This project will use the DSRV ALVIN to directly study the dynamics of turbulent buoyant plumes emanating from active hydrothermal vents. The aim of the project is to provide a sound basis for relating water-comumn measurements of the effluent plumes to the thermal output of the underlying oceanic crust. The PI's propose to mount an instrument package on ALVIN that will measure temperature, conductivity (salinity), vertical and horizontal velocity, light attenuation (particledensity), and concentrations of manganese, silica, and sulfide in real time via in situ flow injection analysis. The instrument will also collect discrete water samples for laboratory analyses. Data and water samples will be collected in real time shile driving ALVIN through buoyant hydrothermal plumes at several heights in the water column. Undiluted hydrothermal source fluids and the surrounding water column will also be studied. Specific objectives incluse: (1) characterization of vertical and lateral variation in physical properties, velocities, chemical concentrations, and suspended particles within the buoyant plume, (2) quantification of entrainment and dilution rates as function of plume height, (3) determine turbulent variability in the buoyant plume and relate to property variations, and (5) testing numerical plume models against field measurements.
