In order to study the geochemistry of thorium isotopes in the hydrosphère, particularly in the océan, a method has been worked out by which Th232 (thorium)A, Th230 (ionium), Th228 (radio thorium), and Th227 (radioactinium) can be deterrained separately. Eight samples of 20 to 40 litres of seawater, from 23 0%" to 3497%|, salinity, were coUected in November 1953, in the Skagerak and the Gullmarfjord (Sweden). Thorium was isolatod by the following procédure: just after collection, the samples were brought to pH 2 and a given amount of Th234 (UX^) was added as tracer. Thorium was first precipitated with Fe(0H)3 as carrier. Further purification was obtained by ionexchange column chromatography followed by solvent extraction; the final fraction was obtained as the citric complex, a form suitable to incorpora tion in the photographie emulsion. The total yield varied from 8 to 23% according to the sample, as determined by the ^activity of the tracer. The varions thorium isotopes were measured through their aactivity, using nuclear photographie emulsions, more precisely the doubleemulsion technique. RdTh and RdAc both generate fivebranched stars; more than 90% of thèse originated from RdTh, as indicated by the length of the tracks: while lo and Th only yield single tracks of range 188 /t and 15 /* respectively in the emulsion. Most samples showed a much lower activity than expected; this did not make it possible to discriminate between lo and Th through the range distribution of their tracks, thus we could only ascertain upper limits of lo and Th concentrations. Average concentrations corresponding to a total volume of 140 litres of water are as foUows (in grams per ml): RdTh = (4 0 ± 14). 10" Th < 2. 10"" RdAc < 7. 10" lo < 6. 10" In one of thèse samples (salinity: 33'7%") we have found an lo concentration of 26. 10"" g/ml. This high value is attributed to a nonhomogeneous distribution of lo in the sea. Before the conclusions are drawn, we must point out the following restriction: (1) Our water samples, including those in the oceanic range of salinity, were not coUected in an oceanic environment, as ail were taken in coastal waters. (2) Our expérimental results should correspond to the total thorium content of the samples. It must be pointed out, however, that a thorium fraction which both would not exchange with UX, at pH 2 and would not eoprecipitate with Fe(0H)3 would remain undetected with our procédure. We assume the following concentration for the other radioactive éléments: U = 15. 10"° g/ml, Ra = 08. 10" g/ml, Th < 6. lOi^ g/ml. The State of radioactive equilibrium between two nuclides A and B shall be defined by their activity ratio : The following conclusions can be drawn from the above data: (1) iîIo/U238 < 002. More than 98% of the lo resulting from U238 disintegration in the océan cannot be accounted for. This lack of lo in the seawater must be correlated with the présence of unsupported lo in the deepsea sédiments. Thèse two corroborating facts definitely prove the hj^jothesis of ionium précipitation with ...
During work on the uptake of phosphate ions by clays and other minerals in sea water, using such low concentrations as bctwcen 30 and 2,000 mg P/m", the phosphate adsorption on a variety of plastics and glass had to bc cxamincd.It was found that at the pH-range between 7.5 and 8 a considerable uptake of phosphate ions takes place.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.