Global distribution of Pu isotopes and 237Np

Kelley, James M.; Bond, L.A.; Beasley, T.M.

doi:10.1016/s0048-9697(99)00160-6

Cited by 470 publications

(383 citation statements)

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“…Furthermore, these values are in good agreement with the reported 240 Pu/ 239 Pu in southern Equatorial (0-30°S) fallout reported by Kelley et al (1999), who determined an average 240 Pu/ 239 Pu atomic ratio of 0.173 ± 0.027. The detected plutonium ratio is directly related to anthropogenic introduction to the environment through nuclear bomb testing in the 1950s (Ketterer and Szechenyi, 2008).…”

Section: Discussionsupporting

confidence: 91%

“…The 240+239 Pu results are consistent with the 240 Pu/ 239 Pu of 0.180 ± 0.014 discussed by Kelley et al (1999), indicating that the source is from Cold War era above-ground nuclear tests deposited globally from the Table 1 (Abril, 2003;Alhajji et al, 2014). Furthermore, these values are in good agreement with the reported 240 Pu/ 239 Pu in southern Equatorial (0-30°S) fallout reported by Kelley et al (1999), who determined an average 240 Pu/ 239 Pu atomic ratio of 0.173 ± 0.027.…”

Section: Discussionsupporting

confidence: 89%

“…For instance, 240 Pu/ 239 Pu atomic ratios from global fallout (~0.18) differ from well-known 240 Pu/ 239 Pu atomic ratios from events such as Fukushima (0.30-0.33) (Zheng et al, 2012) and Chernobyl (~0.43) (Ketterer et al, 2004b). These distinct ratios may be useful for separating phases of sediment deposition because the nuclear accidents and testing dates are well known (Kelley et al, 1999).…”

Section: Introductionmentioning

confidence: 97%

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<sup>240+239</sup>Pu depositional signatures as a viable geochronological tool in the Amazon Basin

et al. 2017

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Anthropogenic radionuclide signatures associated with nuclear testing are increasingly utilized in environmental science to explore recent sedimentation. In this study, we assess the suitability of Pu radioisotope analysis in floodplain lake environments in the Amazon Basin to form geochronologies during the 20 th century. The 240 Pu + 239 Pu ( 240+239 Pu) signatures in six sediment cores indicate sediment accumulation rates in the floodplain lakes of the major rivers; Amazon (2.3 mm year -1 ), Tapajos (10.2 and 2.4 mm year -1 ) and Madeira (3.4, 4.2 and 6.2 mm year -1 ). The results from this study show that 240+239 Pu fallout activities, and the well documented ( 240 Pu/ 239 Pu) atomic ratios of the above ground nuclear tests which began in the 1950's, are sufficient and well preserved in Amazon floodplain lake sediments to infer chronologies. Lead-210 dating analyses in the same sediment cores produced comparable sediment accumulation rates at three of the six sites. The differences between dating methods may be attributed to the different time scale these dating methods represent and/or in the solubility between Pb and Pu along the sediment column. The geochronologies derived from the 240+239 Pu and 210 Pb dating methods outlined in this work are of interest to identify the effects of changing sediment accumulation rates during the previous century as a result of development, including deforestation, along the Amazon Basin which increased towards the middle of the 20 th century. This study shows that Pu dating provides a viable alternative geochronology tool for recent sediment accumulation (previous ~60 years) along the Amazon Basin.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 97%

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<sup>240+239</sup>Pu depositional signatures as a viable geochronological tool in the Amazon Basin

et al. 2017

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“…Among the 9 reactors in operation at Hanford Site, this was the only dual purpose, multi-pass water cooled reactor, and it was designed to supply steam for the production of electricity as a by-product (Garrett and Williams, 1997 analytically challenging to measure at these low levels (10 4 -10 6 atoms), and is rarely reported for environmental samples. Global fallout atom ratios of 241 Pu/ 239 Pu in the Northern hemisphere average 0.00194 (Kelley et al, 1999). In the wells where we had …”

Section: Isotopic Ratios and Source Provenancementioning

confidence: 88%

“…However, when averaged over all the weapons tests, the global integrated fallout 240 Pu/ 239 Pu atom ratio in environmental samples is about 0.18 (Kelley et al, 1999;Krey et al, 1976). These isotopic signatures have been successfully used to trace the specific Pu source such as global weapons testing fallout, debris from specific test series or Pu from reprocessing or a local reactor discharge in differing hydro-geochemical regime (Beasley et al, 1981;Buesseler, 1997;Buesseler and Sholkovitz, 1987;Cooper et al, 2000;Dresel et al, 2002;Perkins and Thomas, 1980;Taylor et al, 2001;Warneke et al, 2002) In this study, we have measured 240 Pu/ 239 Pu ratios ranging from <0.04 to >0.15 in the K-Basin groundwater and 0.18 in the Columbia River downstream of the 100K-Area (Figure 5a).…”

Section: Isotopic Ratios and Source Provenancementioning

confidence: 99%

Plutonium in groundwater at the 100K-Area of the U.S. DOE Hanford Site

Dai

Buesseler

Pike

2005

Journal of Contaminant Hydrology

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We examined the concentration, size distribution, redox state and isotopic composition of plutonium (Pu) in groundwater at the 100K-Area at the US Department of Energy's (DOE) Hanford Site. Total concentrations of Pu isotopes were extremely low (10 -4 to 10 -6 pCi/kg, ≈ 10 4 to 10 6 atoms/kg), but measurable for the first time in the 100K-Area wells using mass spectrometric analyses that are much more sensitive than alpha spectroscopy methods used previously. Size fractionation data from two wells suggests that 7-29% of the Pu is associated with colloids, operationally defined here as particles between 1 kDa -0.2 µm in size. These colloids were collected using a 1 kDa cross-flow ultrafiltration system developed specifically for groundwater actinide studies to include careful controls both in the field and during processing to ensure in-situ geochemical conditions are maintained and size separations can be well characterized. Pu in this colloidal fraction was exclusively in the more reduced Pu(III/IV) form, consistent with the higher affinity of Pu for particle surfaces in the lower oxidation states. While the overall concentrations of Pu were low, the Pu isotopic composition suggests at least two local sources of groundwater Pu, namely local Hanford reactor operations at the 100K-Area, and spent nuclear fuel from the N reactor, which was stored in concrete pools at this site.Differences between this site and the Savannah River Site (SRS) are noted, since groundwater Pu at the F-Area seepage basin at SRS has been found using these same 2 methods, to be characterized by much lower colloidal abundances and higher oxidation states. This difference is not directly attributable to groundwater redox potential or geochemical conditions, but rather the physical-chemical difference in Pu sources, which at SRS appear to be dominated downstream from the seepage basins by decay of 244 Cm, resulting in more oxidized forms of 240 Pu. There is no clear evidence for colloid facilitated transport of Pu in groundwater at this site, since downstream wells have both an order of magnitude lower concentrations of Pu, but also a lower fractional colloidal distribution.

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Neptunium: Radionuclides

Runde¹,

Goff²

2005

Encyclopedia of Inorganic Chemistry

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Following the element uranium, neptunium is the fourth element in the actinide series. Although primordial neptunium isotopes formed during the creation of the solar system billions of years ago have long since decayed away, neptunium continues to be formed by the nuclear reactions in naturally occurring uranium deposits. Currently, trace amounts of neptunium isotopes can be isolated from uranium ore minerals. Most of present‐day inventory of neptunium originates from human activities, such as nuclear weapons testing, nuclear accidents, or irradiation of uranium fuel for producing nuclear energy. All neptunium isotopes are highly radioactive and pose extreme health hazards to humans when ingested or inhaled. Neptunium exhibits five oxidation states (III–VII) in solution and solid state, but only the IV and V oxidation states are relevant under most environmental conditions. In the +IV state, neptunium is insoluble and forms stable complexes with ligands abundant in natural environments (such as hydroxide, carbonate, or humic substances), and can adsorb onto mobile colloidal matter. In contrast, neptunium(V) forms a soluble dioxo‐cation in solution (NpO $_{2}^{+}$ ), which exhibits an increased solubility, weaker complex formation, and higher stability in the aqueous phases of aquatic systems. Thus, neptunium(V) is mostly characterized as the dominant solution species, while Np(IV) is found to be adsorbed on sediments, minerals, and colloidal particles. There is no large‐scale use of neptunium in industrial applications.

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Global distribution of Pu isotopes and 237Np

Cited by 470 publications

References 9 publications

<sup>240+239</sup>Pu depositional signatures as a viable geochronological tool in the Amazon Basin

<sup>240+239</sup>Pu depositional signatures as a viable geochronological tool in the Amazon Basin

Plutonium in groundwater at the 100K-Area of the U.S. DOE Hanford Site

Neptunium: Radionuclides

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