Oxidation states of plutonium in carbonate-rich natural H20

Oxidation states of plutonium in carbonate-rich natural waters

D.M. Nelson∗, K.A. Orlandini, W.R. Penrose

Argonne National Laboratory, Center for Environmental Research, Argonne, Illinois 60439, USA



Abstract

Adsorption of actinide elements to calcium carbonate in waters of moderate to high carbonate concentration has been shown to be dependent on the oxidation state. This property has been exploited for distinguishing the (III) and (IV) oxidation states of plutonium. Ambient plutonium in Mono Lake, California, a natural high-carbonate water, appeared to be entirely in the (IV) oxidation state. Tracer experiments in carbonate media and in Mono Lake water, in the presence of atmospheric oxygen, confirmed that Pu(III) is rapidly oxidized under these conditions.



www.sciencedirect.com/science/article/pii/0265931X8990043X





Journal of Radioanalytical and Nuclear Chemistry

June 2003, Volume 256, Issue 3, pp 445-449

Radiation effects in plutonium and carbonate co-doped calcium hydroxy apatite: An EPR study

V. Natarajan, T. K. Seshagiri, R. Veeraraghavan, M. D. Sastry



Abstract

Electron paramagnetic resonance studies were conducted on synthetic calcium hydroxy apatite samples co-doped with 239Pu and carbonate ion. These investigations were carried out to assess the self-irradiation effects in bone and teeth on exposure to plutonium, as calcium hydroxy apatite is the major constituent of bone and teeth. On self-irradiation, in addition to the signal from O- ion arising from the radiolysis of hydroxide ion, EPR signals due to CO2 -, PO2 2- and another signal assigned to surface O- ions were observed in the samples. In freshly quenched gamma irradiated samples, signals from CO3 -, O- , PO2 2- and O2 - ions were observed. The EPR signal of O2 - ion shows a doublet splitting suggesting that O2 - ion gets preferentially stabilized close to Pu4+. The radiation damage due to Pu4+ at Ca2+ sites, in the sample appears to be lower as compared to that due to external gamma-irradiation. Moreover, the alpha-dose in 239Pu doped samples has self-annealing effects. These are attributed to localized radiation damage due to alpha-particles compared to evenly distributed radical ions produced due to gamma-irradiation.



link.springer.com/article/10.1023%2FA%3A1024591414217





The Isotopic Signature of Fallout

North Pacific

Ken 0. Buesseler

Plutonium in the

Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA

(Received 27 June 1996; accepted 15 August 1996)



Weimer & Langford, 1978). These particles

result from the vaporization and subsequent condensation of nuclear

weapons materials without any interaction with the earth’s surface.

+

All data are from this study and can be found in Table 2. 78 K. 0. Buesseler

Weimer and Langford (1978) found that 30-97% of the 55Fe activity of

a stratospheric fallout aerosol sample was released to solution upon 24-

h contact with seawater.

With surface-based testing on a coral atoll such as Bikini or Enewetak,

the particles carrying fallout Pu would be quite different. Such a blast will

incorporate large quantities of partially and completely vaporized

calcium, carbonates, calcium oxides and calcium hydroxides which are

generated from the coral matrixes (Adams et al., 1960). Upon hydration

of the calcium oxides to calcium hydroxides, the fallout particles swell and

develop into what is described as a ‘crumbly, fluffy structure’ (Adams et

al., 1960). Upon interaction with seawater, there is a partial solubilization

of the calcium hydroxide-based fallout particles. This is accompanied by

the release of hydroxyl ions and the interaction with magnesium ions in

seawater to form a shell of insoluble magnesium hydroxide on the fallout

particle.

The physical/chemical form of tropospheric fallout particles from the

Pacific Proving Grounds is therefore quite different than that of global

stratospheric fallout in general. The enhanced isotopic ratios in the deep

waters and sediments of the NW Pacific suggest that the Pacific Proving

Grounds fallout is more rapidly removed from the surface waters than is

global fallout. This is consistent with sediment and water column 239,240Pu

inventory data that suggest that the percentage of Pu in the sediments out

of the total sediment and water column inventory is largest at the stations

that are closest to the Marshall Islands (Bowen et al., 1980, and unpub-

lished results; Nagaya & Nakamura, 1984).

More extensive Pu isotopic studies in the Atlantic have now demon-

strated that a geochemical separation can occur in the ocean between

Pu from different sources. In the North Atlantic, it has been shown

(Buesseler, 1986; Buesseler & Sholkovitz, 1987a) that silicate-based

fallout debris from surface-based testing on soils at the Nevada Test

Site is more efficiently removed from the surface ocean to deep ocean

sediments than is global fallout Pu. The Nevada Test Site fallout is a

very small fraction of the total Pu inventory in the Atlantic (< 1 O/o),

and hence it is only detected in the deep ocean sediments where it is

enriched relative to global fallout. The Nevada fallout has an average

240Pu/239Pu ratio of 0.035 (Hicks & Barr, 1984; Buesseler, 1986), and in

the North Atlantic (Buesseler, 1986; Buesseler & Sholkovitz, 1987a) and

Gulf of Mexico (Scott et al., 1983) the sediment 240Pu/239Pu ratios

decrease with increasing water depth as the percentage of Nevada fall-

out in the sediment increases.

Silicate-based tropospheric fallout particles from Nevada are not iden-

tical to the calcium carbonate-based Marshall Islands fallout particles, but The isotopic signature of fallout plutonium 79

both are apparently more efficiently removed from the surface waters than

Pu from global fallout sources. In a more recent study, similar principles

of a geochemical fractionation of fallout Pu from different sources have

been applied to account for anomalously low 240Pu/239Pu ratios in a core

off Novava Zemlya (Smith et al., 1995). In this study, a single underwater

test is identified as being the most likely source of local fallout Pu that had

preferentially accumulated in a marine core.

In general, it now appears that global fallout Pu behaves as a rather

soluble tracer in the ocean (< l-6% particulate in sub-surface waters;

Cochran et al., 1987; Livingston et al., 1987). While some fraction of fall-

out Pu is rapidly removed from the surface ocean and accumulates in

marine sediments, the bulk of the stratospheric fallout Pu remains in

solution with a much longer residence time (> 10-100 years). Pacific

Proving Grounds fallout represents a large fraction of the total magnitude

of Pu inputs to the North Pacific. Fallout Pu from this source is prefer-

entially removed from the water column, and hence its influence on the Pu

distribution will be considerable in this basin.



cafethorium.whoi.edu/website/publications/Buesseler%20fallout%20plutonium.pdf





Study on plutonium distribution between sequentially extracted

phases of arable soils





A. Komosa, J. Orzel, S. Michalik



Department of Radiochemistry and Colloid Chemistry, Maria Curie-Sklodowska

University, Lublin, Poland



A. Komosa et al.

4

Because of different origin of reference material samples, thereby large differences in chemical

composition, plutonium distribution between extracted geochemical phases varied in all three cases.

However, it was found that the largest amount of 239+240Pu was associated with organic and carbonate

phases extracted. Relatively small amount of plutonium was bound with Fe/Mn oxide phase.

Reference material IAEA-384 consists of almost pure calcium carbonate, but plutonium was still

bound with organic phase in 40%. It suggests that acetic buffer did not remove all carbonate material

from the sample. There is also possible a cross contamination among extracted phases.



curem.iaea.org/envrad2007/content/rsrc/Envrad2007/114P/114P-Komosa-S1formatted.pdf

Routes of plutonium uptake and their relation to biomagnification in starfish

Jean-Claude Guary∗, ‡, Scott W Fowler, Thomas M Beasley†

a International Laboratory of Marine Radioactivity, IAEA, Musée Océanographique, Monaco1

b School of Oceanography, Oregon State University, Marine Science Center, Newport, OR 97365, USA



Abstract

The distribution of 239 + 240Pu and 238Pu in environmental samples of starfish tissues is identical to the tissue distribution observed in experimental animals following uptake of plutonium directly from water. Plutonium in seawater has a strong affinity for the mucus-rich epidermal layer of starfish which contributes substantially to the relatively high levels of this transuranium nuclide measured in these invertebrates. Transfer of plutonium to starfish via food also occurs; however, the resultant tissue distribution is not consistent with that found in the natural environment where plutonium is available from both contaminated food and water. These data suggest that food chain biomagnification of plutonium by starfish does not occur in nature as has been previously hypothesized.



www.sciencedirect.com/science/article/pii/0025326X82902016



Common starfish - Asterias rubens



Explanation of sensitivity and recoverability ranks for Asterias rubens



Physical Factors



emara et al., (1997) found that heavy metals are selectively distributed among body components of Asterias rubens: Hg concentrations were significantly higher in the pyloric caeca (0.15 µmg Hg g-1 dry weight) and the gonads (0.12 µmg Hg g-1); Zn, Cd, Fe and Cu were high in the pyloric caeca, whilst Pb was significantly more concentrated in the skeleton (8.73 µmg Pb g-1 dry weight). The affinity of Pb for calcite is high and Pb is readily adsorbed to the skeleton of echinoderms. In starfish toxic effects of Pb could come directly from its incorporation into the skeleton or could influence other metabolic pathways and exert an indirect deleterious effect on the species (Temara, et al., 1997). For instance, Pb adsorption occurs actively on the growing parts of the skeleton, where it could reduce skeletogenesis as Pb is one of the most effective inhibitors of calcite dissolution/precipitation kinetics (Morse, 1986)(Siebert 1987)



Heavy metals have also been reported to effect gametogenesis and early larval development in the starfish Asterias rubens. For example, Besten et al., (1991) examined the effects of cadmium on the gametogenesis in females of Asteria rubens, after short term exposure (5 weeks) to 200 µmg Cd l-1 and long term (7 months) exposure to 25 µmg Cd l-1 under semi-natural conditions. It became evident that a short term exposure to 200 µmg Cd l-1 affected gametogensis by reducing ovary growth. The early phase of gametogenesis was also found to be more susceptible to Cd exposure as experiments starting in February has less effect on ovary growth than those commencing in December. The long term exposure of female Asterias rubens to 25 µmg Cd l-1 caused a delay in ovary growth which was evident after 5 months. The oocytes from cadmium exposed females have also been shown to produce defective offspring (Besten, et al., 1989). The aberrations were shown to occur at relatively low exposure levels, and the Cd concentrations found within the body of experimentally (long term) exposed Asterias rubens could also be found within specimens fed with mussels from polluted sites, such as the Dutch Western Scheldt. Consequently, Besten, et al., (1991) concluded that cadmium pollution poses a considerable threat to populations of Asterias rubens in terms of recruitment success.

LC50concentrations exceeding 0.1 mg Cu l-1, 1 mg Zn l-1 and 10 mg Cr l-1 for a duration between 4 -14 days of exposure have been reported for echinoderm species (Table 5.12, Crompton, 1997).



Hydrocarbon contamination

Asterias rubens is intolerant of hydrocarbon pollution:

Bokn et al., (1993) examined of the long term effects of the water-accommodated fraction (WAF) of diesel oil on rocky shore populations. Two doses (average hydrocarbon concentration in diesel oil equivalents; High: = 129.4 µmg l-1, and Low = 30.1 µmg l-1) of WAF of diesel oil were delivered via sea water to established rocky shore mesocosms over a two year period. The numbers of Asterias rubens decreased at all tidal levels (even in the control mesocosms during the study) and Asterias rubens disappeared entirely from upper sublittoral samples in the mesocosm receiving a high dose of WAF diesel oil suggesting a negative effect upon this species caused by the high dose treatment.



Crude oil from the Torrey Canyon in 1967 off Land's End of Cornwall, and the detergent used to disperse it caused mass mortalities of echinoderms; Asterias rubens, Echinocardium cordatum, Psammechinus miliaris, Echinus esculentus, Marthasterias glacialis and Acrocnida brachiata (Smith, 1968). However, Asterias rubens was found to be fairly resistant to the oil dispersant used, BP1002. A concentration of BP1002 at 25 ppm was required in toxicity tests to kill 50% of Asterias rubens within 24 hours (Smith, 1968).



Plutonium in seawater has a strong affinity for the mucus-rich epidermal layer of starfish which contributes to the relatively high levels of this radionuclide measured in these invertebrates. Guary et al., (1982) measured the body burden of 239Pu 240Pu and 238Pu and found 94.5% and 95.6% respectively of the total body burden in the body wall of Asterias rubens. It became apparent that in the environment the water pathway predominates in the uptake of radionuclides by asteroids as the body wall is in constant contact with the transferring medium. However, there is insufficient information on the biological effects of radionuclides to comment further on the intolerance of this species to radionuclide contamination.

Changes in nutrient levels

A population of Asterias rubens may benefit indirectly from an increased nutrient availability because major food items such as mussels filter feed upon phytoplankton and increase in abundance following nutrient enrichment. In combination with other factors an aggregation of feeding starfish may result (see adult distribution). However, an excess of nutrients (eutrophication) facilitating a high pelagic production, in combination with thermal stratification of the water column during summer is likely to cause hypoxia and starfish mortality (see oxygenation) (Josefson & Rosenberg, 1988; Rosenberg & Loo, 1988, Rosenberg et al., 1992). Extensive mortality of benthic populations including Asterias rubens was reported by Bokn et al., (1990) in response to hypoxic conditions caused by a toxic algal bloom of Chrysochromulina polylepsis along the Norwegian coast. However, these adverse effects are indirect and are only likely to occur in extreme situations. Intolerance directly to increased nutrient levels is assessed as low.

Echinoderms are stenohaline owing to the lack of an excretory organ and a poor ability to osmo- and ion-regulate. The inability of echinoderms to osmoregulate extracellularly causes body fluid volume to increase or decrease when individuals are transferred to lower or higher external salinity respectively, e.g. a sudden inflow of river water into an inshore coastal area caused mass mortality of the conspecific species Asterias vulgaris at Prince Edward Island, Canada (Smith, 1940, in Lawrence, 1995).

Decrease in salinity



Changes in oxygenation

Asterias rubens is an aerobic organism and oxygen uptake is by the tube feet and across the body wall. Hypoxic conditions can occur within the habitat of Asterias rubens owing to current changes, thermal stratification of the overlying water column and eutrophication. Theede et al., (1969) undertook experiments on the survival capacity of marine bottom invertebrates in oxygen deficient and hydrogen sulphide (H2S) containing seawater at 10°C. The duration of exposure survived by 50% of Asterias rubens exposed to oxygen deficient seawater (0.15 ml O2l-1 = 0.2 mg 02l-1) was 84 hours. In the presence of H2S (50 mg Na2S.9H2O L-1) the resistance of Asterias rubens to oxygen deficient water dropped to 67 hours, thus it is likely that this species would not survive a week of hypoxic conditions.



www.marlin.ac.uk/speciesbenchmarks.php?speciesID=2657