Volume 13 Issue 8, August 2020

The Archaean atmosphere may have been well oxygenated, according to a reconsideration of sulfur cycling at that time. This challenges the view that sedimentary sulfur records oxygen-poor conditions during Earth’s first two billion years.

Organic carbon in the top metre of Earth’s soils is far older than previously thought, averaging 4,800 years old. These radiocarbon-derived age estimates require us to recalibrate our expectations of ecosystem gains and losses of carbon.

Dynamic interactions between chemical and biological controls govern the stability of soil organic carbon and drive complex, emergent patterns in soil carbon persistence.

A review of the organic carbon cycle explores the interactions between the Earth’s surface and deeper reservoirs, the expanding inorganic controls on the organic carbon cycle, and how these links have strengthened through geological time.

Thermomechanical modelling shows that the formation and diverse morphologies of coronae on Venus can be explained by interactions between the lithosphere and impinging mantle plumes. Some corona structures are consistent with ongoing plume activity.

Soils may accumulate less carbon and with a slower turnover than Earth system models predict, according to analysis of the age distribution of global soil carbon, which finds that the mean age of soil carbon is older than that in simulated in models.

Plant roots in thawing permafrost soils act to enhance microbial decomposition and the loss of soil organic carbon, according to an analysis of observational data and a rhizosphere priming model.

Fast settling rates of suspended silt and clay particles suggest that mud in rivers is largely flocculated and part of suspended bed-material load.

Increased river incision and landscape erosion can be attributed to late Cenozoic cooling/changes in hydroclimate, according to cosmogenic isotope and luminescence ages of a sequence of bedrock terraces in the Yukon River basin.

Formation of mass-independent isotope fractionation of sulfur signatures recorded in Archaean sedimentary rocks could have occurred in an oxygen-rich atmosphere, according to thermodynamic and kinetic calculations and analysis of Earth’s early sulfur cycle.

The mantle lithosphere has thinned more than the crust beneath the Malawi Rift despite being melt-poor, according to seismic wave imaging; this suggests early melting of fusible mantle material.