Seawater transuranic elements

Livingston, H.D., Mann, D.R. and Bowen, V.T., Analytical procedures for transuranic elements in seawater and marine sediments. In Analytical Methods in Oceanography, Advances in Chemistry Series 147. American Chemical Society, 1975. 

Analytical Procedures for Transuranic Elements in Seawater and Marine Sediments... 

Transuranic elements are extracted from seawater by coprecipitation with either ferric hydroxide or calcium/strontium oxalate or are leached from sediments with 8M nitric acid. Radiochemical separations are used to aruilyze PUy... 

Most of the procedures for analysis of transuranic nuclides in seawater and marine sediments have been described in detail elsewhere both by our laboratory and those of other workers. A full discussion of these various procedures is found in a comprehensive state-of-the-art review of techniques proposed for the analyses of transuranic elements in the marine environment (4). Here we concentrate on the procedures used at the Woods Hole Oceanographic Institution, the problems encoim-tered, and what is being learned from the data. 

A full account of the problems considered in collecting, storing, and processing marine samples for transuranic analysis is given in the above-mentioned review (4). The specific methods discussed here were foimd effective at least for the transuranic analyses of seawater and sediments contaminated by global fallout, nuclear fuel reprocessing wastes, or nuclear power plant operation waste. In these cases, a preliminary acid treatment of the sample in the presence of suitable yield monitors seems to solubilize the transuranic elements and achieves isotopic equilibration between the yield monitor and sample. The yield monitors used were either Pu or sep qj. 238,239,240,24ip whereas Am was used for Am, 2 Cm, and by inference, Cf. In addition, it was convenient to use 50 mg of a lanthanide (neodymium) as a carrier for americium to purify the separated americium fraction. 

The extraction of transuranic elements has been made by co-precipi-tation in several ways (5,6). We use either one of two methods, depending on what other nuclides are also sought in the sample. The first method is co-precipitation with 0.5-1.0 g iron as hydroxide at pH 9-10 using ammonium hydroxide while the second method is co-precipitation with calcium and strontium oxalate at pH 5-6 using oxalic acid. There are about 22 g calcium and 0.44 g strontium in 55 1. of open-ocean seawater. Because Sr is usually measured in the same seawater sample, we normally add 2 g strontium to that which is naturally present. 

The transuranic elements extracted from seawater or sediments are further purified such that ... 

The International Atomic Energy Agency organized a series of interlaboratory comparisons for calibration purposes. Those completed so far include two seawater, one seaweed Fucus vesiculosus), and one sediment sample. These materials were contaminated in nuclear waste disposal situations and, in consequence, contain transuranic elements in concentrations much higher than those found in samples contaminated by global fallout of nuclear weapons testing debris. Nevertheless, the data speak directly to questions of calibration of detectors and yield... 

Optimize Conditions for the Radiochemical Separation of Plutonium from Large Volume Seawater Samples, in Reference Methods for Marine Radioactivity Studies II. Ruthenium, Silver, Iodine, Zirconium, and the Transuranic Elements, IAEA Tech, Rep, Ser, (1975) 169, 69. 

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