REE partitioning between Fe-Mn oxyhydroxide precipitates and weakly acid NaCl solutions: Convex tetrad effect and fractionation of Y and Sc from heavy lanthanides.

Kawabe, Iwao; Ohta, Atsuyuki; Ishii, Satoru; Tokumura, Maki; Miyauchi, Kazue

doi:10.2343/geochemj.33.167

Cited by 83 publications

(52 citation statements)

References 31 publications

(38 reference statements)

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“…All the variation patterns exhibit convex tetrad curves, small positive Ce anomalies, log K d (Y) smaller than log K d (Ho), and log K d (Sc) values much larger than those of the other REEs. These characteristics are in agreement with those reported by Bau (1999) and Kawabe et al (1999a …”

Section: Ree Partitioning Coefficients Between Fe Oxyhydroxide Precipsupporting

confidence: 83%

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Rare earth element partitioning between Fe oxyhydroxide precipitates and aqueous NaCl solutions doped with NaHCO3: Determinations of rare earth element complexation constants with carbonate ions.

Ohta

Kawabe

2000

Geochem. J.

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The distribution coefficients of rare earth elements (REEs; all lanthanides except Pm, Y and Sc) between Fe oxyhydroxide precipitates and 0.5 M NaCl solutions with NaHCO 3 (0.0~12.0 mM) at 25°C and 1 bar have been determined. This experimental system is a simple model for REE partitioning between deep-sea ferromanganese nodules and seawater. The distribution coefficients, K d (REE: precipitate/solution), show systematic variations with increasing NaHCO 3 concentrations. We have determined REE(III)-carbonate complexation constants from the experimental distribution coefficients as a function of NaHCO 3 concentration and pH. The REE(III)-carbonate complexation constants show almost the same series variations as reported values obtained by the solvent-extraction method, although our results by the precipitation method are rather higher by 1.0~1.5 in log unit than the literature data at zero ionic strength. amine how REE(III)-carbonate complexation affects the REE partitioning process in seawater. Kawabe et al. (1999a, b) reported preliminary experimental results of REE partitioning between Fe oxyhydroxide precipitates and NaCl solutions with and without carbonate ions. They emphasized that the lanthanide tetrad effect is associated with the distribution coefficients of REEs between Fe oxyhydroxide precipitates and NaCl solutions. They analyzed their experimental results using the refined spin-pairing energy theory, RSPET, (Jørgensen, 1979;Kawabe, 1992). Although Kawabe et al. (1999b) estimated the complexation constants for REE(CO 3 ) 2 -from their experimental results, they could not estimate those for REECO 3 + from the preliminary data. REE(III)-carbonate complexation constants have been reported by Byrne and co-workers (Cantrell and

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Section: Ree Partitioning Coefficients Between Fe Oxyhydroxide Precipsupporting

confidence: 83%

“…(5) can be re-written in the form; log log , log log . Kawabe et al (1999a) suggested that REECl 2+ (aq) and REEOH…”

Section: Ree Partitioning Coefficients Between Fe Oxyhydroxide Precipmentioning

confidence: 99%

Rare earth element partitioning between Fe oxyhydroxide precipitates and aqueous NaCl solutions doped with NaHCO3: Determinations of rare earth element complexation constants with carbonate ions.

Ohta

Kawabe

2000

Geochem. J.

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“…Figure 1, which is quoted from Kawabe et al (1999a) When all the logK d (org/aq) values are used in the least-squares fittings for both cases, the average errors of fittings are 0.09 for the system A and 0.05 for the system B in the logarithmic unit. However, when we exclude the logK d (org/aq) value only for La(III) in the system A, the average fitting error is reduced to be 0.06 from 0.09.…”

Section: Lanthanide Tetrad Effects In Solvent-extraction and Rspet Eqmentioning

confidence: 99%

“…These two terms can be written collectively, (9/13)n(S)C 1 Z* + m(L)C 3 Z* = {n(S) + (13/9)(C 3 /C 1 )m(L)}(9/13)C 1 Z*. (2) When it is assumed that (C 3 /C 1 ) = 0.21 as in Kawabe et al (1999a),…”

Section: Lanthanide Tetrad Effects In Solvent-extraction and Rspet Eqmentioning

confidence: 99%

The original examples of lanthanide tetrad effect in solvent extraction: A new interpretation compatible with recent progress in REE geochemistry.

Kawabe

Masuda²

2001

Geochem. J.

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Geochmeical studies reporting lanthanide tetrad effects in natural samples often cite the original examples of tetrad effect depicted by logK d (org/aq) for Ln(III) in the two solvent-extraction systems (Peppard et al., 1969) and its theoretical interpretation (Jørgensen, 1970;Nugent, 1970). An improved equation for the refined spin-pairing energy theory (RSPET), which has been developed in pursuing tetrad effects in geochemical studies, makes it possible to examine more thoroughly the original examples of tetrad effect by using the digitized logK d (org/aq) data. The logK d (org/aq) values are found to be successfully described by the RSPET equation. Our analyses show that the ratios of relative differences in Racah parameters for Ln 3+ ions in aqueous and organic phases, ∆E 3 /∆E 1 , are 0.29 ± 0.07 and 0.25 ± 0.06 for the two extraction systems. They are comparable with the spectroscopic observations of nephelauxetic effect in Nd(III) compounds (∆E 3 /∆E 1 = 0.23 ± 0.02). The tetrad effects in logK d (org/aq) are experimental evidence for the thermochemical consequence of the nephelauxetic effect in Ln(III) complexes. Although Ln 3+ ions in condensed phases are atomic-like, it is rather surprising that logK d (org/aq) can easily be reproduced by the simple RSPET equation derived from the Slater-Condon-Racah theory for free Ln 3+ ions in vacuum. The effect of coordination change of Ln 3+ ion across the Ln 3+ (aq) series is not obvious in the series variations of logK d (org/aq), suggesting that the coordination changes in the two Ln(III) complex series in the extraction systems are significantly canceled out in ∆G r°. The two sets of logK d (org/aq) are analogous to the Masuda-Coryell plot in REE geochemistry with respect to their coordinates. This gives an insight into the fact that the Masuda-Coryell plot also depicts tetrad effects in the REE patterns for geochemical samples.

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“…Therefore, it is not unreasonable that the thermodynamic parameters for y3+ and H03+ are different in spite of their almost same ionic radii. Kawabe et al (1999) (Figs. 3(a), 3(b) and 4).…”

Section: Resultsmentioning

confidence: 99%

Systematic correlation of the Ce anomaly with the Co/(Ni+Cu) ratio and Y fractionation from Ho in distinct types of Pacific deep-sea nodules.

et al. 1999

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Chemical characteristics of "diagenetic" and "hydrogenous" type deep-sea nodules from the central and northeastern Pacific were studied regarding their Ce anomalies and Y fractionation from heavy REE. Pacific nodules of both types show low Y/Ho ratios less than average shales or chondrites, contrasting to the other marine samples (seawaters, limestones, and phosphorites) having higher Y/Ho ratios than aver age shales or chondrites. The "hydrogenous" type nodules show large positive Ce anomalies up to log(Ce/ Ce*) = +0.6, whereas the "diagenetic" type nodules display only small positive Ce anomalies or even small negative ones. Two nodule subsamples, which are characterized by 10 A manganate but are chemi cally the intermediate between the two types, show Ce anomalies of log(Ce/Ce*) = +0.3 in the middle of the two end members. Interestingly, the Ce anomalies of the nodules vary coherently with their logarith mic Co/(Ni+Cu) ratios. This positive correlation is valid even after combing many literature data of Pa cific nodules with our data. In the plot of Ce anomaly vs. log[Co/(Ni+Cu)], the three distinct types of Pacific nodules are systematically distinguished: "sub oxic-diagenetis" <_ "diagenetic" <_ "hydrogenous". The systematics strongly suggest that: (i) the Ce anomaly and log[Co/(Ni+Cu)] are similar geochemical indexes showing how effectively oxidative uptake of Ce and Co occurred in each nodule relative to non oxidative uptake of nutrient-type metals in the respective metal groups, and (ii) there exists an initial source supplying metals common to all the types of Pacific nodules. We inferred from various reasons that the common initial source is biogenic particulates delivered from overlying surface water. Oxidative up take of Ce and Co by fast sinking large biogenic particulates is less effective, but such particulates can more effectively convey nutrient-type metals involved with them to the sea floor because of their shorter residence time in oxic water. However, the relationship between metal transports of scavenged and nutri ent-type elements is reversed in the case of slowly sinking biogenic particulates. High surface productiv ity inevitably provides high flux of fast sinking large organic particulates, whereas low productivity gives rise to organic particulate flux dominated by slowly sinking small ones. These mechanisms explain the observed systematics of Ce anomaly vs. log[Co/(Ni+Cu)] plots for Pacific nodules.

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REE partitioning between Fe-Mn oxyhydroxide precipitates and weakly acid NaCl solutions: Convex tetrad effect and fractionation of Y and Sc from heavy lanthanides.

Cited by 83 publications

References 31 publications

Rare earth element partitioning between Fe oxyhydroxide precipitates and aqueous NaCl solutions doped with NaHCO3: Determinations of rare earth element complexation constants with carbonate ions.

Rare earth element partitioning between Fe oxyhydroxide precipitates and aqueous NaCl solutions doped with NaHCO3: Determinations of rare earth element complexation constants with carbonate ions.

The original examples of lanthanide tetrad effect in solvent extraction: A new interpretation compatible with recent progress in REE geochemistry.

Systematic correlation of the Ce anomaly with the Co/(Ni+Cu) ratio and Y fractionation from Ho in distinct types of Pacific deep-sea nodules.

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