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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Snow fleas: helpful winter critters

As the Northeast of the United States was hammered by thundersnow this week, students, parents and perhaps those working from home had the opportunity to indulge in outdoor winter activities. For many, being in the snow again is losing its luster. As an Associated Press article noted, “The Northeast has already been pummeled by winter not even halfway into the season. The airport serving Hartford, Conn., got a foot of snow, bringing the total for the month so far to 54.9 inches and breaking the all-time monthly record of 45.3 inches, set in December 1945.” However, those who are venturing outside might discover that snow forts and shovels are not the only things littering the fresh snow. At close examination, perhaps in melting snow around the base of a tree, tiny black flecks might be found sprinkled in the snow. They probably look like bits of dirt at first glance, but they are actually tiny soil animals known as snow fleas. Officially, they are called springtails and are not actually fleas (or even technically insects). On any given summer day, hundreds of thousands of springtails can populate one cubic meter of top soil; at 1-2 mm, they largely go unnoticed by people. In the winter, however, two species of dark blue springtails— Hypogastrura harveyi and Hypogastrura nivicol—can be easily spotted against the white backdrop of snow. These hexapods may have acquired the nickname of snow fleas due to their ability to jump great distances, a feat fleas boast as well. Whereas fleas use enlarged hind legs, springtails have a tail-like appendage called a furcula that unfolds to launch the hexapods great distances. But unlike fleas, springtails are not parasites; they feed on decaying organic matter in the soil (such as leaf litter) and, therefore, play an important part in natural decomposition. Snow fleas in particular are able to withstand the bitter temperatures of winter thanks to a “glycine-rich antifreeze protein,” as reported in a study published in Biophysical Journal. The protein in the snow fleas binds to ice crystals as they start to form, preventing the crystals from growing larger. In addition, by isolating this protein, researchers have been able to study the medical potential of its structure. Specifically, Brad Pentelute from the University of Chicago and colleagues suggested the possible applications of this protein in safely preserving organs for human transplantation. LIN, F., GRAHAM, L., CAMPBELL, R., & DAVIES, P. (2007). Structural Modeling of Snow Flea Antifreeze Protein Biophysical Journal, 92 (5), 1717-1723 DOI: 10.1529/biophysj.106.093435 Photo Credit (distance snow fleas): Jean-Sébastien Bouchard Photo Credit (snow flea close-up): Daniel Thompkins As the Northeast of the United States was hammered...

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Two surprising critters living in the tiny world of moist soil

The unseen world of soil microbiota is full of surprises: Take, for instance, tiny animals called water bears that thrive in almost any location on Earth (and even outer space) through suspended animation. And even a shape-shifting slime mold that cultivates bacteria in order to  harvest it in the future. These are only two of the organisms populating soil—yet there are hundreds of other microcritters on which plants and larger animals rely. Water Bears Water bears, which are named for the bear-like gait with which they walk, use claws at the end of eight pudgy legs to cling to leaves, moss and other debris. Stylets at the end of a tubular mouth pierce plant cells and small invertebrates (and even other water bears in some cases) while a pharynx sucks out the juices. Water bears—officially called tardigrades and also known as moss piglets—possess a compartmentalized brain and nervous system, intestine, eye sockets, anus and, in most cases, gonads.  Some species reproduce internally through intercourse while others rely on fertilizing eggs externally. Water bears are found in moist soil and in extreme environments as well. They also thrive in an ecosystem in Antarctica, in boiling hot springs and can even tolerate long periods (up to a decade) of dehydration. Whereas a majority of living organisms die if exposed to extreme dryness, called dessication, water bears have evolved a unique characteristic: “They can reversibly enter a state of suspended animation called cryptobiosis, in which their metabolism screeches to a halt and their water content plunges to a hundredth of normal,” as the blog The Artful Amoeba described. “This helps protect their DNA, and a sugar called trehalose helps protect their membranes.” In addition, water bears are the only animals to survive the radiation-intense, extremely dry vacuum of space—and later recover to breed again. Slime molds These are definitely not your garden variety slugs. Technically Dictyostelium discoideum, also called slime molds, are social amoeba commonly found in soil. And despite also being featured in science labs as a model organism, it was not until recently that researchers discovered these single-celled organisms were also avid farmers. When times get tough, such as when there is a shortage of bacteria for the slime molds to consume, the individual amoebas will join forces to form a slug and migrate to another location. Once it arrives at a suitable locale, the slug again changes shape—this time into a plant-like formation complete with a stalk and a spore. D. discoideum stays “planted” in this shape until food becomes available; then the stalk dies and the spore breaks free to form amoeba once again. D. discoideum research published...

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From the Community: Pika population sees a boost, birds not spreading West Nile and five women honored for their role as environmentalists

Pika found to be flourishing in the Sierra Nevada region, bird migration patterns suggest mosquitoes are to blame for spreading West Nile and mice courtship rituals could shed light on autism. Here are news stories and studies on ecological science from the first week in March.

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Scientists challenge century-old understanding of rain-soil interaction

In a recent Nature Geoscience study, scientists discovered that soil clings to water from the first rainfall of the summer and holds it so tightly it almost never mixes with other water. This discovery challenges the century-old assumption that rainwater, after it enters the soil through precipitation, displaces leftover water and pushes it deeper into the ground and eventually into neighboring streams.   Scientists discovered two seperate ways soil and water interact Renée Brooks from the Environmental Protection Agency and colleagues determined soil water is actually separated into two “worlds”: mobile water that eventually runs to streams, and stationary water that is used up by plant roots. These worlds are divided by pore size. Small pores in the soil around plant roots fill with water and serve as tiny reservoirs throughout the summer. Any water that enters the soil after the first summer rain moves through larger pores and almost never mixes. Once the plants use up the water in the small pores, the autumn rains replenish these reservoirs and the process repeats. As the study’s co-author Jeff McDonnell explains in a press release from the University of Oregon: Water in mountains such as the Cascade Range of Oregon and Washington basically exists in two separate worlds. We used to believe that when new precipitation entered the soil, it mixed well with other water and eventually moved to streams. We just found out that isn’t true. This could have enormous implications for our understanding of watershed function. The discovery was made using a process called isotope analyses—that is, the researchers were able to identify specific water signatures to tell where it came from and where it moved. The authors say the findings could affect the current understanding of how pollutants move through soils, how nutrients get transported from soils to streams, how streams function and how vegetation might respond to climate change. Photo Credit: http://www.flickr.com/photos/dragonflysky/ / CC BY-NC 2.0 Renée Brooks, J., Barnard, H., Coulombe, R., & McDonnell, J. (2009). Ecohydrologic separation of water between trees and streams in a Mediterranean climate Nature Geoscience DOI:...

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