The University of Southampton
University of Southampton Institutional Repository

The distribution of neodymium isotopes and concentrations in the Eastern Equatorial Pacific: water mass advection versus particle exchange

The distribution of neodymium isotopes and concentrations in the Eastern Equatorial Pacific: water mass advection versus particle exchange
The distribution of neodymium isotopes and concentrations in the Eastern Equatorial Pacific: water mass advection versus particle exchange
The radiogenic isotope composition of the Rare Earth Element (REE) neodymium (Nd) is a powerful water mass proxy for present and past ocean circulation. The processes controlling the Nd budget of the global ocean are not quantitatively understood and in particular source and sink mechanisms are still under debate.

In this study we present the first full water column data set of dissolved Nd isotope compositions and Nd concentrations for the Eastern Equatorial Pacific (EEP), where one of the globally largest Oxygen Minimum Zones (OMZ) is located. This region is of particular interest for understanding the biogeochemical cycling of REEs because anoxic conditions may lead to release of REEs from the shelf, whereas high particle densities and fluxes potentially remove the REEs from the water column. Data were obtained between 1°40?N and 16°S along a nearshore and an offshore transect. Near surface zonal current bands, such as the Equatorial Undercurrent (EUC) and the Subsurface Countercurrent (SSCC), which are supplying oxygen-rich water to the OMZ are characterized by radiogenic Nd isotope signatures (?Nd=?2). Surface waters in the northernmost part of the study area are even more radiogenic (?Nd=+3), most likely due to release of Nd from volcanogenic material. Deep and bottom waters at the southernmost offshore station (14°S) are clearly controlled by advection of water masses with less radiogenic signatures (?Nd=?7) originating from the Southern Ocean. Towards the equator, however, the deep waters show a clear trend towards more radiogenic values of up to ?Nd=?2. The northernmost station located in the Panama basin shows highly radiogenic Nd isotope signatures in the entire water column, which indicates that particle scavenging, downward transport and release processes play an important role. This is supported by relatively low Nd concentrations in deep waters (3000–6000 m) in the EEP (20 pmol/kg) compared to locations in the Northern and Central Pacific (40–60 pmol/kg), which suggests enhanced removal of Nd in the EEP.
neodymium isotopes, Rare Earth Elements, particle scavenging, boundary exchange, oxygen minimum zone, Eastern Equatorial Pacific
0012-821X
198-207
Grasse, Patricia
e4c6d063-887e-4151-9dd0-1be9e2cdd9c7
Stichel, Torben
c04e16ca-782d-47af-b955-7bbdd9e7f91d
Stumpf, Roland
917cd625-0af9-4d1b-b4aa-d2792528b320
Stramma, Lothar
90bb48f0-5d94-4302-873e-2101b4c6974f
Frank, Martin
09ec65ac-f62d-41da-86b2-81908973b8a1
Grasse, Patricia
e4c6d063-887e-4151-9dd0-1be9e2cdd9c7
Stichel, Torben
c04e16ca-782d-47af-b955-7bbdd9e7f91d
Stumpf, Roland
917cd625-0af9-4d1b-b4aa-d2792528b320
Stramma, Lothar
90bb48f0-5d94-4302-873e-2101b4c6974f
Frank, Martin
09ec65ac-f62d-41da-86b2-81908973b8a1

Grasse, Patricia, Stichel, Torben, Stumpf, Roland, Stramma, Lothar and Frank, Martin (2012) The distribution of neodymium isotopes and concentrations in the Eastern Equatorial Pacific: water mass advection versus particle exchange. Earth and Planetary Science Letters, 353-354, 198-207. (doi:10.1016/j.epsl.2012.07.044).

Record type: Article

Abstract

The radiogenic isotope composition of the Rare Earth Element (REE) neodymium (Nd) is a powerful water mass proxy for present and past ocean circulation. The processes controlling the Nd budget of the global ocean are not quantitatively understood and in particular source and sink mechanisms are still under debate.

In this study we present the first full water column data set of dissolved Nd isotope compositions and Nd concentrations for the Eastern Equatorial Pacific (EEP), where one of the globally largest Oxygen Minimum Zones (OMZ) is located. This region is of particular interest for understanding the biogeochemical cycling of REEs because anoxic conditions may lead to release of REEs from the shelf, whereas high particle densities and fluxes potentially remove the REEs from the water column. Data were obtained between 1°40?N and 16°S along a nearshore and an offshore transect. Near surface zonal current bands, such as the Equatorial Undercurrent (EUC) and the Subsurface Countercurrent (SSCC), which are supplying oxygen-rich water to the OMZ are characterized by radiogenic Nd isotope signatures (?Nd=?2). Surface waters in the northernmost part of the study area are even more radiogenic (?Nd=+3), most likely due to release of Nd from volcanogenic material. Deep and bottom waters at the southernmost offshore station (14°S) are clearly controlled by advection of water masses with less radiogenic signatures (?Nd=?7) originating from the Southern Ocean. Towards the equator, however, the deep waters show a clear trend towards more radiogenic values of up to ?Nd=?2. The northernmost station located in the Panama basin shows highly radiogenic Nd isotope signatures in the entire water column, which indicates that particle scavenging, downward transport and release processes play an important role. This is supported by relatively low Nd concentrations in deep waters (3000–6000 m) in the EEP (20 pmol/kg) compared to locations in the Northern and Central Pacific (40–60 pmol/kg), which suggests enhanced removal of Nd in the EEP.

Full text not available from this repository.

More information

Published date: 1 November 2012
Keywords: neodymium isotopes, Rare Earth Elements, particle scavenging, boundary exchange, oxygen minimum zone, Eastern Equatorial Pacific
Organisations: Geochemistry

Identifiers

Local EPrints ID: 368791
URI: http://eprints.soton.ac.uk/id/eprint/368791
ISSN: 0012-821X
PURE UUID: 351fe10c-0e8b-4cfb-a380-ed6be6a0ff45

Catalogue record

Date deposited: 16 Sep 2014 10:23
Last modified: 15 Jul 2019 21:45

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×