Articles in 2016

Mercury is a toxic element with no known biological function. Laboratory studies demonstrate that mercury can be beneficial to microbial growth by acting as an electron acceptor during photosynthesis.

Volcanic eruptions at ocean ridges produce large volumes of glass that is rapidly leached by seawater. Geochemical calculations suggest that this process helps to explain the deposition of carbonates at the end of extreme ice ages.

Streamflow is a mixture of precipitation of various ages. Oxygen isotope data suggests that a third of global river discharge is sourced from rainfall within the past few months, which accounts for less than 0.1% of global groundwater.

Transfer of CO₂ from Earth’s interior to the atmosphere happens largely by volcanic degassing. Measurements of CO₂ emissions from faults in the East African Rift system imply that tectonic degassing is also important for deep carbon release.

Bacteria have been shown to be involved in the reduction of Hg^II to elemental mercury. Laboratory experiments with Hg^II and different carbon sources reveal that purple bacteria can use Hg^II as an electron acceptor, promoting bacterial growth.

The Cryogenian Snowball Earth glaciations were followed by the deposition of massive cap carbonates. Geochemical modelling suggests that shallow-ridge volcanism supplied much of the alkalinity and cations that fuelled this deposition.

Nutrient input from icebergs can fertilize productivity in the ocean. Ten years of satellite measurements reveal that giant icebergs could be responsible for up to 20% of carbon export to depth in the Southern Ocean.

How Himalayan topography is built is unclear. Analysis of surface displacement during the 2015 Gorkha earthquake suggests that large earthquakes may lower the high Himalayan mountains, and topography may grow during the interseismic phase.

The time at which plate tectonics were initiated on Earth is unclear. Geochemical analysis of diamonds suggests that recycled oxidized material could have been introduced to the mantle via subduction zones more than 3 billion years ago.

The volcanic eruption that created the Ontong Java Plateau released large quantities of carbon dioxide. A reconstruction of CO₂ concentrations suggests that the eruption promoted climate change and the expansion of ocean anoxia.

The El Niño/Southern Oscillation (ENSO) affects weather patterns worldwide. Numerical experiments with an Earth system model suggest that cloud feedbacks act to amplify ENSO variability by a factor of two or more.

A period of ocean anoxia about 120 million years ago coincided with high temperatures. A reconstruction of CO₂ concentrations shows that volcanic outgassing from the Ontong Java Plateau caused CO₂ levels to double during the anoxic event.

Lakes are sources of the greenhouse gas methane. A synthesis of measurements of methane emissions reveals that lakes and ponds above 50 °N emit 16.5 Tg methane annually, and emissions may increase by 20 to 50% with longer ice-free seasons.