Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dust in West up 500 percent in past 2 centuries

26.02.2008
Railroads, ranching and livestock brought West its own 'Dust Bowl' in 1800s

The West has become 500 percent dustier in the past two centuries due to westward U.S. expansion and accompanying human activity beginning in the 1800s, according to a new study led by the University of Colorado at Boulder.

Sediment records from dust blown into alpine lakes in southwest Colorado's San Juan Mountains over millennia indicates the sharp rise in dust deposits coincided with railroad, ranching and livestock activity in the middle of the last century, said geological sciences Assistant Professor Jason Neff, lead author on the study. The results have implications ranging from ecosystem alteration to human health, he said.

"From about 1860 to 1900, the dust deposition rates shot up so high that we initially thought there was a mistake in our data," said Neff. "But the evidence clearly shows the western U.S. had it's own Dust Bowl beginning in the 1800s when the railroads went in and cattle and sheep were introduced into the rangelands."

A paper on the research funded by the Andrew W. Mellon Foundation was published in the Feb. 24 issue of Nature Geoscience. Co-authors included CU-Boulder's Ashley Ballantyne, Lang Farmer and Corey Lawrence, Cornell University's Natalie Mahowald, the University of Arizona's Jessica Conroy and Jonathan Overpeck, Christopher Landry of the Center of Snow and Avalanche Studies in Silverton, Colo., the University of Utah's Tom Painter and the U.S. Geological Survey's Richard Reynolds.

The study indicates "dust fall" in the West over the past century was five to seven times heavier than at any time in the previous 5,000 years, said Neff, who is also a faculty member in CU-Boulder's Environmental Studies Program. While some fine-grained dust from Asia periodically falls on Colorado's San Juans, the abundance of larger-sized dust particles in the lake sediments there indicates most of the dust originated regionally in the Southwest, said the authors.

While droughts can trigger erosion and increased dust deposition, western U.S. droughts during the past two centuries have been relatively mild compared to droughts over the past 2,000 years, Neff said. Instead, the increased dustiness in the West coincides with intensive land use, primarily grazing, according to radiocarbon dating and lead isotope analysis of soil cores retrieved from lakebeds, he said.

"There were an estimated 40 million head of livestock on the western rangeland during the turn of the century, causing a massive and systematic degradation of the ecosystems," said Neff. The 1934 Taylor Grazing Act that imposed restrictions on western grazing lands coincided with a decrease in accumulation rates of the San Juan lake sediments in the study -- a decrease that continues to today, he said.

The study also shows more than a five-fold increase in nutrients and minerals in the lakebed sediments during the last 150 years, said Neff. Increases in nitrogen, phosphorus, potassium, calcium and magnesium -- byproducts of ranching, mining and agricultural activity - have been shown to change water alkalinity, aquatic productivity and nutrient cycling.

In the Niwot Ridge alpine region west of Boulder, for example, CU-Boulder researchers have observed increased algal growth in streams and lakes as a result of rising nitrogen deposition, as well as changes in the composition and diversity of wildflowers on the tundra. "Because these types of inputs have the potential to increase plant growth, the ultimate outcome of such depositions could change the fabric of our ecosystems," said Neff.

Excessive dust also can cause significant human health problems, including lung tissue damage, allergic reactions and respiratory problems, Neff said.

The San Juan lakes are located in an area dominated by rocky talus slopes with little soil and vegetation at about 13,000 feet in elevation and are located downwind of several major U.S. deserts like the Colorado Plateau and the Mojave. The site was chosen in part because the San Juans experience frequent wintertime dust deposition events -- usually between four to seven episodes annually, Neff said.

A study published in Geophysical Research Letters in 2007 involving co-authors of the Nature Geoscience paper, including Neff, showed wind-blown dust from disturbed lands in the Southwest shortened the duration of San Juan mountain snow cover by roughly a month. "The dust we see in these lakes is the same dust that causes earlier spring snowmelt here, so we can now definitively say that humans are in large part responsible for this melt," said Neff.

"There seems to be a perception that dusty conditions in the West are just the nature of the region," said Neff. "We have shown here that the increase in dust since the 1800s is a direct result of human activity and not part of the natural system."

Jason Neff | EurekAlert!
Further information:
http://www.colorado.edu

More articles from Earth Sciences:

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

nachricht Canadian glaciers now major contributor to sea level change, UCI study shows
15.02.2017 | University of California - Irvine

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>