High precision {sup 230}Th and {sup 232}Th in the Norwegian Sea and Denmark by thermal ionization mass spectrometry

Journal Article · Sun Oct 01 04:00:00 EDT 1995 · Geophysical Research Letters

DOI:https://doi.org/10.1029/95GL02652· OSTI ID:274075

Moran, S B ^[1]; Hoff, J A; Edwards, R L ^[2]

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1. Univ. of Rhode Island, Narragansett, RI (United States)
2. Univ. of Minnesota, Minneapolis, MN (United States); and others

Seawater samples (1-2 liters) were collected from the Norwegian Sea and Denmark Strait and analyzed for {sup 230}Th and {sup 232}Th using highly sensitive thermal ionization mass spectrometry (TIMS). Depth profiles of dissolved {sup 230}Th and {sup 232}Th are characterized by surface water minima (<1 fg/kg, <5 pg/kg), subsurface maxima (12 fg/kg, 134 pg/kg), and intermediate concentrations that progressively decrease toward the bottom ({approximately}5 fg/kg, {approximately}17 pg/kg), respectively. The lack of an increase in {sup 230}Th with depth is suggested to result from the short ventilation age of Norwegian Sea Deep Water combined with enhanced scavenging near the basin margins. The {sup 230}Th maximum is attributed to advection of high {sup 230}Th in the Arctic Intermediate Water, whereas the {sup 232}Th maximum may he related to a particulate source. The low dissolved {sup 230}Th and {sup 232}Th concentrations observed in the NADW formation regions implies a minor advective export of these long-lived Th tracers to the North Atlantic. 24 refs., 1 fig., 1 tab.

• OSTI ID: 274075
• Journal Information: Geophysical Research Letters, Journal Name: Geophysical Research Letters Journal Issue: 19 Vol. 22; ISSN GPRLAJ; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ABUNDANCE
DENMARK
GEOCHEMISTRY
MASS SPECTROSCOPY
NORWAY
SAMPLING
SEAWATER
THORIUM 230
THORIUM 232