# Central Arctic sedimentary 231Pa/230Th Ratios from the past 35,000 years #----------------------------------------------------------------------- # World Data Center for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program #----------------------------------------------------------------------- # NOTE: Please cite original publication, online resource and date accessed when using these data, # If there is no publication information, please cite investigator, title, online resource and date accessed. # # Online_Resource: http://hurricane.ncdc.noaa.gov/pls/paleox/f?p=519:1:::::P1_STUDY_ID:16914 # Online_Resource: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/contributions_by_author/hoffmann2013/hoffmann2013-bc08.txt # # Archive: Paleoceanography #-------------------- # Contribution_Date # Date: 2014-07-10 #-------------------- # Title # Study_Name: Central Arctic Sedimentary 231Pa/230Th Ratios from the Past 35,000 Years #-------------------- # Investigators # Investigators: Hoffmann, Sharon S.; McManus, Jerry F.; Curry, William B.; Brown-Leger, L. Susan #-------------------- # Description_and_Notes # Description: U-series radionuclide records from seven Arctic sediment cores, with excess 231Pa/230Th ratios interpreted as indicators of 231Pa export in the water column. Age models are from calibrated radiocarbon measurements on polar foraminifer species N. pachyderma (sinistral). #-------------------- # Publication # Authors: Hoffmann, S.S., J.F. McManus, W.B. Curry, and L.S. Brown-Leger # Published_Date_or_Year: 2013 # Published_Title: Persistent export of 231Pa from the deep central Arctic Ocean over the past 35,000 years # Journal_Name: Nature # Volume: 497 # Issue: # Pages: 603-606 # DOI: 10.1038/nature12145 # Abstract: The Arctic Ocean has an important role in Earth’s climate, both through surface processes such as sea-ice formation and transport, and through the production and export of waters at depth that contribute to the global thermohaline circulation. Deciphering the deep Arctic Ocean’s palaeo-oceanographic history is a crucial part of understanding its role in climatic change. Here we show that sedimentary ratios of the radionuclides thorium-230 (230Th) and protactinium-231 (231Pa), which are produced in sea water and removed by particle scavenging on timescales of decades to centuries, respectively, record consistent evidence for the export of 231Pa from the deep Arctic and may indicate continuous deepwater exchange between the Arctic and Atlantic oceans throughout the past 35,000 years. Seven well-dated box-core records provide a comprehensive overview of 231Pa and 230Th burial in Arctic sediments during glacial, deglacial and interglacial conditions. Sedimentary 231Pa/230Th ratios decrease nearly linearly with increasing water depth above the core sites, indicating efficient particle scavenging in the upper water column and greater influence of removal by lateral transport at depth. Although the measured 230Th burial is in balance with its production in Arctic sea water, integrated depth profiles for all time intervals reveal a deficit in 231Pa burial that can be balanced only by lateral export in the water column. Because no enhanced sink for 231Pa has yet been found in the Arctic, our records suggest that deep-water exchange through the Fram strait may export 231Pa. Such export may have continued for the past 35,000 years, suggesting a century-scale replacement time for deep waters in the Arctic Ocean since the most recent glaciation and a persistent contribution of Arctic waters to the global ocean circulation. # #--------------------- # Funding_Agency # Funding_Agency_Name: US National Science Foundation # Grant: OCE-0402565, OCE-0550637, OCE-0902985, AGS-0936496, ARC-0520073 #--------------------- # Site_Information # Site_Name: PL94-AR BC08 # Location: Arctic Ocean # Country: # Northernmost_Latitude: 78.13 # Southernmost_Latitude: 78.13 # Easternmost_Longitude: -176.88 # Westernmost_Longitude: -176.88 # Elevation: -1047 #------------------ # Data_Collection # Collection_Name: PL94-AR BC08 H13 # Earliest_Year: 39470 # Most_Recent_Year: 3700 # Time_Unit: cal yr BP # Core_Length: # Notes: #------------------ # Chronology: # We constructed age models by linear interpolation between radiocarbon-dated intervals, using both published dates (Poore et al., 1999 and Darby et al., 1997) and dates new to this study. Radiocarbon ages were converted to calendar years using the CALIB?5.2 program and the MARINECAL?04 marine calibration data set for ages less than 22?kyr, and the calibration of Fairbanks et al., 2005 for older ages. A local difference in reservoir age of ?R = 40?yr, to provide a reservoir age of 440?yr, following the studies in which a number of the dates used here were published, plus an additional 250-yr DeltaR to account for the likely additional influence of sea ice on air-sea gas exchange, were applied to all ages. Published radiocarbon dates were measured from samples of the polar planktonic foraminifera Neogloboquadrina pachyderma sinistral, for box cores 08, 16 and 17 (from the same subcores that we sampled for nuclide records). Published dates for box core?20 were measured in a different subcore from that used for nuclide sampling. Dates for box cores 28 and 32 (R. Poore, personal communication) were produced from the same subcores as our radionuclide records. Dates from box core 26 (this study) were measured from N. pachyderma sinistral at the NOSAMS facility at Woods Hole Oceanographic Institution. # #------------------ # Variables # # Data line variables format: one variable per line, shortname- 9 components: what, material, error, units, seasonality, archive, detail, method, C or N for Character or Numeric data) # Data line format: tab-delimited text, variable short name as header ## depth_cm Depth,, , cm ,,, , ,N ## age_calkaBP Age,,, calendar ka before 1950AD,,, , , N ## 231Pa 231Pa,,,dpm/g,,paleoceanography,analytical technique: inductively-coupled plasma mass spectrometry,,N ## 231Pa_err 231Pa,,two standard error,dpm/g,,paleoceanography,analytical technique: inductively-coupled plasma mass spectrometry,,N ## 230Th 230Th,,,dpm/g, ,paleoceanography, analytical technique: inductively-coupled plasma mass spectrometry,,N ## 230Th_err 230Th,,two standard error,dpm/g,,paleoceanography,analytical technique: inductively-coupled plasma mass spectrometry,,N ## 238U 238U,,,dpm/g,,paleoceanography,analytical technique: inductively-coupled plasma mass spectrometry,,N ## 238U_err 238U,,two standard error,dpm/g, ,paleoceanography, analytical technique: inductively-coupled plasma mass spectrometry,,N ## 232Th 232Th,,,dpm/g, ,paleoceanography, analytical technique: inductively-coupled plasma mass spectrometry,,N ## 232Th_err 232Th,,two standard error, dpm/g,,paleoceanography,analytical technique: inductively-coupled plasma mass spectrometry,,N ## 238U/232Th 238U/232Th,,, ,,paleoceanography, ,,N ## 238U/232Th_err 238U/232Th,,two standard error, ,,paleoceanography, ,,N ## 231Paxs0 age-corrected excess 231Pa,,,dpm/g,,paleoceanography,analytical technique: inductively-coupled plasma mass spectrometry,,N ## 231Paxs0_err age-corrected excess 231Pa,,two standard error,dpm/g,,paleoceanography, analytical technique: inductively-coupled plasma mass spectrometry,,N ## 230Thxs0 age-corrected excess 230Th, , , dpm/g, ,paleoceanography, analytical technique: inductively-coupled plasma mass spectrometry,, N ## 230Thxs0_err age-corrected excess 230Th, , two standard error, dpm/g, ,paleoceanography, analytical technique: inductively-coupled plasma mass spectrometry,, N ## mass_flux 230Th-normalized sediment mass flux, , , g/(m2kyr), ,paleoceanography, , ,N ## 231Paxs0/230Thxs0_0.5 age-corrected excess 231Pa/230Th,,, ,,paleoceanography,excess corrections assuming 238U/232Th = 0.5 ,,N ## 231Paxs0/230Thxs0_0.7 age-corrected excess 231Pa/230Th,,, ,,paleoceanography,excess corrections assuming 238U/232Th = 0.7 ,,N ## 231Paxs0/230Thxs0_avg average age-corrected excess 231Pa/230Th,,, ,,paleoceanography, , ,N ## 231Paxs0/230Thxs0_avg_err average age-corrected excess 231Pa/230Th,,one standard error, ,,paleoceanography,,,N ## #----------------- # Data: # Missing Value: -999 depth_cm age_calkaBP 231Pa 231Pa_err 230Th 230Th_err 238U 238U_err 232Th 232Th_err 238U/232Th 238U/232Th_err 231Paxs0 231Paxs0_err 230Thxs0 230Thxs0_err mass_flux 231Paxs0/230Thxs0_0.5 231Paxs0/230Thxs0_0.7 231Paxs0/230Thxs0_avg 231Paxs0/230Thxs0_avg_err 0.25 3.7 0.429 0.009 5.47 0.06 1.4426 0.0027 2.253 0.005 0.6403 0.0019 0.396 0.027 4.26 0.17 0.63 0.091 0.096 0.093 0.007 1.25 4.49 0.463 0.01 5.79 0.06 1.5112 0.0027 2.359 0.007 0.6405 0.0021 0.437 0.03 4.56 0.18 0.59 0.094 0.099 0.096 0.008 2.25 5.42 0.442 0.004 5.6 0.06 1.5941 0.0017 2.492 0.003 0.6397 0.0011 0.418 0.029 4.31 0.17 0.62 0.094 0.1 0.097 0.008 3.25 6.07 0.403 0.018 5.29 0.07 1.5856 0.0026 2.505 0.007 0.6329 0.002 0.379 0.026 3.99 0.16 0.67 0.092 0.098 0.095 0.008 4.25 6.62 0.348 0.004 4.67 0.06 1.6331 0.0014 2.485 0.006 0.6571 0.0017 0.32 0.022 3.37 0.13 0.79 0.092 0.099 0.095 0.008 5.25 7.18 0.339 0.003 4.54 0.06 1.7876 0.0069 2.521 0.013 0.709 0.0047 0.311 0.021 3.22 0.13 0.83 0.093 0.101 0.097 0.008 6.25 7.74 0.342 0.009 4.58 0.07 1.8621 0.0036 2.525 0.01 0.7374 0.0032 0.32 0.022 3.29 0.13 0.81 0.094 0.101 0.098 0.008 7.25 7.9 0.279 0.003 4.19 0.06 1.906 0.0045 2.709 0.012 0.7034 0.0034 0.239 0.016 2.74 0.11 0.97 0.084 0.092 0.088 0.007 8.25 7.92 0.2589 0.0024 3.68 0.07 1.9128 0.0039 2.751 0.011 0.6954 0.0032 0.214 0.015 2.17 0.08 1.23 0.093 0.106 0.1 0.008 9.25 7.97 0.2154 0.0023 3.49 0.07 1.7997 0.0033 2.724 0.008 0.6606 0.0024 0.164 0.011 1.98 0.08 1.35 0.078 0.088 0.083 0.007 10.25 8.02 0.2134 0.0022 3.54 0.07 1.9504 0.0083 2.967 0.019 0.6575 0.005 0.154 0.011 1.88 0.07 1.42 0.077 0.088 0.083 0.007 11.25 8.07 0.2083 0.0021 3.45 0.08 1.7954 0.0034 2.887 0.008 0.6219 0.0021 0.151 0.01 1.83 0.07 1.46 0.078 0.089 0.083 0.007 12.25 8.07 0.209 0.006 3.38 0.08 1.6061 0.0063 2.732 0.008 0.588 0.0029 0.159 0.011 1.88 0.07 1.42 0.08 0.091 0.086 0.007 13.25 9.33 0.207 0.003 3.39 0.09 1.5622 0.0029 2.735 0.008 0.5711 0.0019 0.16 0.011 1.91 0.07 1.4 0.079 0.09 0.085 0.007 14.25 10.92 0.196 0.0022 3.33 0.07 1.5753 0.0049 2.682 0.009 0.5875 0.0026 0.152 0.01 1.89 0.07 1.41 0.076 0.086 0.081 0.006 15.25 11.4 0.228 0.005 3.53 0.12 1.7288 0.004 2.82 0.009 0.6132 0.0025 0.19 0.013 2.02 0.08 1.32 0.088 0.101 0.095 0.008 16.25 11.49 0.22 0.005 3.33 0.12 1.6483 0.0038 2.832 0.009 0.5821 0.0024 0.181 0.012 1.82 0.07 1.47 0.093 0.11 0.101 0.008 17.25 11.59 0.255 0.0022 4.03 0.22 1.7003 0.0039 2.878 0.01 0.5908 0.0024 0.224 0.015 2.56 0.1 1.04 0.084 0.093 0.088 0.007 18.25 11.69 0.235 0.011 3.93 0.13 -999 -999 -999 -999 -999 -999 0.295 0.02 4.26 0.17 0.63 0.069 0.069 0.069 0.006 19.25 11.78 0.282 0.003 4.64 0.11 1.7514 0.004 2.878 0.01 0.6086 0.0025 0.258 0.018 3.23 0.13 0.83 0.077 0.083 0.08 0.006 20.25 11.88 0.379 0.003 6 0.12 1.6135 0.0037 2.81 0.009 0.5743 0.0023 0.386 0.027 4.8 0.19 0.56 0.079 0.082 0.08 0.006 21.25 11.98 0.458 0.012 7.59 0.14 -999 -999 -999 -999 -999 -999 0.582 0.04 8.31 0.32 0.32 0.07 0.07 0.07 0.006 22.25 15.35 0.584 0.007 10.21 0.11 1.7655 0.004 3.036 0.01 0.5816 0.0024 0.689 0.047 9.64 0.38 0.28 0.071 0.072 0.072 0.006 23.25 19.81 0.696 0.006 11.76 0.12 1.6845 0.0039 2.916 0.01 0.5776 0.0023 0.933 0.064 11.98 0.47 0.22 0.077 0.079 0.078 0.006 24.25 24.27 0.495 0.005 9.9 0.14 1.6007 0.0037 2.713 0.009 0.5901 0.0024 0.697 0.048 10.31 0.4 0.26 0.067 0.068 0.068 0.005 25.25 29.87 0.257 0.003 5.79 0.09 1.4398 0.0033 2.2 0.007 0.6546 0.0027 0.362 0.025 5.83 0.23 0.46 0.062 0.063 0.062 0.005 26.25 35.85 -999 -999 5.62 0.1 1.4229 0.0033 2.226 0.007 0.6392 0.0026 -999 -999 5.89 0.23 0.45 -999 -999 -999 -999 27.25 37.93 0.243 0.006 5.38 0.12 1.5937 0.0036 2.705 0.009 0.5892 0.0024 0.375 0.026 5.32 0.21 0.5 0.071 0.07 0.07 0.006 28.25 38.7 0.233 0.003 4.27 0.12 1.7956 0.0041 2.925 0.01 0.6138 0.0025 0.346 0.024 3.59 0.14 0.74 0.094 0.099 0.097 0.008 29.25 39.47 0.1631 0.0018 3.48 0.12 1.7813 0.0041 2.959 0.01 0.602 0.0024 0.178 0.012 2.39 0.09 1.12 0.073 0.077 0.075 0.006