Seasonal riverine barium isotopic variation in the middle Yellow River: Sources and fractionation

Gou, Long‐Fei; Jin, Zhangdong; Galy, Αlbert; Gong, Yuefa; Nan, Xiao-Yun; Jin, Chengcheng; Wang, Xiaodan; Bouchez, Julien; Cai, Hongming; Chen, Jiubin; Yu, Haiying; Huang, Fang

doi:10.1016/j.epsl.2019.115990

Cited by 45 publications

(46 citation statements)

References 63 publications

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“…Similarly, the Ba isotopic composition of groundwater derived from each of the lithologic aquifer endmembers exhibited a narrow range (0.14‰) (Table 2 ). For example, the carbonate aquifer endmember had a δ 138 Ba value of 0.09‰ and the extrusive igneous value was 0.18‰, which are both similar to the global riverine average (δ 138 Ba ≈ 0.2 ± 0.1‰) 21 , 26 , 27 . The isotopic compositions of Ba in global river and groundwater fluxes (δ 138 Ba = 0.12 ± 0.03‰) are indistinguishable, but are both conspicuously heavier than Bulk Silicate Earth (≈0.0 ± 0.1‰) 28 .…”

Section: Resultsmentioning

confidence: 67%

Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba

et al. 2021

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Groundwater-derived solute fluxes to the ocean have long been assumed static and subordinate to riverine fluxes, if not neglected entirely, in marine isotope budgets. Here we present concentration and isotope data for Li, Mg, Ca, Sr, and Ba in coastal groundwaters to constrain the importance of groundwater discharge in mediating the magnitude and isotopic composition of terrestrially derived solute fluxes to the ocean. Data were extrapolated globally using three independent volumetric estimates of groundwater discharge to coastal waters, from which we estimate that groundwater-derived solute fluxes represent, at a minimum, 5% of riverine fluxes for Li, Mg, Ca, Sr, and Ba. The isotopic compositions of the groundwater-derived Mg, Ca, and Sr fluxes are distinct from global riverine averages, while Li and Ba fluxes are isotopically indistinguishable from rivers. These differences reflect a strong dependence on coastal lithology that should be considered a priority for parameterization in Earth-system models.

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Section: Resultsmentioning

confidence: 67%

Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba

et al. 2021

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“…By contrast, Ba isotopes may serve as an effective tracer of magmatic fluids because hydrothermal fluids that exsolved from melts will be enriched in light Ba isotopes (Fig. 2), whereas meteoric waters with dissolved Ba are enriched in heavy Ba isotopes (e.g., δ 138/134 Ba ranging from þ0.17 ‰ to þ0.46 ‰; Gou et al, 2020). For example, alkaline intrusions particularly have the capacity to form rare earth element and other metal deposits (e.g., Verplanck et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

Experimental evidence for light Ba isotopes favouring aqueous fluids over silicate melts

Guo¹,

Li²,

Nan³

et al. 2020

Geochem. Persp. Let.

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“…This could be problematic as it has been shown, for example, that δ 138 Ba diss displays temporal variations in the monsoonal Yellow River Basin . However, this variability was attributed to variable degrees of Ba sorption onto particles, enabled by the very high concentration of suspended particulate matter in the Yellow River (several g/L; Gou et al, 2019). As the rivers of the Amazon Basin display much lower sediment contents than that of the Yellow River (on the 210 order of 100 mg/L for the largest tributaries; Bouchez et al, 2011), we contend that temporal variability in δ 138 Ba diss is much less significant.…”

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confidence: 85%

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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Seasonal riverine barium isotopic variation in the middle Yellow River: Sources and fractionation

Cited by 45 publications

References 63 publications

Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba

Groundwater discharge impacts marine isotope budgets of Li, Mg, Ca, Sr, and Ba

Experimental evidence for light Ba isotopes favouring aqueous fluids over silicate melts

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

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