The relationships between dissolved zinc and major nutrients phosphate and silicate along the GEOTRACES GA02 transect in the west Atlantic Ocean

• Published in: Global Biogeochemical Cycles
• Main Authors: Middag, R., de Baar, H.J.W., Bruland, K.W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: Antarctic; Southern Ocean; Antarc*
• Online Access: https://www.vliz.be/imisdocs/publications/75/324675.pdf

Dissolved zinc (Zn) has a nutrient‐type distribution in the ocean that more closely resembles the distribution of silicate (Si) than phosphate (PO 4 ). However, Zn is a trace‐nutrient and mostly present in the organic fraction of phytoplankton rather than the siliceous frustule. It has been suggested the coupling of Zn and Si is caused by the strong depletion of nutrients in the Southern Ocean, possibly combined with scavenging of Zn. Here we assess the distribution of Zn and nutrients along the conduit of southward traveling waters of northern origin and northward traveling waters of Antarctic origin to unravel the influence of various water masses and local biogeochemical processes in the Atlantic Ocean. The distribution of Zn and Si is governed by mixing such that influence of remineralization is barely distinguishable, whereas the distribution of PO 4 is influenced by both processes. The subsurface water masses that supply nutrients to the surface ocean are depleted in Zn. Indeed, the Southern Ocean water masses play a driving role, but remarkably, also subsurface water masses from northern high‐latitude origin are depleted in Zn. Both northern and southern high‐latitude waters have a relatively high Zn:PO 4 uptake and remineralization ratio, implying it is Zn availability and not only chronic iron limitation that leads to increased Zn uptake in the high‐latitude regions. The limited supply of Zn to the surface Atlantic Ocean can explain the lack of an Atlantic Zn remineralization signal and indicates Zn might play a role in phytoplankton community composition and productivity.