Geobites – Page 15 – Down-to-Earth Geoscience Writing

October 22, 2020October 26, 2020

Isotopes Begin to Unlock the Mystery of Methane Source in the Scheldt Estuary

Scheldt Estuary with tidal flats and water shown

Featured Image: Eastern Scheldt Estuary near Zeeland, Netherlands. Photo courtesy Wikimedia Commons/ Luka Peternel, CC BY-SA 4.0 license.

Paper: Carbon and Hydrogen Isotope Signatures of Dissolved Methane in the Scheldt Estuary

Authors: Caroline Jacques, Thanos Gkritzalis, Jean-Louis Tison, Thomas Hartley, Carina van der Veen, Thomas Röckmann, Jack J. Middelburg, André Cattrijsse, Matthias Egger, Frank Dehairs & Célia J. Sapart

Estuaries are dynamic coastal environments where freshwater and saltwater collide and mix. Across the world, estuaries regularly have higher methane concentrations in the water than would be expected from equilibrium with the atmosphere. If the water was in equilibrium, or at a happy balance, with the atmosphere, then there would be no net transfer of methane to the atmosphere. Because there is more methane than expected in the water, estuaries are a source of this potent greenhouse gas, methane (CH₄), to the atmosphere. The problem is that the processes leading to the excess methane in the estuary’s surface water are not well known in many European estuaries.

October 20, 2020October 22, 2020

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.

Continue reading “Tracing the origin of Earth’s water with meteorites”

October 16, 2020October 16, 2020

What’s in the Water?

Paper: Contemporary limnology of the rapidly changing glacierized
watershed of the world’s largest
High Arctic lake

Authors: K. A. St. Pierre, V. L. St. Louis, I. Lehnherr, S. L. Schiff, D. C. G. Muir , A. J. Poulain, J. P. Smol, C. Talbot, M. Ma, D. L. Findlay, W. J. Findlay, S. E . Arnott, Alex S . Gardner

As glaciers recede in the arctic, the increase in meltwater may significantly impact downstream ecosystems. Glacial ice can hold thousands of years’ worth of dust, nutrients, and other materials that are released during melting. As the rate of melt increases with a warming climate, the release has the potential to increase nutrient flows and sediment loads, alter pH, and impact other physical, chemical, and biological aspects of downstream watersheds. These changes could negatively impact water clarity and ecosystem function in lakes, rivers, and the ocean.

October 15, 2020October 15, 2020

Water, but not a drop to drink: multiple salty lakes beneath the south pole of Mars?

Featured image: The south pole of Mars as seen by the HRSC Camera onboard the European Space Agency’s Mars Express mission. Image credit: ESA/DLR/FU Berlin.

Paper: Multiple subglacial water bodies below the south pole of Mars unveiled by new MARSIS data.

Authors: Sebastian Emanuel Lauro, Elena Pettinelli, Graziella Caprarelli, Luca Guallini, Angelo Pio Rossi, Elisabetta Mattei, Barbara Cosciotti, Andrea Cicchetti, Francesco Soldovieri, Marco Cartacci, Federico Di Paolo, Raffaella Noschese and Roberto Orosei.

“Water, water everywhere, but not a drop to drink”- or at least that might be the case beneath the south pole of Mars. In 2018, a team of scientists reported a potential subsurface lake of liquid water 1.5 km beneath the Martian south polar cap. Now, using more observations as well as new analysis methods previously used for ice sheets on Earth, the same team presents new evidence for a large subsurface lake as well as three other lakes in the same area. This raises further questions about how such lakes could be kept liquid in the cold environment of Mars, and whether they could provide a habitable environment for astrobiology.

October 10, 2020October 10, 2020

Rivers underground

Featured Image: The River Styx emerging from Mammoth Cave by Daniel Schwen. From Wikipedia under a CC-BY-SA license.

Paper: Modeling cave cross‐section evolution including sediment transport and paragenesis
Authors: M.P. Cooper and M.D. Covington

It’s not easy to watch caves form. It happens slowly and out of view, so we know relatively little about cave passage erosion compared to our knowledge of how rivers at Earth’s surface work. New research suggests that the same physical erosion processes that cut river channels at the surface might also be at work underground, adding new depth to our understanding of cave genesis.

October 6, 2020October 6, 2020

Strong Atmospheric Updrafts Increase the Danger Associated with Wildfires

Featured Image: Picture of a wildfire by skeeze on Pixabay

Paper: Extreme Pyroconvective Updrafts During a Megafire
Authors: B. Rodriguez, N. P. Lareau, D. E. Kingsmill, and C. B. Clements

Atmospheric updrafts, or columns of air moving quickly upward, are typically associated with severe thunderstorms and tornadoes and have been studied using radar and airplane data for decades. The extreme heat from large, intense fires can also cause updrafts, but this type of updraft has barely been studied by atmospheric science researchers. Understanding the formation and structure of fire-generated updrafts is important because they can be hazardous to aircraft, can loft embers far distances and spark new fires, and can even initiate fire-generated thunderstorms. A recent study has revealed just how powerful these updrafts above large fires can be.

September 24, 2020October 5, 2020

Could corals help study the variability of past Indian monsoons?

Featured image: A coral colony from Maldives, Indian Ocean. Picture credit: Андрей Корман from Pixabay (Public domain)

Paper: Potential of reef building corals to study the past Indian monsoon rainfall variability

Author: Supriyo Chakraborty

Paleooceanographers have often used reef-building corals to study oceanic processes like the El Niño and Southern Oscillation, ocean circulation patterns, air–sea gas exchange, and the Indian Ocean dipole (a.k.a Indian Niño), among others. Yet how exactly do corals provide clues about the physical and chemical conditions of their environments? The answer lies in their skeletons.

September 22, 2020September 28, 2020

What do deep-sea sediment cores tell us about past fish populations?

Black background with fish teeth of different heights and widths

Featured Image: Ichthyoliths (microfossil fish teeth) from deep-sea sediment cores displaying the variety of tooth morphology. Photo courtesy of Elizabeth Sibert, lead author of the paper.

Paper: No state change in pelagic fish production and biodiversity during the Eocene–Oligocene transition

Authors: Elizabeth C. Sibert, Michelle E. Zill, Ella T Frigyik, Richard D. Norris

The seafloor at the bottom of the ocean records what is happening in the water above. Sediments capture silica from diatoms and phytoplankton, carbon from zooplankton poop and detrital marine snow, and teeth after dead fish sink. This last piece of evidence is particularly important: fossilized fish teeth or icthyoliths can help estimate past fish abundance and can show shifts in fish species or biodiversity in the ocean over time.

September 18, 2020September 18, 2020

New 23 million year record of atmospheric carbon dioxide highlights current human influence on the atmosphere

Paper: A 23 m.y. record of low atmospheric CO2

Featured image: Modern vascular land plants (Raphanus sativus), growing in a carbon dioxide experiment (Figure 1A from Jahren et al., 2008)

Authors: Ying Cui, Brian A. Schubert, A. Hope Jahren

Carbon dioxide is a greenhouse gas, trapping warmth within the Earth’s atmosphere. Sixty years of measurements on Hawaii’s Mauna Loa summit have shown rising amounts of carbon dioxide in our atmosphere. In addition, the carbon dioxide levels in our modern atmosphere are significantly higher than those we have seen on Earth over the last 800,000 years, according to measurements on bubbles of ancient air trapped in Antarctic ice. When combined with measurements of global temperatures, these direct measurements are irrefutable evidence for rapid modern climate change. However, understanding our current position relative to Earth’s climate farther back in time is trickier, since scientists have to estimate atmospheric composition indirectly (through a “proxy”). A new study tackles this problem with a new method of estimating past carbon dioxide, showing that modern carbon dioxide levels have been unprecedented since at least 7 million years ago.

September 16, 2020September 16, 2020

Got an apatite for minerals? Of quartz you do!

Minerals, those naturally occurring, inorganic materials with well-defined chemical compositions and crystal structures have long influenced human culture and fascinated (geo)scientists. Some of the earliest descriptions of minerals and their uses date back to Ancient Egypt, recorded on papyri, as well as on stelae (blocks of stone or wood), and ostraca (clay tablets or pottery shards). Minerals and their uses have been intertwined with human history for thousands of years from the gemstone bracelets of the Egyptians and their belief that color was a strong reflection of personality (color symbolism, e.g., the use of gold for crowns on pharaohs and its association with the sun), to the Greeks and their wide use of gemstones in necklaces, and bracelets.