HR: 1340h
AN: B13A-0185    [Abstracts]
TI: Distribution of Particulates in Hydrothermal Plumes of the Endeavour Axial Valley: Preliminary Results from the Sea Breeze Project
AU: * Nassif, T H
EM: Nassif@stpatsdc.org
AF: St Patrick's School, 4700 White Haven Parkway, Washington, DC 20007 United States
AU: McDuff, R E
EM: mcduff@ocean.washington.edu
AF: University of Washington School of Oceanography, Box 357940, Seattle, WA 98195-7940 United States
AU: Robigou, V
EM: vero@ocean.washington.edu
AF: University of Washington School of Oceanography, Box 357940, Seattle, WA 98195-7940 United States
AU: Stahr, F
EM: stahr@ocean.washington.edu
AF: University of Washington School of Oceanography, Box 357940, Seattle, WA 98195-7940 United States
AB: Hydrothermal vent plumes provide zones for chemical reactions between vent fluids and seawater, potential habitats for anaerobic bacteria and zooplankton, and a probable mechanism for the dispersal of vent larvae. Within the Endeavour Integrated Study Site are five known vent fields situated along the axial valley of the Endeavour Segment of the Juan de Fuca Ridge (N.E. Pacific Ocean). Each of these fields has a particle rich neutrally buoyant plume above it almost constantly, a common characteristic of vent systems worldwide. The purpose of this study was to determine 1) how plume particle distribution varies along the Endeavour segment axial valley; 2) whether a correlation exists between vent activity and particle density in the surrounding water, and 3) if the peak signals in backscatter and light transmission fall within a consistent range of potential density values along the axial valley. Light transmission and backscatter data were collected from vertically oscillating CTD casts at 21 stations along the axial valley covering the fields of Mothra, Main Endeavour, High Rise, Salty Dawg, and Sasquatch during the Sea Breeze - REVEL 2004 seagoing program. Plume particle density within ocean water was measured using a Wetlabs transmissometer and a Seapoint turbidity sensor. Preliminary results indicate a positive correlation between "black smoker" activity and signal strength in backscatter and light transmission. Main Endeavour and High Rise, known to exhibit the most rigorous hydrothermal activity, show correspondingly high amplitude signals in both backscatter and light transmission. Predicted diurnal currents seem to effect lateral plume particle movement away from vent sources, greatly impacting the particle density in surrounding areas. Peak signals in backscatter and light transmission occur in less dense water moving northward from Mothra to Salty Dawg.
UR: http://www2.ocean.washington.edu/seabreeze/; http://www.ocean.washington.edu/outreach/revel/
DE: 4815 Ecosystems, structure and dynamics
DE: 7218 Lithosphere and upper mantle
DE: 3015 Heat flow (benthic) and hydrothermal processes
DE: 3035 Midocean ridge processes
DE: 1020 Composition of the crust
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting