isotope – Geobites

April 29, 2022April 29, 2022

Silver Doesn’t Grow on Trees: The Quest for the Ores that Formed Roman Coinage

Featured image: A silver Roman Denarius, featuring the likeness of emperor Marcus Aurelius. CC BY-SA 3.0 via Wikimedia Commons

Paper: Silver isotope and volatile trace element systematics in galena samples from the Iberian Peninsula and the quest for silver sources of Roman coinage

Authors: Jean Milot; Janne Blichert-Toft; Mariano Ayarzagüena Sanz; Chloé Malod-Dognin; Philippe Télouk; Francis Albarède

The Roman Empire was a superpower thousands of years ago, and with great power comes great (fiscal) responsibilities, including minting the money. To mint silver coins, the Romans needed vast amounts of silver, which historians and archeologists believe originated in the Iberian Peninsula, or present-day Spain and Portugal. However, the geologic origin of that silver is unknown as the depleted mines were abandoned long ago.

October 12, 2021October 12, 2021

Ancient trees tell the story of modern climate change

Featured Image: Larch trees. Image courtesy North Cascades National Park, used with permission.

Paper: Spring arctic oscillation as a trigger of summer drought in Siberian subarctic over the past 1494 years

Authors: Olga V. Churakova Sidorova, Rolf T. W. Siegwolf, Marina V. Fonti, Eugene A. Vaganov, Matthias Saurer

Seemingly straight out of a fairytale, ancient trees are able to convey details about Earth’s complex history to the scientists willing and able to listen. Deep in the Siberian Arctic lie the secrets of past weather events, ocean currents, and droughts that occurred thousands of years ago, locked away in petrified wood and in the oldest living larch trees. We often hear in the news how the Siberian forest is victim to extreme drought and fire—something that is new as of the recent century. But how “new” are these events, and what exactly is perpetuating this new cycle?

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.