Moore Willard S.

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Moore
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Willard S.
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0000-0001-5930-5325

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  • Article
    GEOTRACES radium isotopes interlaboratory comparison experiment
    (Association for the Sciences of Limnology and Oceanography, 2012-06) Charette, Matthew A. ; Dulaiova, Henrieta ; Gonneea, Meagan E. ; Henderson, Paul B. ; Moore, Willard S. ; Scholten, Jan C. ; Pham, Mai Khanh
    In anticipation of the international GEOTRACES program, which will study the global marine biogeochemistry of trace elements and isotopes, we conducted a multi-lab intercomparison for radium isotopes. The intercomparison was in two parts involving the distribution of: (1) samples collected from four marine environments (open ocean, continental slope, shelf, and estuary) and (2) a suite of four reference materials prepared with isotopic standards (circulated to participants as 'unknowns'). Most labs performed well with 228Ra and 224Ra determination, however, there were a number of participants that reported 226Ra, 223Ra, and 228Th (supported 224Ra) well outside the 95% confidence interval. Many outliers were suspected to be a result of poorly calibrated detectors, though other method specific factors likely played a role (e.g., detector leakage, insufficient equilibration). Most methods for radium analysis in seawater involve a MnO2 fiber column preconcentration step; as such, we evaluated the extraction efficiency of this procedure and found that it ranged from an average of 87% to 94% for the four stations. Hence, nonquantitative radium recovery from seawater samples may also have played a role in lab-to-lab variability.
  • Article
    Increased fluxes of shelf-derived materials to the central Arctic Ocean
    (American Association for the Advancement of Science, 2018-01-03) Kipp, Lauren ; Charette, Matthew A. ; Moore, Willard S. ; Henderson, Paul B. ; Rigor, Ignatius
    Rising temperatures in the Arctic Ocean region are responsible for changes such as reduced ice cover, permafrost thawing, and increased river discharge, which, together, alter nutrient and carbon cycles over the vast Arctic continental shelf. We show that the concentration of radium-228, sourced to seawater through sediment-water exchange processes, has increased substantially in surface waters of the central Arctic Ocean over the past decade. A mass balance model for 228Ra suggests that this increase is due to an intensification of shelf-derived material inputs to the central basin, a source that would also carry elevated concentrations of dissolved organic carbon and nutrients. Therefore, we suggest that significant changes in the nutrient, carbon, and trace metal balances of the Arctic Ocean are underway, with the potential to affect biological productivity and species assemblages in Arctic surface waters.
  • Dataset
    Particulate Th-234 from in-situ pumps, including large size fraction (> 51 um) and small size fraction (1-51 um), from R/V Thomas G. Thompson cruise TN303 in the Eastern Tropical Pacific in 2013 (U.S. GEOTRACES EPZT project)
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2020-07-09) Buesseler, Kenneth O. ; Charette, Matthew A. ; Moore, Willard S.
    Particulate Thorium-234 from in-situ pumps, including large size fraction (> 51 µm) and small size fraction (1-51 µm), during the 2013 U.S. GEOTRACES cruise. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/643316
  • Dataset
    Radiochemistry data for fluids sampled from the Lost City Hydrothermal Field at the Atlantis Massif in 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-01-11) Moore, Willard S. ; Frankle, Jessica D. ; Benitez-Nelson, Claudia R. ; Fruh-Green, Gretchen ; Lang, Susan Q.
    This dataset includes radiochemistry data for fluids from 7 vent sites (Marker 2, Beehive, Marker 8, Marker 3, Calypso, Marker C. and Sombrero) at the Lost City Hydrothermal Field at the Atlantis Massif (30N, Mid-Atlantic Ridge). Fluid samples were collected in September 2018 during the AT42-01 expedition of the R/V Atlantis with the remotely operated vehicle (ROV) Jason II. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/864434
  • Dataset
    Water column dissolved radium-226 from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-01-14) Charette, Matthew A. ; Moore, Willard S.
    Water column dissolved radium-226 from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/825891
  • Dataset
    Radium isotope measurements from bottom waters in the South Atlantic Bight from 2015-2020 (SAB BMA project)
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-11-02) Pinckney, James ; Moore, Willard S.
    These are measurements of radium isotopes collected from bottom waters in the South Atlantic Bight during 2015-2020. These data were used to verify an episode of submarine groundwater discharge that occurred in August 2019. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/882140
  • Dataset
    Water column dissolved radium-226 from Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from October to November 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-01-14) Charette, Matthew A. ; Moore, Willard S.
    Water column dissolved radium-226 from Leg 2 (Hilo, HI to Papeete, French Polynesia) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1815) on R/V Roger Revelle from October to November 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/825947
  • Preprint
    Actinium and radium fluxes from the seabed in the northeast Pacific Basin
    (Elsevier, 2022-10-22) Kemnitz, Nathaniel ; Hammond, Douglas E. ; Henderson, Paul ; Le Roy, Emilie ; Charette, Matthew ; Moore, Willard ; Anderson, Robert F. ; Fleisher, Martin Q. ; Leal, Anne ; Black, Erin ; Hayes, Christopher T. ; Adkins, Jess ; Berelson, William ; Bian, Xiaopeng
    Five sediment cores were collected along a cruise tract from Hawaii to Alaska in August 2017 (C-Disk-IV cruise) with the objective of characterizing the behavior of 227Ac, 228Ra, and 226Ra and their fluxes into the overlying water column, information that is essential to the interpretation of the distribution of these tracers in the ocean, for example, as measured on GEOTRACES cruises. Solid phase profiles of these isotopes were measured, and reaction-transport models were applied that incorporated molecular diffusion, bioturbation, sedimentation, distribution coefficients (kd), and the fraction of each isotope released to pore water by parent decay (called F). Fits to these profiles used kd values determined in lab experiments for C-Disk-IV sediments. Ra kd values (1000–3000 mL g−1) agreed with previous estimates for deep-sea sediments, and Ac kd values (3500–22,000 mL g−1) correlated with those for Ra but were about 7 times greater. Two independent approaches were used to quantify the benthic fluxes of 227Ac and 228Ra in the Northeast Pacific: (1) use of solid phase profiles with a reaction-transport model, as well as integrated downcore daughter-parent deficiency; and (2) direct measurement of fluxes based on core incubation. The two independent methods agreed within uncertainty, and the average 227Ac and 228Ra sediment fluxes for the Northeast Pacific are 90 ± 20 and 600 ± 200 dpm m−2-yr−1, respectively. The 226Ra sediment flux was only determined by the former approach, and the flux calculated in this study is similar to previous work in the North Pacific, averaging 1300 ± 200 dpm m−2-yr−1. This is over 2× higher than the water column inventory of 226Ra in this region (600 dpm m−2-yr−1), and indicates the importance of lateral 226Ra export from the N. Pacific. The largest 227Ac and Ra isotope fluxes in the study area are near the center of the Northeast Pacific (∼37°N). Smaller 227Ac, 228Ra and 226Ra fluxes occur north of 40°N, primarily due to dilution of their Pa and Th ancestors by higher sediment accumulation rates.
  • Dataset
    Radiochemistry data for rocks and deposits from the Lost City Hydrothermal Field at the Atlantis Massif from 2018-2020
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-01-11) Moore, Willard S. ; Frankle, Jessica D. ; Benitez-Nelson, Claudia R. ; Fruh-Green, Gretchen ; Lang, Susan Q.
    Radiochemistry of serpentinite, carbonate-brucite chimney, and other solid samples from the Lost City Hydrothermal Field at the Atlantis Massif from 2018 and four previous expeditions in 2015, 2005, 2003, and 2000 (Kelley et al., 2001; Kelley et al., 2005; Früh-Green et al.,2018). For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/864460
  • Article
    Global estimate of submarine groundwater discharge based on an observationally constrained radium isotope model
    (John Wiley & Sons, 2014-12-03) Kwon, Eun Young ; Kim, Guebuem ; Primeau, Francois W. ; Moore, Willard S. ; Cho, Hyung-Mi ; DeVries, Timothy ; Sarmiento, Jorge L. ; Charette, Matthew A. ; Cho, Yang-Ki
    Along the continental margins, rivers and submarine groundwater supply nutrients, trace elements, and radionuclides to the coastal ocean, supporting coastal ecosystems and, increasingly, causing harmful algal blooms and eutrophication. While the global magnitude of gauged riverine water discharge is well known, the magnitude of submarine groundwater discharge (SGD) is poorly constrained. Using an inverse model combined with a global compilation of 228Ra observations, we show that the SGD integrated over the Atlantic and Indo-Pacific Oceans between 60°S and 70°N is (12 ± 3) × 1013 m3 yr−1, which is 3 to 4 times greater than the freshwater fluxes into the oceans by rivers. Unlike the rivers, where more than half of the total flux is discharged into the Atlantic, about 70% of SGD flows into the Indo-Pacific Oceans. We suggest that SGD is the dominant pathway for dissolved terrestrial materials to the global ocean, and this necessitates revisions for the budgets of chemical elements including carbon.
  • Preprint
    Isotopic, geophysical and biogeochemical investigation of submarine groundwater discharge : IAEA-UNESCO intercomparison exercise at Mauritius Island
    ( 2011-09) Povinec, Pavel P. ; Burnett, William C. ; Beck, A. ; Bokuniewicz, Henry J. ; Charette, Matthew A. ; Gonneea, Meagan E. ; Groening, M. ; Ishitobi, T. ; Kontar, E. ; Kwong, L. Liong Wee ; Marie, D. E. P. ; Moore, Willard S. ; Oberdorfer, J. A. ; Peterson, R. ; Ramessur, R. ; Rapaglia, J. ; Stieglitz, T. ; Top, Zafer
    Submarine groundwater discharge (SGD) into a shallow lagoon on the west coast of Mauritius Island (Flic-en-Flac) was investigated using radioactive (3H, 222Rn, 223Ra, 224Ra, 226Ra, 228Ra) and stable (2H, 18O) isotopes and nutrients. SGD intercomparison exercises were carried out to validate the various approaches used to measure SGD including radium and radon measurements, seepage-rate measurements using manual and automated meters, sediment bulk conductivity and salinity surveys. SGD measurements using benthic chambers placed on the floor of the Flic-en-Flac Lagoon showed discharge rates up to 500 cm/day. Large variability in SGD was observed over distances of a few meters, which were attributed to different geomorphological features. Deployments of automated seepage meters captured the spatial and temporal variability of SGD with a mean seepage rate of 10 cm/day. The stable isotopic composition of submarine waters was characterized by significant variability and heavy isotope enrichment and was used to predict the contribution of fresh terrestrially derived groundwater to SGD (range from a few % to almost 100 %). The integrated SGD flux, estimated from seepage meters placed parallel to the shoreline, was 35 m3/m day, which was in a reasonable agreement with results obtained from hydrologic water balance calculation (26 m3/m day). SGD calculated from the radon inventory method using in situ radon measurements were between 5 and 56 m3/m per day. Low concentrations of radium isotopes observed in the lagoon water reflected the low abundance of U and Th in the basalt that makes up the island. High SGD rates contribute to high nutrients loading to the lagoon, potentially leading to eutrophication. Each of the applied methods yielded unique information about the character and magnitude of SGD. The results of the intercomparison studies have resulted a better understanding of groundwater-seawater interactions in coastal regions. Such information is an important pre-requisite for the protection management of coastal freshwater resources.
  • Preprint
    Assessment of groundwater discharges into West Neck Bay, New York, via natural tracers
    ( 2006-05-21) Dulaiova, Henrieta ; Burnett, William C. ; Chanton, Jeffrey P. ; Moore, Willard S. ; Bokuniewicz, Henry J. ; Charette, Matthew A. ; Sholkovitz, Edward R.
    A field experiment to compare methods of assessing submarine groundwater discharge (SGD) was held on Shelter Island, NY, in May 2002. We evaluated the use of radon, radium isotopes, and methane to assess SGD rates and dynamics from a glacial aquifer in the coastal zone. Fluxes of radon across the sediment-water interface were calculated from changes in measured surface water inventories following evaluation and correction for tidal effects, atmospheric evasion, and mixing with offshore waters. These fluxes were then converted to SGD rates using the measured radon concentration in the groundwater. We used the short-lived radium isotopes to calculate a horizontal mixing coefficient to assess radon loss by mixing between nearshore and offshore waters. We also made an independent calculation of SGD using the Ra-derived mixing coefficient and the long-lived 226Ra concentration gradient in the bay. Seepage rates were calculated to range between 0 and 34 cm.day-1 using the radon measurements and 15 cm.day-1 as indicated by the radium isotopes. The radiotracer results were consistent and comparable to SGD rates measured directly with vented benthic chambers (seepage meters) deployed during this experiment. These meters indicated rates between 2 and 200 cm.day-1 depending on their location. Both the calculated radon fluxes and rates measured directly by the automated seepage meters revealed a clear reproducible pattern of higher fluxes during low tides. Considering that the two techniques are completely independent, the agreement in the SGD dynamics is significant. Methane concentration in groundwater was very low (~30 nM) and not suitable as SGD tracer at this study site.
  • Article
    Erratum : GEOTRACES radium isotopes interlaboratory comparison experiment
    (Association for the Sciences of Limnology and Oceanography, 2012-06) Charette, Matthew A. ; Dulaiova, Henrieta ; Gonneea, Meagan E. ; Henderson, Paul B. ; Moore, Willard S. ; Scholten, Jan C. ; Pham, Mai Khanh
    In our original paper, Charette, M. A., H. Dulaiova, M. E. Gonneea, P. B. Henderson, W. S. Moore, J. C. Scholten, and M. K. Pham. 2012. GEOTRACES radium isotopes interlaboratory comparison experiment. Limonol. Oceanogr.: Methods 10:451, the incorrect headers were used for Table 9.
  • Preprint
    The release of dissolved actinium to the ocean : A global comparison of different end-members
    ( 2007-04-05) Geibert, Walter ; Charette, Matthew A. ; Kim, Guebuem ; Moore, Willard S. ; Street, Joseph ; Young, Megan ; Paytan, Adina
    The measurement of short-lived 223Ra often involves a second measurement for supported activities, which represents 227Ac in the sample. Here we exploit this fact, presenting a set of 284 values on the oceanic distribution of 227Ac, which was collected when analyzing water samples for short-lived radium isotopes by the radium delayed coincidence counting system. The present work compiles 227Ac data from coastal regions all over the northern hemisphere, including values from ground water, from estuaries and lagoons, and from marine endmembers. Deep-sea samples from a continental slope off Puerto Rico and from an active vent site near Hawaii complete the overview of 227Ac near its potential sources. The average 227Ac activities of nearshore marine end-members range from 0.4 dpm * m-3 at the Gulf of Mexico to 3.0 dpm *m-3 in the coastal waters of the Korean Strait. In analogy to 228Ra, we find the extension of adjacent shelf regions to play a substantial role for 227Ac activities, although less pronounced than for radium, due to its weaker shelf source. Based on previously published values, we calculate an open ocean 227Ac inventory of 1.35 * 1018 dpm 227Acex in the ocean, which corresponds to 37 moles, or 8.4 kg. This implies a flux of 127 dpm*m-2*y-1 from the deep-sea floor. For the shelf regions, we obtain a global inventory of 227Ac of 4.5 * 1015 dpm, which cannot be converted directly into a flux value, as the regional loss term of 227Ac to the open ocean would have to be included. Ac has so far been considered to behave similarly to Ra in the marine environment, with the exception of a strong Ac source in the deep-sea due to 231Paex. Here, we present evidence of geochemical differences between Ac, which is retained in a warm vent system, and Ra, which is readily released (Moore et al., submitted). Another potential mechanism of producing deviations in 227Ac/228Ra and daughter isotope ratios from the expected production value of lithogenic material is observed at reducing environments, where enrichment in uranium may occur. The presented data here may serve as a reference for including 227Ac in circulation models, and the overview provides values for some end-members that contribute to the global Ac distribution.
  • Article
    Radium isotopes across the Arctic Ocean show time scales of water mass ventilation and increasing shelf inputs
    (John Wiley & Sons, 2018-07-13) Rutgers van der Loeff, Michiel M. ; Kipp, Lauren ; Charette, Matthew A. ; Moore, Willard S. ; Black, Erin E. ; Stimac, Ingrid ; Charkin, Alexander ; Bauch, Dorothea ; Valk, Ole ; Karcher, Michael ; Krumpen, Thomas ; Casacuberta, Nuria ; Smethie, William M. ; Rember, Robert
    The first full transarctic section of 228Ra in surface waters measured during GEOTRACES cruises PS94 and HLY1502 (2015) shows a consistent distribution with maximum activities in the transpolar drift. Activities in the central Arctic have increased from 2007 through 2011 to 2015. The increased 228Ra input is attributed to stronger wave action on shelves resulting from a longer ice‐free season. A concomitant decrease in the 228Th/228Ra ratio likely results from more rapid transit of surface waters depleted in 228Th by scavenging over the shelf. The 228Ra activities observed in intermediate waters (<1,500 m) in the Amundsen Basin are explained by ventilation with shelf water on a time scale of about 15–18 years, in good agreement with estimates based on SF6 and 129I/236U. The 228Th excess below the mixed layer up to 1,500 m depth can complement 234Th and 210Po as tracers of export production, after correction for the inherent excess resulting from the similarity of 228Ra and 228Th decay times. We show with a Th/Ra profile model that the 228Th/228Ra ratio below 1,500 m is inappropriate for this purpose because it is a delicate balance between horizontal supply of 228Ra and vertical flux of particulate 228Th. The accumulation of 226Ra in the deep Makarov Basin is not associated with an accumulation of Ba and can therefore be attributed to supply from decay of 230Th in the bottom sediment. We estimate a ventilation time of 480 years for the deep Makarov‐Canada Basin, in good agreement with previous estimates using other tracers.
  • Article
    Radium inputs into the Arctic Ocean from rivers a basin‐wide estimate
    (American Geophysical Union, 2022-09-08) Bullock, Emma J. ; Kipp, Lauren ; Moore, Willard S. ; Brown, Kristina A. ; Mann, Paul J. ; Vonk, Jorien E. ; Zimov, Nikita S. ; Charette, Matthew A.
    Radium isotopes have been used to trace nutrient, carbon, and trace metal fluxes inputs from ocean margins. However, these approaches require a full accounting of radium sources to the coastal ocean including rivers. Here, we aim to quantify river radium inputs into the Arctic Ocean for the first time for 226Ra and to refine the estimates for 228Ra. Using new and existing data, we find that the estimated combined (dissolved plus desorbed) annual 226Ra and 228Ra fluxes to the Arctic Ocean are [7.0–9.4] × 1014 dpm y−1 and [15–18] × 1014 dpm y−1, respectively. Of these totals, 44% and 60% of the river 226Ra and 228Ra, respectively are from suspended sediment desorption, which were estimated from laboratory incubation experiments. Using Ra isotope data from 20 major rivers around the world, we derived global annual 226Ra and 228Ra fluxes of [7.4–17] × 1015 and [15–27] × 1015 dpm y−1, respectively. As climate change spurs rapid Arctic warming, hydrological cycles are intensifying and coastal ice cover and permafrost are diminishing. These river radium inputs to the Arctic Ocean will serve as a valuable baseline as we attempt to understand the changes that warming temperatures are having on fluxes of biogeochemically important elements to the Arctic coastal zone.
  • Dataset
    Water-column total Th-234 from R/V Thomas G. Thompson cruise TN303 in the Eastern Tropical Pacific in 2013 (U.S. GEOTRACES EPZT project)
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2020-07-09) Buesseler, Kenneth O. ; Charette, Matthew A. ; Moore, Willard S.
    Water-column total Th-234 with 4 L method from the 2013 U.S. GEOTRACES EPZT cruise. U-238 from U-salinity relationship was also determined but not reported in this dataset. These data can be made available upon request from the PI and/or dataset contact. Methods are described below. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/643213
  • Article
    Shelf-basin interactions and water mass residence times in the western Arctic Ocean: Insights provided by radium isotopes
    (American Geophysical Union, 2019-04-26) Kipp, Lauren ; Kadko, David C. ; Pickart, Robert S. ; Henderson, Paul B. ; Moore, Willard S. ; Charette, Matthew A.
    Radium isotopes are produced through the decay of thorium in sediments and are soluble in seawater; thus, they are useful for tracing ocean boundary‐derived inputs to the ocean. Here we apply radium isotopes to study continental inputs and water residence times in the Arctic Ocean, where land‐ocean interactions are currently changing in response to rising air and sea temperatures. We present the distributions of radium isotopes measured on the 2015 U.S. GEOTRACES transect in the Western Arctic Ocean and combine this data set with historical radium observations in the Chukchi Sea and Canada Basin. The highest activities of radium‐228 were observed in the Transpolar Drift and the Chukchi shelfbreak jet, signaling that these currents are heavily influenced by interactions with shelf sediments. The ventilation of the halocline with respect to inputs from the Chukchi shelf occurs on time scales of ≤19–23 years. Intermediate water ventilation time scales for the Makarov and Canada Basins were determined to be ~20 and >30 years, respectively, while deep water residence times in these basins were on the order of centuries. The radium distributions and residence times described in this study serve as a baseline for future studies investigating the impacts of climate change on the Arctic Ocean.
  • Article
    The transpolar drift as a source of riverine and shelf-derived trace elements to the central Arctic Ocean
    (American Geophysical Union, 2020-04-08) Charette, Matthew A. ; Kipp, Lauren ; Jensen, Laramie T. ; Dabrowski, Jessica S. ; Whitmore, Laura M. ; Fitzsimmons, Jessica N. ; Williford, Tatiana ; Ulfsbo, Adam ; Jones, Elizabeth M. ; Bundy, Randelle M. ; Vivancos, Sebastian M. ; Pahnke, Katharina ; John, Seth G. ; Xiang, Yang ; Hatta, Mariko ; Petrova, Mariia V. ; Heimbürger, Lars-Eric ; Bauch, Dorothea ; Newton, Robert ; Pasqualini, Angelica ; Agather, Alison ; Amon, Rainer M. W. ; Anderson, Robert F. ; Andersson, Per S. ; Benner, Ronald ; Bowman, Katlin ; Edwards, R. Lawrence ; Gdaniec, Sandra ; Gerringa, Loes J. A. ; González, Aridane G. ; Granskog, Mats A. ; Haley, Brian ; Hammerschmidt, Chad R. ; Hansell, Dennis A. ; Henderson, Paul B. ; Kadko, David C. ; Kaiser, Karl ; Laan, Patrick ; Lam, Phoebe J. ; Lamborg, Carl H. ; Levier, Martin ; Li, Xianglei ; Margolin, Andrew R. ; Measures, Christopher I. ; Middag, Rob ; Millero, Frank J. ; Moore, Willard S. ; Paffrath, Ronja ; Planquette, Helene ; Rabe, Benjamin ; Reader, Heather ; Rember, Robert ; Rijkenberg, Micha J. A. ; Roy-Barman, Matthieu ; van der Loeff, Michiel Rutgers ; Saito, Mak A. ; Schauer, Ursula ; Schlosser, Peter ; Sherrell, Robert M. ; Shiller, Alan M. ; Slagter, Hans ; Sonke, Jeroen E. ; Stedmon, Colin ; Woosley, Ryan J. ; Valk, Ole ; van Ooijen, Jan ; Zhang, Ruifeng
    A major surface circulation feature of the Arctic Ocean is the Transpolar Drift (TPD), a current that transports river‐influenced shelf water from the Laptev and East Siberian Seas toward the center of the basin and Fram Strait. In 2015, the international GEOTRACES program included a high‐resolution pan‐Arctic survey of carbon, nutrients, and a suite of trace elements and isotopes (TEIs). The cruises bisected the TPD at two locations in the central basin, which were defined by maxima in meteoric water and dissolved organic carbon concentrations that spanned 600 km horizontally and ~25–50 m vertically. Dissolved TEIs such as Fe, Co, Ni, Cu, Hg, Nd, and Th, which are generally particle‐reactive but can be complexed by organic matter, were observed at concentrations much higher than expected for the open ocean setting. Other trace element concentrations such as Al, V, Ga, and Pb were lower than expected due to scavenging over the productive East Siberian and Laptev shelf seas. Using a combination of radionuclide tracers and ice drift modeling, the transport rate for the core of the TPD was estimated at 0.9 ± 0.4 Sv (106 m3 s−1). This rate was used to derive the mass flux for TEIs that were enriched in the TPD, revealing the importance of lateral transport in supplying materials beneath the ice to the central Arctic Ocean and potentially to the North Atlantic Ocean via Fram Strait. Continued intensification of the Arctic hydrologic cycle and permafrost degradation will likely lead to an increase in the flux of TEIs into the Arctic Ocean.
  • Dataset
    Water column dissolved radium-226 from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-12-29) Charette, Matthew A. ; Moore, Willard S.
    Water column dissolved radium-226 from Leg 1 (Seattle, WA to Hilo, HI) of the US GEOTRACES Pacific Meridional Transect (PMT) cruise (GP15, RR1814) on R/V Roger Revelle from September to October 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/825891