Oceanic stratified euphotic zone as elucidated by /sup 234/Th:/sup 238/U disequilibria

Journal Article · Thu Jan 01 00:00:00 EST 1987 · Limnol. Oceanogr.; (United States)

DOI:https://doi.org/10.4319/lo.1987.32.1.0189· OSTI ID:6593170

Coale, K H; Bruland, K W

Profiles of dissolved and particulate /sup 234/Th were determined at the VERTEX 2 and 3 stations off Manzanillo, Mexico, and at the VERTEX 4 station about 900 km north of Hawaii. By modeling the disequilibria between /sup 234/Th and /sup 238/U in the dissolved and particulate form, estimates of scavenging rates for Th from the dissolved to particulate phases, particle residence times, and the flux of Th via particle removal can be obtained. /sup 234/Th:/sup 238/U activity ratio profiles indicate that the euphotic zone can be separated into two layers: an upper oligotrophic layer characterized by low new production values, low net scavenging, and long dissolved /sup 234/Th residence times; and a subsurface eutrophic layer with higher new production values, more intense scavenging, and shorter dissolved /sup 234/Th residence times. New production, rather than total primary production may determine net scavenging rates of reactive elements from oceanic surface waters. These results contribute to the emerging descriptions of the layered structure of oligotrophic euphotic zones and support the notion that this may be a general and ubiquitous feature of global stratified oligotrophic regimes.

• Research Organization: Univ. of California, Santa Cruz, CA (United States)
• OSTI ID: 6593170
• Journal Information: Limnol. Oceanogr.; (United States), Vol. 32:1
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
THORIUM 234
RADIONUCLIDE MIGRATION
URANIUM 238
BIOGEOCHEMISTRY
MEXICO
PACIFIC OCEAN
PARTICULATES
SEAWATER
ACTINIDE ISOTOPES
ACTINIDE NUCLEI
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DEVELOPING COUNTRIES
ENVIRONMENTAL TRANSPORT
EVEN-EVEN NUCLEI
GEOCHEMISTRY
HEAVY NUCLEI
HYDROGEN COMPOUNDS
ISOTOPES
LATIN AMERICA
MASS TRANSFER
NORTH AMERICA
NUCLEI
OXYGEN COMPOUNDS
PARTICLES
RADIOISOTOPES
SEAS
SURFACE WATERS
THORIUM ISOTOPES
URANIUM ISOTOPES
WATER
YEARS LIVING RADIOISOTOPES
520300* - Environment
Aquatic- Radioactive Materials Monitoring & Transport- (1989)