A Kansas State
University scientist is
digging deep to solidify information about potential tungsten contamination in
the nation's ground water and aquifers.
Tungsten is
a naturally occurring metallic element that in its alloy or solid form is
primarily used for incandescent lightbulb filaments and X-ray tubes.
In an
effort to limit toxins in the environment, tungsten is replacing lead in
fishing weights and in ammunition for hunting and recreational shooting. The
military is substituting tungsten in its high kinetic energy penetrators and
small arms ammunition, as well as other ammunitions.
"Tungsten
originally was thought to be nontoxic, as it was believed to be an inert metal
of low environmental mobility," says Saugata Datta, assistant professor of
geology at K-State. "But tungsten is a contaminant in ground water and a
growing concern."
Scientists
and health officials began connecting tungsten to clusters of childhood leukemia
cases in the western United
States after finding high concentrations of
the element in residents' bodies. People examined lived in towns near
tungsten-bearing ore deposits and even hard metal processing plants. Drinking
water in these areas has an elevated concentration of tungsten.
"Animal
model studies have shown tungsten can be toxic and even carcinogenic,"
Datta says. "Because of this, we need to understand tungsten's
biogeochemistry in the environment, about which very little is known."
To find out
how tungsten reacts and relates to ground water and the surrounding environment
– referred to as biogeochemistry – Datta recently began collaborating with
Karen Johannesson, professor of earth and environmental sciences at Tulane University.
Their
research is being funded by a three-year grant issued by the Hydrology Division
of the National Science Foundation in fall 2010.
The project
investigates the biogeochemistry of tungsten reaction and transport in the
environment. More specifically, it's an evaluation of how tungsten
concentrations change along ground water flow paths and modify the ground water
makeup.
When
tungsten is exposed to oxygen – a process called oxidation – it often seeps
into the ground and even into ground water-bearing aquifers. During this process,
the tungsten can also mix with organic matter present in natural soils. In the
presence of sulfur rich solutions, it forms thiotungstate complexes, which also
are toxic.
To gather
information, the researchers are looking at pristine aquifers, like the Ogallala,
as well as affected aquifers. Data from these findings can be used to create a
conceptual model for this project and future studies, Datta explains.
"Looking
at emerging contaminants is one of the biggest things for an environmental
geoscientist, and health is a big issue connected to any elemental or
environmental study we do," Datta says.
"We
are trying to approach this project from the standpoint of understanding this
element and its behaviors in the environment before taking our findings to the
general public so the situation can be addressed," he says.
Datta's
previous work studied arsenic levels in the ground water in West Bengal, India
and Bangladesh.
Along with a K-State graduate student, he looked at why naturally occurring
arsenic – another toxin in nature – got into ground water from river-borne
sediments, and finding well locations for cleaner water.