Dissolved and labile particulate Zr, Hf, Nb, Ta, Mo and W in the western North Pacific Ocean

Firdaus, M. Lutfi; Norisuye, Kazuhiro; Nakagawa, Yusuke; Nakatsuka, Seiji; Sohrin, Yoshiki

doi:10.1007/s10872-008-0019-z

Cited by 104 publications

(78 citation statements)

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“…These trends indicate the inter-ocean fractionation of the Zr-Hf system. A comparison with this work and the previous observations 10,11,13,22,23 reveals that Hf concentration does not increase progressively along the pathway of the deep circulation, in contrast to Zr and to Nd. Hafnium should be scavenged from deep water more promptly than Zr and Nd.…”

supporting

confidence: 75%

“…All these results indicate that there are bottom and coastal sources of Zr and Hf. For Nb and Ta, there are no distribution data other than ours 13 . Our previous and present data suggest that Nb and Ta are more uniformly distributed than Zr and Hf, and they also have both bottom and coastal sources.…”

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confidence: 59%

“…The 13 . In surface water, the concentrations of Zr and Hf significantly increase at coastal stations 2,12 .…”

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Strong elemental fractionation of Zr–Hf and Nb–Ta across the Pacific Ocean

et al. 2011

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Understanding the circulation of water masses in the world's oceans is critical to our knowledge of the Earth's climate system. Trace elements and their isotopes have been explored as tracers for the movement of water masses 1 . One type of candidate elements 2 are the high-field-strength elements zirconium (Zr), hafnium (Hf), niobium (Nb) and tantalum (Ta). Here we measure the distributions of dissolved Zr, Hf, Nb and Ta along two meridional sections in the Pacific Ocean that extend from 65 • to 10 • S and from 10 • to 50 • N. We find that all four elements tend to be depleted in surface water. In the deep oceans, their concentrations rise along our transects from the Southern Ocean to the North Pacific Ocean, and show strong correlations with the concentration of silicate. These results indicate that terrigenous sources are important to the budget of Zr, Hf, Nb and Ta in sea water, compared with hydrothermal input. Unexpectedly, the weight ratios for Zr/Hf fall between 45 and 350 and those for Nb/Ta between 14 and 85 in Pacific sea water, higher than the ratios observed in fresh water, in the silicate Earth or in chondritic meteorites. We conclude that the fractionation of Zr/Hf and Nb/Ta ratios will be useful for tracing water masses in the ocean.In the modern ocean, deep water is formed in the northern North Atlantic and the Southern oceans and flows to the Indian and the Pacific oceans. This thermohaline circulation results in an oceanic mixing time in the range 500 to 1,000 years. Silicate (Si(OH) 4 ), a major nutrient, is taken up by diatoms from surface sea water to form siliceous tests, and remineralized from the sinking tests in deep water 3 . The silicate concentration increases with the age of the deep water. Such a biogeochemical cycle is important in controlling the biological productivity in the ocean. An international research collaboration program, GEOTRACES, has been launched recently to determine the global distribution of trace elements and their isotopes (TEIs) and to characterize more completely their biogeochemical cycles 1 . Refractory elements have a low supply to the oceans relative to their abundance in the Earth's crust 2 . They are also rapidly removed from sea water by adsorption on sinking particles, a process referred to as scavenging. These factors result in large variations in the oceanic distributions that typically reflect their sources, making them potential tracers of water masses. For this purpose, rare earth elements (REEs), which occur as carbonate complexes of a trivalent (+3) been measured in iron-manganese (Fe-Mn) crusts and nodules, sediments, and rocks 5-9 . The first dissolved seawater Hf isotope data were recently published 10,11 . Together with neodymium isotope ratios ( 143 Nd/ 144 Nd, expressed as ε Nd ), the Hf-Nd isotope system is used as an excellent proxy to elucidate the past change in continental weathering and/or hydrothermal sources to the ocean. It is now well known that for a given ε Nd , sea water and precipitates, such as ironmagnanese (Fe-Mn) crust...

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Strong elemental fractionation of Zr–Hf and Nb–Ta across the Pacific Ocean

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“…Mo is present in oxic seawater predominantly as dissolved MoO 4 2- (Bertine, 1972). Mo has a concentration as high as 107 nmol/kg (normalized to a salinity (S) of 35) and is distributed uniformly in the modern oxic ocean with a residence time of ~800 ky (Collier, 1985;Sohrin et al, 1987;Tuit and Ravizza, 2003;Firdaus et al, 2008). Because of this uniformity, it has been implicitly assumed that Mo isotopes are homogeneously distributed in the ocean, with δ 98/95 Mo of ~2.3‰ on the basis of measure- Fig.…”

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The molybdenum isotopic composition of the modern ocean

et al. 2012

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Wang et al., 2011 (1) and is converted to δ 97/95 Mo by multiplying 0.67 when the system follows mass-dependent fractionation. Though no commonly-used Mo isotopic standard currently exists (see later), the standards used by different laboratories do appear to be isotopically similar at the level of 0.1-0.2‰. Continental rock samples, such as granite, basalt, and clastic sediments, have δ 98/95 Mo of ~0.1‰ Siebert et al., 2003). Ferromanganese oxides, which scavenge Mo from seawater in oxic conditions, have a light isotopic signature (δ 98/95 Mo = -1.0 to -0.5‰; Siebert et al., 2003), whereas sediments formed in euxinic conditions (aqueous H 2 S concentrations higher than ~11 µM, the action point pro-The molybdenum isotopic composition of the modern ocean (Received September 13, 2011; Accepted January 5, 2012) Natural variations in the isotopic composition of molybdenum (Mo) are showing increasing potential as a tool in geochemistry. Although the ocean is an important reservoir of Mo, data on the isotopic composition of Mo in seawater are scarce. We have recently developed a new method for the precise determination of Mo isotope ratios on the basis of preconcentration using a chelating resin and measurement by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS), which allows us to measure every stable Mo isotope . In this study, 172 seawater samples obtained from 9 stations in the Pacific, Atlantic, and Southern Oceans were analyzed, giving global coverage and the first full depth-profiles. The average isotope composition in δ Three-isotope plots for the Mo isotopes were fitted with straight lines whose slopes agreed with theoretical values for mass-dependent isotope fractionation. These results demonstrate that Mo isotopes are both uniformly distributed and follow a mass-dependent fractionation law in the modern oxic ocean. In addition, Mo isotopic analysis revealed that δ 98/95 Mo of the standard used in this study was 0.117 ± 0.009‰ lighter than the Mo standard that was used by Archer and Vance (2008). A common Mo standard is urgently required for the precise comparison of Mo isotopic compositions measured in different laboratories. On the other hand, our results strongly support the possibility of seawater as an international reference material for Mo isotopic composition.

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“…The interest in these last two elements is due to their high reactivity and short residence time in the ocean making them potential tracers of water masses or in establishing a firm proxy in paleoceanography [5]. Unfortunately, their distributions, dominated by hydroxide species, Zr(OH) 5 À and Hf(OH) 5 À and the difficulty in their analysis with conventional methods, have limited their study in the hydrological cycle. Understanding geochemical processes in marine systems is only possible if the identification and quantification of these elements in seawater is obtained using reliable and comparable chemical measurements.…”

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confidence: 99%

Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide

Raso

Censi

Saiano

2013

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. . However in the analysis of YLOID in seawater, a better determination needs an efficient combination of ICP-MS measurement with a preconcentration technique. To perform an ultra-trace analysis in seawater, we have validated an analytical procedure involving an improved modified co-precipitation on iron hydroxides to ensure the simultaneous quantitative recovery of YLOID, Zr and Hf contents with measurement by a quadrupole ICP-MS.The validity of the method was assessed through a series of co-precipitation experiments and estimation of several quality control parameters for method validation, namely working range and its linearity, detection limit, quantification limit, precision and spike recoveries, and the methodological blank choice, are introduced, evaluated and discussed. Analysis of NASS-6, is the first report on the latest seawater reference material for YLOID, hafnium and zirconium.

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Dissolved and labile particulate Zr, Hf, Nb, Ta, Mo and W in the western North Pacific Ocean

Cited by 104 publications

References 28 publications

Strong elemental fractionation of Zr–Hf and Nb–Ta across the Pacific Ocean

Strong elemental fractionation of Zr–Hf and Nb–Ta across the Pacific Ocean

The molybdenum isotopic composition of the modern ocean

Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide

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