NatureFirst USA

Global Warming Is Changing Organic Matter In Soil: Atmosphere Could Change As A Result

November 28, 2008

New research shows that we should be looking to
the ground, not the sky, to see where climate change could have its most
perilous impact on life on Earth.

Scientists at the University of Toronto Scarborough have published research
findings in the journal Nature Geoscience that show global warming actually
changes the molecular structure of organic matter in soil.

"Soil contains more than twice the amount of carbon than does the atmosphere,
yet, until now, scientists haven't examined this significant carbon pool
closely," says Myrna J. Simpson, principal investigator and Associate Professor
of Environmental Chemistry at UTSC. "Through our research, we've sought to
determine what soils are made up of at the molecular level and whether this
composition will change in a warmer world."

Soil organic matter is what makes dirt fertile and able to support plant life
both of which are especially important for agriculture. Organic matter retains
water in the soil and prevents erosion. Natural processes of decomposition of
soil organic matter provide plants and microbes with the energy source and water
they need to grow, and carbon is released into the atmosphere as a by-product of
this process. Warming temperatures are expected to speed up this process which
will increase the amount of CO2 that is transferred to the atmosphere.

"From the perspective of agriculture, we can't afford to lose carbon from the
soil because it will change soil fertility and enhance erosion" says Simpson.
"Alternatively, consider all the carbon locked up in permafrost in the Arctic.
We also need to understand what will happen to the stored carbon when microbes
become more active under warmer temperatures."

Until Simpson's research, scientists didn't know much about soil's molecular
composition. Part of the reason is that, from a chemical perspective, soil is
difficult to analyze due to its many components, including bacteria, fungi and
an array of fresh, partially degraded, or old plant material. Simpson's team,
which includes research collaborators Professors Dudley Williams and Andre
Simpson, is uniquely positioned to address this new frontier. The team uses a
NMR (Nuclear Magnetic Resonance) facility - the only NMR facility in Canada
specifically dedicated to environmental research to gain a detailed view of
soil's molecular structure and reactivity.

In their current study, Simpson's team used an outdoor field experiment in the
valley behind the UTSC campus to ensure natural ecosystem processes were
preserved. Electrodes warmed the test soil between three and six degrees through
winter and summer seasons, over a 14-month period. Throughout the test period,
the team analyzed the molecular composition of soil samples.



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