BLOOMINGTON, Ind. -- The world's largest antimony mine has become the world's largest laboratory for studying the environmental consequences of escaped antimony -- an element whose environmental and biological properties are still largely a mystery.
"Antimony is an emergent contaminant," said IU Bloomington Ph.D. student Faye Liu, the paper's lead author. "People have not paid enough attention to it."
Used in small quantities, antimony has a wide variety of applications -- from hardening the lead in bullets and improving battery performance to combating malaria.
Little is known about antimony's toxicity, in part because the metalloid element is usually found at low, parts-per-billion concentrations in natural environments. At Xikuangshan, Liu and her colleagues found that aqueous antimony concentrations could be as high 11 parts per million, 1,000 times the antimony levels found in uncontaminated water.
The alarming circumstances at Xikuangshan present an opportunity to understand what happens to antimony, geologically and chemically, when large quantities of it are introduced to the environment. That knowledge will be useful to investigations of antimony contamination near factories and military bases around the world.
The U.S. Environmental Protection Agency and similar regulatory agencies in Europe operate under the assumption that antimony's properties are similar to those of arsenic, another element in antimony's chemical group.
"That will need to change," said IU Bloomington geologist Chen Zhu, Liu's advisor and the project's principal investigator. "We saw that antimony behaves very differently from arsenic -- antimony oxidizes much more quickly than arsenic when exposed."
The vast majority of antimony the scientists isolated at Xikuangshan was of the "V" type, an oxidation state in which the metal has given up five electrons. It is believed V is the least toxic of the three oxidation states
|Contact: David Bricker|