Marie Salmi
Chemical dynamics based on methane, light backscatter, and redox potential of hydrothermal plumes at Rumble III, Kermadec arc, New Zealand
The University of Washington student scientific cruise along the Kermadec volcanic arc, north of New Zealand was performed March, 2-17, 2009. Research included characterizing the chemical and physical properties to determine the location and nature of hydrothermal plumes over Rumble III, an underwater volcano located at 35° 44.377’ S, 178° 29.839’ E. Rumble III is unique due to the presence of a shallow hydrothermal system that will have a mixture of chemosynthetic and photosynthetic biology present along with a high potential of interacting with the surface oceanic water. Sensors and collection bottles for water samples were attached to a rosette frame. This frame was deployed vertically over the side a stationary ship or raised and lowered in cycles through the water column while the ship was moving. My research involved comparing data from various sensors that measured particle concentration and size, oxygen and the concentrations of reduced chemical species, such as methane, reduced iron, and hydrogen sulfide that are within hydrothermal plumes and can be utilized by chemosynthetic organisms. Along with sensor measurements, methane (CH4) concentrations were also measured from collected water samples. The hydrothermal plumes were discovered at ~250 m above the summit of the volcano that corresponded with an oxygen low, and high concentrations for particulates and reduced species. Chemosynthesis and spontaneous reactions is believed to be the reason for the anomalous low oxygen based on the relationship between the redox potential and oxygen. There was no obvious correlation between methane and redox potential. The direction of plume movement was in the north-west direction, corresponded with current velocities.