title: Depleted uranium mobility across a weapons testing site: isotopic investigation of porewater, earthworms, and soils.
abstract: The mobility and bioavailability of depleted uranium (DU) in soils at a UK Ministry of Defence (UK MoD) weapons testing range were investigated. Soil and vegetation were collected near a test-firing position and at eight points along a transect line extending approximately 200 m down-slope, perpendicular to the firing line, toward a small stream. Earthworms and porewaters were subsequently separated from the soils and both total filtered porewater (<0.2 microm) and discrete size fractions (0.2 microm-100 kDa, 100-30 kDa, 30-3 kDa, and <3 kDa)obtainedvia centrifugal ultrafiltration were examined. Uranium concentrations were determined by inductively coupled plasma optical emission spectrometry (ICP-OES) for soils and ICP-mass spectrometry (MS) for earthworms and porewaters, while 235U:238U atom ratios were determined by multicollector (MC)-ICP-MS. Comparison of the porewater and earthworm isotopic values with those of the soil solids indicated that DU released into the environment during weapons test-firing operations was more labile and more bioavailable than naturally occurring U in the soils at the testing range. Importantly, DU was shown to be present in soil porewater even at a distance of approximately 185 m from the test-firing position and, along the extent of the transect was apparently associated with organic colloids.
authors.affiliation: Scottish Universities Environmental Research Centre, Rankine Avenue, Scottish Enterprise Technology Park, East Kilbride, UK. Ian.Oliver@alumni.adelaide.edu.au
authors.forename: Ian W
authors.initials: IW
authors.lastname: Oliver
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Graham
authors.forename: Angus B
authors.initials: AB
authors.lastname: MacKenzie
authors.forename: Robert M
authors.initials: RM
authors.lastname: Ellam
authors.forename: John G
authors.initials: JG
authors.lastname: Farmer
mesh_terms: D000818:Animals; D004784:Environmental Monitoring; D005843:Geography; D007554:Isotopes; D009835:Oligochaeta / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis; D010316:Particle Size; D010944:Plants / Q000737:chemistry; D016062:Porosity; D012987:Soil; D006113:United Kingdom; D014501:Uranium / Q000032:analysis*; D014867:Water / Q000737:chemistry*; D054041:Weapons
chemical_list: D007554:Isotopes; D009930:Organic Chemicals; D012987:Soil; D014867:Water; D014501:Uranium