Archive for August 30, 2019

Earth Is Sucking Down Way More Water Than We Thought, And No One’s Sure Where It’s Going

Slow-motion collisions of tectonic plates under the ocean drag about three times more water down into the deep Earth than previously believed, according to a seismic study that spans the Mariana Trench.

The observations from the deepest ocean trench in the world have important implications for the global water cycle, researchers say.

“People knew that subduction zones could bring down water, but they didn’t know how much water,” says Chen Cai, who recently completed his doctoral studies at Washington University in St. Louis and is first author of the paper, which appears in Nature.

“This research shows that subduction zones move far more water into Earth’s deep interior—many miles below the surface—than previously thought,” says Candace Major, a program director in the National Science Foundation’s Division of Ocean Sciences, which funded the study. Read more

How Mars lost its water to space

How the sun pumps out water from Mars into space

Russian and German physicists have offered an explanation for the new data obtained by Martian satellites, capturing the “escape” of hydrogen atoms from the upper Martian atmosphere into outer space. The developed model fits well with the observations and explains a number of puzzling phenomena related to the atmosphere of Mars. The research was published in the journal Geographical Research Letters.

The atmosphere of Mars is cold and rarefied, like the Earth atmosphere at high altitudes. Under such conditions, there is no liquid water, but rather clouds consisting of tiny ice crystals. On Earth, such clouds — called “feathery” — are formed at 6 kilometers above the surface. As the ice crystals are rather heavy, the bulk of the water is contained in the lower atmospheric layer, approximately 60 kilometers thick. However, the data obtained from the U.S. satellite MAVEN (short for “Mars Atmosphere and Volatile EvolutioN”) and the Hubble Space Telescope evidences a periodic stream of hydrogen atoms escaping the planet. Their only source may be water dissociating into oxygen and hydrogen in the upper atmospheric layers (70-80 kilometers from the ground) as a result of exposure to ultraviolet radiation. Read more

The Water Future of Earth’s ‘Third Pole’

Himalaya. Karakoram. Hindu Kush. The names of Asia’s high mountain ranges conjure up adventure to those living far away, but for more than a billion people, these are the names of their most reliable water source.

Follow the Freshwater: By predicting droughts and floods and tracking blooms of algae, NASA’s view of freshwater around the globe helps people manage their water.

Snow and glaciers in these mountains contain the largest volume of freshwater outside of Earth’s polar ice sheets, leading hydrologists to nickname this region the Third Pole. One-seventh of the world’s population depends on rivers flowing from these mountains for water to drink and to irrigate crops.

Rapid changes in the region’s climate, however, are affecting glacier melt and snowmelt. People in the region are already modifying their land-use practices in response to the changing water supply, and the region’s ecology is transforming. Future changes are likely to influence food and water security in India, Pakistan, China and other nations.

Rapid changes in the region’s climate are affecting glacier flows and snowmelt. Local people are already modifying their land-use practices in response to the changing supply, and the region’s ecology is transforming. Scientists estimate that by 2100, these glaciers could be up to 75% smaller in volume.

NASA is keeping a space-based eye on changes like these worldwide to better understand the future of our planet’s water cycle. In this region where there are extreme challenges in collecting observations on the ground, NASA’s satellite and other resources can produce substantial benefits to climate science and local decision makers tasked with managing an already-scarce resource. Read more

A new catalyst for water splitting that is the best of both worlds

However, catalysts, including those used to “split” water, have either worked well but are expensive and unstable, or are affordable and stable, but don’t work as well. Now, researchers report in ACS Central Science a new catalyst that is really the best of both worlds.

Identifying ideal materials that can split water is a long-standing problem in renewable energy storage. Catalysts, which help reactions occur, are often used in this process. “Homogeneous” ones dissolve into the reaction solution and are usually active and selective. However, they don’t work well in some applications because they are unstable and expensive. In contrast, “heterogeneous” catalysts are solids that are stable, recyclable and convenient to work with, but they are usually not very active or selective. Dunwei Wang and colleagues proposed they could get closer to the ideal catalyst by producing a hybrid material. Read more

Pine and poplar wood improve sunlight-driven water purification

Engineers at the University of Maryland have found that porous types of wood from trees like poplar and pine can greatly increase the efficiency of water-to-steam conversion under sunlight. The findings, published November 15 in the journal Joule, could be used in a simple and inexpensive biodegradable device for water purification.

“I think there are many, many materials that can be used in solar steam generation, but wood really stands out in terms of performance as well as cost,” says senior author Liangbing Hu, Associate Professor of Materials Science and Engineering in the A. James Clark School of Engineering and the University of Maryland Energy Innovation Institute. Read more