Graham, M.C., Oliver, I.W., MacKenzie, A.B., Ellam, R.M. and Farmer, J.G. (2011) Mechanisms controlling lateral and vertical porewater migration of depleted uranium (DU) at two UK weapons testing sites. Science of the Total Environment, 409(10), pp. 1854-1866. (doi: 10.1016/j.scitotenv.2011.01.011)
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Abstract
<p>Uranium associations with colloidal and truly dissolved soil porewater components from two Ministry of Defence Firing Ranges in the UK were investigated. Porewater samples from 2-cm depth intervals for three soil cores from each of the Dundrennan and Eskmeals ranges were fractionated using centrifugal ultrafiltration (UF) and gel electrophoresis (GE). Soil porewaters from a transect running downslope from the Dundrennan firing area towards a stream (Dunrod Burn) were examined similarly. Uranium concentrations and isotopic composition were determined using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Multi-Collector-Inductively Coupled Plasma-Mass Spectrometry (MC-ICP-MS), respectively.</p> <p>The soils at Dundrennan were Fe- and Al-rich clay–loam soils whilst at Eskmeals, they were Fe- and Al-poor sandy soils; both, however, had similar organic matter contents due to the presence of a near-surface peaty layer at Eskmeals. These compositional features influenced the porewater composition and indeed the associations of U (and DU). In general, at Dundrennan, U was split between large (100 kDa–0.2 μm) and small (3–30 kDa) organic colloids whilst at Eskmeals, U was mainly in the small colloidal and truly dissolved fractions. Especially below 10 cm depth, association with large Fe/Al/organic colloids was considered to be a precursor to the removal of U from the Dundrennan porewaters to the solid phase. In contrast, the association of U with small organic colloids was largely responsible for inhibiting attenuation in the Eskmeals soils.</p> <p>Lateral migration of U (and DU) through near-surface Dundrennan soils will involve both large and small colloids but, at depth, transport of the smaller amounts of U remaining in the porewaters may involve large colloids only. For one of the Dundrennan cores the importance of redox-related processes for the re-mobilisation of DU was also indicated as MnIV reduction resulted in the release of both MnII and UVI into the truly dissolved phase.</p>
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Ellam, Professor Rob and MacKenzie, Professor Angus |
Authors: | Graham, M.C., Oliver, I.W., MacKenzie, A.B., Ellam, R.M., and Farmer, J.G. |
College/School: | College of Science and Engineering > Scottish Universities Environmental Research Centre |
Journal Name: | Science of the Total Environment |
ISSN: | 0048-9697 |
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