Barium-isotopic fractionation in seawater mediated by barite cycling and oceanic circulation

Horner, Tristan J.; Kinsley, Christopher W.; Nielsen, Sune G.

doi:10.1016/j.epsl.2015.07.027

Earth and Planetary Science Letters

2015

DOI: 10.1016/j.epsl.2015.07.027

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Barium-isotopic fractionation in seawater mediated by barite cycling and oceanic circulation

Tristan J. Horner

¹

,

Christopher W. Kinsley

²

,

Sune G. Nielsen

³

Abstract: Highlights• First full seawater depth profile of co-located [Ba]-δ 138/134 Ba NIST• Origin of Ba-isotopic variations are best explained by barite cycling• Regional circulation strongly influences depth structure of δ 138/134 Ba NIST• Data establish a baseline of Ba-isotopic variability in the marine realm Keywords: barium; isotopic fractionation; barite; seawater; biogeochemistry AbstractThe marine biogeochemical cycle of Ba is thought to be controlled by particulate BaSO 4 (barite) precipitation associated wi… Show more

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Cited by 178 publications

(291 citation statements)

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“…Using Δ 138/134 Ba XS−diss. = −0.41 ± 0.09‰ (this study), Archean barites from the Dresser Formation imply a dissolved Ba source with δ 138/134 Ba NIST = +0.37 ± 0.09‰, similar to the range reported for modern seawater 31 – 33 , and considerably offset with respect to igneous rock standards (data are for AGV-1, G-2, BHVO-1, QLO-1, BIR-1, JG-1a, JB-1a, JR-1, and JA-1 36 ). Values for NBS-127, a barite standard reference material commonly used for S- and O-isotopic normalization, were determined as δ 138/134 Ba NIST = −0.27 ± 0.02‰ (±2 SD, n = 4), which we report here as a reference value for future studies.…”

Section: Resultssupporting

confidence: 85%

Pelagic barite precipitation at micromolar ambient sulfate

Horner

¹

,

Pryer

²

,

Nielsen

³

et al. 2017

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Exaggerated anticipatory anxiety is common in social anxiety disorder (SAD). Neuroimaging studies have revealed altered neural activity in response to social stimuli in SAD, but fewer studies have examined neural activity during anticipation of feared social stimuli in SAD. The current study examined the time course and magnitude of activity in threat processing brain regions during speech anticipation in socially anxious individuals and healthy controls (HC). Method Participants (SAD n = 58; HC n = 16) underwent functional magnetic resonance imaging (fMRI) during which they completed a 90s control anticipation task and 90s speech anticipation task.

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“…Using Δ 138/134 Ba XS−diss. = −0.41 ± 0.09‰ (this study), Archean barites from the Dresser Formation imply a dissolved Ba source with δ 138/134 Ba NIST = +0.37 ± 0.09‰, similar to the range reported for modern seawater 31 – 33 , and considerably offset with respect to igneous rock standards (data are for AGV-1, G-2, BHVO-1, QLO-1, BIR-1, JG-1a, JB-1a, JR-1, and JA-1 36 ). Values for NBS-127, a barite standard reference material commonly used for S- and O-isotopic normalization, were determined as δ 138/134 Ba NIST = −0.27 ± 0.02‰ (±2 SD, n = 4), which we report here as a reference value for future studies.…”

Section: Resultssupporting

confidence: 85%

Pelagic barite precipitation at micromolar ambient sulfate

Horner

¹

,

Pryer

²

,

Nielsen

³

et al. 2017

Self Cite

Get access via publisher Add to dashboard Cite

Exaggerated anticipatory anxiety is common in social anxiety disorder (SAD). Neuroimaging studies have revealed altered neural activity in response to social stimuli in SAD, but fewer studies have examined neural activity during anticipation of feared social stimuli in SAD. The current study examined the time course and magnitude of activity in threat processing brain regions during speech anticipation in socially anxious individuals and healthy controls (HC). Method Participants (SAD n = 58; HC n = 16) underwent functional magnetic resonance imaging (fMRI) during which they completed a 90s control anticipation task and 90s speech anticipation task.

show abstract

“…One naturally grown tropical coral from Florida (A. agaricites) exhibits a d 137/134 Ba value significantly higher than that of Mediterranean surface water, suggesting heterogeneous Ba isotope compositions of surface seawaters, which is consistent with recently published data by Horner et al (2015) and Cao et al (2016). While the Ba isotope system is still in its infancy, these findings provide support to the use of coral Ba isotopes as a palaeo-proxy for water masses and the productivity related isotope composition they carried.…”

Section: Discussionsupporting

confidence: 88%

Constraints on barium isotope fractionation during aragonite precipitation by corals

Pretet

¹

,

Zuilen

²

,

Nägler

³

et al. 2015

The Depositional Record

Get access via publisher Add to dashboard Cite

Exaggerated anticipatory anxiety is common in social anxiety disorder (SAD). Neuroimaging studies have revealed altered neural activity in response to social stimuli in SAD, but fewer studies have examined neural activity during anticipation of feared social stimuli in SAD. The current study examined the time course and magnitude of activity in threat processing brain regions during speech anticipation in socially anxious individuals and healthy controls (HC). Method Participants (SAD n = 58; HC n = 16) underwent functional magnetic resonance imaging (fMRI) during which they completed a 90s control anticipation task and 90s speech anticipation task.

show abstract

“…The [Ba] and d 138/134 Ba data from this study are consistent with those from previous studies. For example, they are similar to those of Horner et al (2015) in the east basin of the South Atlantic (Fig. 2) and [Ba] is in good agreement with GEOSECS data (Fig.…”

Section: Resultssupporting

confidence: 81%

Barium stable isotopes in the global ocean: Tracer of Ba inputs and utilization

Hsieh

¹

,

Henderson

²

2017

Earth and Planetary Science Letters

Get access via publisher Add to dashboard Cite

Exaggerated anticipatory anxiety is common in social anxiety disorder (SAD). Neuroimaging studies have revealed altered neural activity in response to social stimuli in SAD, but fewer studies have examined neural activity during anticipation of feared social stimuli in SAD. The current study examined the time course and magnitude of activity in threat processing brain regions during speech anticipation in socially anxious individuals and healthy controls (HC). Method Participants (SAD n = 58; HC n = 16) underwent functional magnetic resonance imaging (fMRI) during which they completed a 90s control anticipation task and 90s speech anticipation task.

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