The cleanliness of our water faces pressures from many directions. More factories mean more discharges, a growing population leads to more wastewater, and more runoff from lawns and farms carries pollutants into waterways. While there are many elements in water that may be harmful to people and the environment, one of the newest constituents are particles too tiny to see -- yet they are drawing heightened attention of environmental engineers.
Nanoparticles – so-called because they are about 1/10,000 the diameter of a human hair – are finding their way into industrial processes, common consumer products and fertilizers. Their use is becoming increasingly common because their miniscule size gives them special properties that their normal sized counterparts don’t have.
Since they came into broader use in the past decade, these nanoparticles have not been as rigorously researched as other agents; scientists are only now starting to figure out which nanoparticles are the most dangerous to human health, as well as animal and plant life.
In the latest step toward better understanding the true nature of the problem, a new international consortium, funded by a four-year, $4 million grant from the U.S. Environmental Protection Agency (EPA) and the United Kingdom's Environmental Nanoscience Initiative, has been formed to determine the environmental behavior, bioavailability and effects of manufactured nanomaterials in ecosystems on land.
Known as the Transatlantic Initiative for Nanotechnology and the Environment, the consortium will be directed by scientists at the Center for the Environmental Implications of NanoTechnology, or CEINT, which is based at Duke University. The new consortium is made up of scientists from the UK, Carnegie Mellon University, the University of Kentucky and Duke. Kentucky’s Paul Bertsch is the consortium’s project leader.
“One area in CEINT that will grow as a consequence of this initiative is research on the potential impacts of nanomaterials on agricultural lands,” said CEINT director Mark Wiesner, James L. Meriam Professor of Civil and Environmental Engineering at Duke’s Pratt School of Engineering and CEINT director. Wiesner specializes in nanoparticle movement and transformation in the environment.
“Our risk assessment work to date has shown that many nanomaterials in consumer products are likely to make their way into wastewater sludges that are in turn applied to land as fertilizer,” Wiesner continued. “This new effort bolsters CEINT’s research efforts by adding top soil scientists and prominent new collaborators in the United Kingdom.”
It is estimated that approximately 60 percent of the eight million tons of biosolids produced each year in the US and the UK are applied to agricultural lands. Biosolids are what remains after wastewater and sewage has been treated. After additional treatment to remove toxins and pathogens, these biosolids are often used on farmlands (WHY?).
However, it is not known whether these treatments are effective in removing nanoparticles, and if they aren’t, what effects these nanoparticles could have on the environment.
Research has shown more than 90 percent of certain nanomaterials, such as nanosilver, end up in biosolids. Thus, land-applied biosolids can become an important source of nanomaterials in soil where they can be taken up by microorganisms, earthworms or plants, with the potential for transfer up the food chain to animals and humans. Runoff and erosion from agricultural lands receiving biosolid applications can also introduce nanomaterials directly into streams and rivers.
"Accumulating evidence suggests that sewage sludge or biosolids generated from wastewater treatment will be a major source of manufactured nanomaterials to terrestrial ecosystems,” Bertsch said. “Our consortium has assembled some of the world's top scientists working on the fate, transport, bioavailability and toxicity of nanomaterials in terrestrial systems, as well as those working in the area of assessing the risks associated with the release of nanomaterials to the environment."
The consortium will conduct research to quantify the amount of nanomaterials added to soil via biosolids, examine how nanomaterials introduced into the waste stream are modified in the waste treatment process and in soil, and how this influences their transport or uptake by plants, animals and other organisms, as well as assess the relative risks to ecoreceptors and humans.
Duke professor of chemistry, Jie Liu, joins Wiesner as the consortium’s other Duke scientist.
CEINT is a participant in two of the three recently funded EPA-UK initiatives. The second involves CEINT’s Rich Di Giulio, professor in Duke's Nicholas School, who will collaborate in nanomaterial ecotoxicology work with researchers at Rutgers University.
CEINT was created two years ago with a $14.4 million grant from the National Science Foundation and the EPA.