During World War II, the U.S. Air Force bomber pilots flew Kansas-made bombers overseas to bomb Axis strongholds.  Leading up to their missions, those pilots practiced by dropping bombs over Cheyenne Bottoms.  Debris from these practice runs prompted Chad Hobson, a Kansas State University graduate student, to include the wetlands area in a study recently.

Tungsten may be harmful in high concentration
Hobson is studying under Dr. Saugata Datta, Associate Professor at KSU Department of Geology.  He picks up where other researchers have left off in the study of how tungsten leaches into surface and groundwater.  
“The main goal of the project is to quantify tungsten, and learn what factors control how it leaches into the surrounding water,” Datta said.  This is important because prior to 2000, it was believed that tungsten was benign, he said.  But now scientists aren’t so sure.   
The element is very dense, and has the highest melting point of all elements.  Because of this, it has been used to replace lead in bullets and shot, blades, radiation shields, filaments in light bulbs,  as well as for jewelry.  In small concentrations, it seems to be harmless, but in large concentrations, it may be poisonous, Datta said.
According to the article on the department website, in 2002, the Centers for Disease Control investigated several clusters of acute lymphatic leukemia in both Nevada and Arizona.  These were located near areas where there were current or former military or smelting operations nearby. 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.”

Background
“Made from tungsten steel alloy, bombing debris has been left to react to the surrounding sediments  and leach into the water ever since,” he said.  “While there isn’t a high bulk concentration in the surface water, there are small areas that are highly concentrated.”
According to the U.S. Department of Defense,  The Great Bend Air-to-Ground Gunnery Range (see diagram) was used by Great Bend Army Airfield and Smoky Hill Army Airfield from 1943 to 1947 when the lease was not renewed.  The site consisted of five ranges: a gunnery range located in the northern half, a bombing range in the southeast portion, and a rifle range and a machine gun range in the southwest portion.
In a Bureau of Environmental Remediation Identified Sites List Information page, the Kansas Department of Health and Environment noted the finding of numerous .50 caliber casings and other debris during clean-up efforts in the 1990s.  In 1992, the Army Corps of Engineers declared the area an ordnance and explosive waste (OEW) cleanup site.  This was four years after the area was declared a Wetland of International Importance in 1988 by the Ramsar Convention on Wetlands.

Studies not conclusive
It’s important to keep in mind that even though there appears to be a link, there is no substantiated proof that tungsten in drinking water plays a part in the onset of childhood leukemia, Datta said.  And it is an unknown at what levels of concentration the element may become harmful.  There is also the possibility that there is no direct link at all, and that the effects could be from other trace elements.  
“There simply has not been enough study done yet to draw conclusions,” he said.  

Water condition concerns
Cheyenne Bottoms has also been in the spotlight recently because the U.S. Army Corps of Engineers is considering requests by two corporations who would like to drill for oil inside the wetlands area.  Maintaining water quality among other environmental concerns resulted in several individuals and organizations speaking out against the permits being awarded.  
Recently, U.S. Fish and Wildlife Field Supervisor Heather Whitlaw sent a letter in protest of the permits during a public response period.  In addition to several environmental complaints, she cited the condition of the Cheyenne Bottoms as already “not fully functioning.”
“Cheyenne Bottoms currently suffers from water quality problems and is on the Kansas 303d list for siltation, dissolved oxygen and eutrophication,” Whitlaw stated in the July 15 letter.  The federal Clean Water Act requires all states to list (under section 303d) bodies of water that are in need of improvement.  The current level of dissolved oxygen in the water is considered lower than average, and with the ongoing increase of silt and nutrient levels which encourage algae blooms, there is no solution in sight.  
While their study is independent of these concerns, some of what Hobson and Datta have learned about how chemicals react and move in the wetlands may add clarity to the conversation. They have concluded two things about tungsten and how it reacts to dissolved oxygen. First, when tungsten is surrounded by oxygen in the water and is in the presence of phosphates and other transition metals, they bind together, and in this state, tungsten can become more soluble in water.
Weather is another factor, Hobson said.  Hot summers increase the amount of evaporation and decreases the amount of oxygen in the water.   
The researchers also found that aquifers with less dissolved oxygen had greater traces of tungsten in the groundwater than aquifers with higher dissolved oxygen levels.
The process of tungsten being leached from the surrounding sediment into the groundwater can be reduced if ironoxides are in the water and the water has a neutral pH level, according to Datta.

Finding the next clues
While Hobson is concluding his part of the study, and plans to defend his thesis soon, Datta can foresee possible next steps.  Since searching for higher concentrations of tungsten in the natural environment can be “like finding a needle in a haystack,” lab experiments are needed to learn how the element behaves with different sediments.  The results can be conjoined with these natural sediment studies, he said.
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.