August 2007, Vol. 19, No.8

Research Notes

Researchers Examine Silver Nanoparticles in Wastewater Systems

It’s a nano world. Many everyday consumer items now utilize the emerging science of nanotechnology, so researchers at the University of Missouri–Columbia will examine whether the technology poses future problems for the environment, according to a university news release. The study focuses on silver nanoparticles usage in wastewater treatment plants.

“Silver nanoparticles are emerging as one of the fastest growing nanomaterials with wide applications,” said Zhiqiang Hu, assistant professor of civil and environmental engineering in the College of Engineering. “Currently, little is known about the adverse effects of silver nanoparticles to human health and their fate in ecological systems.”

Hu will be working with Baolin Deng, an associate professor of civil and environmental engineering in the college, to study silver nanoparticles — specifically, their potential affects on wastewater treatment systems, the news release notes. They have received an $84,000 grant from the National Science Foundation (Arlington, Va.). The study began in June and will take about 1 year to complete, according to the news release. Hu and Deng will determine how silver nanoparticles interact with bacteria that are used for wastewater treatment.

“Nitrifying bacteria is extremely sensitive to metal toxins and could serve as a potential environmental health indicator,” Hu said. “Over time, a small volume of nanoparticles will accumulate in our sewage plants.”

The engineers want to find out if silver nanoparticles, known for their bacteria-fighting ability, effectively defend against bacteria found in treatment plants. Hu said the particles enter sewage systems following the washing of hands after people have handled the “nanotechnology enhanced” products. Some of those products include bandages, clothing, cosmetics, car wax, and toys.

Hu said laundry detergents, soaps, water filters, and washing machines also employ nanotechnology and can directly dispense silver nanoparticles into the sewage system.

Contact Hu at huzh@missouri.edu.

Ski Area Affects Mountain Watershed, Study Shows

In recent decades, mountain regions in many parts of the world have faced growing development pressures from recreation and tourism uses, such as vacation homes and ski areas. Despite these new uses, most scientific studies of soil and water in high-elevation areas have focused on the effects of traditional resource extraction, such as logging, according to a University of Vermont (UV; Burlington) news release. The impact of ski-resort developments on watersheds is little understood.

In the first study to document the effects of existing ski-resort development on water flows and water quality in the northeastern United States, Beverley Wemple, associate professor of geography at UV, and her colleagues have studied two side-by-side mountain watersheds on the eastern slopes of Mount Mansfield in Vermont. The nearly pristine Ranch Brook watershed served as a control, while the adjacent West Branch watershed contains the Stowe Mountain Resort.

Their results — published April 24 in the journal Hydrological Processes — show surprising differences between the two watersheds, according to Wemple. The differences, the news release notes, include greater water volume, chloride (likely from parking-lot salt runoff), and sediment (likely from land clearing) flowing out of the developed watershed.

“Our results suggest the hydrologic effects of resort development may be more pronounced than the effects of timber extraction,” Wemple said.

The data presented in Hydrological Processes “will give us a baseline for evaluating the impacts of the new resort expansion that has taken place at Stowe [Vt.] in recent years,” Wemple said, and is part of a long-term study there that “will provide scientific grounding for other proposed resort expansions in the region.”

The study analyzes data collected from 2001 to 2003. Next, the researchers are moving on to analyze the data they have been collecting during a major expansion of the ski area that began in 2004.

“We’re concerned that folks are going to interpret these results to say, ‘this is all the ski area’ or ‘the ski area is a problem,’” said James Shanley, one of Wemple’s co-authors, who works for the U.S. Geological Survey in Montpelier, Vt. “But we can’t — and don’t — say that. We’re just laying out what we’re seeing.” For example, he points out that a considerable portion of the water volume differences may be caused by natural variation between the two watersheds, the press release states.

“The ski areas may be pleased by these results because there are no glaring water quality impacts that we show are connected to the existence of the ski area,” Shanley said.

Nevertheless, Wemple said, “there is a lot more water coming off this developed watershed than we would have thought originally,” and a “measurable” amount of change in the water flowing through the West Branch watershed can be attributed to the ski area. In the developed watershed, water yields were 18% to 36% higher than the control, chloride about 20 times higher than a natural forest basin, and suspended sediment more than 2.5 times greater.

“The way we deal with that, when we do development, is to plan for more stormwater than we have traditionally or than existing studies suggest we should,” Wemple said. “If we know what we’re dealing with, we can design for effective stormwater management on the side of Mount Mansfield as well as we can in Ferrisburgh.”

Whether the new ski lifts, vacation homes, and other developments built at Stowe in the last 3 years will produce big changes in the hydrology of the West Branch watershed remains to be seen, according to the news release. “Our results from after the expansion began won’t be published for a couple of years,” Shanley said.

In any case, Wemple said one of the overarching lessons of her study is that “we need more information about stormwater management in the mountain environment.”

Contact Wemple at bwemple@uvm.edu.

Research To Forecast Ecological Consequences of Environmental Changes

How do climate change and other global environmental changes affect the average person? Researchers at Kansas State University (K-State; Manhattan) are working to find out.

K-State, along with the University of Kansas (Lawrence), recently received grants totaling $9.25 million from the National Science Foundation (Arlington, Va.) and the Kansas Technology Enterprise Corp. (Topeka) to study ecological change in the Kansas River Basin and establish a virtual ecological forecasting center in Kansas, according to a K-State news release.

“We have a world-class group of ecological researchers here,” said Walter Dodds, professor of biology, who leads the research for K-State. “We’re also very open to collaboration at K-State. This project plays to our strengths.”

Dodds said related research at K-State includes that at the Konza Prairie Biological Station, a 3847-ha (8616-ac) native prairie preserve owned by The Nature Conservancy (Arlington, Va.) and K-State.

Dodds noted that forecasting biological and ecological consequences of accelerating global changes is one of the biggest challenges of the 21st century. The National Science Foundation is developing a National Ecological Observatory Network, with ecological observatories around the country to measure and observe the environment in hopes of answering regional- to continental-scale scientific questions. The work in Kansas is hoped to become part of this network, according to K-State.

“The Kansas River Basin is of economic and ecological interest to Kansas,” Dodds said. “But it can also answer questions of interest to the nation and the world.” Kansas’ central plains are ecologically complex and provide a model ecosystem to assess and forecast impacts of global change, he said.

The grants will bring equipment, people and research to the university, Dodds said. The ecological forecasting project is divided into subgroups involving researchers from areas including hydrology, ecology, geography, sociology, computer information technology, and agronomy. Subgroups include biodiversity, biogeochemistry or nutrient flux, climate and hydrology, human dimensions, and information and data management. Ecological forecasting must consider changes in land-use patterns, climate, biota, and hydrological and biogeochemical cycles, Dodds said. Research will include collecting and analyzing existing biological, environmental, and social data, and developing predictive models for testing.

A better understanding and ability to forecast these changes and their consequences is fundamental to sustaining the ecosystem and all it provides to us, including supplying clean water, recycling essential nutrients, sequestering carbon, preserving biodiversity, and guarding against invasive species and emerging diseases, Dodds explained.

Researchers will try to figure out what happens to land use and water use if more corn is used to make ethanol, and what happens to fish populations where reservoirs are created and streamflows change.

More information on the project, including a list of researchers involved, is available at www.k-state.edu/ecoforecasting.

Soil Model Estimates Organic Carbon Content

Storing carbon in agricultural soils presents an immediate option to reduce atmospheric carbon dioxide and slow global warming, according to the American Society of Agronomy (Madison, Wis.). Farmers who adopt practices that store carbon in soil may be able to sell the stored carbon to buyers seeking to offset greenhouse gas emissions. Before farmers can sell carbon credits, however, they need to be able to verify that changing soil management has increased the soil organic carbon (SOC) in their fields.

Researchers at Montana State University (Bozeman) and Colorado State University (Fort Collins) now have evidence that a soil model can be used to make accurate estimates of carbon levels in soil under certain climate and land conditions, states a news release from the American Society of Agronomy. By using this model, farmers and landowners will be able to verify soil carbon change for carbon trading. Scientists report their findings on the reliability of the Century soil model in the May–June 2007 issue of the Soil Science Society of America Journal.

“The Century model estimates soil organic carbon content and soil organic carbon change using soil texture, weather, and farm management information,” said Ross Bricklemyer, lead author of the study.

Working together with farmers from Montana, researchers compared Century model estimates of soil carbon storage to field SOC measurements. Scientists measured carbon storage and soil texture in 10 paired fields under no-till and conventional-till management. They estimated the increase in carbon stored under no-tillage adoption as the difference between carbon levels in no-till and till fields. They then compared the soil carbon values predicted by the Century model to measured SOC and SOC rate of change.

The Century model accurately predicted SOC content and rate of carbon change, according to the news release; however, differences between measured soil texture data and state and county soil texture maps greatly influenced carbon storage estimates.

“The accuracy and scale of soil texture data highly influence the accuracy of Century model estimations of soil carbon,” Bricklemyer said. “The model accurately estimated soil carbon content and the influence soil clay content had on the amount of carbon in the soil.”

Although texture was important in determining SOC storage estimates, the effect of no-tillage management on the rate of carbon storage was not influenced by texture in this study, the news release states. Some scientists have found that high clay content, or heavy soils, store carbon more rapidly under no-tillage management than soils with little clay content, while others have found that clay content has no affect on carbon storage rates under no-tillage practice.

Bricklemyer said that because the effects of clay content on the rate of soil carbon under no-tillage change are not well understood by the research community, clay content information was not directly used by the Century model for carbon change calculations.

“This study also points out the importance of establishing benchmark monitoring sites, under actual farm conditions, where soil texture, soil carbon and other soil properties can be accurately measured and remeasured over time,” Bricklemyer said. “Such a system, which currently doesn’t exist in the U.S., would help us improve and validate estimates of carbon sequestration over time.”

To view the article abstract, see soil.scijournals.org/cgi/content/abstract/71/3/784.