Plutonium in groundwater at the 100K-Area of the U.S. DOE Hanford Site
MetadataShow full item record
KeywordPlutonium; Isotopic composition; Size fractionation; Redox speciation; Groundwater; Hanford Site
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 Energys (DOE) Hanford Site. Total concentrations of Pu isotopes were extremely low (10-4 to 10-6 pCi/kg, ≈ 104 to 106 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 244Cm, resulting in more oxidized forms of 240Pu. 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.
Author Posting. © The Authors, 2004. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Contaminant Hydrology 76 (2005): 167-189, doi:10.1016/j.jconhyd.2004.08.004.
Suggested CitationPreprint: Dai, Minhan, Buesseler, Ken O., Pike, Steven M., "Plutonium in groundwater at the 100K-Area of the U.S. DOE Hanford Site", 2004-01-27, https://doi.org/10.1016/j.jconhyd.2004.08.004, https://hdl.handle.net/1912/907
Showing items related by title, author, creator and subject.
The distribution and history of nuclear weapons related contamination in sediments from the Ob River, Siberia as determined by isotopic ratios of Plutonium, Neptunium, and Cesium Kenna, Timothy C. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2002-02)This thesis addresses the sources and transport of nuclear weapons related contamination in the Ob River region, Siberia. In addition to being one of the largest rivers flowing into the Arctic Ocean, the bulk of the ...
Buesseler, Ken O. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1986-09)The artificial radionuclide Plutonium (Pu) has been introduced into the environment primarily as fallout from atmospheric nuclear weapons testing during the 1950's and 1960's. Earlier studies of Pu geochemistry are ...
Panteleyev, George P. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1995-05)Much of the nuclear activity of the former Soviet Union took place within or adjacent to the confines of the Ob River drainage basin. These activities include weapons production and reprocessing at Chelyabinsk-65 (also ...