Eileen Jang of Cary, North Carolina was named the U.S. winner of the 2009 Stockholm Junior Water Prize (SJWP) - the most prestigious international competition for water-related research. Her project was selected from more than 40 state SJWP winners at the national competition held this year in Anchorage, Alaska on June 25-27th.
Her project, "Natural Organics Control Aggregation of Mercury Sulfide Nanoparticles in Freshwater Systems", introduced a novel process for studying how mercury sulfide nanoparticles -- the precursors to methylmercury -- persist in freshwater systems. Jang's research deepened the understanding of mercury, a substance that bioaccumulates in fish and is toxic to humans, in its aqueous phase and furthered the emerging field of nanogeoscience.
A senior at the North Carolina School of Science and Mathematics in Durham, NC, Jang received $3,000 and an all-expense paid trip to Stockholm, Sweden, where she will compete against national winners from more than 30 countries for the international SJWP during World Water Week, August 16-22, 2009.
Jang's research had already taken her to the 2009 Intel International Science & Engineering Fair (ISEF), where she won a Second Place award in Environmental Sciences and special awards from the American Geological Institute and the Association for Women Geoscientists, and to China, to the Beijing Youth Science Creation Competition. (Read the NC delegation's blog.)
Summary: Mercury (Hg) is an environmental contaminant that is neurotoxic to humans, particularly to individuals exposed through consumption of fish. In aquatic environments, mercury sulfides, such as HgS nanoparticles, are precursors to methylmercury -- the form of Hg that bioaccumulates in fish. Current knowledge is limited regarding processes through which HgS nanoparticles persist in its aqueous phase.
The goals of this study were to: 1) synthesize uncapped HgS nanoparticles, 2) characterize these nanoparticles, and 3) test aggregation rates of nanoparticles in solutions simulating natural conditions. A novel aqueous synthesis process for uncapped nanoparticles was developed using a controlled precipitation process. The resulting metacinnabar-HgS(s) was characterized through transmission electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction spectroscopy.
Using dynamic light scattering, the aggregation rate of HgS nanoparticles was found to increase as salinity increased. Furthermore, the aggregation rate decreased in the presence of cysteine, an amino acid prevalent in sediment porewater. Through comparison of cysteine to a structurally-similar organic acid, serine, it is believed that the sulfhydryl group in cysteine is responsible for controlling aggregation rates. By studying the biogeochemical processes of these ubiquitous nanoparticles in aquatic systems, this research has deepened the understanding of mercury in its aqueous phase and furthered the emerging field of nanogeoscience.
Three other U.S. finalists, Scott Boisvert (Arizona), Li Boynton (Texas), and Collin McAliley (Florida) each received $1,000 awards. See summaries of their projects and list of all 2009 SJWP state winners.