Minerals let Earth’s oceans seep down deeper than expected

Amphiboles could carry the volume of the Arctic Ocean into Earth’s mantle in 200 million years

A bigger volume of the world’s oceans is seeping deeper into Earth’s mantle than expected: That is the result of a study investigating a water-bearing mineral abundant in the oceanic crust. High-pressure experiments at DESY’s X-ray source PETRA III show that the mineral glaucophane is surprisingly stable up to 240 kilometres underground, which means it also carries water down to this depth. Scientists attribute this to the gradual cooling of Earth’s interior over geological timescales. The cooler temperatures let glaucophane and possibly other water-bearing minerals survive to greater pressures, as the team headed by Yongjae Lee from Yonsei University in South Korea reports in the journal Nature Communications. The scientists estimate that in about 200 million years, an additional volume equal to the Arctic Ocean could seep deep into Earth’s mantle this way.

Read more on the DESY website

Image: In the high-pressure cell, glaucophane samples are heated and squeezed between two diamond anvils

Credit: Yonsei University, Yoonah Bang/Huijeong Hwang

X-Rays reveal the biting truth about parrotfish teeth

Interwoven crystal structure is key to coral-crunching ability

So, you thought the fictional people-eating great white shark in the film “Jaws” had a powerful bite. But don’t overlook the mighty mouth of the parrotfish – its hardy teeth allow it to chomp on coral all day long, ultimately chewing and grinding it up through digestion into fine sand. That’s right: Its “beak” creates beaches. A single parrotfish can produce hundreds of pounds of sand each year.

Now, a study by scientists – including those at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) – has revealed a chain mail-like woven microstructure that gives parrotfish teeth their remarkable bite and resilience.

The natural structure they observed also provides a blueprint for creating ultra-durable synthetic materials that could be useful for mechanical components in electronics, and in other devices that undergo repetitive movement, abrasion, and contact stress.

Matthew Marcus, a staff scientist working at Berkeley Lab’s Advanced Light Source (ALS) – an X-ray source known as a synchrotron light source that was integral in the parrotfish study – became intrigued with parrotfish during a 2012 visit to the Great Barrier Reef off of the coast of Australia.

>Read More on the ALS website

Image: Scientists studied the microstructure of the coral-chomping teeth of the steephead parrotfish, pictured here, to learn about the fish’s powerful bite.
Credit: Alex The Reef Fish Geek/Nautilus Scuba Club, Cairns, Australia

Direct and Efficient Utilization of Solid-phase Iron by Diatoms

A research team indicates that diatoms, can directly uptake iron from insoluble iron sediments, and thereby potentially affect atmospheric carbon dioxide level.

A research team from Columbia University indicates that diatoms, photosynthetic marine organisms responsible for as much as 20% of photosynthesis in the world’s oceans, can directly uptake iron from insoluble iron sediments, and thereby potentially affect atmospheric carbon dioxide level. Although iron is often present in the ocean, usually there is insufficient iron for diatoms and other organisms to grow quickly unless this iron is dissolved and in a form that can be used readily. This research establishes that iron from mineral phases can be quite bioavailable, and that the diatoms can use most forms of iron, but appear to have a preference for a specific form of iron, ferrous iron, in the mineral phases. This research is applicable to a wide variety of questions in earth and ocean sciences, including basic biology of nutrient acquisition, the coupling of physical and geological processes such as glaciers to climate and geoengineering.

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Picture: Glacial striations seen near Upsala Glacier, Argentina, where scientists collected glacial samples. This physical scraping produces sediments and dust that can fertilize plankton when it is delivered to the ocean.
Photo by Michael Kaplan/Lamont-Doherty Earth Observatory