Neodymium isotopic composition of the Mediterranean outflow and the eastern North Atlantic

Journal Article · Thu Dec 01 04:00:00 EST 1988 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(88)90144-5· OSTI ID:5014159

Spivack, A J; Wasserburg, G J ^[1]

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1. California Institute of Technology, Pasadena (USA)

The neodymium concentration and isotopic composition of the Mediterranean outflow in the Strait of Gibraltar has been directly determined. The outflow has a dissolved Nd concentration of {approximately}23 pmoles/kg with {epsilon}{sub Nd}(O) = {minus}9.4. These results are in clear disagreement with previous values inferred for the Mediterranean. This concentration and {epsilon}{sub Nd}(O) do not sharply contrast with North Atlantic Deep Water (NADW) values and can produce isotopic anomalies no larger than 1 {epsilon} unit in the North Atlantic. A new profile in the eastern North Atlantic does not exhibit an {epsilon}{sub Nd}(O) anomaly at the depth of the Mediterranean Water core, in accordance with the above inferences, while concentrations and {epsilon}{sup Nd}(O) at this site indicate that Nd is conservative in the deep eastern North Atlantic. A previously reported {epsilon}{sub Nd}(O) anomaly in the eastern North Atlantic, originally associated with the Mediterranean outflow, has a different source. The direct contribution of the Mediterranean outflow to the NADW Nd budget is small, {approximately}10% of the high latitude sources. Concentrations of dissolved Nd in the outflow are enriched compared to the Atlantic inflow, which has 16 pmoles/kg with {epsilon}{sub Nd}(O) = {minus}11.8. The principal source of the excess dissolved Nd is inferred to be partial dissolution of detrital particles. Simple mass balance calculations suggest that {approximately}0.6% of the Nd associated with detrital river-transported sediments and/or {approximately}3.5% of the Nd associated with eolian particles delivered to the Mediterranean is mobilized during passage into the marine environment. If general, these mobilization efficiencies imply that the dissolution of detrital particles is a significant source of dissolved Nd in seawater.

• OSTI ID: 5014159
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 52:12; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
ATLANTIC OCEAN
CHEMICAL ANALYSIS
CHEMICAL COMPOSITION
CHEMISTRY
CONCENTRATION RATIO
DISSOLUTION
GEOCHEMISTRY
HYDROGEN COMPOUNDS
ISOTOPE RATIO
MASS BALANCE
MEDITERRANEAN SEA
NEODYMIUM COMPOUNDS
NEODYMIUM ISOTOPES
OXYGEN COMPOUNDS
QUANTITATIVE CHEMICAL ANALYSIS
QUANTITY RATIO
RARE EARTH COMPOUNDS
SEAS
SEAWATER
SURFACE WATERS
WATER
WATER CHEMISTRY