Efficient Extraction of Past Seawater Pb and Nd Isotope Signatures From Southern Ocean Sediments

Huang, Huang; Gutjahr, Marcus; Kuhn, Gerhard; Hathorne, Ed C; Eisenhauer, Anton

doi:10.1029/2020gc009287

Cited by 14 publications

(8 citation statements)

References 95 publications

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“…Approximately 0.2 to 1 g of SPM was treated with a diluted reductive solution consisting of 0.005 M hydroxylamine hydrochloride/1.5% acetic acid/0.03 M Na-EDTA (sodium-ethylenediaminetetraacetate) solution buffered to pH 4 with NaOH (sodium hydroxide) for 10 minutes, following Huang et al 66 for extracting the labile Fe–Mn oxyhydroxide fraction. Total procedural blanks were below 15 pg for Nd ( n = 2) and are hence negligible.…”

Section: Methodsmentioning

confidence: 99%

Overlooked riverine contributions of dissolved neodymium and hafnium to the Amazon estuary and oceans

Hathorne

Laukert

2023

Nat Commun

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The Amazon River accounts for 20% of global freshwater runoff and supplies vital trace metals to the Atlantic Ocean. Suspended particles within its plume are thought to partially dissolve, constituting a large potential source of metals, which is, however, not well constrained. Here we used combined neodymium (Nd) and hafnium (Hf) isotopes to disprove the release of Nd and Hf from particles as the cause of the observed dissolved concentration increases and isotopic variability across the plume. Instead, the changes reflect admixture of nearby Pará River freshwater with exceptionally high dissolved Nd and Hf concentrations contributing 45–100% of the riverine fraction to the southern and outer estuary. This result led us to develop an empirical relationship between riverine Nd concentration and pH to revise the global dissolved riverine Nd flux, which accordingly is at least three times higher than commonly used estimates. Future work should focus on contributions of low-pH rivers to global metal fluxes.

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Section: Methodsmentioning

confidence: 99%

Overlooked riverine contributions of dissolved neodymium and hafnium to the Amazon estuary and oceans

Hathorne

Laukert

2023

Nat Commun

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“…5A). However, (Huang et al, 2021). The lack of correlation between εNd and Ca/Fe suggests that Fe-rich sediment phases (e.g.…”

Section: Limitations Of the Leaching Approachmentioning

confidence: 98%

Continental weathering as the source of iron in Jurassic iron oolites from Switzerland

et al. 2023

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Iron is extremely insoluble in oxic seawater. The lack of a large aqueous reservoir means that sediments rich in authigenic iron are rare in the modern ocean. In the Middle Jurassic, however, condensed iron-rich sedimentary rocks are widely distributed. Their formation coincides with increased volcanic activity and continental weathering related to the breakup of Pangea, suggesting iron supply through one of these processes. We studied three Swiss shallow-marine iron oolites from Herznach, Windgällen and Erzegg, all from condensed sedimentary sequences of Middle to early Late Jurassic age, to constrain the source of iron to these rocks, combining radiogenic neodymium, strontium and stable iron isotope analyses. Leached authigenic neodymium isotope compositions, which appear to preserve the primary signature, serve as a tracer for the potential involvement of hydrothermal fluids in the formation of the iron oolites. The three iron oolite successions yield crustal Nd isotope compositions (εNd between − 9 and − 7), providing no evidence for the involvement of such fluids. It is, thus, more likely that iron in the sediments derived from detrital fluvial inputs. Strontium isotope compositions, which could potentially support these findings, point to metamorphic overprinting associated with Alpine thrusting. The light iron isotope signatures associated with Middle to early Late Jurassic condensed sequences, δ56Fe between − 1.49 and − 0.57‰, suggest that microbially-mediated iron reduction was also involved in generating these sediments.

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“…We collected trace metal samples from the RR1804 cruise using the ship's regular CTD rosette and Niskin bottles, which is not a standard TMC sampling technique. But previous studies have shown that ship's regular sampling system can be clean for some trace metals, such as Mn, Cd, and Nd (Janssen et al 2014;Huang et al 2021;Zhang et al 2021). In order to assess the cleanliness of the ship's regular sampling system, we compared the RR1804 concentrations with those of RR1805-when a TMC sampling technique was used.…”

Section: Sampling For Trace Metals With a Non-clean Systemmentioning

confidence: 99%

Biogeochemical cycling of Cd, Mn, and Ce in the Eastern Tropical North Pacific oxygen‐deficient zone

Bian

Yang

Bolster

et al. 2022

Limnology & Oceanography

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Oxygen‐deficient zones (ODZs) play an important role in the distribution and cycling of trace metals in the ocean, as important sources of metals including Fe and Mn, and also as possible sinks of chalcophile elements such as Cd. The Eastern Tropical North Pacific (ETNP) ODZ is one of the three largest ODZs worldwide. Here, we present results from two sectional surveys through the ETNP ODZ conducted in 2018, providing high‐resolution concentrations of several metals, along with complimentary measurements of nutrients and iodine speciation. We show that samples obtained from the ship's regular rosette are clean for Cd, Mn, Ni, and light rare earth elements, while uncontaminated Fe, Zn, Cu, and Pb samples cannot be obtained without a special trace‐metal clean sampling system. Our results did not show evidence of Cd sulfide precipitation, even within the most oxygen‐depleted water mass. High Mn and Ce concentrations and high Ce anomalies were observed in low‐oxygen seawater. These maxima were most pronounced in the upper water column below the oxycline, coincident with the secondary nitrite maxima and the lowest oxygen concentrations, in what is generally considered the most microbially active part of the water column. High Mn and Ce features were also coincident with maxima in excess iodine, a tracer of shelf sediment sources. Mn and Ce maxima were most prominent within the 13°C water mass, spanning a density horizon that enhances isopycnal transport from the shelf sediments, resulting in transport of Mn and Ce at least 2500 km offshore.

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Efficient Extraction of Past Seawater Pb and Nd Isotope Signatures From Southern Ocean Sediments

Abstract: Radiogenic lead (Pb) and neodymium (Nd) isotope compositions have been successfully applied as sensitive and powerful palaeoceanographic proxies for the reconstruction of past circulation changes and water mass mixing for decades (

Cited by 14 publications

References 95 publications

Overlooked riverine contributions of dissolved neodymium and hafnium to the Amazon estuary and oceans

Overlooked riverine contributions of dissolved neodymium and hafnium to the Amazon estuary and oceans

Continental weathering as the source of iron in Jurassic iron oolites from Switzerland

Biogeochemical cycling of Cd, Mn, and Ce in the Eastern Tropical North Pacific oxygen‐deficient zone

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