Products of in Situ Corrosion of Depleted Uranium Ammunition in Bosnia and Herzegovina Soils

Abstract

Hundreds of tons of depleted uranium (DU) ammunition were used in previous armed conflicts in Iraq, Bosnia and Herzegovina, and Serbia/Kosovo. The majority (>90%) of DU penetrators miss their target and, if left in the environment, corrode in these postconflict zones. Thus, the best way to understand the fate of bulk DU material in the environment is to characterize the corrosion products of intact DU penetrators under field conditions for extended periods of time. However, such studies are scarce. To fill this knowledge gap, we characterized corrosion products formed from two intact DU penetrators that remained in soils in Bosnia and Herzegovina for over seven years. We used a combination of X-ray powder diffraction, electron microscopy, and X-ray absorption spectroscopy. The results show that metaschoepite (UO 3 (H 2 O) 2 ) was a main component of the two DU corrosion products. Moreover, studtite ((UO 2 )O 2 (H 2 O) 2 ·2(H 2 O)) and becquerelite (Ca(UO 2 ) 6 O 4 (OH) 6 ·8(H 2 O)) were also identified in the corrosion products. Their formation through transformation of metaschoepite was a result of the geochemical conditions under which the penetrators corroded. Moreover, we propose that the transformation of metaschoepite to becquerelite or studtite in the DU corrosion products would decrease the potential for mobilization of U from corroded DU penetrators exposed to similar environments in postconflict areas.

Stabilization Effects of Mn(II)-Salts on Metaschoepite in Soil under Different Water Regimes

“…The transformation of U(VI) minerals in DUcorroded products would increase the overall solubility of uranium in the soil. 8,29 The XPS U(4f) spectra of metaschoepite-amended soils are shown in Figure 4. The U4f7/2 spectrum consists of two components with binding energy levels of approximately 381.3 and 382.0 eV, both annotated as U(VI) in the metaschoepiteamended soil (M treatment) of the flooding group (Figure 4b).…”

“…The metallic form of DU is prone to oxidation and will corrode over time in natural systems. The oxidation, dissolution, and recrystallization processes that can occur during the weathering of DU penetrators and penetrator fragments can result in the formation of soluble and crystalline phases such as schoepite (UO 3 ·2.25H 2 O), dehydrated schoepite (UO 3 ·0.75H 2 O), and metaschoepite (UO 3 ·2H 2 O) along with more complex minerals such as becquerelite and studtite. − A site study in the southwestern U.S. described residues around corroded DU penetrators as silica-cemented, mixed schoepite–metaschoepite/clay/silt aggregates, as schoepite/metaschoepite-only aggregates, or rarely as coatings upon soil grains . A more recent study showed UO 2.8 and UO 3 to be present in the DU metallic fragment/soil systems in saturated soil regimes .…”

“…The corrosion or dissolution of DU occurs when the U­(IV) oxidation products of the zero-valent U metal further undergo oxidization of U­(IV) oxide to U­(V) minerals . The corrosion processes of DU penetrators have been shown to depend on soil biogeochemical conditions such as pH, Eh, soil chemical composition, and water moisture conditions. ,, The U­(V) solid phases in the schoepite family (UO 3 · n H 2 O) represent possible sources of more mobile uranium species in the dissolved or colloidal state . A recent field study indicated that schoepites (UO 3 · n H 2 O) were present as the major uranium-containing mineral family at the Yuma Proving Weapon Testing sites …”

Recent advances in analysis of trace elements in environmental samples by X-ray based techniques (IUPAC Technical Report)

“…The radioactive mutagenic element uranium has been released into the environment as a result of the mining and milling of U ores and the disposal of its waste products [111], as a result of aboveground nuclear testing, and via the use of depleted uranium (DU) ammunition [112], among other pathways. In a holistic study, Campbell et al [111] combined XANES and EXAFS data with Mössbauer spectroscopy, traditional XRD and XRF, liquid chemical extractions, and Phospholipid Fatty Acid (PLFA) and DNA analysis to monitor the biotic and abiotic cycling of U in lake sediments.…”

Recent Advances in Analysis of Trace Elements in Environmental Samples by X-Ray Based Techniques (IUPAC Technical Report)

“…The radioactive mutagenic element uranium has been released into the environment as a result of the mining and milling of U ores and the disposal of its waste products [111], as a result of aboveground nuclear testing, and via the use of depleted uranium (DU) ammunition [112], among other pathways. In a holistic study, Campbell et al [111] and XRF, liquid chemical extractions, and Phospholipid Fatty Acid (PLFA) and DNA analysis to monitor the biotic and abiotic cycling of U in lake sediments.…”