Project Title: Environmental Mobility and Bioaccessibility of Tellurium
Mendenhall Fellow: Sarah Hayes, (650) 329-5449, email@example.com
Duty Station: Menlo Park, CA
Start Date: October 12, 2010
Education: Ph.D., 2010, Soil and Water Science, University of Arizona
Research Advisors: Andrea Foster, (650) 329-5437, firstname.lastname@example.org; Laurie Balistrieri, (206) 543-8966, email@example.com; Jim Rytuba, (650) 329-5418, firstname.lastname@example.org; Lisa Stillings, (775) 784-5803, email@example.com; Larry Miller (650) 329-4475, firstname.lastname@example.org; Scott Wood (University of Idaho), (208) 885-5966, email@example.com
Project Description: Technological advances and development of alternative energy sources have resulted in increased demand for scarce, technologically important metals (STIM); in particular, lithium (Li), indium (In), tellurium (Te), and gallium (Ga). However, little is understood of the geochemical controls responsible for mobility and release of many STIM in the environment. Addressing this knowledge gap is critical for understanding the environmental and health implications of increased extraction and widespread dispersion of these elements.
As part of a current U.S. Geological Survey effort that is seeking to improve understanding of the environmental and human health impact resulting from increasing use of STIM, this research is focused specifically on the lifecycle (extraction, manufacture, use, disposal, and recycling) of Te. The relatively recent development of high efficiency cadmium telluride (CdTe) solar panels is expected to increase the industrial demand for Te and will likely be accompanied by geographic redistribution of Te to population centers. This demand and other uses of Te in high technology devices highlight the necessity of studies focusing on Te behavior and toxicity under environmentally and biologically relevant conditions.
Tellurium (Te) is a rare metalloid (average crustal abundance 0.001 mg kg-1) and has received relatively little research attention with regard to toxicity and environmental mobility. Much of what we know about tellurium is extensional, based on observations of selenium (Se), a related metalloid that has been studied (for example, Balistrieri, 1990; Hayes, 1987). Few studies report direct observations of Te toxicity or environmental behavior, generally in conjunction with Se observations (Schroeder, 1971; Taylor, 1996; Harada, 2009). These studies indicate that the two metalloids do not behave identically, calling into question the assumption that Te behavior can be predicted by Se studies. However, what is clear from studies of Se and other elements is that chemical speciation exerts primary control over environmental mobility and human toxicity.
The overarching goal of this research is to understand the geochemical controls that determine Te mobility and speciation in the environment and to provide information that assists in assessing risks to human health. Because adsorption is the main process controlling the mobility of other oxyanions in the environment, a detailed sorption study of Te oxyanions (TeO32- and TeO42-) on ferrihydrite will be conducted. A subset of these samples will be used to determine the geometry of the Te sorption complex using x-ray absorption spectroscopy and to determine fractionation of stable Te isotopes during the adsorption process. Samples of Te-contaminated geomedia (mine tailings and soils) will be collected and characterized for Te bioacessibility and speciation in the effort to extend the results from the laboratory to field conditions. These integrated laboratory and field studies will contribute to both the fundamental knowledge of Te geochemistry, as well as address the potential risks associated with the use of Te in high technology devices.
Balistrieri, L.S., and Chao, T.T., 1990, Adsorption of selenium by amorphous iron oxyhydroxide and manganese-dioxide: Geochimica et Cosmochimica Acta, v. 54, p. 739–751.
Harada, T., and Takahashi, Y., 2008, Origin of the difference in the distribution behavior of tellurium and selenium in a soil-water system: Geochimica et Cosmochimica Acta, v. 72, p. 1281–1294.
Hayes, K.F., Roe, A.L., Brown, G.E., Hodgson, K.O., Leckie, J.O., and Parks, G.A., 1987, In situ X-ray absorption study of surface complexes—Selenium oxyanions on alpha-FeOOH: Science, v. 4828, no. 238, p. 783–786.
Schroeder, H.A., and Mitchener, M., 1971, Selenium and tellurium in rats: Effects on growth, survival and tumors: Journal of Nutrition, v. 101, no. 11, p. 1531–1540.
Taylor, A., 1996, Biochemistry of tellurium: Biological Trace Element Research, v. 55, p. 231.
Rockwell, T.A., Keller, E.A., Clark, M.N., and Johnson, D.L., 1984, Chronology and rates of faulting of Ventura River terraces, California: Geological Society of America Bulletin, v. 95, p. 1466–1474.
Rockwell, T.A., Keller, E.A., and Dembroff, G.R., 1988, Quaternary rate of folding of the Ventura Avenue anticline, western Transverse Ranges, southern California: Geological Society of America Bulletin, v. 100.
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