860,000 Years of foraminifera-bound nitrogen isotope data from the South China Sea Ren, H.; Sigman, D.M.; Martínez-Garcia, A.; Anderson, R.F.; Chen, M.-T.; Ravelo, A.C.; Straub, M.; Wong, G.T.F.; Haug, G.H. Ren, H. Sigman, D.M. Martínez-Garcia, A. Anderson, R.F. Chen, M.-T. Ravelo, A.C. Straub, M. Wong, G.T.F. Haug, G.H. earth science/paleoclimate/paleoceanography (age,null,null,calendar kiloyear before present,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 15N,Globigerinoides ruber,null,per mil AIR,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 15N,Orbulina universa,null,per mil AIR,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (delta 18O,Cibicidoides wuellerstorfi,null,per mil VPDB,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleoceanography (depth,null,null,centimeter,null,paleoceanography,null,null,N,null) earth science/paleoclimate/paleocean earth science/paleoclimate/paleocean (MD97-2142>LATITUDE 12.68>LONGITUDE 119.45) The continental shelves are the most biologically dynamic regions of the ocean, and they are extensive worldwide, especially in the western North Pacific. Their area has varied dramatically over the glacial/interglacial cycles of the last million years, but the effects of this variation on ocean biological and chemical processes remain poorly understood. Conversion of nitrate to N2 by denitrification in sediments accounts for half or more of the removal of biologically available nitrogen (Ԧixed Nԩ from the ocean. The emergence of continental shelves during ice ages and their flooding during interglacials have been hypothesized to drive changes in sedimentary denitrification. Denitrification leads to the occurrence of phosphorus-bearing, N-depleted surface waters, which encourages N2 fixation, the dominant N input to the ocean. An 860,000-y record of foraminifera shell-bound N isotopes from the South China Sea indicates that N2 fixation covaried with sea level. The N2 fixation changes are best explained as a response to changes in regional excess phosphorus supply due to sea level-driven variations in shallow sediment denitrification associated with the cyclic drowning and emergence of the continental shelves. This hypothesis is consistent with a glacial ocean that hosted globally lower rates of fixed N input and loss and a longer residence time for oceanic fixed Nء ԳluggishԠocean N budget during ice ages. In addition, this work provides a clear sign of sea level-driven glacial/interglacial oscillations in biogeochemical fluxes at and near the ocean margins, with implications for coastal organisms and ecosystems. STUDY NOTES: A 860,000-year nitrogen isotope record from South China Sea foraminifera shells indicates that regional nitrogen fixation rates are associated with changes in sea level. Updated with d18O data table on 11/27/17. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Ren, H. Investigator : Sigman, D.M. Investigator : Martínez-Garcia, A. Investigator : Anderson, R.F. Investigator : Chen, M.-T. Investigator : Ravelo, A.C. Investigator : Straub, M. Investigator : Wong, G.T.F. Investigator : Haug, G.H. 2017-08-13 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/22390 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ren2017/ren2017-fb-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ren2017/ren2017-d18o.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ren2017/ren2017-fb-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ren2017/ren2017-d18o.txt English https://www.ncdc.noaa.gov/paleo/study/22390 https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ren2017/ren2017-fb-d15n.txt https://www1.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/ren2017/ren2017-d18o.txt Ren, H.; Sigman, D.M.; Martinez-Garcia, A.; Anderson, R.F.; Chen, M.-T.; Ravelo, A.C.; Straub, M.; Wong, G.T.F.; Haug, G.H.2017Impact of glacial/interglacial sea level change on the ocean nitrogen cycleProceedings of the National Academy of Scienceswww.pnas.org/cgi/doi/10.1073/pnas.1701315114 START YEAR: 860000 cal yr BP * END YEAR: 0 cal yr BP 119.45 12.68 119.45 12.68