A different kind of mine disaster

Apr 12, 2010
Heaps of ore tailings are exposed directly to the open air at Xikuangshan. Credit: Chen Zhu

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 . 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. 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 in which the metal has given up five electrons. It is believed V is the least toxic of the three oxidation states of which antimony is capable (I, III and V). It is not known whether antimony-V's relatively diminished toxicity is upended at Xikuangshan by its overwhelming presence.

Mine workers are often exposed directly to stibnite ore (antimony sulfide) and to airborne antimony via inhalation and skin exposure. Credit: Chen Zhu

Land within and around the mining area is used for farming. The drinking water plant for local residents was built in the mining area. Zhu says health problems are common at Xikuangshan, possibly the result of antimony intoxication.

Zhu says he is discussing a possible collaboration with IU School of Medicine toxicologist Jim Klaunig. Researchers would return to Xikuangshan to determine whether the elevated antimony can be tied to acute and chronic health problems among those who live in the vicinity. Another possible study group might be those Chinese who live downstream of Xikuangshan along the Qing River.

As part of their Environmental Geochemistry and Health study, Zhu and scientists from the Chinese Academy of Sciences conducted field work at Xikuangshan in 2007, drawing multiple water samples from 18 different sample sites. Samples were shipped back to Bloomington for atomic fluorescence spectroscopic analysis and to Alberta for inductively coupled plasma mass spectroscopy analysis. The scientists learned antimony-III was rare, beyond detection or present at trace levels. The near totality of antimony in each water sample was antimony-V.

The Xikuangshan antimony mine is the world's largest. Since antimony mining began there more than 200 years ago, mine production has increased steadily to the present day. Today, Xikuangshan produces 60 percent of the world's antimony.

While Zhu was on sabbatical leave in 2008, Faye Liu was advised by IU Bloomington biogeochemist and inaugural Provost's Professor Lisa Pratt. Zhu and Pratt recently began a joint project to learn more about the biogeochemistry of antimony. The scientists' antimony research complements their concurrent NSF-funded research on arsenic.

IU Bloomington geologists Claudia Johnson and Erika Elswick, both participants in the Environmental Geochemistry and Health study, have also taken seawater samples from the Caribbean. Liu is investigating the samples' antimony content.

Explore further: India court slams Delhi's worsening air pollution

More information: "Antimony speciation and contamination of waters in the Xikuangshan antimony mining and smelting area, China," Environmental Geochemistry and Health, by Faye Liu, X. Chris Le, Anthony McKnight-Whitford, Yunlong Xia, Fengchang Wu, Erika Elswick, Claudia C. Johnson, and Chen Zhu (early access online)

add to favorites email to friend print save as pdf

Related Stories

Promising new material that could improve gas mileage

Oct 09, 2008

With gasoline at high prices, it's disheartening to know that up to three-quarters of the potential energy you are paying for is wasted. A good deal of it goes right out the tailpipe instead of powering your car.

Greenhouse gas burial

Jun 26, 2007

Deep coal seams that are not commercially viable for coal production could be used for permanent underground storage of carbon dioxide (CO2) generated by human activities, thus avoiding atmospheric release, according to two stu ...

Recommended for you

India court slams Delhi's worsening air pollution

4 hours ago

India's environment court has slammed the government over the capital's horrendous air pollution, which it said was "getting worse" every day, and ordered a string of measures to bring it down.

US proposes stricter ozone limits

15 hours ago

The US Environmental Protection Agency announced plans Wednesday to strengthen emission regulations for ozone, a smog-causing pollutant blamed for respiratory ailments affecting millions of Americans.

Deforestation drops 18 percent in Brazil's Amazon

18 hours ago

Deforestation in the Amazon rain forest dropped 18 percent over the past 12 months, falling to the second-lowest level in a quarter century, Brazil's environment minister said Wednesday.

The unbelievable underworld and its impact on us all

19 hours ago

A new study has pulled together research into the most diverse place on earth to demonstrate how the organisms below-ground could hold the key to understanding how the worlds ecosystems function and how they ...

Toolkit for ocean health

22 hours ago

The ocean is undergoing global changes at a remarkable pace and we must change with it to attain our best possible future ocean, warns the head of The University of Western Australia's Oceans Institute.

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.