Research articles

Organic phosphorus is removed from the ocean by its conversion to phosphorite. Laboratory incubations suggest that bacteria catalyse phosphorite formation, and that the rate of conversion is greatest under anoxic conditions.

Modelling studies suggest that management of solar radiation could produce stabilized global temperatures and reduced global precipitation. An analysis of a large-ensemble simulation of 54 temperature-stabilization scenarios suggests that it may not be possible to achieve climate stabilization through management of solar radiation simultaneously in all regions.

Sea-level rise is not globally uniform. A combination of observations and climate-model simulations reveals a pattern of sea-level changes in the Indian Ocean, with a decrease in the southern tropical Indian Ocean and a rise elsewhere, that can be attributed to changes in the atmospheric overturning circulation.

The composition, structure and evolution of the Moon’s mantle is poorly constrained. A global survey of the Moon’s surface, using the spectral profiler onboard the lunar explorer SELENE/Kaguya, identifies a number of exposures of olivine in concentric regions around lunar craters, with a possible mantle origin.

Methylmercury is a neurotoxin that accumulates in food webs and poses a significant risk to human health. Laboratory experiments suggest that complexation of methylmercury with sulphur-containing ligands can stimulate its degradation.

Sequestration of carbon dioxide has been proposed for the mitigation of ongoing global warming. Projections with an Earth system model over 100,000 years suggest that leakage from carbon-storage reservoirs of no more than 1% per thousand years, or continuous resequestration, would be required to maintain conditions similar to a low-emissions scenario.

Some faults slip at high angles to the greatest principal compressive stress. The discovery of shear veins formed at angles of about 80 degrees relative to the greatest principal compressive stress in the Chrystalls Beach complex, New Zealand, suggests that slip can be facilitated by a pre-existing rock fabric under high fluid pressure.

The metal content of ore deposits formed during subduction-zone volcanism was thought to be established when the ore fluid separates from the parent magma. Analyses of metal concentrations in erupted melts and the volcanic gases emitted after an eruption in Indonesia reveal that metals can be added to the ore fluid later, during mixing with separated melts.

Thinning ice in West Antarctica is currently contributing about 10% of the observed rise in global sea level. Observations obtained from an autonomous underwater vehicle operating beneath Pine Island Glacier, West Antarctica, reveal that the glacier was recently grounded on a transverse ridge in the sea floor, but now warm sea water flows through the widening gap above the ridge.

River canyons are thought to be cut slowly over millions of years. However, at Lake Canyon Gorge, Texas, a seven-metre-deep canyon was cut in just three days in 2002, providing insight into the erosion processes operating during megaflood events.

A large earthquake has been a national hazard concern for decades in the Tokai region of Japan. The 2009 Suruga Bay earthquake increased seismic stress in strongly locked patches of the Tokai fault plane, potentially increasing the likelihood of a major earthquake in the region.

The deposition of iron formations ceased about 1.84 billion years ago. Reconstructions of ocean chemistry suggest that the advent of euxinic conditions along ocean margins preferentially removed dissolved iron from the water column in the form of the mineral pyrite, inhibiting widespread iron-oxide mineral deposition.

Extension at mid-ocean ridges can be accommodated by detachment faults, forming oceanic core complexes that develop under low rates of magma intrusion. Modelling reveals that oceanic core complexes can also form under high rates of magma intrusion, if the magma is injected into the lower ductile layer of the crust.

The climate of early Mars could have supported a complex hydrological system. Analysis of ancient deltaic deposits and valley networks reveals the presence of a planet-wide equipotential surface in the northern lowlands, indicative of the existence of a vast ocean on Mars 3.5 billion years ago.

An episode of climate warming 200 Myr ago was associated with catastrophic environmental changes. Experimental and palaeontological data suggest that a climate-driven shift to more flammable leaf shapes contributed to increased fire activity in East Greenland at this time.

The diversity of marine life has varied throughout the past 500 million years. Statistical analyses suggest that fluctuations in the availability of marine nutrients has been one important regulator of rates of origination during this time.

The decay of soil and sedimentary organic matter yields organic compounds with a high molecular weight, termed humic substances. Sediment-incubation experiments suggest that microbial reduction of solid-phase humics can accelerate iron(III) oxide reduction in wetland soils.

The Earth formed through accretion of many planetary embryos that were probably differentiated into a metallic core and a silicate mantle. The metals and silicates were assumed to fully mix during accretion, but models of Earth’s formation that assume only partial mixing are found to be equally compatible with geochemical observations.

Vertical motions of the rocky margins of Greenland and Antarctica respond to mass changes of their respective ice sheets, but these motions can be obscured by ancient episodes of glacial advance or retreat. An analysis of the acceleration of vertical motion indicates that accelerated ice loss in western Greenland started in the late 1990s.

Lake Tanganyika has become warmer, increasingly stratified and less productive over the past 90 years. Analyses of lake sediments show that this recent warming is unprecedented within the past 1,500 years.