Suspended sediment on the Amazon continental shelf, and its relationship to sedimentary processes
Suspended-sediment concentrations (SSC) commonly exceed 100 mg/1 on the inner shelf (<30 m water depth) near the mouth of the Amazon River. Vertical profiles of SSC generally reveal an exponential increase toward the sea bed, indicating resuspension of sediment. On the Amazon shelf, the presence of high SSC reflects the inhibition of sediment accumulation rather than the potential for accumulation. SSC becomes significant (>10 mg/1) landward of the 40-m isobath and generally increases toward shore, as a result of shoaling surface waves and intense tidal currents. A number of chemical components dissolved in river water and ocean water, whose removal is dependent on SSC, are concentrated in the sea bed in an along-shelf region centered about the 40-m isobath. Strong tidal currents create significant temporal variability of SSC on semi-diurnal time scales. The frequent resuspension and deposition of sediment causes physical mixing of the sea bed to dominate over biological mixing, and physical sedimentary structures to characterize much of the shelf. Suspended sediment is advected northwestward by the North Brazilian Coastal Current, with most of the transport occurring landward of the 10-m isobath.
- Research Organization:
- North Carolina State Univ., Raleigh (USA)
- OSTI ID:
- 6320939
- Report Number(s):
- CONF-8510489-
- Journal Information:
- Geol. Soc. Am., Abstr. Programs; (United States), Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Vol. 17; ISSN GAAPB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580100* -- Geology & Hydrology-- (-1989)
580400 -- Geochemistry-- (-1989)
AMAZON RIVER
BRAZIL
CHEMICAL COMPOSITION
CHEMISTRY
CONTINENTAL MARGIN
CONTINENTAL SHELF
DEPOSITION
DEVELOPING COUNTRIES
GEOLOGY
GEOPHYSICAL SURVEYS
LATIN AMERICA
RIVERS
SEA BED
SEDIMENTS
SEISMIC SURVEYS
SOUTH AMERICA
STRATIGRAPHY
STREAMS
SURFACE WATERS
SURVEYS
WATER CHEMISTRY