Unseen and unforeseen: measuring nanomaterials in the environment

International interest and investment in nanotechnology is growing—said panelists in this morning’s public forum in Washington, D.C. hosted by RTI International—and development and commercialization of this technology need to meet societal expectations. That is, explained moderator Jim Trainham of RTI, the public is concerned with understanding and controlling nanotechnology since, if it cannot be controlled, the technology is not considered helpful to society. Perhaps surprisingly, nanoparticles are not just synthetic, engineered nanotubes—nanoparticles occur naturally as salt from ocean spray or as ash from a volcanic eruption. “We are exposed to nanomaterials constantly,” said Cole Matson from Duke University’s Center for the Environmental Implications of Nanotechnology, “every breath we take.” It is this abundance of tiny materials that makes measuring the engineered nanoparticles more difficult. As Michele Ostraat from RTI’s Center for Aerosol and Nanomaterials Engineering explained, it is almost impossible for researchers to distinguish between background—that is the common, everyday nanoparticles—and engineered particles. Even more complicated, she said, there is a general lack of instrumentation that can perform real-time field measurements. Therefore, the concern with regulating nanotechnology is finding a way to measure how the engineered particles interact with the environment, including how  the environment alters these particles once released. It is a matter of measuring the risk to human and ecosystem health by determining the exposure to and hazard of the materials, Matson explained. “Everything has an impact,” said Matson, “the question is, is it detrimental?” So far there are general answers to these broad environmental questions. According to Matson, nanoparticles will reach the environment, they will be taken up by organisms, they may be toxic, they can alter ecosystems—including “managed” ecosystems such as wastewater treatment facilities—and they do interact with other contaminants. For all that is still unknown, there are some existing tools that are known being used to track the effects of nanomaterials, said Sally Tinkle from the U.S. National Science and Technology Council. For example, she said, “we have a long history of tracking particulate matter.” Matson and Ostraat agreed that aerosol research is the most prepared for tracking the distribution of nanoparticles. “We are farther ahead with air than water and particularly soils,” said Matson. One of the primary challenges is that, like any material, nanoparticles change when introduced to an environment. The physical and chemical properties shift, said Tinkle, “gold becomes red, carbon becomes electric.” As Matson outlined as an example, salt alters particles in a marine ecosystem. Therefore, how nanoparticles are affected by salinity in the ocean determines where the particles will be distributed in the water column. Understanding this dispersal could help determine which marine organisms would likely be the most...

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Iron-plated Snail

This post contributed by Nadine Lymn, ESA Director of Public Affairs  Another example of the ingenuity of nature: researchers are finding inspiration in the extraordinarily strong exoskeleton of a deep-sea snail, Crysomallon squamiferum.  The mollusk’s iron-plated shell is giving researchers insights that could lead to stronger materials for airplane hulls, cars, and military equipment. Researchers at the National Science Foundation (NSF)-supported Materials Research Science and Engineering Center at the Massachusetts Institute of Technology (MIT) write about the snail’s iron-plated protection in the January 19 issue of the Proceedings of the National Academy of Sciences. Also called the “scaly-foot gastropod”, Crysomallon squamiferum was discovered back in 1999, over two miles below the central Indian Ocean, deep within hydrothermal vent fields.  Fluids in these vents are high in sulfides and metals, which the snail incorporates into its shell.  The gastropod’s shell has three layers: a highly calcified inner layer, a thick organic middle layer, and an outer layer that is fused with granular iron sulfide.  It is unlike any other known natural or synthetically engineered armor. MIT project leader Christine Ortiz and her colleagues have been testing the shell’s properties, simulating predatory attacks with computer models as well as with “indentation testing”—striking the top of shells with a sharp probe to measure the hardness and stiffness of the shell. In a NSF press release Ortiz says: Our study suggests that the scaly-foot gastropod undergoes very different deformation and protection mechanisms compared to other gastropods.  It is very efficient in protection, more so than the typical mollusk. Potential predators that are found in the same regions as C. squamiferum include the cone snail, which penetrates its prey with a harpoon-like tooth before paralyzing it with venom, and sea-faring crabs, which use their claws to squeeze for days until the mollusk’s shell gives way.  The researchers write in the PNAS report that C. squamiferum’s impressive exoskeleton is: …..advantageous for penetration resistance, energy dissipation, mitigation of fracture and crack arrest, reduction of back deflections, and resistance to bending and tensile loads. Another vivid example of the evolutionary race between prey and predator which in this case also holds promise for better protective materials for humans. Photo credit: Dr. Anders Warén, Swedish Museum of Natural History, Stockholm, Sweden. Yao, H., Dao, M., Imholt, T., Huang, J., Wheeler, K., Bonilla, A., Suresh, S., & Ortiz, C. (2010). Protection mechanisms of the iron-plated armor of a deep-sea hydrothermal vent gastropod Proceedings of the National Academy of Sciences, 107 (3), 987-992 DOI: 10.1073/pnas.0912988107...

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