Nav: Home

Critical zone, critical research

December 07, 2016

The Earth's critical zone isn't called critical for nothing. Known as our planet's outer skin, it is essential for human survival.

The critical zone extends from the top of the tallest tree down through the soil and into the water and rock beneath it. It stops at what's called the weathering zone -- or where soils first begin to develop. This zone allows crops to grow well and supports our buildings. It also allows for animals and microbes to live, and filters our water. These soil characteristics affect everything from the ground up.

Henry Lin of Pennsylvania State University follows the research on the critical zone and recently wrote a review on work in the area. Over the last five years there have been over 200 peer-reviewed articles published on topics related to the critical zone.

"The critical zone is where soil, rock, water, air, and living organisms all interact, which determines how many resources we are able to use," Lin says. "The critical zone provides various services to human society."

Lin explains the critical zone isn't just something physical. It is also a research approach. Scientists can study the critical zone as a whole to understand the Earth's layers across space and time. The approach also assists with long-term management of natural resources.

"The critical zone approach provides a framework for combining belowground and aboveground, non-living and living, and space and time in our ecosystems," he says. "To truly understand this zone, research from many areas must be mixed into one framework. It includes perspectives on time, depth, and coupling."

Each of these three concepts in the framework has specific impacts on the critical zone. For example, slow changes to soil over time lead to specific soil structures that control water movement. However, at the same time, each pulse of water moving through soil causes changes to the soil as well. How do these fast and slow processes affect each other?

When looking at depth, Lin points to an example of work being done using ground-penetrating radar to map what the critical zone looks like below what human eyes can see. Lastly, the coupled approach combines the study of the critical zone with its impact on natural resources and the benefits the ecosystem provides humans.

Lin says research in these three areas is important to understand the effects humans can have on the critical zone. By studying this zone, it is even possible to look at how it's changed over time and predict what will happen to it down the road.

Looking to that future, Lin calls for more work to be done. For example, he would like to see the global community work together to create a network of critical zone study and develop a library of databases about the zone.

"With our ongoing development, the critical zone is under ever-increasing pressures from humans, such as rapid growth of human and livestock population, land use increases, and global environmental changes," he says. "Possible negative effects include degraded soil health and water quality. It's important to continue closely studying this area."
-end-
Read Lin's review in Vadose Zone Journal. His research is supported in part by the National Science Foundation Hydrologic Sciences Program and the Critical Zone Observatory Program. Our thanks to Venkat Lakshmi for contributions to this story.

American Society of Agronomy

Related Water Articles:

Source water key to bacterial water safety in remote Northern Australia
In the wet-dry topics of Australia, drinking water in remote communities is often sourced from groundwater bores.
Our water cycle diagrams give a false sense of water security
Pictures of the earth's water cycle used in education and research throughout the world are in urgent need of updating to show the effects of human interference, according to new analysis by an international team of hydrology experts.
Water management helped by mathematical model of fresh water lenses
In this paper, the homeostasis of water lenses was explained as an intricate interaction of the following physical factors: infiltration to the lens from occasional (sporadic) rains, permanent evaporation from the water table, buoyancy due to a density contrast of the fresh and saline water, and the force of resistance to water motion from the dune sand.
The age of water
Groundwater in Egypt's aquifers may be as much as 200,000 years old and that's important to know as officials in that country seek to increasing the use of groundwater, especially in the Eastern Desert, to mitigate growing water stress and allow for agricultural projects.
Water that never freezes
Can water reach minus 263 degrees Celsius without turning into ice?
More Water News and Water Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...