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	Plutonium in groundwater at the 100K-Area of the US DOE Hanford site
	Dai MH ; Buesseler K ; Pike SM
	2005-02
关键词	plutonium isotopic composition size fractionation redox speciation groundwater Hanford site
英文摘要	We examined the concentration, size distribution, redox state and isotopic composition of plutonium (Pu) in groundwater at the 100K-Area at the U.S. Department of Energy's (DOE) Hanford Site. Total concentrations of Pu isotopes were extremely low (10(-4) to 10(-6) pCi/kg, approximate to 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 suggest that 7-29% of the Pu is associated with colloids, operationally defined here as particles between 1 kDa-0.2 mum in size. These colloids were collected using a 1 kDa cross-flow ultrafiltration (CFF) 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 Pit in the lower oxidation states for particle surfaces. While the overall concentrations of Pu were low, the Pit 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 Pit at the F-Area seepage basin at SRS has been found using these same methods, to be characterized by 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 Cm-244, resulting in more oxidized forms of Pu-240. There is no clear evidence for colloid facilitated transport of Pu in groundwater at the Hanford Site, since downstream wells have both an order of magnitude lower concentrations of Pu and a lower fractional colloidal distribution. (C) 2004 Elsevier B.V. All rights reserved.
语种	英语
出版者	ELSEVIER SCIENCE BV, PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS
内容类型	期刊论文
源URL	[http://dspace.xmu.edu.cn/handle/2288/1353]
专题	海洋环境－已发表论文
推荐引用方式 GB/T 7714	Dai MH,Buesseler K,Pike SM. Plutonium in groundwater at the 100K-Area of the US DOE Hanford site[J],2005.
APA	Dai MH,Buesseler K,&Pike SM.(2005).Plutonium in groundwater at the 100K-Area of the US DOE Hanford site..
MLA	Dai MH,et al."Plutonium in groundwater at the 100K-Area of the US DOE Hanford site".(2005).

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