• Article |

    Typically, microbial methane production occurs under oxygen-free conditions and abiotic methane production occurs under harsh conditions. Here, the authors show methane production from organosulphur compounds under ambient conditions, suggesting a role for these compounds in methane formation in the environment.

    • Frederik Althoff
    • , Kathrin Benzing
    •  & Frank Keppler
  • Article |

    The organic geochemical biomarker IP25 has been widely applied in the reconstruction of Arctic sea ice, yet its source remains undetermined. Here, the authors report the identification of IP25in common pan-Arctic sea ice diatoms, thus establishing its applicability as a palaeo Arctic sea ice proxy.

    • T. A. Brown
    • , S. T. Belt
    •  & C. J. Mundy
  • Article |

    Peatlands both store and emit potent greenhouse gases, yet their contribution to carbon dynamics during the past is poorly constrained. Here, Packalen et al.present new age constraints for peat development in the Hudson Bay Lowlands and quantify carbon storage and methane emissions during the Holocene.

    • Maara S. Packalen
    • , Sarah A. Finkelstein
    •  & James W. McLaughlin
  • Article
    | Open Access

    Arctic sea ice has been in rapid decline in recent decades, yet the impact on biogeochemical cycling is unknown due to insufficient sampling. Watanabe et al.combine year-long mooring observations with numerical models to show that an eddy-induced biological pump would be enhanced by sea ice retreat.

    • Eiji Watanabe
    • , Jonaotaro Onodera
    •  & Michio J. Kishi
  • Article
    | Open Access

    Seagrass beds are effective blue-carbon sinks, yet their role as a lime mud source in the tropical carbonate factory is less well known. Here, the authors demonstrate that the species Thalassia testudinumcan significantly contribute to carbonate production via the precipitation of aragonite needles.

    • Susana Enríquez
    •  & Nadine Schubert
  • Article |

    As global population and food demand rises, it is increasingly unclear how reactive nitrogen pollution will be mitigated. Bodirsky et a series of model simulations and show that even under ambitious mitigation, reactive nitrogen pollution is likely to exceed critical environmental thresholds in the year 2050.

    • Benjamin Leon Bodirsky
    • , Alexander Popp
    •  & Miodrag Stevanovic
  • Article |

    Lakes play an important role in the global carbon cycle and understanding their organic matter cycling is vital. Kellerman et al.apply an ultrahigh-resolution technique to 120 lakes across Sweden and show that the molecular composition is shaped by water dynamics and temperature.

    • Anne M. Kellerman
    • , Thorsten Dittmar
    •  & Lars J. Tranvik
  • Article
    | Open Access

    The world’s tropical forests represent a terrestrial carbon sink, yet its size is uncertain. Espírito-Santo et al.characterize full Amazon disturbances combining forest inventories and remote sensing data, and use statistical modelling to quantify the Amazon aboveground forest carbon balance.

    • Fernando D.B. Espírito-Santo
    • , Manuel Gloor
    •  & Oliver L. Phillips
  • Article |

    Little is known about extracellular electron uptake by microbes. Here Bose et al. show that the anoxygenic photoautotroph Rhodopseudomonas palustrisTIE-1 accepts electrons from a poised electrode, which can be uncoupled from photosynthesis, and the pioABC system has a role in this uptake.

    • A. Bose
    • , E.J. Gardel
    •  & P.R. Girguis
  • Article |

    The microbes responsible for releasing the potent greenhouse gas methane from thawing permafrost remain largely unknown. Mondav and Woodcroft et al. investigate methane flux across a thaw gradient in Sweden and recover a near-complete genome of the dominant methanogen Candidatus ‘Methanoflorens stordalenmirensis’.

    • Rhiannon Mondav
    • , Ben J. Woodcroft
    •  & Gene W. Tyson
  • Article
    | Open Access

    Ocean acidification is affecting the stability of coral reefs, but the exact mineralogical response is poorly understood. Diaz-Pulido et that, under warming conditions, the relative abundance of dolomite increases by as much as 200% and could therefore slow the climate-induced break-up of coral reefs.

    • Guillermo Diaz-Pulido
    • , Merinda C. Nash
    •  & Ulrike Troitzsch
  • Article |

    Iron emitted from hydrothermal vents is stabilized by organic matter and dispersed into the world ocean, yet the pathways leading to iron–carbon interactions are unknown. Dick et al.propose that a new ‘microbial iron pump’ is responsible for converting hydrothermal iron into bioavailable forms.

    • Meng Li
    • , Brandy M. Toner
    •  & Gregory J. Dick
  • Article |

    Methane emission occurs in natural wetlands on a large scale, but the corresponding trace element emissions have not been studied. Here, the authors study selenium and arsenic emission in a pristine peatland and show that this causes large amounts of those trace elements to enter the biogeochemical cycle.

    • Bas Vriens
    • , Markus Lenz
    •  & Lenny H.E. Winkel
  • Article
    | Open Access

    Clay-sized particles bind organic matter and sequester carbon and nitrogen in soils, yet extent and localization of organic matter coverage remain unclear. Using NanoSIMS, Vogel et al.chemically image soils at ultra-high resolution and show that only particles with rough surfaces react with organic matter.

    • Cordula Vogel
    • , Carsten W. Mueller
    •  & Ingrid Kögel-Knabner
  • Article |

    Africa is one of the fastest growing regions for the voluntary carbon market. Here, Greve et al.quantify the potential for aboveground C stocking across tropical Africa and assess the optimal placement of carbon-stocking projects when also taking co-benefits and feasibility into account.

    • Michelle Greve
    • , Belinda Reyers
    •  & Jens-Christian Svenning
  • Article |

    Recent increases in the dissolved organic carbon (DOC) content of northern aquatic systems are likely to lead to increases in CO2 emissions, yet the mechanisms are poorly understood. Here, evidence from hundreds of Canadian aquatic systems suggests a causal link between DOC concentrations and CO2flux.

    • Jean-François Lapierre
    • , François Guillemette
    •  & Paul A. del Giorgio
  • Article |

    The presence of earthworms in soil may significantly increase CO2 emissions, but the impacts of earthworms on net carbon sequestration are poorly understood. Zhang et al. introduce a new concept by which the effects of earthworms on the balance of carbon mineralization and stabilization can be quantified.

    • Weixin Zhang
    • , Paul F. Hendrix
    •  & Shenglei Fu
  • Article |

    Isoprene and monoterpenes, emitted by terrestrial plants, have an important role in both plant biology and environment, but they are poorly quantified at the ecosystem level. Peñuelas et that the photochemical reflectance index can be used to indirectly estimate foliar isoprenoid emissions remotely.

    • Josep Peñuelas
    • , Giovanni Marino
    •  & Iolanda Filella
  • Article |

    Deep oceanic crust could host a wealth of microbial life, but biogeochemical reactions therein are poorly understood. Orcutt et al.combine measurements of sedimentary oxygen and pore water chemistry from basement crust with a reactive transport box model to shed light on oxygen consumption in basaltic crust.

    • Beth N. Orcutt
    • , C. Geoffrey Wheat
    •  & Wolfgang Bach
  • Article |

    Hitherto, Siberian vegetation was not considered to cause the south-to-north ion content gradient of thaw lakes. Herzschuh et al.propose that higher evapotranspiration in larch forests compared with that in the tundra leads to local salt accumulation in permafrost soils, which are transported as solutes to nearby lakes.

    • Ulrike Herzschuh
    • , Luidmila A. Pestryakova
    •  & H. John B. Birks
  • Article |

    Accurate estimates of tropical forest carbon stocks are needed for policies to reduce emissions from loss of forests. By looking at a central area in the Congo Basin, Kearsleyet al.find that inconsistencies in height–diameter relationships across Central Africa cause overestimations between regions.

    • Elizabeth Kearsley
    • , Thales de Haulleville
    •  & Hans Verbeeck
  • Article
    | Open Access

    The dissolution of iron from sediments along ocean margins may stimulate photosynthesis and moderate global climate. This study shows how margin sediments supply iron in varying amounts between regions, and by distinct mechanisms, which may be due to geological characteristics and hydrological controls on land.

    • William B. Homoky
    • , Seth G. John
    •  & Rachel A. Mills
  • Article |

    Debates on the formation of banded iron formations (BIFs) in ancient iron-rich oceans are dominated by contradictions between biological and non-biological iron cycling. This study provides environmental evidence that directly implicates photosynthetic iron-oxidizing microorganisms in vast-scale BIF deposition.

    • Ernest Chi Fru
    • , Magnus Ivarsson
    •  & Marco Stampanoni
  • Article
    | Open Access

    Deep subsurface formations are potential sites for carbon capture and storage but how subsurface microbial communities may respond to this is not clear. Here, Mayumi et al. construct microcosms and show that increasing CO2partial pressure via carbon capture and storage more than doubles the rate of methanogenesis.

    • Daisuke Mayumi
    • , Jan Dolfing
    •  & Yoichi Kamagata
  • Article |

    Iron plays a key role in controlling biological production in the Southern Ocean, yet mechanisms regulating iron availability are not completely understood. Here, Ingall et that structural incorporation of reduced, organic iron into biogenic silica represents a new and substantial removal pathway.

    • Ellery D. Ingall
    • , Julia M. Diaz
    •  & Jay A. Brandes
  • Article |

    A strong increase in atmospheric 14C was measured in tree rings at AD 774 to 775, providing potential evidence of large cosmic ray fluxes to Earth, but the cause of this event is unclear. Here, Miyake et al. report a second 14C event in AD 993, which suggests that the most likely cause was a large solar proton event.

    • Fusa Miyake
    • , Kimiaki Masuda
    •  & Toshio Nakamura
  • Article |

    The role of bacteria in the origin of iron formations (IF) remains unclear because no direct evidence for their involvement exists. This study shows that spherical siderite in deep-water IF represents a biosignature for photoferrotrophy, whereas massive siderite reflects high cyanobacterial biomass in shallow-water.

    • Inga Köhler
    • , Kurt O Konhauser
    •  & Andreas Kappler
  • Article |

    Clear evidence between sulphidic conditions and denitrification in the Proterozoic ocean should be observable in the rock record. Here, minimalistic biogeochemical modelling shows how periods of extensive sulphate reduction must have gone hand-in-hand with low denitrification and available nitrate.

    • R.A. Boyle
    • , J.R. Clark
    •  & T.M. Lenton
  • Article |

    Rivers receive more terrestrial carbon than they transport to the ocean, leaving carbon stored along the way. Here, with an estimate of carbon storage in the headwater rivers of the Rocky Mountains, the authors show that broad valley bottoms with old-growth forest store most of the above- and below-ground carbon.

    • Ellen Wohl
    • , Kathleen Dwire
    •  & Roberto Bazan
  • Article |

    Microbes appear to play an important role in carbon sequestration. Here, the composition of microbial residues in a California grassland with elevated carbon dioxide, warming and nitrogen deposition reveals that warming and nitrogen deposition can both alter the fraction of carbon derived from microbes in soils.

    • Chao Liang
    •  & Teri C. Balser
  • Article |

    Methane is an important anthropogenic greenhouse gas and is thought to be produced by industrial processes and prokaryotic methanogenic Archaea. In this study, the saprotrophic fungi,Basidiomycetes, is shown to produce methane in the absence of methanogenic Archaea.

    • Katharina Lenhart
    • , Michael Bunge
    •  & Frank Keppler
  • Article |

    A record of the daily light cycle in tropical regions is difficult to extract from biogenic marine carbonates such as shells. Here, the precise analysis of Sr/Ca ratios is shown in a cultivated giant clam shell, revealing variations that reflect the daily light cycle and the potential for future development of a proxy.

    • Yuji Sano
    • , Sayumi Kobayashi
    •  & Kenji Iwai
  • Article |

    Peatlands are a sink for atmospheric carbon dioxide and make up a large soil carbon reservoir. Here, studies of the interaction between drainage and fire show that long-term carbon emissions will likely exceed rates of carbon uptake, reducing the northern peatland carbon sink.

    • M.R. Turetsky
    • , W.F. Donahue
    •  & B.W. Benscoter
  • Article
    | Open Access

    Dissolved organic matter, the main form of aquatic organic carbon, supports the aquatic food web and regulates light penetration in lakes. This study probes the main influences on the optical properties of dissolved organic matter in a global dataset of alpine and remote lakes revealing latitudinal trends.

    • N. Mladenov
    • , R. Sommaruga
    •  & I. Reche
  • Article |

    Through fine-root nutrient chemistry, it is possible to study ecosystem-scale biogeochemical cycling. Compiling data from 211 studies measuring nitrogen and phosphorus in plant roots, Yuanet al. find that tropical ecosystems are more phosphorous-limited than higher latitudes.

    • Z.Y. Yuan
    • , Han Y.H. Chen
    •  & Peter B. Reich