Constraining barium isotope fractionation in the upper water column of the South China Sea

Cao, Zhimian; Li, Yating; Rao, Xinting; Yu, Yang; Hathorne, Ed C; Siebert, Christopher; Dai, Minhan

doi:10.1016/j.gca.2020.08.008

Cited by 26 publications

(37 citation statements)

References 78 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition to river systems such as the middle Yellow River (Gou et al., 2020), adsorption‐induced enrichment of lighter Ba isotopes in the particulate phase has also been observed in soils (Gong et al., 2019) and in seawater (Cao et al., 2016; Cao, Li, et al., 2020). In the latter case, 138 ε values of −0.4‰ to −0.5‰, consistent with those for the PRE, were obtained in the euphotic zone of the offshore South China Sea.…”

Section: Resultsmentioning

confidence: 99%

“…Inspired by the pioneering study of von Allmen et al. (2010), recent measurements of stable Ba isotopic compositions of seawater and river waters (δ 138 Ba DBa ; Bates et al., 2017; Bridgestock et al., 2018, 2021; Cao, Li, et al., 2020; Cao, Siebert, et al., 2020; Geyman et al., 2019; Gou et al., 2020; Hemsing et al., 2018; Horner et al., 2015; Hsieh & Henderson, 2017; Pretet et al., 2016) have provided a new avenue to better understand the biogeochemistry of Ba in river estuaries. These studies have shown that major rivers are generally characterized by relatively light δ 138 Ba DBa signatures (0.2‰–0.3‰ on average), reflecting dissolution of lithogenic material, whereas surface seawater shows significantly heavier δ 138 Ba DBa signatures (around 0.6‰) due to preferential removal of light Ba isotopes from the dissolved phase via adsorption to or incorporation into particulate phases.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stable Barium Isotope Dynamics During Estuarine Mixing

Cao

Rao

et al. 2021

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

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 (

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Stable Barium Isotope Dynamics During Estuarine Mixing

Cao

Rao

et al. 2021

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…First, the data underscore the importance of physical mixing (i.e., ocean circulation) in mediating patterns of dissolved δ 138 Ba and, by extension, [Ba]. Second, both the regression of dissolved Ba isotopic data (Bates et al., 2017; Hsieh & Henderson, 2017) and comparison of colocated seawater and particulates (Cao, Li, et al., 2020; Horner et al., 2017) imply an average particulate–dissolved Ba isotopic offset ≈−0.5‰, which is somewhat larger than the experimental results reported by Von Allmen et al. (2010).…”

Section: Bariummentioning

confidence: 90%

Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES‐Era Data

Horner

Little

Conway

et al. 2021

Global Biogeochemical Cycles

View full text Add to dashboard Cite

1. What is the modern marine distribution of this TEI system? 104 2. Which biological, chemical, and physical processes are most important for maintaining this 105 distribution? 106 3. In what form is this TEI system incorporated into sediments? 107 4. Are there clear priorities for improving the utility of this system to track paleoproductivity? 108 This structure results in some repetition of the main distributions, drivers, and sedimentary archives 109 between individual TEI systems. This redundancy is deliberate: each section can be read independently 110 without reference to other TEIs. We close our review by assessing the 'maturity' of each system based on 111 a comparison to more established productivity proxies, offer suggestions for future studies, and discuss 112 prospects for paleoproductivity reconstructions using bioactive TEI isotope systems.

show abstract

“…Field based Δ 138 Babarite-dBa calculated by the comparisons of seawater and co-located particulates (Horner et al, 2017;Cao et al, 2020), regression of dissolved seawater data (Bates et al, 2017;Hsieh and Henderson, 2017), and the isotopic analysis of Ba in seawater and barite in marine sediments (Bridgestock et al, 2018;Crockford et al, 2019) are largely in agreement with oneanother. To reliably use Ba isotopes to interrogate the marine Ba-isotopic cycle, it is important to constrain the magnitude of processes fractionating Ba isotopes in pelagic BaSO4 throughout the mineral's formation in surface waters, during sinking, and when buried in the sediments.…”

Section: Introductionmentioning

confidence: 75%

“…To date, only two studies have experimentally investigated Δ 138 Babarite-dBa related to BaSO4 precipitation in a solution containing methanol, and between -0.28 and -0.35 ‰ for BaSO4 formation during transformation from gypsum (CaSO4•2H2O). In the ocean, the comparisons of seawater and co-located particulates (Horner et al, 2017;Cao et al, 2020), regression of dissolved seawater data (Horner et al, 2015;Bates et al, 2017;Hsieh and Henderson, 2017), and the isotopic analysis of Ba in seawater and barite in marine sediments (Bridgestock et al, 2018; imply a larger magnitude of Δ 138 Babarite-dBa near -0.5 ‰. The magnitude of fractionation observed in field data likely represents an amalgam of multiple processes and/or differences in the dominant controls on fractionation when compared to laboratory experiments.…”

Section: A New Dimension Of Analysis: Barium Isotopesmentioning

confidence: 99%

Barium isotope cycling in the marine environment: pathways of fractionation and implications for paleoceanographic applications

Middleton¹

View full text Add to dashboard Cite

Removal of particulate organic carbon (POC) from sunlit surface waters into the deep ocean represents a climatically important sink of atmospheric carbon dioxide (CO2), linking the biogeochemical cycling of POC to CO2-driven climate change. As POC is not well preserved in the sediment record, other proxies, including the chemistry of barium (Ba) in the ocean and through the sedimentary record, offer an avenue to investigate oceanic carbon export through Earth’s history. This thesis seeks to constrain the controls on the formation, cycling, and isotopic signature of the main particulate phase of marine barium, the mineral barite (BaSO4) through its inception in the water column, during deposition, and ultimately into the rock record. To that end, I characterize the depth, spatial region, and general controls on particulate Ba formation in the South Pacific Ocean through shipboard experimentation and find that particulate Ba forms mainly in the surface of the Polar Frontal Zone in the presence of large particles and microbial activity. Next, I characterize the effect of ion exchange on BaSO4, a process previously unstudied under marine conditions, in a laboratory setting. Ion exchange occurs rapidly between dissolved Ba and BaSO4 and imparts a characteristic net offset between the Ba isotope composition of the dissolved and solid phase, which arises through a combination of Ba isotope fractionation during both precipitation and dissolution. Finally, I investigate the role of ion exchange in marine settings using co-located pore fluids and sedimented BaSO4. Modeling constrained by data from natural samples produce results that are consistent with the laboratory study, suggesting that this mode of isotopic fractionation impacts Ba isotopes in the environment and must be accounted for when applying Ba based climate proxies.

show abstract

Constraining barium isotope fractionation in the upper water column of the South China Sea

Cited by 26 publications

References 78 publications

Stable Barium Isotope Dynamics During Estuarine Mixing

Stable Barium Isotope Dynamics During Estuarine Mixing

Bioactive Trace Metals and Their Isotopes as Paleoproductivity Proxies: An Assessment Using GEOTRACES‐Era Data

Barium isotope cycling in the marine environment: pathways of fractionation and implications for paleoceanographic applications

Contact Info

Product

Resources

About