(Press-News.org) MANHATTAN, Kan. -- Two Kansas geologists are helping shed new light on how tungsten metal is leached from the sediment surrounding aquifers into the groundwater. The findings may have implications for human health.
Tungsten is a naturally occurring metal that is primarily used for incandescent light bulb filaments, drill bits and an alternative to lead in bullets. Though it is thought to be nonhazardous to the environment and nontoxic to humans, it can be poisonous if ingested in large amounts. In recent years, tungsten has been tentatively linked to cases of childhood leukemia in the Western U.S.
"Very little is known about the biogeochemistry of tungsten in the environment," said Saugata Datta, professor of geology at Kansas State University. "We need to understand how this metal is leached from the soils into groundwater because humans can be exposed to tungsten through multiple pathways."
Datta, along with Chad Hobson, master's student in geology, Lavonia, Ga., and colleagues at Tulane University and the University of Texas, Arlington, found that the likelihood that tungsten will seep into an aquifer's groundwater depends on the groundwater's pH level, the amount of oxygen in the aquifer and the number of oxidized particles in the water and sediment. Analysis also showed that tungsten-IV is the most common form of tungsten in natural sediments.
These latest findings appear in the study "Controls on tungsten concentrations in groundwater flow systems: The role of adsorption, aquifer sediment Fe(III) oxide/oxyhydroxide content, and thiotungstate formation," published in the journal Chemical Geology.
In addition to the publication, Datta and Hobson presented the findings at the International Conference on Biogeochemistry of Trace Elements.
For the study, researchers looked at Fallon, Nev.; Sierra Vista, Ariz.; and at the Cheyenne Bottoms Refuge near Hoisington, Kan. The sites were chosen based on previous studies analyzing plants and dust collected on trees in the locations. Additionally, these areas have natural tungsten mineral deposits, nearby military bases, and mining and smelting operations in the area, Datta said.
In 2002, the Centers for Disease Control investigated several clusters of acute lymphatic leukemia in both Nevada and Arizona. The investigation found that residents' urine had tungsten levels above the 95th percentile.
"This was important for us to know because the goal is to clarify valuable information about tungsten's geochemistry," Datta said. "So, we needed sites that had tungsten -- and enough tungsten to measure easily. The benefit of this study is that tungsten's geochemistry has been overlooked and until recently, largely unknown. This work will help fill the gaps in the knowledge of tungsten, which is possibly carcinogenic, and help determine its future use."
Datta and Hobson analyzed sediment samples lining the aquifers while researchers at Tulane University and the University of Texas, Arlington analyzed the groundwater samples. The National Synchrotron Light Source was used for spectroscopic analysis of the individual particles. This helped researchers understand the speciation of tungsten in natural sediments in the environment and helped them detect why tungsten forms organosulphur complexes that can be soluble in groundwater, Datta said. Analysis also showed that tungsten-VI is the most common form of tungsten in natural sediments.
Analysis of the sediment and groundwater showed that iron oxide and oxyhydroxide particles in both substances play a key role in regulating how much tungsten is in the groundwater. The fewer iron oxides or oxyhydroxide particles, the higher the amount of tungsten, Datta said.
Similarly, the team found that the number of tungsten-regulating iron oxide particles is controlled by the pH in the groundwater. A higher pH results in more tungsten entering the water.
"Tungsten is specifically bound to these iron oxides and oxyhydroxides," Datta said. "One of the major factors controlling tungsten's mobility and bioavailability is pH. Ranging values of pH can affect how tungsten behaves or transforms between different tungsten species, which have different properties and factors controlling mobility."
When tungsten is in the water it is surrounded by oxygen atoms and forms an anion, Datta said. When in the presence of phosphates, this anion tends to bind with other transition metals, commonly iron, to form poloyoxometalates. In this form, tungsten can become more soluble in water.
Researchers also found that aquifers with less dissolved oxygen had greater traces of tungsten in the groundwater than aquifers with high dissolved oxygen levels.
The process of tungsten being leached from the surrounding sediment into the groundwater can be reduced if the ironoxides are in the water and the water has a neutral pH level, according to Datta.
The study is part of a three-year, $515,000 National Science Foundation-funded project between Kansas State University and Karen Johannesson at Tulane University that is titled "Collaborative Research: Chemical Hydrogeologic Investigations of Tungsten: Field, Laboratory, and Modeling Studies of an Emerging Environmental Contaminant." It focuses on biogeochemistry of tungsten's reaction to the environment and how it is transported from sediments into groundwaters once it becomes geochemically mobilized.
INFORMATION: END
Younger patients with colorectal cancer that has spread to other parts of the body represent a high-risk group that is less likely to respond to treatment. Colorectal cancer in patients younger than 40 is more likely to grow despite treatment and young patients are at greater risk of death than people in other age groups.
That's according to research presented to the 2013 European Cancer Congress in Amsterdam. The team of scientists is led by an investigator at University of Colorado Cancer Center.
An analysis of 20,034 patients in 24 phase III clinical trials showed ...
DURHAM, N.C. – By detailing a process required for repairing DNA breakage, scientists at the Duke Cancer Institute have gained a better understanding of how cells deal with the barrage of damage that can contribute to cancer and other diseases.
The insights, reported online the week of Sept. 30, 2013, in the journal Proceedings of the National Academy of Sciences, build on earlier work by the research team and identify new prospects for developing cancer therapies.
The researchers have focused on a complex series of events that cells routinely undertake to repair DNA ...
Blending cremated remains into tattoos, creating "virtual tombstones" online and displaying "Rest in Peace" car decals or T-shirts are unconventional ways people increasingly are using to honor the dead this century, a Baylor University researcher says.
"With 'do-it-yourself' memorials, people are creating their own ways of memorializing the dead, particularly in a more secularized society," said Candi Cann, Ph.D., an assistant professor of religion in Baylor's Honors College. "Some people are alienated from some common traditions such as a long funeral Mass. Cohesive ...
Alexandria, VA – In the first study of its kind, the American Geosciences Institute (AGI) Workforce Program has published the results of the National Geoscience Student Exit Survey, which documents the experiences of graduating geosciences majors. Initial findings support that these new graduates, at all levels, shared some common traits such as the importance of field experiences and exposure to Earth science at the K-12 level.
The need for continued growth in the geoscience workforce is well documented and supported by its continuance as one of the most lucrative ...
ANN ARBOR—A microfluidic chip developed at the University of Michigan is among the best at capturing elusive circulating tumor cells from blood—and it can support the cells' growth for further analysis.
The device, believed to be the first to pair these functions, uses the advanced electronics material graphene oxide. In clinics, such a device could one day help doctors diagnose cancers, give more accurate prognoses and test treatment options on cultured cells without subjecting patients to traditional biopsies.
"If we can get these technologies to work, it will advance ...
BOSTON (Sept. 30, 2013) — Short-term hearing loss during childhood may lead to persistent hearing deficits, long after basic auditory sensitivity has returned to normal. The processing of sound in the brain is shaped by early experience. New research from Massachusetts Eye and Ear has identified two critical periods occurring shortly after hearing onset that regulate how sounds from each ear are fused into a coherent representation in the brain. Their research is described in Nature Communications.
Hearing scientist Daniel Polley, Ph.D., an investigator at Massachusetts ...
UCLA chemical engineering researchers have created a new synthetic metabolic pathway for breaking down glucose that could lead to a 50 percent increase in the production of biofuels.
The new pathway is intended to replace the natural metabolic pathway known as glycolysis, a series of chemical reactions that nearly all organisms use to convert sugars into the molecular precursors that cells need. Glycolysis converts four of the six carbon atoms found in glucose into two-carbon molecules known acetyl-CoA, a precursor to biofuels like ethanol and butanol, as well as fatty ...
Membrane proteins are responsible for transporting chemicals and messages between a cell and its environment. But determining their structure has proved challenging for scientists. A study by UC Santa Barbara's Han Research Group demonstrates a new tool to resolve the structure of membrane-embedded and membrane-associating proteins using the water dynamics gradient they found across and above the lipid bilayer as a unique ruler.
More than 25 percent of all human proteins are membrane proteins, which perform other essential functions, such as sensing and signaling. They ...
LA JOLLA, CA—September 30, 2013¬–A team led by scientists at The Scripps Research Institute (TSRI) has created the first comprehensive roadmap of the protein interactions that enable cells in the pancreas to produce, store and secrete the hormone insulin. The finding makes possible a deeper scientific understanding of the insulin secretion process—and how it fails in insulin disorders such as type 2 diabetes.
"The development of this insulin interaction map is unprecedented, and we expect it to lead us to new therapeutic approaches for type 2 diabetes," said William E. ...
COLUMBIA, Mo. ¬— As the oldest of the baby boomers begin to reach retirement age, a large percentage of Americans are thinking more and more about how much money they must save to be able to retire comfortably. Also, more and more employers are changing retirement benefits from defined-benefit plans, which guarantee some level of retirement income, to defined-contribution plans, which require employees to invest on their own for retirement. All of these changes, plus the recent economic recession, have created a difficult financial environment for future retirees. Now, ...
