Carbon-13/carbon-12 ratios in surface water and sea ice organic matter-variability and contributions to the sediments of the Ross Sea, Antarctica

• Main Author: Rogers, Jennifer Carol
• Other Authors: Dunbar, Robert B.
• Format: Thesis
• Language: English
• Published: 1995
• Subjects: Biochemistry; Ross Sea; Antarc*; Antarctica; Sea ice
• Online Access: https://hdl.handle.net/1911/13991

Elemental and carbon isotopic analyses of suspended and sea ice particulate organic matter (POC) from Antarctica show enrichments in $\sp{13}$C unrelated to atmospheric CO$\sb2$ variations. Phytoplankton bloom-related POC from the southwestern Ross Sea during 1992 had a range in $\delta\sp{13}$C of 7$\rm\perthous.\ \delta\sp{13}C\sb{POC}$ collected from pack ice had an 11$\rm\perthous$ range, with highest values found in the Bellingshausen and Amundsen Seas and lower values found in Ross Sea pack ice. Organic matter $\delta\sp{13}$C from phytoplankton blooms in the southwestern Ross Sea is strongly correlated with POC concentration, suggesting high rates of bloom-related CO$\sb2$(aqueous) drawdown that may cause disequilibrium as a result of stable stratification of the upper water column and partial isolation of the surface water CO$\sb2$ pool. Isotopic and organic carbon composition of surface sediments is similar to the upper water column, thus primary isotopic signals are preserved. Surface sediment $\delta\sp{13}$C values are 1 to 3$\rm\perthous$ enriched in $\sp{13}$C relative to surface water POC $\delta\sp{13}$C. Highest isotopic values were found in areas that receive large amounts of phytoplankton bloom detritus. Future downcore carbon isotopic analyses may prove useful as tracers of bloom dynamics and sea ice production.