Barium isotopes in mid-ocean ridge hydrothermal vent fluids: A source of isotopically heavy Ba to the ocean

Hsieh, Yu-Te; Bridgestock, Luke; Scheuermann, Peter P.; Seyfried, William E.; Henderson, Gideon M.

doi:10.1016/j.gca.2020.09.037

Cited by 31 publications

(18 citation statements)

References 78 publications

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“…The marine Ba isotope budget (Horne & Crockford, 2021) indicates that there must be a major unaccounted dBa source other than rivers and hydrothermal vents: the average δ 138/134 Ba of pBa xs , assumed to be the principal form of Ba output from the ocean, is ∼+0.1‰ (Bridgestock et al., 2018). Rivers and hydrothermal fluids have δ 138/134 Ba of ∼0.2‰ (Cao et al., 2016, 2020) and −0.17‰ to 0.04‰ (Hsieh et al., 2020), respectively. This additional source may be SGD, the fresh component of which has a δ 138/134 Ba of +0.1‰ (Mayfield et al., 2021).…”

Section: Resultsmentioning

confidence: 99%

“…Regarding other dBa inputs, recent studies suggest that hydrothermal vent inputs (Hsieh et al, 2020) of dBa may be lower than the 2-3 Gmol year −1 estimated in previous marine budgets (Dickens et al, 2003;. For the flux from the continent to the ocean, desorption or dissolution of carrier phases along a salinity gradient as riverine sediment loads that enter the ocean has been estimated to be an additional significant flux of dBa to the marine budget, anywhere from 3 to 13 Gmol year −1 (Bridgestock et al, 2021) though some work suggests that desorption may be less important to the global Ba marine cycle (Joung & Shiller, 2014).…”

Section: Marine Barium Cyclementioning

confidence: 99%

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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

Shiller

Anderson

et al. 2022

Global Biogeochemical Cycles

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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 (pBaxs) formation and dissolution rates were tracked by normalizing particulate excess 230Th activities. Th‐normalized pBaxs 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 pBaxs 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.

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Section: Resultsmentioning

confidence: 99%

Section: Marine Barium Cyclementioning

confidence: 99%

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

Shiller

Anderson

et al. 2022

Global Biogeochemical Cycles

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“…Although we identify that dBa flux is occurring from the ridge crest, the small (2–3 nmol kg −1 ) signal and limited extent (i.e., observed at only one station) of the signal suggests this is a minor component of the deep Arctic Ba mass balance. Nonetheless, given that recent evidence that net hydrothermal δ 138 Ba is heavy (Hsieh et al., 2021 ), analysis of δ 138 Ba in the deep Eurasian Basin could be instructive regarding the importance of the Ba hydrothermal flux.…”

Section: Discussionmentioning

confidence: 99%

Strong Margin Influence on the Arctic Ocean Barium Cycle Revealed by Pan‐Arctic Synthesis

et al. 2022

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Early studies revealed relationships between barium (Ba), particulate organic carbon and silicate, suggesting applications for Ba as a paleoproductivity tracer and as a tracer of modern ocean circulation. But, what controls the distribution of barium (Ba) in the oceans? Here, we investigated the Arctic Ocean Ba cycle through a one‐of‐a‐kind data set containing dissolved (dBa), particulate (pBa), and stable isotope Ba ratio (δ138Ba) data from four Arctic GEOTRACES expeditions conducted in 2015. We hypothesized that margins would be a substantial source of Ba to the Arctic Ocean water column. The dBa, pBa, and δ138Ba distributions all suggest significant modification of inflowing Pacific seawater over the shelves, and the dBa mass balance implies that ∼50% of the dBa inventory (upper 500 m of the Arctic water column) was supplied by nonconservative inputs. Calculated areal dBa fluxes are up to 10 μmol m−2 day−1 on the margin, which is comparable to fluxes described in other regions. Applying this approach to dBa data from the 1994 Arctic Ocean Survey yields similar results. The Canadian Arctic Archipelago did not appear to have a similar margin source; rather, the dBa distribution in this section is consistent with mixing of Arctic Ocean‐derived waters and Baffin Bay‐derived waters. Although we lack enough information to identify the specifics of the shelf sediment Ba source, we suspect that a sedimentary remineralization and terrigenous sources (e.g., submarine groundwater discharge or fluvial particles) are contributors.

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“…Similarly, our findings of lighter δ 138 Ba DBa_eff than δ 138 Ba DBa_sal = 0 in two of the world's largest river estuaries emphasize the importance of solution‐particle interactions in modifying the Ba properties of river water endmember, the largest source term of the global oceanic Ba budget (Carter et al., 2020). Employing the decreased δ 138 Ba DBa_eff value brings the global oceanic Ba isotope mass balance closer to a steady state (Bridgestock et al., 2021), given that hydrothermal inputs contribute Ba with extremely heavy δ 138 Ba (1.7 ± 0.7‰) to the ocean (Hsieh et al., 2021).…”

Section: Discussionmentioning

confidence: 99%

Stable Barium Isotope Dynamics During Estuarine Mixing

Cao

Rao

et al. 2021

Geophysical Research Letters

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Accurate reconstruction of changes in precipitation on the continents via sea surface salinity in the adjacent ocean is of great importance to understand the monsoon system and assess the impacts of climate change. The barium to calcium (Ba/Ca) ratio recorded by marine calcifiers such as planktonic foraminifera and corals is widely used as a quantitative proxy for paleosalinity in the proximity to large river plumes significantly enriched in Ba at low salinities, and has been linked to climate-driven changes in monsoon intensity and land-sea interactions (

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Barium isotopes in mid-ocean ridge hydrothermal vent fluids: A source of isotopically heavy Ba to the ocean

Cited by 31 publications

References 78 publications

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

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

Strong Margin Influence on the Arctic Ocean Barium Cycle Revealed by Pan‐Arctic Synthesis

Stable Barium Isotope Dynamics During Estuarine Mixing

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