Volume 2 Issue 9, September 2009

The rapid draining of India's aquifers over the past six years warrants urgent attention.

The terrestrial biosphere is assumed to take up most of the carbon on land. However, it is becoming clear that inland waters process large amounts of organic carbon and must be considered in strategies to mitigate climate change.

Anna Armstrong reviews Big River Man by John Maringouin, Self Pictures: 2009. UK release date: 4 September 2009.

The fate of sinking particulate organic matter in the world ocean is a key source of uncertainty in the global carbon cycle. Model simulations suggest that atmospheric carbon dioxide concentrations depend critically on the depths that these particles typically reach.

The Pacific and Australian plates collide and interact in complex ways around New Zealand. Electrical resistivity data reveal that subduction-zone fluids exert an important influence on deformation in the region.

Purported 3,465-million-year-old microfossils from Australia have been the subject of considerable debate. A method to distinguish between pristine fossils, mineral artefacts and subsequent microbial contamination will aid the search for ancient biogenic material.

Titan's surface is covered by vast fields of linear dunes, probably composed of organic sand-sized particles. The study of linear dunes in China suggests that sediment cohesiveness can be as important as wind direction in the creation of these dune forms.

Slab fluids drive mantle melting and return ocean water to the Earth's surface through arc volcanism. New ways of estimating the temperature of slab fluids indicate relatively hot conditions, and hint at a shallow and fast return path for ocean water.

Gigantic jets emerge from the top of thunderstorms and extend all the way to the ionosphere at altitudes of 90 km. Simultaneous video images and magnetic field measurements of a gigantic jet demonstrate an electric charge transfer between the thunderstorm and the ionosphere that is comparable to that observed in cloud-to-ground lightning.

The oxidation of ammonia to nitrate, known as nitrification, is a key process in the nitrogen cycle. Real-time polymerase chain-reaction measurements show that nitrification is driven by bacteria rather than archaea in nitrogen-rich grassland soils in New Zealand.

The micronutrient molybdenum is necessary for nitrogen fixation, but is very rare and highly soluble in soils. X-ray spectroscopy analysis of forest soil samples indicates that most of the molybdenum in the litter layer binds to organic matter.

The depth at which particulate organic carbon sinking from the surface ocean is converted back to carbon dioxide is known as the remineralization depth. A three-dimensional global ocean biogeochemistry model suggests that a modest change in remineralization depth can have a substantial impact on atmospheric carbon dioxide concentrations.

The Australian–Indonesian summer monsoon affects rainfall variability across the Indo–Pacific region. Reconstructions of monsoon strength from stalagmites show that precipitation increased from 11,000 to 7,000 years ago, as rising global sea level caused the flooding of the Indonesian continental shelf.

The earliest fossils of cyanobacteria have been controversially reported from the 3,465-million-year-old Apex chert in Western Australia. Mineralogical analyses of the rock near the fossil site indicate that the site experienced repeated alterations at low and medium temperatures, and is therefore unlikely to have preserved any early forms of life.

It has been debated whether rivers or glaciers are more effective agents of erosion. A global compilation of erosion rates reveals that both are capable of generating rates of erosion that match or exceed the highest rates of rock uplift.

The sedimentary wedge in the Nankai Trough off the coast of Japan is cut by a landward-dipping thrust fault, which is an important plate boundary structure in this region. Geological and seismic reflection data indicate that the fault initiated ∼1.95 million years ago and underwent uplift and reactivation ∼1.55 million years ago.

The formation of dunes is controlled by the direction of the prevailing winds and the characteristics of the sediments. Linear dunes in the Qaidam Basin, China, are shown to form from cohesive sediments, a model that could be applicable to dunes on Titan.

Atmospheric concentrations of nitrous oxide, a greenhouse gas, have increased since 1860. A regression model indicates that conversion of 2% of manure nitrogen and 2.5% of fertilizer nitrogen could explain the pattern of increasing nitrous oxide concentrations between 1860 and 2005, including a rise in the rate of increase around 1960.

Mike Gagan, Michael Griffiths and colleagues negotiated knee-deep mud while up to their neck in water in an Indonesian cave, all to reconstruct Australasian monsoon rainfall over the past 12,000 years.

David Rubin and Patrick Hesp spent a night in a labour camp come hotel while trying to uncover the factors that shape sand dunes in the Qaidam Basin, China.