Muddy waters lead to decreased oxygen in Chesapeake Bay

Featured Image: Plumes of muddy, sediment-laden water at the Chesapeake Bay Bridge near Annapolis, MD. Photo courtesy of Jane Thomas/ IAN, UMCES.

Paper: Seabed Resuspension in the Chesapeake Bay: Implications for Biogeochemical Cycling and Hypoxia
Authors: Julia Moriarty, Marjorie Friedrichs, Courtney Harris

A memorable feature of the Chesapeake Bay, the largest estuary in the USA, is that the water is very murky and looks like chocolate milk. Former Senator Bernie Fowler has conducted public “wade-ins” over the past 50 years in one of the Bay’s tributaries, seeing how deep the water is before he can no longer see his white tennis shoes, and let’s just say it is never very deep. This is because of the high concentrations of sediment, or small particles of sand and organic material, in the water. Besides making it harder for seagrasses to grow and serving as food for the economically-important oyster, sediment impacts the biological processes that determine how much oxygen and nutrients are available in the water for algae and fish.

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Mosaics of Life Along a River

Featured Image: Small headwater stream in Oregon’s Mountains. Image courtesy Jessica Buser-Young, used with permission.

Paper: The River Continuum Concept

Authors: Robin L. Vannote, G. Wayne Minshall, Kenneth W. Cummins, James R. Sedell, Colbert E. Cushing

Perhaps last time you went for a hike, you stumbled upon a burbling spring pushing its way up through the leaf litter after a heavy rainfall, creating a tiny rivulet of water crisscrossing over your path before plunging back into the forest. What a find! Excitedly, you squatted down and gently uncovered the spring to notice gnats lazily floating away, some nearby fruiting mushrooms, and great clumps of decomposing twigs and leaves which you assume harbor uncountable numbers of microorganisms. This unique little ecosystem is profiting from the nutrients and water being pushed from the ground, using the opportunity to have a feast. But what happens to the nutrients and carbon that gets past these plants and animals?

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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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Antarctic krill and their role in ocean carbon cycling

Antarctic Krill under a microscope. Photo courtesy of Uwe Kils, CC-BY-SA 3.0

Paper: Manno et al. (2020)

The transfer of carbon from the surface ocean to the deep ocean, or carbon export, can strongly influence climate. The main pathway of carbon export in the ocean is through sinking particles, also known as the biological carbon pump. These sinking particles can include plankton biomass, aggregates of cells, and zooplankton feces and molts. Understanding what contributes to carbon export is important in understanding how this may change as temperatures warm due to climate change.

A recent study by Manno et al. found that Antarctic krill in the Southern Ocean may play a significant role in transporting carbon to the deep ocean through their carcasses, fecal material, and most notably their molts, or shedding of their shells. Exoskeletons are not only an important vehicle for carbon export but also provide food to animals living on the seafloor. This is the first study to investigate the contribution of krill molts to carbon export in the Southern Ocean.

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When Lightning Strikes! Fulgurite Formation and Earth’s Weather

Paper: Lightning-induced weathering of Cascadian volcanic peaks


Authors: Jonathan M. Castro, Franziska Keller, Yves Feisel, Pierre Lanari, Christoph Helo, Sebastian P. Mueller, C. Ian Schipper, Chad Thomas

The bright flashes followed by the loud thunderclaps of large storms are inherently transient, but a recent study by Castro et al proposes a new approach to investigating the history of storm activity and extreme weather events on Earth: through fossilized lightning strikes, or fulgurites.

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How did valleys form on early Mars? Some say in ice…

Featured image: The Nirgal Vallis river valley on Mars as seen by the HRSC Camera onboard the European Space Agency’s Mars Express mission. Image credit: ESA/DLR/FU Berlin.

Paper: Valley formation on early Mars by subglacial and fluvial erosion.

Authors: Anna Grau Galofre, A. Mark Jellinek & Gordon R. Osinski.

“Some say the world will end in fire/ Some say in ice” begins the famous poem by Robert Frost. But what about how worlds begin? For years the theory of a “warm and wet” early Mars has been the conventional explanation for the vast valley networks formed billions of years ago that we can see on the surface today. Now, a new study suggests that at least some of these valleys could have formed under colossal ice sheets, in a distinctly more icy world.

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Looking below ground for secrets to drought resilience

Santa Ynez Mountains

Featured image: Oak savanna near the Santa Ynez mountains in California. Clyde Frogg, public domain.

Paper: Low Subsurface Water Storage Capacity Relative to Annual Rainfall Decouples Mediterranean Plant Productivity and Water Use From Rainfall Variability

Authors: Hahm, W. J., Dralle, D. N., Rempe, D. M., Bryk, A. B., Thompson, S. E., Dawson, T. E., & Dietrich, W. E.

Between 2011 and 2016, a severe drought killed over 100 million trees in California. However, not all places responded to this drought in the same way. In some locations, trees and other plants seemed hardly affected, while in other places mortality was widespread. What caused this difference? In a 2019 study, Hahm and colleagues explored the role that water storage in ecosystems has on their resilience to drought. With extreme droughts becoming more common due to climate change, understanding why certain areas are more vulnerable is important for making predictions and improving forest management.

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Satellite Technology Helps Discover New Weather Phenomena: Lightning Megaflashes

Featured Image from Bethany Laird on Unsplash

Paper: Where are the Most Extraordinary Lightning Megaflashes in the Americas?

Author: Michael Peterson

Most lightning flashes only last 0.2 seconds, meaning if you blink at the wrong moment, you could miss it. However, scientists have developed new lightning-detection instruments, known as Geostationary Lightning Mappers (GLMs), that never miss a flash. The GLMs are aboard the two Geostationary Operational Environmental Satellites (GOES-West and GOES-East), which are in stationary orbits over the Earth’s western hemisphere. With the data from the GLMs, atmospheric scientists have discovered new lightning phenomena called “megaflashes” which can light up the sky for as long as 16 seconds.

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Building mountains

Featured image: Yushan (Jade Mountain) in Taiwan. From Wikimedia Commons by Kailing3 under a CC-BY-SA 3.0 license.

Paper: Coseismic Uplift of the 1999 Mw7.6 Chi‐Chi Earthquake and Implication to Topographic Change in Frontal Mountain Belts

Authors: R.Y. Chuang, C.H. Lu, C.J. Yang, Y.S. Lin, and T.Y. Lee

Journal: Geophysical Research Letters

The height of a mountain range results from a hard-fought battle between tectonic plates and the forces of erosion. Earthquakes generated by clashes between plates cause the upward motion of rock even as they shake the landscape, causing large and numerous landslides. When a large earthquake occurs, which process wins? Does more rock go up than come down, leading to a higher mountain range? Or does shaking-induced erosion remove more material than is uplifted by the earthquake? New research suggests that earthquakes might be able to build mountains up faster than landslides can bring them down.

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The role of carbon in a changing Arctic

Paper: Freshening of the western Arctic negates anthropogenic carbon uptake potential

Authors: R.J. Woosley and F.J. Millero

Journal: Limnology and Oceanography

As human generated emissions of carbon dioxide continue to increase, scientists seek to understand the potential for ‘sinks’, or places that the excess CO2 can move in the global carbon cycle, to take up and store some of the increased emissions. Understanding how these carbon sinks may react to increasing global emissions helps to better predict both the rate of atmospheric increase in the future and the potential response of global ecosystems, including major sinks in forests and oceans.

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