Nature Geoscience contents: August 2012 Volume 5 Number 8 pp517-584

TABLE OF CONTENTS August 2012 Volume 5, Issue 8 Editorial In the press Books and Arts Research Highlights News and Views Review Letters Articles Subscribe   Facebook   RSS   Recommend to library   Twitter   Advertisement Nature Geoscience - New Impact Factor The 2011 ISI impact factor for Nature Geoscience is 11.754*, according to the ISI Journal Citation Reports®. This places Nature Geoscience first among all primary research journals in multi-disciplinary geosciences. *2011 Journal Citation Reports® (Thomson Reuters, 2012)   Editorial Top Space buzz heads east   p517 doi:10.1038/ngeo1550 While the Olympics kick off in London, a new international sporting arena is taking shape beyond Earth's orbit. Recent advances in space exploration by China and Japan remind us that curiosity about our universe is a truly universal trait. In the press Top Interstellar achievement   p518 Mark Schrope doi:10.1038/ngeo1537 Books and Arts Top Journeys west   p519 Craig H. Jones reviews Rough-Hewn Land: A Geologic Journey from California to the Rocky Mountains by Keith Heyer Meldahl doi:10.1038/ngeo1533 Research Highlights Top Planetary surfaces: Titan renewed | Cryosphere: Microbes on the edge | Tectonics: Ancient channel flow | Palaeoclimate: Minimal ice growth News and Views Top Geomorphology: Flood-built land   pp521 - 522 Wonsuck Kim doi:10.1038/ngeo1535 The southeastern US coastline is under threat as land subsides and sea level rises. Measurements of the 2011 Mississippi River flood suggest that the river carries enough sandy sediment to offset some of this coastal drowning. See also: Letter by Nittrouer et al. Sociology: Plugging the leaks   p522 Alicia Newton doi:10.1038/ngeo1542 Core processes: Earth's eccentric magnetic field   pp523 - 524 Christopher C. Finlay doi:10.1038/ngeo1516 Earth's magnetic field is characterized by a puzzling hemispheric asymmetry. Calculations of core dynamo processes suggest that lopsided growth of the planet's inner core may be part of the cause. See also: Letter by Olson & Deguen Planetary science: Slippery sliding on icy Iapetus   pp524 - 525 Antoine Lucas doi:10.1038/ngeo1532 Enigmatically, some landslides flow farther than normal frictional resistance allows. Cassini images of Saturn's icy moon Iapetus reveal a multitude of long-runout landslides that may have been enabled by flash heating along the sliding surface. See also: Article by Singer et al. Geoscience JOBS of the week Academic Positions in Synchrotron Geoscience Monash University Opportunities in Marine Geoscience National Oceanography Centre Academic Positions in Synchrotron Geoscience Monash University Posts in Marine Geoscience The National Oceanography Centre Posts in Marine Geoscience The National Oceanography Centre More Science jobs from Geoscience EVENT Hawaiian Volcanoes: From Source to Surface 20.-24.08.12 Hawaii, US More science events from Review Top Possible links between long-term geomagnetic variations and whole-mantle convection processes   pp526 - 533 A. J. Biggin, B. Steinberger, J. Aubert, N. Suttie, R. Holme, T. H. Torsvik, D. G. van der Meer & D. J. J. van Hinsbergen doi:10.1038/ngeo1521 The geomagnetic field varies on a wide range of timescales. A review of emerging research suggests that field variations on the order of tens of millions of years may be linked to changes in heat flow across the core–mantle boundary. Letters Top Mitigating land loss in coastal Louisiana by controlled diversion of Mississippi River sand   pp534 - 537 Jeffrey A. Nittrouer, James L. Best, Christopher Brantley, Ronald W. Cash, Matthew Czapiga, Praveen Kumar & Gary Parker doi:10.1038/ngeo1525 The Bonnet Carré Spillway diverts floodwaters from the Mississippi River to Lake Pontchartrain, and was opened for 42 days during the 2011 flood. According to measurements of the newly deposited sediments, at least 31–46% of the river's sand load was diverted into the spillway at this time, suggesting that such diversions can help mitigate coastal wetland loss. See also: News and Views by Kim Nitrogen loss from soil through anaerobic ammonium oxidation coupled to iron reduction   pp538 - 541 Wendy H. Yang, Karrie A. Weber & Whendee L. Silver doi:10.1038/ngeo1530 In marine and freshwater ecosystems, anaerobic ammonium oxidation is coupled to nitrite reduction, and accounts for a significant fraction of ecosystem nitrogen loss. Laboratory incubations suggest that ammonium oxidation coupled to iron reduction contributes to nitrogen loss in anaerobic slurries of tropical forest soils. Seismic imaging of a large horizontal vortex at abyssal depths beneath the Sub-Antarctic Front   pp542 - 546 K. L. Sheen, N. J. White, C. P. Caulfield & R. W. Hobbs doi:10.1038/ngeo1502 The exchange of water between subtropical North Atlantic Deep Water and the Antarctic Circumpolar Current is important, but poorly constrained. A subsurface acoustic image taken in the confluence region shows a prominent swirling structure, 500 m high and 10 km wide, that could be either a thermohaline intrusion or a localized and intermittent overturning event. Global rates of water-column denitrification derived from nitrogen gas measurements   pp547 - 550 Tim DeVries, Curtis Deutsch, Francois Primeau, Bonnie Chang & Allan Devol doi:10.1038/ngeo1515 Biologically available nitrogen limits phytoplankton growth over much of the ocean. Data-constrained model simulations suggest that bioavailable nitrogen losses match gains in the global ocean, indicative of a balanced budget. Reduction in carbon uptake during turn of the century drought in western North America   pp551 - 556 Christopher R. Schwalm, Christopher A. Williams, Kevin Schaefer, Dennis Baldocchi, T. Andrew Black, Allen H. Goldstein, Beverly E. Law, Walter C. Oechel, Kyaw Tha Paw U & Russel L. Scott doi:10.1038/ngeo1529 The severity and incidence of climatic extremes, including drought, have increased as a result of climate warming. Analyses of observational and reanalysis data suggest that the strength of the western North American carbon sink declined by 30–298 Tg carbon per year during the drought at the turn of the century. Hydrologic cycling over Antarctica during the middle Miocene warming   pp557 - 560 Sarah J. Feakins, Sophie Warny & Jung-Eun Lee doi:10.1038/ngeo1498 Global warmth 20–15 million years ago allowed vegetation to grow on formerly ice-covered areas of Antarctica. Leaf wax and pollen data show that this growth was supported by increased hydrologic activity over the Antarctic coast, derived from a local moisture source. Granular disruption during explosive volcanic eruptions   pp561 - 564 Josef Dufek, Michael Manga & Ameeta Patel doi:10.1038/ngeo1524 Volcanic eruptions can inject hazardous ash clouds into the atmosphere. Numerical simulations and experiments on volcanic rock samples show that clasts initially formed deep in the volcanic conduit break-up during collisions in the conduit, thus generating fine-grained clouds of ash. Eccentricity of the geomagnetic dipole caused by lopsided inner core growth   pp565 - 569 Peter Olson & Renaud Deguen doi:10.1038/ngeo1506 The axis of the geomagnetic field is offset eastwards from Earth's centre by more than 500 km. Simulations of Earth's geomagnetic field using a numerical dynamo model show that lopsided growth of the inner core, with faster solidification occurring in one hemisphere, could cause the offset. See also: News and Views by Finlay Unradiogenic lead in Earth's upper mantle   pp570 - 573 Kevin W. Burton, Bénédicte Cenki-Tok, Fatima Mokadem, Jason Harvey, Abdelmouhcine Gannoun, Olivier Alard & Ian J. Parkinson doi:10.1038/ngeo1531 The mantle and continental crust contain excessive amounts of radiogenic lead, implying that a complementary reservoir of unradiogenic lead should exist somewhere on Earth. Isotopic analyses of mantle rocks exposed on the Atlantic Ocean floor reveal that sulphide inclusions can have extremely unradiogenic lead compositions, suggesting that the reservoir could exist within the mantle itself. Articles Top Massive ice avalanches on Iapetus mobilized by friction reduction during flash heating   pp574 - 578 Kelsi N. Singer, William B. McKinnon, Paul M. Schenk and Jeffery M. Moore doi:10.1038/ngeo1526 The great distance travelled by long-runout landslides, observed previously on the Earth and Mars, requires a mechanism of friction reduction. Identification and analysis of long-runout landslides on Saturn's moon Iapetus suggests that the Iapetian landslides are enabled by flash heating of the icy sliding surface. See also: News and Views by Lucas Localized subduction of anthropogenic carbon dioxide in the Southern Hemisphere oceans   pp579 - 584 Jean-Baptiste Sallée, Richard J. Matear, Stephen R. Rintoul and Andrew Lenton doi:10.1038/ngeo1523 The Southern Ocean makes a substantial contribution to the oceanic carbon sink. Observationally based estimates of carbon subduction suggest that carbon sequestration depends on physical properties, such as mixed layer depth, ocean currents, wind and eddies, that are potentially sensitive to climate variability and change. Top Advertisement Feel like your paper is lost in a sea of submissions? Scientific Reports publishes your research quickly and efficiently, and makes it freely available to the global scientific community. Learn more with our one minute illustrative video.   Natureevents is a fully searchable, multi-disciplinary database designed to maximise exposure for events organisers. The contents of the Natureevents Directory are now live. 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