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 Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

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: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>