Environmental Effects of Tungsten: Damage Mitigation and Green Alternatives

9/20/2010

HOBOKEN, N.J. - by Doug Fabrizio 

The chemistries of both lead and depleted uranium have been studied for over 30 years. These materials were commonly used as a functional, cost-effective and reliable choice in the manufacturing of munitions. Depleted uranium was typically seen as constituent of kinetic energy penetrators (which uses kinetic energy to penetrate the target) in medium to large caliber munitions. Little was known about the environmental effects of each. In fact, lead, which was most frequently used in small arms ammunition, was even found in a variety of household products such as gasoline, rubber, paint and printing supplies.

The use of these materials was wide-spread and long-term. Ultimately, however, researchers discovered that each pose serious threats to the environment. The need for a new 'green' alternative was critical.

Extensive analysis resulted in the testing of Tungsten (W), a naturally occurring element that exists in the form of minerals and other compounds, as a replacement for lead in small arms ammunition. Tungsten was thought to be environmentally benign and relatively insoluble in water as well as nontoxic, making it a perfect solution for a new 'green' munitions. As a safer, the lead core in military bullets was replaced with tungsten composites through the Department of Defense's (DoD) Green Ammunition Program, with the expectation of saving millions in remediating contamination while at the same time contributing towards advancements in green technology.

Tungsten seemed to be the ideal solution. Tungsten-based munitions performed the same, were similar in costs to lead alternatives, and ensured the safety of the environment.

However, after years of use, researchers and the DoD have identified a growing concern that necessitates a re-evaluation of the environmental impacts of Tungsten. They are investigating how a cooperative pursuit of improved environmental protection and sustainable engineering may be beneficial.

In response to this concern, Professors Christos Christodoulatos and Washington Braida of the Center for Environmental Systems have undertaken a massive research effort aimed at identifying the specific nature of Tungsten based munitions and ultimately at minimizing the life-cycle environmental impacts and cost of munitions by researching the DoD's triple bottom line: mission, environment and community.

Follow up:

In the Lab at the Center for Environmental Systems

Researchers at Stevens needed to determine whether dissolved forms of tungsten were released from munitions.

In 2004, Professors Christodoulatos, Braida, Dimitris Dermatas and Nikolay Strigul highlighted their initial results in an article appearing in Environmental Forensics, 5:5-13.

"This study found large amounts of dissolved tungsten when powder or alloy pieces were exposed to aqueous solutions, contradicting most of the scarcely available information regarding its solubility," they said. "This research represents one of the first systematic studies on environmental fate and transport of tungsten and adds information to the toolbox of environmental forensics regarding a heavy metal of potential environmental concern."

A 2009 article on the American Chemical Society's Chemical & Engineering News, Volume 87, Number 3 pp. 63-65 states: "...tungsten metal oxidizes to the tungstate anion. Previous toxicology studies indicate that tungsten would be stable in the environment. Although thermodynamically stable under most environmental conditions, the tungstate ion does have biological effects. For example, tungsten may substitute for molybdenum in certain enzymes, inactivating the enzymes."

Essentially this research had for the first time proven that Tungsten may have a negative impact on the environment. Findings presented in these reports have led to growing discussion over its practical governance and the possibility of environmental regulations. This difficulty in predicting the behavior of Tungsten is actually one of the primary reasons Ph.D. candidate Gulsah Sen entered into the field. Working with Professor Braida for the past three years, Gulsah's research focuses on the fate and transport of tungsten in the vadose, or unsaturated, zone.

According to Adebayo A. Ogundipe, Research Engineer and Adjunct Professor at Stevens, "this research effectively showed that tungsten heavy alloys are not environmentally inert. We proved this by uncovering the various mechanisms involved in the environmental degradation of these alloys, the kinetics of release of tungsten and other alloy components and the subsequent effects on environmental conditions. Our research highlighted how the initial design and choice of alloying materials were essential factors in the patterns of chemical behavior. We developed morphological and spectroscopic analyses techniques for analyzing the manner and extent of the environmental degradation of various tungsten heavy alloy formulations.

Tungsten may not be as green as we once thought. But what can we make from this knowledge? In the world of environmental science, knowledge is a key driver of innovation and the ultimate resource in improving technology.

Through their on-going collaborative efforts, the DoD is dramatically improving its assessment of the environmental impact and cost consequences of today's decision making.
Research innovations led by Stevens will spread to future developments as well. In fact, governments are now factoring these green concerns directly into the research and development phase. This streamlines the development process, avoids costs that may arise if materials are later deemed hazardous, and highlights a paradigm shift in which the environmental concerns become an equal focus throughout.

This focus also creates tremendous opportunities for technology transfer efforts and the development of new procedures, methodologies and companies that push the envelope of sustainable engineering products.

Ultimately, enhancements and discoveries made through the efforts of Stevens faculty are increasing the awareness of the issues, spurring discussion on alternatives, ensuring a more environmentally friendly future and providing a unique educational experiences through student participation.

To learn more about this innovative research or to inquire about joining us, please visit the Center for Environmental Systems and the Department of Civil, Environmental and Ocean Engineering.

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About Stevens Institute of Technology

Founded in 1870 and celebrating 140 Years of Innovation, Stevens Institute of Technology, The Innovation University TM , lives at the intersection of industry, academics and research.  The University's students, faculty and partners leverage their collective real-world experience and culture of innovation, research and entrepreneurship to confront global challenges in engineering, science, systems and technology management.

Based in Hoboken, N.J. and with a location in Washington, D.C., Stevens offers baccalaureate, master’s, certificates and doctoral degrees in engineering, the sciences and management, in addition to baccalaureate degrees in business and liberal arts.  Stevens has been recognized by both the US Department of Defense and the Department of Homeland Security as a National Center of Excellence in the areas of systems engineering and port security research. The University has a total enrollment of more than 2,200 undergraduate and 3,700 graduate students with almost 450 faculty. Stevens’ graduate programs have attracted international participation from China, India, Southeast Asia, Europe and Latin America as well as strategic partnerships with industry leaders, governments and other universities around the world.  Additional information may be obtained at www.stevens.edu and www.stevens.edu/press.