Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

17-year study confirms that lead in the soil descends slowly

17.07.2003


In a 17-year experiment on Vermont’s Camel’s Hump, three Dartmouth researchers find that lead moves very slowly though the soil. Using the highly accurate technique of isotopic analysis for the first time at this field site, the researchers traced several varieties of lead with different atomic weights.

Their study was published online on July 12 on the Environmental Science & Technology Web site, a journal of the American Chemical Society.

"This definitively supports a few earlier studies," says Friedland, "that show that lead in forests in the Northeast moves very, very slowly. The lead that was emitted from gasoline and settled into the soil over about 30 or 40 years is not going to end up in our drinking water anytime soon."



This doesn’t mean we should be complacent, say the researchers. The Dartmouth team and others are working on mountains worldwide to discover how soil retains pollutants such as lead and why the lead moves so slowly through the soil.

According to the researchers, lead is one of the most widely dispersed natural contaminants in the world. At elevated levels, it can cause nervous system disorders. In children it has been linked to learning disabilities and other behavioral and developmental problems. Throughout most of the 20th century, people added lead to the atmosphere primarily by burning leaded gasoline, which eventually settled to the earth. High elevation forests, such as the one at Camel’s Hump, are good environmental indicators because they are very sensitive to atmospheric and climate conditions, and they effectively collect lead. Lead pollution is easily intercepted by the leaves on mountain trees, and rain washes it into the soil.

One piece of this study began in 1984 as part of Andrew Friedland’s dissertation research. Friedland, now a Professor and Chair of the Environmental Studies Program at Dartmouth, applied a trace amount of lead over a one-square-meter area in a mountain forest in Vermont. This lead, which was enriched with a stable isotopic signature of 207, is not toxic in small concentrations, and its atomic signature makes it easy to find, even when it descends into the soil.

In 2001, Friedland, James Kaste, a post-doctoral researcher in the Earth Sciences Department and with the Environmental Studies Program, and Stefan Sturup, Director of Dartmouth’s Trace Metal Analysis Core Facility, returned to the exact plot where the lead 207 was applied on Camel’s Hump, a heavily forested, undeveloped mountain near the village of Huntington, Vt. They took soil samples at the site, which is about 200 hundred yards off of a popular hiking trail at an elevation of about 3,300 feet, and brought them to the lab at Dartmouth for analysis.

"We found that the lead 207 applied in 1984 had only moved down into the soil about seven centimeters," says Kaste, the lead author on the paper. "And it will probably move slower in the future because the soil becomes denser. It’s pretty rare to have a long-term study in this field, and here’s a 17-year experiment that we were able to conduct."

Kaste also followed lead 210, which is a natural lead isotope that falls out of the atmosphere. He traced it to learn how long the forest floor, which is the top 10 centimeters of organic material at the top of the soil, retains it. He found that atmospherically deposited lead, like lead 210, will remain in the forest floor between 60 and 150 years, depending on the vegetation.

"The next step is to identify how the lead binds to the soil," he says. "We want to learn if it binds to organic matter, for example, or if it precipitates out."

The researchers explain that their findings are representative of deciduous and coniferous forests throughout much of the Northeastern U.S. and in some areas in Europe and Scandinavia.

"Since the forest floor retains lead for decades and decades," says Kaste, "it could build up if we keep depositing it in levels that would be problematic, so it’s definitely good that we stopped adding lead to our gasoline."

Adds Friedland, "No matter what you do, the natural environment records your history. So we’re leaving a legacy of this spike of lead. It will probably still be there in 500 years."

Sue Knapp | EurekAlert!
Further information:
http://www.dartmouth.edu

More articles from Ecology, The Environment and Conservation:

nachricht Malaysia's unique freshwater mussels in danger
27.09.2016 | The University of Nottingham Malaysia Campus

nachricht How to detect water contamination in situ?
22.09.2016 | Tomsk Polytechnic University (TPU)

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

 
Latest News

New imaging technique in Alzheimer’s disease - opens up possibilities for new drug development

28.09.2016 | Medical Engineering

Innovate coating extends the life of materials for industrial use

28.09.2016 | Materials Sciences

Blockchain Set to Transform the Financial Services Market

28.09.2016 | Business and Finance

VideoLinks
B2B-VideoLinks
More VideoLinks >>>