Biogeochemistry

  • Article |

    The presence of blubber and distribution of melanophores in a countershading pattern in an Early Jurassic ichthyosaur demonstrate that the evolutionary convergence of these reptiles with extant marine amniotes extends to the cellular and molecular levels.

    • Johan Lindgren
    • , Peter Sjövall
    •  & Mary H. Schweitzer
  • Article |

    High-resolution imaging techniques show that aromatic amino acids such as tryptophan formed abiotically and were subsequently preserved at depth beneath the Atlantis Massif of the Mid-Atlantic Ridge, supporting the hydrothermal theory for the origin of life.

    • Bénédicte Ménez
    • , Céline Pisapia
    •  & Matthieu Réfrégiers
  • Letter |

    Satellite data for the period 1982–2016 reveal changes in land use and land cover at global and regional scales that reflect patterns of land change indicative of a human-dominated Earth system.

    • Xiao-Peng Song
    • , Matthew C. Hansen
    •  & John R. Townshend
  • Letter |

    Triple oxygen isotope measurements of 1.4-billion-year-old sedimentary sulfates reveal a unique mid-Proterozoic atmosphere and demonstrate that gross primary productivity in the mid-Proterozoic was between 6% and 41% of pre-anthropogenic levels.

    • Peter W. Crockford
    • , Justin A. Hayles
    •  & Boswell A. Wing
  • Letter |

    This study of whole-soil carbon dynamics finds that, of the atmospheric carbon that is incorporated into the topmost metre of soil over 50 years, just 19 per cent reaches the subsoil, in a manner that depends on land use and aridity.

    • Jérôme Balesdent
    • , Isabelle Basile-Doelsch
    •  & Christine Hatté
  • Letter |

    Phytotransferrin, a functional analogue of transferrin, has an obligate requirement for carbonate to bind iron, which suggests that acidification-driven declines in the concentration of seawater carbonate ions may negatively affect diatom iron acquisition.

    • Jeffrey B. McQuaid
    • , Adam B. Kustka
    •  & Andrew E. Allen
  • Brief Communications Arising |

    • T. W. Crowther
    • , M. B. Machmuller
    •  & M. A. Bradford
  • Letter |

    Nutrient amendment experiments at the boundary of the South Atlantic gyre reveal extensive regions in which nitrogen and iron are co-limiting, with other micronutrients also approaching co-deficiency; such limitations potentially increase phytoplankton community diversity.

    • Thomas J. Browning
    • , Eric P. Achterberg
    •  & C. Mark Moore
  • Letter |

    The authors provide evidence for the existence of life on Earth in the earliest known sedimentary rocks and suggest that the presence of organic carbon, and low stable-isotope values of graphite from sedimentary rocks in Labrador pushes back the existence of organic life to beyond 3.95 billion years.

    • Takayuki Tashiro
    • , Akizumi Ishida
    •  & Tsuyoshi Komiya
  • Letter |

    Steroid biomarkers provide evidence for a rapid rise of marine planktonic algae between 659 and 645 million years ago, establishing more efficient energy transfers and driving ecosystems towards larger and increasingly complex organisms.

    • Jochen J. Brocks
    • , Amber J. M. Jarrett
    •  & Tharika Liyanage
  • Letter |

    Long-term records of global carbonyl sulfide levels reveal that terrestrial gross primary production (GPP) increased by around 30% during the twentieth century—a finding that may aid understanding of the connection between GPP growth and climate change.

    • J. E. Campbell
    • , J. A. Berry
    •  & M. Laine
  • Letter |

    Steranes in ancient rocks have been used as ‘molecular fossils’, but the very earliest records of steranes have been shown to be contaminants; here, the presence of two key sterol biosynthesis enzymes in eukaryotes and bacteria suggests at least one gene transfer between bacteria and the earliest eukaryotes occurred some 2.3 billion years ago.

    • David A. Gold
    • , Abigail Caron
    •  & Roger E. Summons
  • Review Article |

    The recent expansion of observational data has changed our understanding of the ocean iron cycle and its linkages with nutrients such as carbon and nitrogen.

    • Alessandro Tagliabue
    • , Andrew R. Bowie
    •  & Mak A. Saito
  • Letter |

    Examination of the ecosystem properties of treeline ecotones in seven temperate regions of the world shows that the reduction in temperature with increasing elevation does not affect tree leaf nutrient concentrations, but does reduce ground-layer community-weighted plant nitrogen levels, leading to a strong stoichiometric convergence of ground-layer plant community nitrogen to phosphorus ratios across all regions.

    • Jordan R. Mayor
    • , Nathan J. Sanders
    •  & David A. Wardle
  • Letter |

    Low phosphorus burial in shallow marine sedimentary rocks before about 750 million years ago implies a change in the global phosphorus cycle, coinciding with the end of what may have been a stable low-oxygen world.

    • Christopher T. Reinhard
    • , Noah J. Planavsky
    •  & Kurt O. Konhauser
  • Letter |

    A compilation of global soil carbon data from field experiments provides empirical evidence that warming-induced net losses of soil carbon could accelerate climate change.

    • T. W. Crowther
    • , K. E. O. Todd-Brown
    •  & M. A. Bradford
  • Letter |

    There is an abrupt transition from alkaline to acid soil pH when mean annual precipitation exceeds mean annual potential evapotranspiration, demonstrating that climate creates a nonlinear pattern in soil solution chemistry at the global scale.

    • E. W. Slessarev
    • , Y. Lin
    •  & O. A. Chadwick
  • Brief Communications Arising |

    • J. Evaristo
    • , S. Jasechko
    •  & J. J. McDonnell
  • Article |

    Bacteria of the SAR11 clade constitute up to one half of all marine microbes and are thought to require oxygen for growth; here, a subgroup of SAR11 bacteria are shown to thrive in ocean oxygen minimum zones and to encode abundant respiratory nitrate reductases.

    • Despina Tsementzi
    • , Jieying Wu
    •  & Frank J. Stewart
  • Letter |

    Climate models require an understanding of ecosystem-scale respiration and photosynthesis, yet there is no way of measuring these two fluxes directly; here, new instrumentation is used to determine these fluxes in a temperate forest, showing, for instance, that respiration is less during the day than at night.

    • R. Wehr
    • , J. W. Munger
    •  & S. R. Saleska
  • Perspective |

    The potential of soils to mitigate greenhouse gas emissions has not been exploited; here we discuss and recommend research and technology developments to implement mitigation practices.

    • Keith Paustian
    • , Johannes Lehmann
    •  & Pete Smith