Antarctic seafloor oxygen is diminishing–and glaciers may be to blame

Featured Image: Iceberg floating through thin sea ice. Image courtesy NASA ICE, used with permission.

Paper: Glacial melt disturbance shifts community metabolism of an Antarctic seafloor ecosystem from net autotrophy to heterotrophy

Authors: Ulrike Braeckman, Francesca Pasotti, Ralf Hoffmann, Susana Vázquez, Angela Wulff, Irene R. Schloss, Ulrike Falk, Dolores Deregibus, Nene Lefaible, Anders Torstensson, Adil Al-Handal, Frank Wenzhöfer, Ann Vanreusel

Nothing compares to the ethereal beauty of a clear lake. Looking down, you can see a whole world flourishing below: plants, fish, and critters. Compare that to a cloudy, or turbid, lake and suddenly you may feel very small, worried about what’s lurking beneath you. New research shows that the Antarctic ocean is transitioning from clear to turbid water, with big implications for ocean ecosystems.

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Rust to the Rescue?

Featured Image: Shewanella putrefaciens CN-32 (a microbe capable of eating iron) on hematite (a rock containing iron). Image courtesy Environmental Molecular Sciences Laboratory (EMSL). Used with permission.

Paper: Organic matter mineralization in modern and ancient ferruginous sediments

Authors: André Friese, Kohen Bauer, Clemens Glombitza, Luis Ordoñez, Daniel Ariztegui Verena B. Heuer, Aurèle Vuillemin, Cynthia Henny, Sulung Nomosatryo, Rachel Simister Dirk Wagner, Satria Bijaksana, Hendrik Vogel, Martin Melles, James M. Russell, Sean A. Crowe, Jens Kallmeyer

Just as a crow may use a rock to crack a nut, certain microbes can use solid iron to crack open methane.  This consumption limits the amount of methane lost from lakes into the atmosphere, making it a crucial process in mitigating production of greenhouse gasses.  These microbes are abundant in freshwater sediments, and their specialized mechanism for cracking open methane is most likely one of the oldest metabolisms on Earth, providing a modern-day window into the past.

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Capturing Early Sun within meteorite inclusions

Paper: Astronomical context of solar system formation from molybdenum isotopes in meteorite inclusions.

Featured image: Artistic impression of the protoplanetary disk. Image used with permission from Wikipedia (A. Angelich).

Authors: Gregory A. Brennecka, Christoph Burkhardt, Gerrit Budde, Thomas S. Kruijer, Francis Nimmo, Thorsten Kleine.

If you ask a cosmochemist what the oldest objects in the solar system are, they will swiftly answer the Calcium Aluminium Inclusions (CAIs), a small light-coloured inclusion within primitive meteorites known as Chondrites (see figure 2C). However, if you ask what event in the solar system evolution CAIs correspond to, it is a more challenging question. Previously, CAI formation was associated with the various evolutionary stages of our Sun.  However, as the timescale of evolution of Sun, calculated to be around 1 million years by observing Sun like stars, is longer than the CAI forming period (~ 40,000 – 200,000 years), the association between CAI formation and the early stages of our Sun is not always clear. In a quest to put the CAI formation in an astronomical context, a recent study from Brennecka et al. analysed CAIs present within various Carbonaceous chondrite meteorites and linked the CAI formation to a specific stage in the Sun’s evolution.

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Tracing the origin of Earth’s water with meteorites

Paper: Earth’s water may have been inherited from material similar to enstatite chondrite meteorites

Authors: Laurette Piani, Yves Marrocchi, Thomas Rigaudier, Linel G. Vacher, Dorian Thomassin, Bernard Marty

To date, Earth is the only planetary object known to have extensive bodies of liquid water (H2O) at its surface. Water is fundamental to supporting life as we know it with every single organism on our planet requiring water to survive. Even our own human bodies are made up of 60-70% water. However, the origin of Earth’s water has long been debated.


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Do Microbes Release Fluorine from Rocks?

Image of soil microcosm

Featured Image used with permission of photographer (Cassi Wattenburger)

Paper: Indigenous microbes induced fluoride release from aquifer sediments

Authors: Xubo Gao, Wenting Luo, Xuesong Luo, Chengcheng Li, Xin Zhang, Yanxin Wang

My science textbook taught me that fluorine (F) was really important for dental health, and I’ve since learned that both excessive and insufficient amounts of fluoride in groundwater can cause health issues. While the chemistry behind the release of fluoride ions from rocks or sediments into groundwater is well understood, the microbiology of this process is not. Specifically, scientists have been wondering whether microbes could speed up the release of F from sediments into groundwater. 

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