Southern Ocean 120KYr Nitrogen and Silicon Isotope Data Robinson, R.S.; Brzezinski, M.A.; Beucher, C.P.; Horn, M.G.S.; Bedsole, P. Robinson, R.S. Brzezinski, M.A. Beucher, C.P. Horn, M.G.S. Bedsole, P. biogeochemical cycles earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,meters below sea floor) earth science/paleoclimate/paleoceanography (age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth,null,null,meter,null,paleoceanography,null,null,N,common meters) earth science/paleoclimate/paleoceanography (delta 30Si,diatom,null,per mil,null,paleoceanography,null,null,N,per mil v. NBS28) earth science/paleoclimate/paleoceanography (delta 15N,diatom,null,per mil AIR,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 30Si,diatom,one standard deviation,per mil,null,paleoceanography,null,null,N,per mil v. NBS28) earth science/paleoclimate/paleoceanography (notes,null,null,null,null,paleoceanography,null,null,C,Sample Description) earth science/paleoclimate/paleoceanography (depth,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean (ODP1094>LATITUDE -53.18035>LONGITUDE 5.130333) (NBP9802-06PC>LATITUDE -61.88>LONGITUDE -169.98) (NBP9802-09PC>LATITUDE -56.9>LONGITUDE -170.2) (E11-2>LATITUDE -56.07>LONGITUDE -115.1) (E17-9>LATITUDE -63.08>LONGITUDE -135.12) The Southern Ocean plays a critical role in the air-sea CO2 balance through biological and physical mechanisms. Vertical supply of deep waters returns nutrients and CO2 to the surface and stimulates phytoplankton growth. Photosynthesis in the Southern Ocean is limited by iron and only a fraction of the carbon and nutrients that return to the surface are consumed for potential sequestration in the deep sea. Here we present the most spatially extensive data set of silicon and nitrogen isotope measurements from diatom frustules to date to examine the controls on nutrient drawdown during the last glacial period and across the glacial termination in both the Antarctic and Subantarctic zones. The new data confirm existing views that differing silicon and nitrate consumption patterns in the Antarctic zone are likely the result, at least in part, of iron addition during the last glacial maximum (LGM). However, earlier in the glacial, a more coordinated response in the two proxy records, with both reflecting enhanced consumption during episodes of increased iron accumulation and export production, implies a different system response than observed for the LGM. A collapse of the expected equatorward gradient in silicon isotope values and contraction of the nitrogen isotope gradient during the deglaciation suggests that nutrient supply increased not only in the Antarctic Zone, but also in the Subantarctic, perhaps due to enhanced deep mixing locally. Enhanced deep water ventilation across the Southern Ocean likely increased the nutrient content of mode waters during the deglaciation. STUDY NOTES: Nitrogen (d15N) and Silicon (d30Si) isotope data measured on diatoms from Southern Ocean sediment cores. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Robinson, R.S. Investigator : Brzezinski, M.A. Investigator : Beucher, C.P. Investigator : Horn, M.G.S. Investigator : Bedsole, P. 2015-01-27 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/17917 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014e11-2.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014nbp9802-06.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014e17-9.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014nbp9802-09.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014odp1094.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014e11-2.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014nbp9802-06.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014e17-9.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014nbp9802-09.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014odp1094.txt English https://www.ncdc.noaa.gov/paleo/study/17917 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014e11-2.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014nbp9802-06.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014e17-9.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014nbp9802-09.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/robinson2014b/robinson2014odp1094.txt Rebecca S. Robinson, Mark A. Brzezinski, Charlotte P. Beucher, Matthew G. S. Horn and Patrick Bedsole2014The changing roles of iron and vertical mixing in regulating nitrogen and silicon cycling in the Southern Ocean over the last glacial cyclePaleoceanography29121179-119510.1002/2014PA002686http://www.sciencedirect.com/science/article/pii/S0012821X13007280 START YEAR: 284500 cal yr BP * END YEAR: 1000 cal yr BP -170.2 -63.08 5.130333 -53.18035