Role of colloids in upper ocean biogeochemistry in the northeast Pacific Ocean elucidated from {sup 238}U-{sup 234}Th disequilibria

Journal Article · Mon May 01 04:00:00 EDT 1995 · Limnology and Oceanography

OSTI ID:96383

Huh, Chih-An; Prahl, F G ^[1]

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1. Oregon, State Univ., Corvallis, OR (United States)

Detailed upper ocean profiles of {sup 234}Th is dissolved (<10,000 Daltons), colloidal (10,000 Da-0.45 {mu}m), and particulate (>0.45 {mu}m) forms were measured at a station (46{degrees}45{prime}N, 126{degrees}W) in the northeast Pacific Ocean. On average, dissolved, colloidal, and particulate {sup 234}Th accounted for {approximately} 78, 12 and 10% of the total {sup 234}Th in the euphotic zone (0-100 m). A highly positive correlation exists between colloidal {sup 234}Th and chlorophyll {alpha}; both are characterized by higher concentrations in surface waters, a subsurface maximum at 5 m in the seasonal thermocline, and undetectable levels below the euphotic zone. POC: Chl {alpha} ratios in the water column suggest phytoplankton as primary producers of the colloidal material. Scavenging residence times of dissolved, colloidal, and particulate {sup 234}Th with respect to their removal processes in the euphotic zone are {approximately}50, 6, and 8 d. The scavenging rate constant of Th apparently increases with the concentration of colloids. 23 refs., 3 figs., 1 tab.

• OSTI ID: 96383
• Journal Information: Limnology and Oceanography, Journal Name: Limnology and Oceanography Journal Issue: 3 Vol. 40; ISSN LIOCAH; ISSN 0024-3590
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
BIOGEOCHEMISTRY
CARBON CYCLE
CHLOROPHYLL
COLLOIDS
DYNAMIC FUNCTION STUDIES
PACIFIC OCEAN
PHYTOPLANKTON
SCAVENGING
SURFACE WATERS
THORIUM 234
TRACER TECHNIQUES