permaculture

[Lawrence London <lfljvenaura@gmail.com>]

On Mon, May 26, 2014 at 11:37 PM, Lawrence London 
<lfljvenaura@gmail.com>wrote:

>
> Buried fossil soils found to be awash in carbon | e! Science News
>
> http://esciencenews.com/articles/2014/05/26/buried.fossil.soils.found.be.awash.carbon?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+eScienceNews%2Fpopular+(e!+Science+News+-+Popular)
>
> Buried fossil soils found to be awash in carbon
> Published: Monday, May 26, 2014 - 19:37 in Earth & 
> Climate<http://esciencenews.com/topics/earth.climate>
>
> Soils that formed on Earth's surface thousands of years ago and that are
> now deeply buried features of vanished landscapes have been found to be
> rich in carbon, adding a new dimension to our planet's carbon cycle. The
> finding, reported in the journal *Nature Geoscience*, is significant as
> it suggests that deep soils can contain long-buried stocks of organic
> carbon which could, through erosion, agriculture, deforestation, mining and
> other human activities, contribute to global climate change.
>
>
Soils that formed on Earth's surface thousands of years ago and that are
now deeply buried features of vanished landscapes have been found to be
rich in carbon, adding a new dimension to our planet's carbon cycle. The
finding, reported in the journal *Nature Geoscience*, is significant as it
suggests that deep soils can contain long-buried stocks of organic carbon
which could, through erosion, agriculture, deforestation, mining and other
human activities, contribute to global climate change.

"There is a lot of carbon at depths where nobody is measuring," says Erika
Marin-Spiotta, a University of Wisconsin-Madison assistant professor of
geography and the lead author of the new study. "It was assumed that there
was little carbon in deeper soils. Most studies are done in only the top 30
centimeters. Our study is showing that we are potentially grossly
underestimating carbon in soils."

The soil studied by Marin-Spiotta and her colleagues, known as the Brady
soil, formed between 15,000 and 13,500 years ago in what is now Nebraska,
Kansas and other parts of the Great Plains. It lies up to six-and-a- half
meters below the present-day surface and was buried by a vast accumulation
of windborne dust known as loess beginning about 10,000 years ago, when the
glaciers that covered much of North America began to retreat.

The region where the Brady soil formed was not glaciated, but underwent
radical change as the Northern Hemisphere's retreating glaciers sparked an
abrupt shift in climate, including changes in vegetation and a regime of
wildfire that contributed to carbon sequestration as the soil was rapidly
buried by accumulating loess.

"Most of the carbon (in the Brady soil) was fire derived or black carbon,"
notes Marin-Spiotta, whose team employed an array of new analytical
methods, including spectroscopic and isotopic analyses, to parse the soil
and its chemistry. "It looks like there was an incredible amount of fire."

The team led by Marin-Spiotta also found organic matter from ancient plants
that, thanks to the thick blanket of loess, had not fully decomposed. Rapid
burial helped isolate the soil from biological processes that would
ordinarily break down carbon in the soil.

Such buried soils, according to UW-Madison geography Professor and study
co-author Joseph Mason, are not unique to the Great Plains and occur
worldwide.

The work suggests that fossil organic carbon in buried soils is widespread
and, as humans increasingly disturb landscapes through a variety of
activities, a potential contributor to climate change as carbon that had
been locked away for thousands of years in arid and semiarid environments
is reintroduced to the environment.

The element carbon comes in many forms and cycles through the environment
-- land, sea and atmosphere -- just as water in various forms cycles
through the ground, oceans and the air. Scientists have long known about
the carbon storage capacity of soils, the potential for carbon
sequestration, and that carbon in soil can be released to the atmosphere
through microbial decomposition.

The deeply buried soil studied by Marin-Spiotta, Mason and their
colleagues, a one-meter-thick ribbon of dark soil far below the modern
surface, is a time capsule of a past environment, the researchers explain.
It provides a snapshot of an environment undergoing significant change due
to a shifting climate. The retreat of the glaciers signaled a warming
world, and likely contributed to a changing environment by setting the
stage for an increased regime of wildfire.

"The world was getting warmer during the time the Brady soil formed," says
Mason. "Warm-season prairie grasses were increasing and their expansion on
the landscape was almost certainly related to rising temperatures."

The retreat of the glaciers also set in motion an era when loess began to
cover large swaths of the ancient landscape. Essentially dust, loess
deposits can be thick -- more than 50 meters deep in parts of the
Midwestern United States and areas of China. It blankets large areas,
covering hundreds of square kilometers in meters of sediment.
Source: University of Wisconsin-Madison <http://www.wisc.edu>


-- 
Lawrence F. London
lfljvenaura@gmail.com
http://www.avantgeared.com
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Skype: lawrence.f.london