Rubin, S. I.. Columbia University, Lamont-Doherty Earth Observatory, rubin@ldeo.columbia.edu
Takahashi, T. I.. Columbia University, Lamont-Doherty Earth Observatory, taka@ldeo.columbia.edu
Millero, F. J.. University of Miami, Rosenstiel School of Marine and Atmospheric Science, fmillero@rsmas.miami.edu

 
CARBON DIOXIDE AND NUTRIENT UTILIZATION IN THE UPPER WATER COLUMN ACROSS THE POLAR FRONTAL ZONE
 
Seasonal changes of upper water column chemical properties reflect the physical, chemical, and biological processes that control the export of carbon to the deep ocean. Between October 1997 and March 1998, several hydrographic cruises were undertaken in the SWPacific Sector of the Southern Ocean as part of the U.S. JGOFS program. On these cruises, the partial pressure of carbon dioxide and concentration of total carbon dioxide were determined in surface waters and throughout the water column, accompanied by oxygen and nutrient measurements. We will show estimates of primary production, export production and nutrient utilization and regeneration based on seasonal changes in these properties in the water column above the remnant winter water across the Polar Front. While the biological drawdown of carbon dioxide and nutrients in the euphotic zone is greater south of the front, the primary productivity (~2-4 gC/m^2/day) and export production (~1-3 gC/m^2/day) are comparable. The observed C/N/P ratios for biological utilization are lower, (60-80)/(10-12)/1, south of the front than north, (100-120)/(14-16)/1. The departures from the "Redfield ratio" arise from non-Redfieldian phosphate uptake. The silica to carbon utilization ratio is greater south of the front than north, reflecting differences in phytoplankton populations.
 
Day: Thursday, Feb. 4
Time: 04:15 - 04:30pm
Location: Sweeney Center
 
Code: SS31TH0415S