Controls on the barium isotope compositions of marine sediments

Bridgestock, Luke; Hsieh, Yu-Te; Porcelli, D.; Homoky, William B.; Bryan, Allison; Henderson, Gideon M.

doi:10.1016/j.epsl.2017.10.019

Cited by 98 publications

(128 citation statements)

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“…The remaining stream sediments show similar δ 138/134 Ba values (−0.04 ± 0.03‰ to 0.01 ± 0.03‰) to that of the river sediments from north China (−0.05‰ to 0.04‰) (Nan et al ) and marine sediments from the South Atlantic (−0.09‰ to 0.10‰) (Bridgestock et al ). Therefore, variations in Ba isotopic compositions of the stream sediments analysed in this study probably reflect changes in the relative contributions of different Ba sources, such as detrital (bedrock lithologies) and authigenic sources, river, seawater or hydrothermal components and recycled biogenic materials (Dymond ).…”

Section: Discussionmentioning

confidence: 72%

“…); open triangles for marine sediments (Bridgestock et al . ); solid grey triangles for river sediments (Nan et al . ); open diamonds for I/S‐type granites; and solid grey diamonds for the A‐type granites (Nan et al .…”

Section: Discussionmentioning

confidence: 99%

“…Barium is mainly present in the following forms: discrete barite particles, as a trace element in the main sediment constituents (such as calcium carbonate, biogenic opal, terrigenous matter, organic carbon (TOC) (Dymond et al , Gingele and Dahmke ) and poorly crystalline manganese oxyhydroxide (Dymond et al )). Previous studies have shown that the Ba isotopic compositions of marine sediments could potentially record insights into past changes in the marine Ba cycle (Bridgestock et al ).…”

Section: Discussionmentioning

confidence: 99%

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Barium Isotopic Compositions in Thirty‐Four Geological Reference Materials Analysed by MC‐ICP‐MS

Zhang

2019

Geostandard Geoanalytic Res

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Measurement of Ba isotope ratios of widely available reference materials is required for interlaboratory comparison of data. Here, we present new Ba isotope data for thirty‐four geological reference materials, including silicates, carbonates, river/marine sediments and soils. These reference materials (RMs) cover a wide range of compositions, with Ba mass fractions ranging from 6.4 to 1900 µg g−1, SiO2 from 0.62% to 90.36% m/m and MgO from 0.08% to 41.03% m/m. Accuracy and precision of our data were assessed by the analyses of duplicate samples and USGS rock RMs. Barium isotopic compositions for all RMs were in agreement with each other within uncertainty. The variation of δ138/134Ba in these RMs was up to 0.7‰. The shale reference sample, affected by a high degree of chemical weathering, had the highest δ138/134Ba (0.37 ± 0.03‰), while the stream sediment obtained from a tributary draining carbonate rocks was characterised by the lowest δ138/134Ba (−0.30 ± 0.05‰). Geochemical RMs play a fundamental role in the high‐precision and accurate determination of Ba isotopic compositions for natural samples with similar matrices. Analyses of these RMs could provide universal comparability for Ba isotope data and enable assessment of accuracy for interlaboratory data.

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Section: Discussionmentioning

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Barium Isotopic Compositions in Thirty‐Four Geological Reference Materials Analysed by MC‐ICP‐MS

Zhang

2019

Geostandard Geoanalytic Res

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“…soluble in acid digestions than barite in water column samples (Bridgestock et al, 2018;Dymond et al, 1992;Eagle et al, 2003).…”

Section: Accepted Manuscriptmentioning

confidence: 98%

Oceanic fronts control the distribution of dissolved barium in the Southern Ocean

et al. 2018

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The globally-observed relationship between oceanic barium and the macronutrient silicic acid results from the shared influence of large-scale ocean circulation and mixing on the two elements, and the inherent link between barium and organic matter formation and dissolution. A detailed examination of deviations from barium-silicon correlations can reveal variations in non-conservative processes within the marine barium cycle. Here, we present a high-resolution dataset of dissolved barium and macronutrients from the Drake Passage and the Scotia and Weddell Seas. Our new results highlight the influence of Southern Ocean frontal zones on barium cycling and the deviations of barium and macronutrient distributions as a result of spatial variations in phytoplankton assemblages and in barite formation processes. These new data also reinforce findings that water mass mixing and ocean circulation, in particular the location of oxygen minima, play a key role in barium distribution. Our findings have implications for the use of sedimentary barium as a proxy for export production, which may be complicated by physical water circulation changes or shifts in plankton community structure.

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“…Nevertheless, we can try to assess a Ba isotope fractionation 760 factor during formation of clays and oxides using our own measurements and previously published data. Marine clays do not show large variations in δ 138 Ba, with an isotope composition slightly depleted (by ∼ -0.05 ‰) in heavy isotopes with respect to igneous and sedimentary rocks (Bridgestock et al, 2018;Charbonnier et al, 2018). Barium isotope fractionation during formation of secondary weathering products can also be estimated from data on soils.…”

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confidence: 99%

Barium stable isotopes as a fingerprint of biological cycling in the Amazon River Basin

Charbonnier¹,

Bouchez²,

Gaillardet³

et al. 2020

Preprint

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Abstract. Although biological cycling of rock-derived nutrients is a major operator of element cycles at the Earth surface, its magnitude still remains elusive. The isotope composition of rock-derived nutrients, which can be fractionated during biological uptake, is a powerful tool to quantify biological cycling. In this paper we use the elemental and isotopic composition of such a rock-derived nutrient, the trace element barium (Ba), measured in river dissolved and sediment load samples collected across the Amazon Basin. We show that dissolved Ba derives mainly from silicate rocks, while a correlation between dissolved Ba and K abundances suggests a strong role of biological cycling on the Ba river budget. The isotope composition of Ba (δ138Ba) of the dissolved load is significantly different from that of silicate rocks and is affected by i) formation of secondary phases and ii) biological uptake and release from dead organic matter. Results from an isotope mass balance model applied to the river dissolved load data indicate that after its release to solution by rock weathering, Ba is partitioned between the dissolved load, the secondary weathering products such as those found in soils and river sediments, and the biota. In most sub-catchments of the Amazon, river dissolved Ba abundance and isotope composition are significantly affected by biological cycling. Relationships between estimates of Ba cycling and independent metrics of ecosystem dynamics (such as Gross Primary Production and Terrestrial Ecosystem Respiration) allows us to discuss the role of erosion rates on the cycling of rock-derived nutrients. In addition, river catchment-scale mass and isotope budgets of Ba show that the measured riverine export of Ba is lower than the estimated delivery of Ba to the Earth surface through rock alteration. This indicates the existence of a missing Ba component, that we attribute to the formation of a Ba-bearing particulate organic component, possibly accumulating as soil organic matter or currently growing biomass within the catchments; and to organic-bound exported as unsampled river particulate organic matter. Given our findings on the minor nutrient Ba, we explore whether the river fluxes of most major rock-derived nutrients (K, Mg, Ca) might also be significantly affected by biological uptake or release. A first-order correction of river-derived silicate weathering fluxes from biological cycling shows that, at the Amazon at mouth, the CO2 consumption by silicate weathering should be 20 % higher than the yet-reported value. Overall, our study clearly shows that the chemical and isotope composition of the Amazon (and most likely of most rivers) bears a biological imprint.

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Controls on the barium isotope compositions of marine sediments

Abstract: This is a repository copy of Controls on the barium isotope compositions of marine sediments.

Cited by 98 publications

References 49 publications

Barium Isotopic Compositions in Thirty‐Four Geological Reference Materials Analysed by MC‐ICP‐MS

Barium Isotopic Compositions in Thirty‐Four Geological Reference Materials Analysed by MC‐ICP‐MS

Oceanic fronts control the distribution of dissolved barium in the Southern Ocean

Barium stable isotopes as a fingerprint of biological cycling in the Amazon River Basin

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