Assessing the utility of barium isotopes to trace Eurasian riverine freshwater inputs to the Arctic Ocean

Bridgestock, Luke; Nathan, Joseph; Hsieh, Yu-Te; Holdship, Phil; Porcelli, Don; Andersson, Per; Henderson, Gideon M.

doi:10.1016/j.marchem.2021.104029

Cited by 6 publications

(7 citation statements)

References 66 publications

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“…Riverine δ 138 Ba composition compiled from global observations range between ∼0.2‰ and 0.46‰ (δ 138 Ba; Cao et al., 2020 ; Charbonnier et al., 2018 ; Gou et al., 2020 ; Horner & Crockford, 2021 ). Recent work in the Arctic Ocean estimates Eurasian rivers have effective δ 138 Ba endmembers that range between ∼0.20 ± 0.06‰ and ∼0.31 ± 0.04‰ and have an average of roughly 0.23 ± 0.04‰ (Bridgestock, Nathan, Hsieh, et al., 2021 ).…”

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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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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“…Baltic Sea water is generated by mixing of freshwater from the Baltic Sea drainage area and North Atlantic seawater entering via the Danish straits. Freshwater is generally characterized by higher Ba concentrations and a lower d 138 Ba than seawater (e.g., Cao et al, 2016;Cao et al, 2020;Bridgestock et al, 2021a;Bridgestock et al, 2021b;Rahman et al, 2022). Therefore, it is likely that the Ba concentration and isotopic distribution in Kiel Bight is to some extent a function of mixing of freshwater and seawater.…”

Section: Freshwater-seawater Mixing Within Kiel Bightmentioning

confidence: 99%

“…5. Because no Ba isotope data for rivers entering the Baltic Sea are available, the Ba concentration (116 nM) and d 138 Ba (+0.23 ‰) of Eurasian riverine freshwater (Bridgestock et al, 2021b) were used in Eq. 5 and 6.…”

Section: Freshwater-seawater Mixing Within Kiel Bightmentioning

confidence: 99%

“…During chemical weathering, some of the Ba mobilized from crustal material is adsorbed to secondary minerals such as iron (Fe) and manganese (Mn) oxides or clay minerals. Given that the light Ba isotopes are preferentially adsorbed (Gong et al, 2020), river water is generally characterized by higher d 138 Ba (+0.1 to +0.35 ‰) (Cao et al, 2016;Bridgestock et al, 2021a;Bridgestock et al, 2021b;Cao et al, 2021) than crustal rocks (0.0 ± 0.03 ‰) (Nan et al, 2018) but a lower d 138 Ba than seawater. Dissolved Ba concentrations in rivers are generally higher than those in seawater (Rahman et al, 2022) and additional Ba is released from riverine particles by ion exchange during estuarine mixing (Hanor and Chan, 1977;Coffey et al, 1997;Bridgestock et al, 2021a).…”

Section: Introductionmentioning

confidence: 99%

“…Dissolved Ba concentrations in rivers are generally higher than those in seawater (Rahman et al, 2022) and additional Ba is released from riverine particles by ion exchange during estuarine mixing (Hanor and Chan, 1977;Coffey et al, 1997;Bridgestock et al, 2021a). The differences in river water and seawater Ba concentrations and isotope compositions have been proposed as a (paleo-)proxy for freshwater input (Bridgestock et al, 2021b;Yu et al, 2022 and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Benthic-pelagic coupling and isotopic fractionation of barium in Kiel Bight, SW Baltic Sea

et al. 2023

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Barium (Ba) isotopes are a promising new tracer for riverine freshwater input to the ocean and marine biogeochemical cycling. However, many processes that affect Ba cycling at continental margins have not yet been investigated with respect to Ba isotope fractionation. Here, we present a comprehensive data set of Ba concentration and isotope data for water column, pore water and sediment samples from Kiel Bight, a seasonally stratified and hypoxic fjord in the southwestern Baltic Sea. The surface water Ba concentration and Ba isotope inventory of the water column can generally be explained by mixing of riverine freshwater and Atlantic seawater. However, the deep-water below the seasonal pycnocline (10 - 15 m water depth) is characterized by a pronounced positive Ba concentration anomaly (up to 915 nM) that is accompanied by a δ138Ba of ~+0.25 ‰, which is lighter than expected from the seawater-freshwater mixing line (Ba: 77 nM, δ138Ba: +0.32 ‰ at a salinity of 18). Pore water profiles indicate a Ba flux across the sediment-water interface, which contributes to the enrichment in isotopically light Ba in the deep-water. Pore waters of surface sediments and deep-waters are oversaturated with respect to barite. Therefore, barite dissolution is unlikely to account for the benthic Ba flux. Water column Ba concentrations closely correlate with those of the nutrients phosphate and silica, which are removed from surface waters by biological processes and recycled from the sediment by diffusion across the sediment-water interface. As nutrient-to-Ba ratios differ among sites and from those observed in open-marine systems, we propose that Ba is removed from surface waters by adsorption onto biogenic particles (rather than assimilation) and regenerated within surface sediments upon organic matter degradation. Pore water data for subsurface sediments in Kiel Bight indicate preferential transfer of isotopically heavy Ba into an authigenic phase during early diagenesis. Quantifying the burial flux associated with this authigenic Ba phase along continental margins could potentially help to settle the isotopic imbalance between known Ba source and sink fluxes in the ocean.

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The significant role of submarine groundwater discharge in an Arctic fjord nutrient budget

Yu,

Liu,

Zhu

et al. 2024

Acta Oceanol. Sin.

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Assessing the utility of barium isotopes to trace Eurasian riverine freshwater inputs to the Arctic Ocean

Cited by 6 publications

References 66 publications

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

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

Benthic-pelagic coupling and isotopic fractionation of barium in Kiel Bight, SW Baltic Sea

The significant role of submarine groundwater discharge in an Arctic fjord nutrient budget

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