Science Corner
By Erik Zettler, Science Coordinator
During the first Oceans and Climate program, Dr. Jan Witting along with the scientists and students on cruise S-210 used an instrument borrowed from WETLabs (Philomath, OR) to collect depth profiles of CDOM fluorescence (Colored Dissolved Organic Matter) during their transect across the equator.
Data from SEA cruise S-208 on SSV Robert C. Seamans in Nov/Dec 2006. Colors represent DOM-FL concentrations (QSD equivalent in ppb) on an oblique section across the equator from Puerto Vallarta, Mexico (right side), to the Marquesas Islands (surface spike in CDOM on the left). Contour lines represent a. in-vivo chl fluorescence (relative units) in the upper panel and b. oxygen concentration (mg/L) in the lower panel
This data was included in a proposal titled: “Documenting inherent optical properties along repeated cruise tracks in the Atlantic and Pacific by Sea Education Association’s vessels,” and in October 2007 Sea Education Association received funding from NASA to enhance the global ocean sampling capabilities of both our ships. The grant will provide funding from 2007-2010 to purchase optical instruments for both vessels, process the data, and submit it to national archives. Data from these instruments will support student projects, faculty research, and NASA’s Ocean Biology and Biogeochemistry Program. The grant also provides approximately one month per year of salary for an Assistant Scientist to process the data for submission to NASA’s database. Both vessels will be equipped with WET Labs instruments to measure inherent optical properties and basic biogeochemical measurements including Colored Dissolved Organic Matter (CDOM) fluorescence, in-vivo chlorophyll fluorescence, and beam attenuation (measured by a transmissometer) from both surface waters and depth profiles. CDOM correlates with the amount of dissolved organic carbon in the water, beam attenuation correlates with the total number of particles in the water, and in-vivo chlorophyll correlates with the amount of phytoplankton carbon (biomass) in the water. These three measurements together will allow SEA to generate a biogeochemical database of basic measurements of the carbon cycle.
Instruments for depth profiling with the CTD are being used on both boats for Class 215 that sailed on 13 March. The instruments for surface water measurements underway will be integrated into the clean seawater system during Class 216. Building on NSF-funded instrumentation already in place the new equipment will contribute data on Global Ocean Carbon/Particle abundance along SEA’s repeated cruise tracks through under-sampled areas such as the Equatorial Pacific.