Hydrothermal Plume.

What are the drivers of the distributions of cadmium, nickel, zinc, copper and cobalt, manganese and aluminium in the Atlantic Ocean? Two papers are tackling this issue

Chen and co-authors reveal that the distributions of dissolved tracers at depth in the South Atlantic are predominantly controlled by the mixing of North Atlantic Deep Water and waters of Antarctic origin…

Disentangling the sources and transport of iron in the Southern Ocean using a water mass mixing model analysis

Traill and co-workers used an extended optimum multiparameter analysis water‐mass mixing model to determine the interplay between physical and biological processes, and sources/sinks driving dissolved iron distributions…

Rechercher