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Buoyant plumes in cross flows

Diffuse venting and background contributions to chemical anomalies in a neutrally buoyant ocean hydrothermal plume (Abstract)

Problem Description:
High-temperature, focused venting leads to significant vertical mixing and redistribution of tracers in the benthic ocean. Vent discharge and background benthic water entrained into a plume lead to altered geochemical and microbial payloads found well above the seafloor. Take the case of aluminum. Observations in the Atlantic show Al profiles naturally enhanced near bottom. That is caused by Al rich particles settling to the sea floor and the subsequent remobilization of elemental AL. But diffuse hydrothermal flows also introduce Al to the near-bottom waters surrounding high temperature vents. A question to be answered is how focused, diffuse, and background sources of Al all contibute to Al levels in neutrally bouyant plumes. This study looks at Al distributions at the TransAtlantic Geotraverse (TAG) site in the Atlantic using one- and three- dimensional models of convective plumes. Contributions of the background and diffuse Al fields dominante.

model images, click for large size

Vertical (x-z) sections along the flow direction and though the TAG mound for each source component species:

a) Al from focused sources,
b) Al from background fluid,
c) Al from diffuse sources.
Concentrations are in nmol l-1.

click for larger view

FLI Animation (1.1 mb)
Mov Animation (1.2 mb)
Mpeg Animation (3.9 mb)

 
 

Related Papers:

Chronic focused-source plumes

Lavelle, J.W. (1997): Buoyancy-driven plumes in rotating, stratified cross flows: Plume dependence on rotation, turbulent mixing, and cross-flow strength. Journal of Geophysical Research, 102(C2), 3405-3420.
Lavelle, J.W., and D.C. Smith IV (1996): Effects of rotation on convective plumes from line segment sources. Journal of Physical Oceanography, 26(6), 863-872. [FY96]

Geochemical Transport

Lavelle, J.W., J.P. Cowen, and G.J. Massoth (1992): A model for the deposition of hydrothermal manganese near ridge crests. Journal of Geophysical Research, 97(C5), 7413-7427.

 
     
  Modeling focuses: Chronic focused-source | Event Plumes | Axial Valley transport | Ridge Flow | Geochemical Transport | Hydrographic-Tracer Relationships