HR: 0830h
AN: B21B-0714    [PDF]
TI: Variations in Particulate Organic Matter Across the Drake Passage
AU: * Federici, L
EM: lunaf@stanford.edu
AF: Stanford University, Department of Geological and Environmental Sciences, Stanford, Ca 94305-2115 United States
AU: Dunbar, R B
EM: dunbar@stanford.edu
AF: Stanford University, Department of Geological and Environmental Sciences, Stanford, Ca 94305-2115 United States
AU: Mucciarone, D A
EM: dam@pangea.stanford.edu
AF: Stanford University, Department of Geological and Environmental Sciences, Stanford, Ca 94305-2115 United States
AB: Modeling studies have shown that the Southern Ocean plays an important role in the global carbon cycle and is a relatively large sink for anthropogenic CO2. The formation, sinking, and eventual burial of particulate organic matter (POM) is a crucial component of this cycle, which removes gaseous carbon from the short-term atmospheric system and deposits it in a long-term sedimentary system. This study analyses surface POM from five cruise tracks taken between 1997 and 2002 across the Drake Passage between 54.11 S and 67.22 S. We determine the relationship between the stable carbon and nitrogen isotopes of the POM from underway samples and the pCO2, temperature, and salinity of the surface water for these cruises. The d13C of these samples, a proxy for productivity, ranges from -18.13 per mil to -33.40 per mil, with the least negative values closest to South America. The isotope values become more negative further south, showing the highest levels of seasonal variability (11 per mil) around 65 S at the approximate location of the Antarctic Divergence. The d13N record, a proxy for nutrient utilization, shows an equally large range from -7.22 per mil to 8.64 per mil. Like the carbon isotopes, these nitrogen POM isotopes exhibit the highest values near South America. Between 54 S and 56 S, the values drop to - 4 per mil and then show an increasing trend further southward, with a relative maximum at 65 S. The nitrogen POM isotopes show considerable seasonal variability throughout all five of the tracks studied here. We use this data to define the latitudinal and seasonal variation of these parameters, as well as address the significance of the seasonally varying locations of water fronts across the Drake Passage.
DE: 4207 Arctic and Antarctic oceanography
DE: 4271 Physical and chemical properties of seawater
DE: 4805 Biogeochemical cycles (1615)
DE: 4850 Organic marine chemistry
DE: 4870 Stable isotopes
SC: Biogeosciences [B]
MN: 2003 Fall Meeting