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Dissolved and Particulate Barium Distributions Along the US GEOTRACES North Atlantic and East Pacific Zonal Transects (GA03 and GP16): Global Implications for the Marine Barium Cycle

Rahman, Shaily and Shiller, Alan M. and Anderson, Robert F. and Charette, Matthew A. and Hayes, Christopher T. and Gilbert, Melissa and Grissom, Karen R. and Lam, Phoebe J. and Ohnemus, Daniel C. and Pavia, Frank J. and Twining, Benjamin S. and Vivancos, Sebastián M. (2022) Dissolved and Particulate Barium Distributions Along the US GEOTRACES North Atlantic and East Pacific Zonal Transects (GA03 and GP16): Global Implications for the Marine Barium Cycle. Global Biogeochemical Cycles, 36 (6). Art. No. e2022GB007330. ISSN 0886-6236. doi:10.1029/2022gb007330.

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Processes controlling dissolved barium (dBa) were investigated along the GEOTRACES GA03 North Atlantic and GP16 Eastern Tropical Pacific transects, which traversed similar physical and biogeochemical provinces. Dissolved Ba concentrations are lowest in surface waters (∼35–50 nmol kg⁻¹) and increase to 70–80 and 140–150 nmol kg⁻¹ in deep waters of the Atlantic and Pacific transects, respectively. Using water mass mixing models, we estimate conservative mixing that accounts for most of dBa variability in both transects. To examine nonconservative processes, particulate excess Ba (pBa_(xs)) formation and dissolution rates were tracked by normalizing particulate excess ²³⁰Th activities. Th-normalized pBa_(xs) fluxes, with barite as the likely phase, have subsurface maxima in the top 1,000 m (∼100–200 μmol m⁻² year⁻¹ average) in both basins. Barite precipitation depletes dBa within oxygen minimum zones from concentrations predicted by water mass mixing, whereas inputs from continental margins, particle dissolution in the water column, and benthic diffusive flux raise dBa above predications. Average pBa_(xs) burial efficiencies along GA03 and GP16 are ∼37% and 17%–100%, respectively, and do not seem to be predicated on barite saturation indices in the overlying water column. Using published values, we reevaluate the global freshwater dBa river input as 6.6 ± 3.9 Gmol year⁻¹. Estuarine mixing processes may add another 3–13 Gmol year⁻¹. Dissolved Ba inputs from broad shallow continental margins, previously unaccounted for in global marine summaries, are substantial (∼17 Gmol year⁻¹), exceeding terrestrial freshwater inputs. Revising river and shelf dBa inputs may help bring the marine Ba isotope budget more into balance.

Item Type:Article
Related URLs:
URLURL TypeDescription Information S1 S1
https://www.bco-dmo.orgRelated ItemBiological and Chemical Oceanography Data Management Office
Rahman, Shaily0000-0002-3912-7258
Shiller, Alan M.0000-0002-2068-7909
Anderson, Robert F.0000-0002-8472-2494
Charette, Matthew A.0000-0003-3699-592X
Hayes, Christopher T.0000-0002-5636-2989
Gilbert, Melissa0000-0002-5698-6548
Grissom, Karen R.0000-0002-1639-6850
Lam, Phoebe J.0000-0001-6609-698X
Ohnemus, Daniel C.0000-0001-6362-4134
Pavia, Frank J.0000-0003-3627-0179
Twining, Benjamin S.0000-0002-1365-9192
Vivancos, Sebastián M.0000-0002-8057-5685
Additional Information:© 2022. The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Issue Online: 09 June 2022; Version of Record online: 09 June 2022; Accepted manuscript online: 23 May 2022; Manuscript accepted: 19 May 2022; Manuscript revised: 18 May 2022; Manuscript received: 21 January 2022. Many thanks to the captain, crew, and scientists on the R/V Knorr and R/V Thompson during these expeditions. The authors give a special thanks to the in situ pumping group for particle sample collection and processing during the GA03 and GP16 cruises, Martin Fleisher for operating the Lamont-Doherty Earth Observatory ICP-MS facility, Pu Zhang, Larry Edwards, and Hai Cheng at the University of Minnesota for their contributions to the GP16 particulate ²³⁰Th concentrations data set, and to Maija Heller and Jong-Mi Lee at UCSC for their measurements of pBa in the GP16 pump samples. The International GEOTRACES Programme is possible in part thanks to the support from the U.S. National Science Foundation (Grant OCE-1840868) to the Scientific Committee on Oceanic Research (SCOR). This research was supported by the National Science Foundation under Grant No. NSF OCE-0927951, NSF OCE-1137851, NSF OCE-1261214, and NSF OCE-1925503 to A. M. Shiller; NSF OCE-1829563 to R. F. Anderson; NSF OCE-0927064 and NSF OCE-1233688 to R. F. Anderson and M. Q. Fleisher; NSF OCE-0927754 to R. Lawrence Edwards; NSF OCE-1233903 to R. Lawrence Edwards and H. Cheng; NSF OCE-0926860 to L. F. Robinson; NSF OCE-0963026 and NSF OCE-1518110 to P. J. Lam; and NSF OCE-1232814 to B. S. Twining. The authors declare no conflicts of interest relevant to this study. Data Availability Statement: All data supporting the conclusions of this manuscript can be found through the Biological and Chemical Oceanography Data Management Office website ( Additional details supporting the manuscript may be found in the Supporting Information file provided.
Funding AgencyGrant Number
Subject Keywords:barium; excess barium; barite; GEOTRACES; Th-normalized flux; burial efficiency
Issue or Number:6
Record Number:CaltechAUTHORS:20220526-391435000
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Official Citation:Rahman, S., Shiller, A. M., Anderson, R. F., Charette, M. A., Hayes, C. T., Gilbert, M., et al. (2022). Dissolved and particulate barium distributions along the US GEOTRACES North Atlantic and East Pacific Zonal Transects (GA03 and GP16): Global implications for the marine barium cycle. Global Biogeochemical Cycles, 36, e2022GB007330.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:114949
Deposited By: George Porter
Deposited On:01 Jun 2022 17:17
Last Modified:30 Jun 2022 18:46

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