Review of the analysis of 234Th in small volume (2–4 L) seawater samples: improvements and recommendations

Clevenger, Samantha J.; Benítez-Nelson, Claudia R.; Drysdale, Jessica A.; Pike, Steven; Puigcorbé, Viena; Buesseler, Ken O.

doi:10.1007/s10967-021-07772-2

Cited by 8 publications

(6 citation statements)

References 40 publications

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“…(2001), and further detailed in Clevenger et al. (2021). 234 Th was co‐precipitated with Mn‐oxide and collected onto a 25 mm quartz microfiber (QMA) filter and measured on Risø Laboratories anti‐coincidence beta counters.…”

Section: Methodsmentioning

confidence: 99%

“…Total 234 Th samples were collected at all stations along the GEOTRACES GP15 (2 L samples) and GP16 (4 L samples) transects in addition to regular underway surface sampling. Total 234 Th analyses were done in accordance with the method developed in Buesseler et al (2001), and further detailed in Clevenger et al (2021). 234 Th was co-precipitated with Mn-oxide and collected onto a 25 mm quartz microfiber (QMA) filter and measured on Risø Laboratories anti-coincidence beta counters.…”

Section: Determination Of 234 Thmentioning

confidence: 99%

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Re‐Evaluating Hydrogen Sulfide as a Sink for Cadmium and Zinc in the Oxic to Suboxic Upper Water Column of the Pacific Ocean

Buckley,

Black,

Kenyon

et al. 2024

Global Biogeochemical Cycles

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Hydrogen sulfide is produced by heterotrophic bacteria in anoxic waters and via carbonyl sulfide hydrolysis and phytoplankton emissions under oxic conditions. Apparent losses of dissolved cadmium (dCd) and zinc (dZn) in oxygen minimum zones (OMZs) of the Atlantic and Pacific Oceans have been attributed to metal‐sulfide precipitation formed via dissimilatory sulfate reduction. It has also been argued that such a removal process could be a globally important sink for dCd and dZn. However, our studies from the North Pacific OMZ show that dissolved and particulate sulfide concentrations are insufficient to support the removal of dCd via precipitation. In contrast, apparent dCd and dZn deficits in the eastern tropical South Pacific OMZ do reside in the oxycline with particulate sulfide maxima, but they also coincide with the secondary fluorescence maxima, suggesting that removal via sulfide precipitation may be due to a combination of dissimilatory and assimilatory sulfate reduction. Notably, dCd loss via precipitation with sulfide from assimilatory reduction was found in upper oxic waters of the North Pacific. While dissimilatory sulfate reduction may explain local dCd and dZn losses in some OMZs, our evaluation of North Pacific OMZs demonstrates that dCd and dZn losses are unlikely to be a globally relevant sink. Nevertheless, metal sulfide losses due to assimilatory sulfate reduction in surface waters should be considered in future biogeochemical models of oceanic Cd (and perhaps Zn) cycling.

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Section: Methodsmentioning

confidence: 99%

Section: Determination Of 234 Thmentioning

confidence: 99%

Re‐Evaluating Hydrogen Sulfide as a Sink for Cadmium and Zinc in the Oxic to Suboxic Upper Water Column of the Pacific Ocean

Buckley,

Black,

Kenyon

et al. 2024

Global Biogeochemical Cycles

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“…Th analyses are described in Ratnarajah et al (2022). Briefly, 4 L seawater samples were collected at 12-14 depths along the water column at each station and processed using the manganese oxide co-precipitation technique (Clevenger et al, 2021), while 238 U activity concentrations were derived from salinity data (Owens et al, 2011). Th-234 samples were counted onboard using a gas flow proportional low-level RISO beta counter (counting statistics <5%) and recounted >6 months later to account for background activities.…”

Section: Sampling Of Free-living and Particle-attached Prokaryotic Co...mentioning

confidence: 99%

Impact of particle flux on the vertical distribution and diversity of size-fractionated prokaryotic communities in two East Antarctic polynyas

Puigcorbé

Ruiz‐González²,

Masqué³

et al. 2023

Front. Microbiol.

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Antarctic polynyas are highly productive open water areas surrounded by ice where extensive phytoplankton blooms occur, but little is known about how these surface blooms influence carbon fluxes and prokaryotic communities from deeper waters. By sequencing the 16S rRNA gene, we explored the vertical connectivity of the prokaryotic assemblages associated with particles of three different sizes in two polynyas with different surface productivity, and we linked it to the magnitude of the particle export fluxes measured using thorium-234 (234Th) as particle tracer. Between the sunlit and the mesopelagic layers (700 m depth), we observed compositional changes in the prokaryotic communities associated with the three size-fractions, which were mostly dominated by Flavobacteriia, Alphaproteobacteria, and Gammaproteobacteria. Interestingly, the vertical differences between bacterial communities attached to the largest particles decreased with increasing 234Th export fluxes, indicating a more intense downward transport of surface prokaryotes in the most productive polynya. This was accompanied by a higher proportion of surface prokaryotic taxa detected in deep particle-attached microbial communities in the station with the highest 234Th export flux. Our results support recent studies evidencing links between surface productivity and deep prokaryotic communities and provide the first evidence of sinking particles acting as vectors of microbial diversity to depth in Antarctic polynyas, highlighting the direct influence of particle export in shaping the prokaryotic communities of mesopelagic waters.

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“…-2012: intercalibration initiative by Maiti et al (2012), which carried out an intercomparison of 234 -improvement of the small-volume technique recently carried out by Clevenger et al (2021), which introduces a revised protocol that decreases sample volumes to 2 L, shortens wait times between steps, and simplifies the chemical recovery process, expanding the ability to more rapidly and safely apply the 234 Th method;…”

Section: Era 2: "The Sea Around Us"mentioning

confidence: 99%

Revisiting five decades of <sup>234</sup>Th data: a comprehensive global oceanic compilation

Ceballos-Romero

Buesseler

Villa-Alfageme

2022

Earth Syst. Sci. Data

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Abstract. We present here a global oceanic compilation of 234Th measurements that collects results from researchers and laboratories over a period exceeding 50 years. The origin of the 234Th sampling in the ocean goes back to 1967, when Bhat et al. (1969) initially studied 234Th distribution relative to its parent 238U in the Indian Ocean. However, it was the seminal work of Buesseler et al. (1992) – which proposed an empirical method to estimate export fluxes from 234Th distributions – that drove the extensive use of the 234Th–238U radioactive pair to evaluate the organic carbon export out of the surface ocean by means of the biological carbon pump. Since then, a large number of 234Th depth profiles have been collected using a variety of sampling instruments and strategies that have changed during the past 50 years. The present compilation is made of a total 223 data sets: 214 from studies published in either articles in refereed journals, PhD theses, or repositories, as well as 9 unpublished data sets. The data were compiled from over 5000 locations spanning all the oceans for total 234Th profiles, dissolved and particulate 234Th activity concentrations (in dpm L−1), and POC:234Th ratios (in µmol dpm−1) from both sediment traps and filtration methods. A total of 379 oceanographic expeditions and more than 56 600 234Th data points have been gathered in a single open-access, long-term, and dynamic repository. This paper introduces the dataset along with informative and descriptive graphics. Appropriate metadata have been compiled, including geographic location, date, and sample depth, among others. When available, we also include water temperature, salinity, 238U data (over 18 200 data points), and particulate organic nitrogen data. Data source and method information (including 238U and 234Th) is also detailed along with valuable information for future data analysis such as bloom stage and steady-/non-steady-state conditions at the sampling moment. The data are archived on the PANGAEA repository, with the dataset DOI https://doi.org/10.1594/PANGAEA.918125 (Ceballos-Romero et al., 2021). This provides a valuable resource to better understand and quantify how the contemporary oceanic carbon uptake functions and how it will change in future.

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Review of the analysis of 234Th in small volume (2–4 L) seawater samples: improvements and recommendations

Cited by 8 publications

References 40 publications

Re‐Evaluating Hydrogen Sulfide as a Sink for Cadmium and Zinc in the Oxic to Suboxic Upper Water Column of the Pacific Ocean

Re‐Evaluating Hydrogen Sulfide as a Sink for Cadmium and Zinc in the Oxic to Suboxic Upper Water Column of the Pacific Ocean

Impact of particle flux on the vertical distribution and diversity of size-fractionated prokaryotic communities in two East Antarctic polynyas

Revisiting five decades of <sup>234</sup>Th data: a comprehensive global oceanic compilation

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Review of the analysis of 234Th in small volume (2–4 L) seawater samples: improvements and recommendations

Cited by 8 publications

References 40 publications

Re‐Evaluating Hydrogen Sulfide as a Sink for Cadmium and Zinc in the Oxic to Suboxic Upper Water Column of the Pacific Ocean

Re‐Evaluating Hydrogen Sulfide as a Sink for Cadmium and Zinc in the Oxic to Suboxic Upper Water Column of the Pacific Ocean

Impact of particle flux on the vertical distribution and diversity of size-fractionated prokaryotic communities in two East Antarctic polynyas

Revisiting five decades of &lt;sup&gt;234&lt;/sup&gt;Th data: a comprehensive global oceanic compilation

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Revisiting five decades of <sup>234</sup>Th data: a comprehensive global oceanic compilation