Fifty days after scientists applied a single low dose of silver nanoparticles, the experimental environments produced about a third less biomass in some plants and microbes.
These preliminary findings are important, the researchers said, because little is known about the environmental effects of silver nanoparticles, which are found in textiles, clothing, children's toys and pacifiers, disinfectants and toothpaste.
"No one really knows what the effects of these particles are in the environment," said Benjamin Colman, a post-doctoral fellow in Duke's biology department and a member of the Center for the Environmental Implications of Nanotechnology (CEINT).
"We're trying to come up with the data that can be used to help regulators determine the risks to the environment from silver nanoparticle exposures," Colman said. CEINT's research is funded by the National Science Foundation and the Environmental Protection Agency
Previous studies have involved high concentrations of the nanoparticles in a laboratory setting, which the researchers point out, doesn't represent "real-world" conditions.
"Results from laboratory studies are difficult to extrapolate to ecosystems, where exposures likely will be at low concentrations and there is a diversity of organisms," Colman said.
Silver nanoparticles are used in consumer products because they can kill bacteria, inhibiting unwanted odors. They work through a variety of mechanisms, including generating free radicals of oxygen which can cause DNA damage to microbial membranes without harming human cells.
The main route by which these particles enter the environment is as a by-product of sewage treatment plants. The nanoparticles are too small to be filtered out, so they and other materials end up in the resulting wastewater treatment "sludge," which is then spread on the land surface as a fertilizer.
For their studies, the researchers created mesocosms, which are small, man-made structures containing different plants and microorganisms meant to represent the environment. They applied sludge with low doses of silver nanoparticles in some of the mesocosms, then compared plants and microorganisms from treated and untreated mesocosms after 50 days.
The study appeared online Feb. 27 in the journal PLOS One.
The researchers found that one of the plants studied, a common annual grass known as Microstegium vimeneum, had 32 percent less biomass in the mesocosms treated with the nanoparticles. Microbes were also affected by the nanoparticles, Colman said. One enzyme associated with helping microbes deal with external stresses was 52 percent less active, while another enzyme that helps regulate processes within the cell was 27 percent less active. The overall biomass of the microbes was also 35 percent lower, he said.
"Our field studies show adverse responses of plants and microorganisms following a single low dose of silver nanoparticles applied by a sewage biosolid," Colman said. "An estimated 60 percent of the average 5.6 million tons of biosolids produced each year is applied to the land for various reasons, and this practice represents an important and understudied route of exposure of natural ecosystems to engineered nanoparticles."
"Our results show that silver nanoparticles in the biosolids, added at concentrations that would be expected, caused ecosystem-level impacts," Colman said. "Specifically, the nanoparticles led to an increase in nitrous oxide fluxes, changes in microbial community composition, biomass, and extracellular enzyme activity, as well as species-specific effects on the above-ground vegetation."
The researchers plan to continue to study longer-term effects of silver nanoparticles and to examine another ubiquitous nanoparticle – titanium dioxide.
The rest of the team were Duke's Christina Arnaout, Claudia Gunsch, Curtis Richardson, Emily Bernhardt, Bonnie McGill and Justin Wright; Sarah Anciaux of Coe College, Iowa; Michael Hochella and Bojeong Kim of Virginia Tech University; Gregory Lowry and Brian C. Reinsch of Carnegie Mellon University, Pittsburgh; Jason Unrine at the University of Kentucky; and Liyan Yin of Wuhan Botanical Garden, China.
Richard Merritt | EurekAlert!
Taking a molecular approach to conserving freshwater biodiversity
09.11.2015 | Universiti Putra Malaysia (UPM)
Faster digestion in kangaroos reduces methane emissions
05.11.2015 | Universität Zürich
Normalerweise werden Unterwasser-Roboter über lange Kabel von Booten oder von Land aus gesteuert. Forschern der Jacobs University in Bremen ist nun ein Durchbruch in der Mensch-Maschine-Kommunikation gelungen: Erstmals konnten sie einen Unterwasser-Roboter mit Hilfe von Gesten navigieren. Eine spezielle Kamera half dabei, die Zeichensprache in Befehle umzusetzen. Die Feldtests fanden im Rahmen des EU-geförderten Projektes CADDY „Cognitive Autonomous Diving buddy“ statt.
Archäologische Untersuchungen im Ozean und vergleichbare komplexe Forschungsprojekte unter Wasser sind auf die Unterstützung von Robotern angewiesen, um in...
Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.
In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...
Die Simulation von Prozessen bei der Lasermaterialbearbeitung ist in den letzten Jahren immer besser geworden. Die Software kann heute relativ gut voraussagen, was am Werkstück passiert. Leider ist sie hochkomplex und erfordert viel Rechenzeit. Durch eine clevere Vereinfachung können Experten vom Fraunhofer-Institut für Lasertechnik ILT erstmals eine Simulationssoftware anbieten, die Prozesse in Echtzeit rechnet und auch auf Tablets oder Smartphones läuft. Mit der schnellen Software lassen sich teure Versuche einsparen und noch besser optimale Prozessparameter finden.
Eine verlässliche Simulation von Laserprozessen war bislang eine Sache für Experten. Mit ausgefeilten Software-Paketen und viel Zeit auf Computerclustern...
In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.
Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...
Heidelberger Physiker imitieren mit ultrakalten Atomen das Verhalten von Elektronen in einem Festkörper
Einen neuen Ansatz zur Erforschung des Phänomens Magnetismus haben Wissenschaftler der Universität Heidelberg entwickelt. Mithilfe von ultrakalten Atomen nahe...
24.11.2015 | Veranstaltungen
24.11.2015 | Veranstaltungen
23.11.2015 | Veranstaltungen
24.11.2015 | Materialwissenschaften
24.11.2015 | Messenachrichten
24.11.2015 | Messenachrichten