Replacing fertiliser nitrogen with biologically fixed nitrogen (BFN) through legumes has been suggested as a strategy for nitrous oxide (N₂O) mitigation from intensively managed grasslands. On our site the mitigation strategy reduced N₂O emissions by 54 % and 39 % in 2015 and 2016, while annual yields were similar under mitigation management. We conclude that N₂O emissions can be effectively reduced without losses in yield by increasing the clover proportion and reducing fertilisation.

The investigation of water mass transport pathways and timescales is important to understand the global ocean circulation. Following earlier studies, we use artificial radionuclides introduced to the oceans in the 1950s to investigate the water transport in the subpolar North Atlantic (SPNA). For the first time, we combine measurements of the long-lived iodine-129 and uranium-236 to confirm earlier findings/hypotheses and to better understand shallow and deep ventilation processes in the SPNA.

Lakes emit significant amounts of carbon dioxide. However, it requires hard work or expensive equipment to quantify the emission directly. In this study, we present a cost-efficient method to measure the exchange of carbon dioxide on lakes continuously. Using a modified floating chamber the exchange can be measured automatically with a minimum of effort. The modifications are simple to perform, allowing use of the method by a broad audience.

Forest management is widely used to mitigate climate change. However, forest greenhouse gas (GHG) budgets neglect to consider that clear-cuts often release carbon and nitrogen into streams and lakes and may affect aquatic GHG emissions. Here, we show that such emissions remain unaffected by experimental boreal forest clear-cutting despite increased groundwater carbon dioxide and methane concentrations, highlighting that riparian zones or in-stream processes may have buffered clear-cut leachates.

The Si biogeochemical cycle was studied during two oceanographic cruises in the tropical South Pacific in 2005 and 2015, between New Caledonia and the Chilean upwelling (8–34° S). Some of the lowest levels of biogenic silica stocks were found in the southern Pacific gyre, where Chlorophyll a concentrations are most depleted worldwide. Size-fractionated biogenic silica concentrations as well as Si kinetic uptake experiments revealed biological Si uptake by the picoplanktonic size fraction.

This study used a detailed microbial-based soil decomposition biogeochemistry model to examine the fate of much arctic soil carbon under changing climate conditions. We found that the detailed microbial decomposition biogeochemistry model estimated a much lower carbon accumulation in the region during this century. The amount of soil carbon considered in the 21st-century simulations determines the regional carbon sink and source strengths, regardless of the complexity of models used.

Land carbon fluxes are controlled in part by the responses of terrestrial ecosystems to atmospheric conditions near the Earth's surface. This study offers a comprehensive evaluation of the consequences of multiple facets of spatiotemporal variability in atmospheric CO₂ for carbon cycle dynamics. Globally, consideration of the diurnal CO₂ variability reduces the gross primary production and net land carbon uptake. The relative contributions of other variability vary regionally and seasonally.

The fugacity of carbon dioxide in seawater (fCO₂) was measured hourly in the surface waters of the NW Mediterranean Sea during two 3-year sequences separated by 18 years. A decrease of pH of 0.0022 yr⁻¹ was computed. About 85 % of the accumulation of dissolved inorganic carbon (DIC) comes from chemical equilibration with increasing atmospheric CO₂; the remaining 15 % accumulation is consistent with estimates of transfer of Atlantic waters through the Gibraltar Strait.

The silicon stable isotope distribution determined from samples collected from the North Atlantic Ocean indicates that water mass subduction and circulation are the dominant processes controlling the distribution of dissolved silicon in this region. In addition, these data provide a clear view of the direct interaction between northern and southern water masses and the extent to which the silicon isotope composition of these silica-poor waters is influenced by hydrography.

Terrestrial biosphere models employ various representations of ecosystem nitrogen loss, some based on soil N availability, some based on net N mineralization. We show in local and global simulations that this variety leads to pronounced uncertainty in the predicted magnitude and sign of ecosystem N loss change under elevated CO₂. Suprisingly, this uncertainty barely affects predicted carbon storage responses to elevated CO₂, illustrating the need for new benchmarks especially in the boreal zone.

Over the past decades temperate forests were a carbon (C) sink to the atmosphere. Yet the drivers of C uptake and how these affect the future carbon cycle remain uncertain. Our simulation and study revealed that the future C sink of central European forest landscapes is strongly driven by historic land use, while climate change reduces forest C uptake. Compared to land-use change, past natural disturbances (wind and bark beetles) have only marginal effects on the future carbon cycle.

Abrupt climate changes in Earth’s history might have been triggered by magmatic intrusions into organic-rich sediments, which can potentially release large amounts of greenhouse gases. In the Guaymas Basin, vigorous hydrothermal venting at the ridge axis and off-axis inactive vents show that magmatic intrusions are an effective way to release carbon but must be considered as very short-lived processes in a geological sense. These results need to be taken into account in future climate models.

The main objective of this work was to evaluate the potential degradation of phenol, a highly toxic pollutant, by cloud microorganisms. Phenol concentrations measured on five cloud samples collected at the PUY station in France were from 0.15 to 0.74 µg L⁻¹. Metatranscriptomic analysis suggested that phenol could be biodegraded directly in clouds, likely by Gammaproteobacteria. A large screening showed that 93 % of 145 bacterial strains isolated from clouds were able to degrade phenol.