Anthropogenic activities, such as ore mining and processing, nuclear power generation, and weapon tests, have generated depleted U (DU) contamination to soils and waters. The Davy Crockett Weapon System and the armor defeating penetrators contain DU. DU is an effective material to use as a penetrator because of its density and its self-sharpening characteristic. However, DU is a radioactive material and is also a flammable metal. The aerosol produced during impact and combustion of depleted uranium munitions potentially contaminate wide areas around the impact sites or can be inhaled by civilians and military personnel. The mobility, bioavailability, and redistribution of DU are influenced by its sources and speciation, and plants species. Phytoremediation has emerged as an environmentally friendly, cost-effective green technology to remediate radioisotope and heavy metal contaminated soils. The main objectives of this study were to investigate biogeochemistry of DU in Army shooting soils and explore the feasibility using coupled electro-kinetic and phytoremediation in cleaning up DU polluted soils. Especially, Sunflower and Indian mustard were tested in cleaning up soils contaminated with UO2, UO3 and UO2(NO3)2, as well as field DU polluted soil. DU was found to be bioaccumulated in plant roots over plant shoots. U uptake by both plant species was significantly higher from the UO3 and uranyl contaminated soils than from UO2 contaminated soils. UO3 and UO2(NO3)2 contaminated soils showed higher concentrations of exchangeable, weak acid extractable, and liable U than the UO2 contaminated soils. After a growing season, these three U forms decreased as redistribution/transformation of U resulted in U species with lower extractability.. Overall U removal efficiency after one growing season reached 3.5% in the UO3 polluted soil with Indian mustard, followed by uranyl and least in UO2 polluted soils. Effects of electrokinetic treatment on efficiency of phytoremediation of DU will be discussed as well. This study indicates the importance of U speciation in soil with regards to the potential use of Sunflower and Indian Mustard for phytoremediation of U contaminated soils.

Biogeochemistry of depleted uranium in US army shooting site and potential remediation

2019 Spring National Meeting

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