Uranium:Current Phytoremediation

Methods and Potential Applications

By Dustin Kovac and Monica Long

BZ572 – Phytoremediation – Fall 2010

Uranium and Its Uses

• Uranium is a naturally occurring primordial radionuclide: consisting of four isotopes of mass number 230, 234, 235, and 238

• About 20% of contamination results from anthropogenic sources

• Uses for Uranium include: nuclear weapons, power generation, rate-of-decay dating methods, high-energy X-rays, manufacturing color pigments, guidance systems and more…

Intake of Depleted Uranium

• Inhalation or ingestion– UO3 is a byproduct found to

be most soluble in human fluids and is rapidly absorbed

• Fragments that have been left in the body – ie: shrapnel, stray bullets etc.

• Increased prevalence of deformations since the Gulf War

Adverse Health Effects Child born to parents with

“Gulf War Syndrome”

• The uranyl ion is the form of mobile uranium within the body– deposits itself on the bone,

harboring in the matrix, and being filtered by the kidneys

• Increase in the occurrence of cancer– particularly in stomach,

breast, lung, bronchial, bladder, and skin

Midnight Mine, Washington State

Mines in Respect to National Lands

Population in Uranium Mine Vicinity

Figure 3.1. Uranium Mine Pit LakePit lake of Yazzi-312 surface mine in Cameron, Arizona, referred to by local citizens

as the “swimming hole.” Suspended sediment transformed the pit waterto a milky white color. The pit lake has been reclaimed.

Heavy Metal Levels of Pond in Cunha Baxia, Portugal; 2006 (μg/l)

Lime Treatment• Used for treating acidic waters• Forms a sludge -like precipitate of calcium diuranate and

other heavy metals • Remaining water is then treated to lower the pH and then

discharged• Sludge is disposed ofProblem• The remaining sludge is very difficult to dewater. The

sludge remaining is 2% solids and can be difficult to dispose of.

Current Water Treatment Techniques Used During Mine Reclamation

Lime Treatment• Used for treating acidic waters• Forms a sludge -like precipitate of calcium diuranate and

other heavy metals • Remaining water is then treated to lower the pH and then

discharged• Sludge is disposed ofProblem• The remaining sludge is very difficult to dewater. The

sludge remaining is 2% solids and can be difficult to dispose of.

Barium Chloride Treatment • Adds Barium Chloride to contaminated waters to remove

Radium• Forms a precipitate of radium• 30-60 mg of Barium Chloride per liter will precipitate close

to 100% of radium Problem• The crystal precipitate is very hard to remove from the

water.

Ion Exchange and Absorbtion

• The use of cations and anions to bind with the contaminant.

• Very effective in treating a wide variety of contaminants.

Problem• This technology is not economically viable.

Permeable Reactive Barrier

• Uses a permeable barrier which water can flow through

• Uranium and other contaminants stick to reactive iron, activated carbon, other chemicals and clays

• Found effective fry canyon where 100% of Uranium stuck to the first 1.5 ft of the barrier

Current Costs of Reclamation

Phytoremediation

• In many small scale studies, rhizofiltration has been proven to be a viable technique for removing Uranium and Radium from contaminated water.

• Uranium is transported to plants mainly as uranyl (UO2)2+

– The release of organic acids from the root has been suggested as a general mechanism for metal solubilization from the soil insoluble mineral phase

Popular Species for Remediation

Sunflower (Helianthus annuus L.)

Willow (Salix spp.)

Indian Mustard(Brassica juncea)

Tree Spinach(Chenopodium amaranticolor)

Common Bean(Phaseolus vulgaris L.)

Developments in Genetic Transformations

• Infected hairy root cultures of B. juncea and C. amaranticolor with Agrobacterium Rhizogenes to increase uptake

•Hairy roots took up 90% of Uranium 10 hours into treatment via rhizofiltration

pH Dependency and Citric Acid

• Optimal pH levels found to be between 3-5

• Low dose of citric acid applied to soil caused an increase in phytoextraction and bioaccumulation of uranium in leaves after 5 weeks in willow and sunflower species

Hydroponic Systems to Remediate Polluted Groundwater

• Sunflower seedlings at only 4 weeks are able to remove 70-90% after only 2 days of exposure

• Primarily found Uranium translocated into roots

• Batch experiments allowed time for the plant to develop a tolerance to uranium in groundwater

• Multiple solutions were generated, one with 5 levels of varying concentrations, and another of genuine groundwater

Sunflower (artificial conc.)

Sunflower (actual conc.)

Conclusion• Hairy root cultures from B. juncea

and C. amaranticolor have potential for use in bioreactors

• The use of citric acid in soil improves uptake of Uranium in the leaves of willow and sunflower

• Helianthus annuus L. is very effective in the removal of Uranium and Radium from water via rhizofiltration– Further research and field studies

might prove this to be a very economical reclamation and remediation technique.

• It is very important that more effective reclamation and remediation techniques be developed and used for Uranium mines. Currently these sights are said to be inhabitable for thousands and even millions of years.

Antunes, S., de Figueiredo, D., Marques, S., Castro, B., Pereira, R., & Gonçalves, F. (2007). Evaluation of water column and sediment toxicity from an abandoned uranium mine using a battery of bioassays. Science of the Total Environment, 374(2/3), 252-259. doi:10.1016/j.scitotenv.2006.11.025.

Bult-Ito, Abel. "Nothing depleted about 'depleted uranium'." Global Research.ca. Center for Research on Globalization, 06 Jan 2006. Web. <http://www.globalresearch.ca/index.php?context=va&aid=1777>.

C.W. Francis, M.E. Timpson, J.H. Wilson, Bench- and pilot-scale studies relating to the removal of uranium from uranium-contaminated soils using carbonate and citrate lixiviants, J. Hazard. Mater. 66 (1999) 67–87.

Craft, E., Abu-Qare, A., Flaherty, M., Garofolo, M., Rincavage, H., & Abou-Donia, M. (2004). Depleted and Natural Uranium: Chemistry and Toxicological Effects. Journal of Toxicology & Environmental Health: Part B, 7(4), 297-317. Retrieved from Academic Search Premier database.

Dushenkov, S. (2003). Trends in phytoremediation of radionuclides. Plant & Soil, 249(1), 167-175. Retrieved from Academic Search Premier database.

Eapen, Susan, K Suseelan, Suchita Tivarekar, S Kotwal, and R Mitra. "Potential for rhizofiltration of uranium using hairy root cultures of Brassica juncea and Chenopodium amaranticolor." Environmental Research 91. (2003): 127-133.

E.J.P. Phillips, E.R. Landa, D.R. Lovley, Remediation of uranium contaminated soils with bicarbonate extraction and microbial U(VI) reduction, J. Ind. Microbiol. 14 (1995) 203–207.

Lee, M., & Yang, M. (2010). Rhizofiltration using sunflower (Helianthus annuus L.) and bean (Phaseolus vulgaris L. var. vulgaris) to remediate uranium contaminated groundwater. Journal of Hazardous Materials, 173(1-3), 589-596. doi:10.1016/j.jhazmat.2009.08.127.

Mihalı´k, Jan, Pavel Tlustosˇ, and Jirˇina Szakova. "Comparison of willow and sunflower for uranium phytoextraction induced by citric acid." J Radioanal Nucl. Chem. 285. (2010): 279-285.

N.H. Harley, E.C. Foulkes, L.H. Hilborne, A. Hudson, C.R. Anthony,AReview of the

Scientific Literature as it Pertains to Gulf War Illness, vol. 7, National Defense Research Institute MR-1018/7-OSD, Rand, 1999.

U.S. Environmental Protection Agency. Technical Report on Technologically Enhanced Naturally Occurring Radioactive Materials fromUranium Mining Volume 1 . Washington DC: Office of Radiation and Indoor Air Radiation Protection Division (6608J), 2006.

S. Ebbs, D. Brady, W. Norvell, L. Kochian, Uranium speciation, plant uptakes, and phytoremediation, Pract. Period. Hazard. Toxic. Radioact. Waste Manag. 5 (2001) 130–135.

Sevostianova, E., Lindemann, W., Ulery, A., & Remmenga, M. (2010). Plant Uptake of Depleted Uranium from Manure-Amended and Citrate Treated Soil. International Journal of Phytoremediation, 12(6), 550-561. doi:10.1080/15226510903353153.

Tome, F. Vera, P. Blanco Rodriguez, and J.C Lozano. "Elimination of Natural Uranium and 226Ra from Contaminated Waters by Rhizofiltration using Helianthus annuus L.." Science of the Total Environment. 393. (2008): 351-357

U.S.. Technical Report on Technologically Enhanced Naturally Occurring Radioactive Materials from Uranium Mining Volume 2: Investigation of Potential Health, Geographic, And Environmental Issues of Abandoned Uranium Mines. Washington D.C.: Office of Radiation and Indoor Air Radiation Protection Division (6608J), 2007. Print.