Archive for August 8, 2019

Deep hydrous mantle reservoir provides evidence for crustal recycling before 3.3 billion years ago

Water strongly influences the physical properties of the mantle and enhances its ability to melt or convect. Its presence can also be used to trace recycling of surface reservoirs down to the deep mantle1, which makes knowledge of the water content in the Earth’s interior and its evolution crucial for understanding global geodynamics.

Komatiites (MgO-rich ultramafic magmas) result from a high degree of mantle melting at high pressures2 and thus are excellent probes of the chemical composition and water contents of the deep mantle. An excess of water over elements that show similar geochemical behaviour during mantle melting (for example, cerium) was recently found in melt inclusions in the most magnesium-rich olivine in 2.7-billion-year-old komatiites from Canada3 and Zimbabwe4. Read more

Water monitor

Seismic noise – the low-level vibrations caused by everything from subway trains to waves crashing on the beach – is most often something seismologists work to avoid. They factor it out of models and create algorithms aimed at eliminating it so they can identify the signals of earthquakes.

But Tim Clements thinks it might be tool to monitor one of the most precious resources in the world – water.

A graduate student working in the lab of Assistant Professor of Earth and Planetary Sciences Marine Denolle, Clements is the lead author of a recent study that used seismic noise to measure the size and the water levels in underground aquifers in California. The technique could even be used to track whether and how aquifers rebound following precipitation, and understand geological changes that might occur as water is pumped out. The study is described in a recently-published paper in Geophysical Research Letters. Read more

Wringing water from the air

Scientists estimate that half a billion people in the world lack sufficient water to meet their daily needs, and that number is only expected to rise with the ever-growing population and a changing climate. Therefore, researchers are working on technologies to soak up water from an abundant resource — the air. An article in Chemical & Engineering News (C&EN), the weekly newsmagazine of the American Chemical Society, describes several promising approaches.

Many water-harvesting devices are inspired by nature, Senior Correspondent Bethany Halford writes. For example, giant sequoia trees collect water from fog on their needles, which are parallel to one another. The water rolls downward and then drips to the tree’s roots. Using the same principle, researchers have developed a fog-harvesting apparatus (called a “fog harp”) with vertical parallel wires that catch microscopic droplets from the air and direct them into a water collector. Other fog-harvesting systems have been inspired by the tiny hairs on the Salsola crassa shrub, parallel grooves on rice leaves and the slippery lubricant of carnivorous pitcher plants. Read more

How water rules the world

Why should I care about water when I can get as much as I want from my kitchen sink? That question might sound very different if you lived in Flint, Michigan or in a region of the world experiencing severe drought.

Water is everything. Actually, water is shockingly bizarre in its properties and of unsurpassed importance throughout human history, yet so mundane as to often be invisible in our daily lives. Water shaped civilization. People are increasingly aware of the intimate role that water plays in our quality of life and our relationship with society and the environment. Water Is… The Indispensability of Water in Society and Lifeexplores the ways-big and small-that water rules the world. It provides a holistic perspective on water, capturing the full breadth of the science, technology, policy, history, and future outlook for the most important substance on earth, written at a level accessible to non-experts in each of these areas. Read more