Southern Ocean Diatom-bound Nitrogen and Nitrogen Isotope Data ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Southern Ocean Diatom-bound Nitrogen and Nitrogen Isotope Data LAST UPDATE: 4/2008 (Original receipt by WDC Paleo) CONTRIBUTOR: Rebecca S. Robinson, University of Rhode Island IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2008-037 WDC PALEO CONTRIBUTION SERIES CITATION: Robinson, R.S., et al. 2008. Southern Ocean Diatom-bound Nitrogen and Nitrogen Isotope Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2008-037. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Robinson, R.S., B.G. Brunelle, and D.M. Sigman. 2004. Revisiting nutrient utilization in the glacial Antarctic: Evidence from a new method for diatom-bound N isotopic analysis. Paleoceanography, Vol. 19, PA3001, doi:10.1029/2003PA000996. ABSTRACT: Isotopic measurements of diatom-bound nitrogen, using a wet chemical oxidation combined with the "denitrifier" method for nitrate analysis, show significant offsets from previously published combustion-based measurements. This offset is attributed to a gaseous nitrogen blank associated with the diatom's opal frustule. Moreover, experimentation with multiple chemical cleaning protocols demonstrates that diatom microfossils from the clay-rich sediments of the glacial Antarctic are more difficult to clean than Holocene materials. New downcore profiles from the Antarctic show no change in the diatom-bound N 15N/14N between the last glacial and the Holocene in the Atlantic sector, and the elevation of glacial diatom-bound 15N/14N relative to the Holocene in the Indian sector is smaller than in previous measurements. These data suggest no change in the degree of nitrate utilization in the Atlantic sector and at most a 20% increase (from ~25 to 45%) in the Indian sector. The new measurements suggest that, during the last ice age in the Atlantic sector of the Antarctic, the atmospheric source of biologically available iron was not so great as to become significant relative to the iron supply from below. Given the apparent spatial variability in the degree of nitrate drawdown, more work is required to develop an adequate picture of the glacial Antarctic nutrient field. GEOGRAPHIC REGION: Southern Ocean/Antarctic PERIOD OF RECORD: Last Glacial Maximum/Holocene, ~20KYrBP - present FUNDING SOURCES: US National Science Foundation grant OCE-0081686 (to D.M.S.) and DEB-0083566 (to Simon Levin) and from British Petroleum and Ford Motor Company through the Princeton Carbon Mitigation Initiative. R.S.R. was supported through a Huber Fellowship from the Princeton Environmental Institute. B.G.B. was supported by the NDSGE Graduate Fellowship. DESCRIPTION: Southern Ocean Diatom-bound Nitrogen and Nitrogen Isotope Data d15N of diatom-bound N from a surface sediment (4–5 cm) transect (ANTARES) from 56° to 46°S, and from three Southern Ocean sediment cores: Core NBP 96-4-2 MC4 (64°S, 170°E) (Holocene) Core IO1277-10PC (52°S, 21°E) (Holocene/LGM) Core MD84-552 (55°S, 74°E) (Holocene/LGM) All data were generated by the persulfate-dentrifer method outlined in Robinson et al., 2004, Paleoceanography. DATA: 1. Core IO1277-10PC Column 1: Depth (cm) Column 2: umolN/g opal Column 3: diatom-d15N depth N-opal d15N 2.5 11.68 3.24 10.5 10.37 4.80 10.5 10.47 4.82 10.5 11.32 4.21 20.5 12.29 3.44 20.5 9.52 3.60 20.5 11.21 3.19 30.5 12.69 3.38 40.5 10.99 3.19 40.5 10.99 3.81 50.5 11.24 3.42 60.5 12.81 2.79 70.5 3.06 80.5 10.81 3.04 90.5 10.82 2.67 100.5 11.91 3.04 110.5 12.13 4.16 130.5 11.65 3.39 140.5 11.47 3.78 150.5 11.25 3.49 160.5 4.03 170.5 11.42 4.32 180.5 12.20 4.17 190.5 12.54 3.56 190.5 12.58 4.11 200.5 12.02 4.51 230.5 11.27 3.85 240.5 11.75 4.22 260.5 12.78 3.30 270.5 11.30 3.72 280.5 11.47 4.41 280.5 11.61 4.04 280.5 12.55 4.16 290.5 10.45 4.70 290.5 11.39 4.34 300.5 12.82 4.05 310.5 12.67 4.89 310.5 11.80 5.03 310.5 8.88 4.98 320.5 9.85 4.30 320.5 10.95 4.02 320.5 10.89 4.45 330.5 11.96 3.61 340.5 12.15 4.08 350.5 11.96 4.53 350.5 12.19 4.19 360.5 11.66 3.73 370.5 12.06 4.23 380.5 11.97 4.52 400.5 12.00 4.49 400.5 11.72 4.82 410.5 4.31 420.5 4.42 440.5 11.32 4.59 450.5 12.95 3.75 450.5 13.15 3.90 460.5 3.96 500.5 11.85 5.16 500.5 11.75 5.04 500.5 11.42 4.75 520.5 12.73 4.06 520.5 11.68 4.75 540.5 12.47 3.96 550.5 10.86 3.18 550.5 10.92 3.59 550.5 11.82 2.96 570.5 12.85 2.86 570.5 11.14 4.48 600.5 15.07 3.74 600.5 12.97 4.77 630.5 16.20 3.46 630.5 15.36 4.01 630.5 13.89 3.91 640.5 17.19 3.37 640.5 14.74 4.95 660.5 15.46 4.26 660.5 16.12 4.50 660.5 12.65 4.71 700.5 13.35 4.75 700.5 13.90 4.60 700.5 15.33 4.89 740.5 14.41 4.81 740.5 14.22 4.85 740.5 13.80 4.92 740.5 13.35 760.5 10.51 4.18 790.5 10.43 3.41 790.5 10.07 3.37 790.5 9.76 3.57 800.5 9.96 3.56 830.5 3.86 840.5 9.96 4.6 840.5 8.55 3.79 850.5 7.47 4.1 850.5 7.23 4.34 2. Core MD84-552 Column 1: Depth (cm) Column 2: umolN/g opal Column 3: diatom-d15N depth N-opal d15N 13.5 13.44 2.76 33.5 14.02 2.65 53.5 13.63 3.06 83.5 12.2 2.06 115.5 15.18 4.91 135.5 12.95 4.19 164.5 6.9 4.06 194.5 7.4 3.66 215.5 5.98 4.71 253.5 8.13 3.18 3. Core NBP 96-4-2 MC4 Column 1: Depth (cm) Column 2: umolN/g opal Column 3: diatom-d15N depth N-opal d15N 0.25 10.8 5.43 0.75 11.25 5.01 1.25 12.04 4.72 1.25 11.26 4.72 1.75 12.25 4.13 2.25 11.21 2.75 11.2 3.78 3.25 10.61 3.97 3.75 10.54 4.07 3.75 10.99 4.19 4.25 10.95 3.97 4.75 11.04 3.58 5.5 10.93 3.8 6.5 11.07 3.66 7.5 11.05 3.56 8.5 11.91 2.91 9.5 11.37 3.61 11 12.07 3.62 11 11.16 3.25 13 11.7 13 12.01 3.42 15 11.23 3.26 15 11.53 2.93 4. ANTARES Surface Sediment Transect Column 1: Latitude (°S) Column 2: umolN/g opal Column 3: diatom-d15N Latitude N-opal d15N 45 12.5 4.6 46 14.04 4.4 47 12.39 4.3 48 14.39 4.8 48 14.39 4.6 49 11.16 3.7 49 11.16 3.5 50 12.14 4.4 52 16.21 2.9 55 15.74 2.9