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 Joint research project on wastewater for reuse examines pond system in Namibia
19.12.2016 | Technische Universität Darmstadt

nachricht Scientists produce a new roadmap for guiding development & conservation in the Amazon
09.12.2016 | Wildlife Conservation Society

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: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Water - as the underlying driver of the Earth’s carbon cycle

17.01.2017 | Earth Sciences

Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

17.01.2017 | Materials Sciences

Smart homes will “LISTEN” to your voice

17.01.2017 | Architecture and Construction

VideoLinks
B2B-VideoLinks
More VideoLinks >>>