Biogeochemistry

  • Article
    | Open Access

    The N2-fixing symbiont ‘Candidatus Celerinatantimonas neptuna’ lives inside the root tissue of the seagrass Posidonia oceanica, providing ammonia and amino acids to its host in exchange for sugars and enabling highly productive seagrass meadows to thrive in the nitrogen-limited Mediterranean Sea.

    • Wiebke Mohr
    • , Nadine Lehnen
    •  & Marcel M. M. Kuypers
  • Article |

    Oceanic deposition of wildfire aerosols can enhance marine productivity, as supported here by satellite and in situ profiling floats data showing that emissions from the 2019–2020 Australian wildfires fuelled phytoplankton blooms in the Southern Ocean.

    • Weiyi Tang
    • , Joan Llort
    •  & Nicolas Cassar
  • Article |

    Structural, functional and localization studies reveal that Geobacter sulfurreducens pili cannot behave as microbial nanowires, instead functioning in a similar way to secretion pseudopili to export cytochrome nanowires that are essential for extracellular electron transfer.

    • Yangqi Gu
    • , Vishok Srikanth
    •  & Nikhil S. Malvankar
  • Article |

    The aboveground carbon stock of a montane African forest network is comparable to that of a lowland African forest network and two-thirds higher than default values for these montane forests.

    • Aida Cuni-Sanchez
    • , Martin J. P. Sullivan
    •  & Etienne Zibera
  • Article |

    Modelling suggests that the Montreal Protocol may be mitigating climate change by protecting the land carbon sink, as well as by protecting the ozone layer and reducing greenhouse gas emissions.

    • Paul J. Young
    • , Anna B. Harper
    •  & Rolando R. Garcia
  • Article |

    Aircraft observations of atmospheric carbon dioxide and monoxide concentrations in Brazil show higher carbon emissions in eastern Amazonia than in the western part, which are linked to increased ecosystem stress and fire occurrence.

    • Luciana V. Gatti
    • , Luana S. Basso
    •  & Raiane A. L. Neves
  • Article |

    Analysis of shallow-water marine carbonate samples from 101 stratigraphic units allows construction of a record of lithium isotopes from the past 3 billion years, tracking the evolution of the global carbon and silicon cycles.

    • Boriana Kalderon-Asael
    • , Joachim A. R. Katchinoff
    •  & Philip A. E. Pogge von Strandmann
  • Article |

    Sulfur isotope and iron–sulfur–carbon systematics on marine sediments indicate that permanent atmospheric oxygenation occurred around 2.22 billion years ago, about 100 million years later than currently estimated.

    • Simon W. Poulton
    • , Andrey Bekker
    •  & David T. Johnston
  • Article
    | Open Access

    Candidatus Azoamicus ciliaticola’ transfers energy to its ciliate host in the form of ATP and enables this host to breathe nitrate, demonstrating that eukaryotes with remnant mitochondria can secondarily acquire energy-providing endosymbionts.

    • Jon S. Graf
    • , Sina Schorn
    •  & Jana Milucka
  • Article |

    Bottom-up and top-down approaches are used to quantify global nitrous oxide sources and sinks resulting from both natural and anthropogenic sources, revealing a 30% increase in global human-induced emissions between 1980 and 2016.

    • Hanqin Tian
    • , Rongting Xu
    •  & Yuanzhi Yao
  • Article |

    When tropical forest soils are warmed in situ, they release more CO2 than predicted by theory, creating a potentially substantial positive feedback to climate change.

    • Andrew T. Nottingham
    • , Patrick Meir
    •  & Benjamin L. Turner
  • Article |

    A co-culture of two newly identified microorganisms—‘Candidatus Manganitrophus noduliformans’ and Ramlibacter lithotrophicus—exhibits exponential growth that is dependent on manganese(II) oxidation, demonstrating the viability of this metabolism for supporting life.

    • Hang Yu
    •  & Jared R. Leadbetter
  • Article |

    A detailed assessment of the techno-economic potential of enhanced rock weathering on croplands identifies national CO2 removal potentials, costs and engineering challenges if it were to be scaled up to help meet ambitious global CO2 removal targets.

    • David J. Beerling
    • , Euripides P. Kantzas
    •  & Steven A. Banwart
  • Article |

    Sea surface density observations in the Arctic Ocean reveal a relationship between the present-day surface water density and the anthropogenic carbon inventory and coincident acidification, suggesting that recent acidification projections are underestimates.

    • Jens Terhaar
    • , Lester Kwiatkowski
    •  & Laurent Bopp
  • Article |

    Over the past 18,000 years, the residence time and amount of soil carbon stored in the Ganges–Brahmaputra basin have been controlled by the intensity of Indian Summer Monsoon rainfall, with greater carbon destabilization during wetter, warmer conditions.

    • Christopher J. Hein
    • , Muhammed Usman
    •  & Valier V. Galy
  • Article |

    Carbon dioxide enrichment of a mature forest resulted in the emission of the excess carbon back into the atmosphere via enhanced ecosystem respiration, suggesting that mature forests may be limited in their capacity to mitigate climate change.

    • Mingkai Jiang
    • , Belinda E. Medlyn
    •  & David S. Ellsworth
  • Article |

    Analyses of microbial communities that live 10–750 m below the seafloor at Atlantis Bank, Indian Ocean, provide insights into how these microorganisms survive by coupling energy sources to organic and inorganic carbon resources.

    • Jiangtao Li
    • , Paraskevi Mara
    •  & Virginia P. Edgcomb
  • Article |

    Isotopic evidence from ice cores indicates that preindustrial-era geological methane emissions were lower than previously thought, suggesting that present-day emissions of methane from fossil fuels are underestimated.

    • Benjamin Hmiel
    • , V. V. Petrenko
    •  & E. Dlugokencky
  • Article |

    An analysis based on Landsat imagery shows that the extent of river ice has declined extensively over past decades and that this trend will continue under future global warming.

    • Xiao Yang
    • , Tamlin M. Pavelsky
    •  & George H. Allen
  • Article |

    Anoxygenic photosynthetic microorganisms can biomineralize manganese oxides without molecular oxygen being present and without high-potential photosynthetic reaction centres, which sheds doubt on proposed dates for the origins of oxygenic photosynthetic metabolism.

    • Mirna Daye
    • , Vanja Klepac-Ceraj
    •  & Tanja Bosak
  • Article |

    Marine Proteobacteria use the β-hydroxyaspartate cycle to assimilate glycolate, which is secreted by algae on a petagram scale, providing evidence of a previously undescribed trophic interaction between autotrophic phytoplankton and heterotrophic bacterioplankton.

    • Lennart Schada von Borzyskowski
    • , Francesca Severi
    •  & Tobias J. Erb
  • Article |

    Emission of methane from ‘point sources’—small surface features or infrastructure components—is monitored with an airborne spectrometer, identifying possible targets for mitigation efforts.

    • Riley M. Duren
    • , Andrew K. Thorpe
    •  & Charles E. Miller
  • Article |

    Analysis of two-million-year-old ice from Antarctica provides a direct comparison of atmospheric gas levels before and after the shift from glacial cycles of 100 thousand years to 40-thousand-year cycles around one million years ago.

    • Yuzhen Yan
    • , Michael L. Bender
    •  & John A. Higgins
  • Review Article |

    The processes that control the movement of carbon from microfossils on the seafloor to erupting volcanoes and deep diamonds, in a cycle driven by plate tectonics, are reviewed.

    • Terry Plank
    •  & Craig E. Manning
  • Letter |

    After the Cretaceous/Palaeogene mass extinction event, nannoplankton communities exhibited volatility for 1.8 million years before a more stable community emerged, coinciding with restoration of the carbon cycle and a fully functioning biological pump between the surface and deep sea.

    • Sarah A. Alvarez
    • , Samantha J. Gibbs
    •  & Andy Ridgwell
  • Review Article |

    Abiotic processes can mimic or alter the biogenic traces of early life but advances in micro- and nanoscale analyses provide evidence that—with geological contextualization—improves our ability to address this issue.

    • Emmanuelle J. Javaux
  • Letter |

    Soil radiocarbon dating reveals that combusted ‘legacy carbon’—soil carbon that escaped burning during previous fires—could shift the carbon balance of boreal ecosystems, resulting in a positive climate feedback.

    • Xanthe J. Walker
    • , Jennifer L. Baltzer
    •  & Michelle C. Mack
  • Letter |

    Comparing the eyes of crane-fly fossils with those of extant species demonstrates that they contain eumelanic screening pigments and that the lenses are calcified during fossilization, with implications for interpreting optical systems in other extinct arthropods such as trilobites.

    • Johan Lindgren
    • , Dan-Eric Nilsson
    •  & Per Ahlberg
  • Letter |

    Overfishing and warming ocean temperature have caused an increase in methylmercury concentrations in some Atlantic predatory fish, and this trend is predicted to continue unless stronger mercury and carbon emissions standards are imposed.

    • Amina T. Schartup
    • , Colin P. Thackray
    •  & Elsie M. Sunderland
  • Letter |

    Estimates of spatial patterns of nitrogen discharge into water bodies across China between 1955 and 2014 show that current discharge rates are almost three times the acceptable threshold, and ways to restore a clean water environment are suggested.

    • ChaoQing Yu
    • , Xiao Huang
    •  & James Taylor
  • Article |

    Convergent estimates of nitrogen fixation from an inverse biogeochemical and a prognostic ocean model show that biological carbon export in the ocean is higher than expected and that stabilizing nitrogen-cycle feedbacks are weaker than we thought.

    • Wei-Lei Wang
    • , J. Keith Moore
    •  & François W. Primeau
  • Letter |

    Satellite observations reveal over 200 ammonia hotspots associated with agricultural and industrial point sources, which emit much larger quantities of ammonia to the atmosphere than previously thought.

    • Martin Van Damme
    • , Lieven Clarisse
    •  & Pierre-François Coheur