Year of selection 2012
Institution University of Warsaw
When a poison contaminates our environment, not only can it pollute the soil and water, it can also be taken up by plants, rendering them—or specific parts of them—toxic. Natalia Ospina-Alvarez is working to shed light on this situation with regard to the metal thallium. This element, which is introduced into the environment mainly through mining of lead and zinc, comes in different “flavors”, with different levels of toxicity: thallium-I is, by far, the most common, but thallium-III is several thousand times more noxious. To really assess contamination levels and the danger they represent, you need to know how much of each kind is present—including in the vegetation.
For this, Dr. Ospina-Alvarez turned to the plant Sinapis alba, a member of the mustard family known to accumulate high levels of thallium. Since the highly toxic thallium-III is present in only trace amounts, she is developing a new method to extract it directly from the complex material of plant leaves. This technique should yield more concentrated samples of this kind of thallium, leading to more accurate measurements. This could mean better detection of thallium and other trace contaminants, and more accurate assessments of risk—for the environment and for people consuming plants grown in contaminated soil. Her work could even contribute to a solution: a clearer understanding of the way these plants accumulate thallium could let them be used in clean-up efforts to draw the poison from the soil, leaving the Earth cleaner than they found it.
Thallium occurs in the environment in two oxidation states, as Tl(I) and Tl(III), but Tl(III) is a thousand times more toxic than Tl(I). As thallium toxicity depends on the redox state of the metal is essential to determine both forms in the environment.
Tl(III) is naturally present at very low concentrations, therefore the element has to be pre-concentrate before its determination. Solid-liquid extraction (SLE) is a method widely used for evaluation of thallium bioavailability from soil as well as for extraction of thallium from plant and soil samples. This project aims to evaluate the application of a similar approach, known as solid-phase extraction (SPE), for separation of Tl(III) from samples with complex matrices.
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