The oceans play the dual role of carbon sinks and greenhouse gases (GHGs) sources in global climate change, but there are still gaps in understanding the GHG fluxes and regulation mechanisms across e...

De aarde vraagt jouw stem. Op dinsdag 21 oktober zullen experts bij Nieuwspoort toelichten waarom klimaatactie zo belangrijk is voor de gezondheid van de aarde en dus onze gezondheid en die van onze k...

Sediment resuspension, driven by wind, waves, and tides, mixes benthic and pelagic environments by introducing sediment, nutrients, and microorganisms…

Pyrogenic carbon (PC) plays a critical role in regulating greenhouse gas emissions by influencing methanogenesis and methane oxidation in aquatic envi…

Climate change-induced extreme heat, flooding and drought events influence the carbon and nitrogen cycling, including the denitrifying anaerobic metha…

The discovery of complete ammonia oxidation (comammox) bacteria has challenged traditional paradigms. Previous studies often assumed that comammox pro…

Nitrous oxide (N2O) is a serious concern due to its role in global warming and ozone destruction. Agricultural practices account for ∼80% of all anthropogenic N2O produced in the US, due in large part to the stimulation of microbial denitrification. Stable isotopes are uniquely suited to examine both microbial N2O sources and the mechanism of N2O biosynthesis through the use of Site Preference (δ15NSP; the difference in δ15N between the central and outer N atoms in N2O) and kinetic isotope effects (KIEs), respectively. Using trace gas isotope ratio mass spectrometry (TG-IRMS), we determined the δ15N, δ15Nα, δ15Nβ, and δ18O of N2O produced by a purified cytochrome c nitric oxide reductase (cNOR) from Paracoccus denitrificans. We also calculated δ15NSP, the KIEs, and associated isotopic enrichment factors (ε) for Nbulk, Nα, and Nβ. A normal isotope effect was observed for bulk 15N, with a KIE value of 1.0086 ± 0.0009 (ε = −8.6 ± 0.9‰). The isotope effects for both 15Nα and 15Nβ were also normal, with position-specific KIEs of 1.0072 ± 0.0010 (ε = −7.2 ± 1.0‰) and 1.0100 ± 0.0010 (ε = −9.9 ± 1.0‰), respectively, and δ15NSP values ranged from 0.5 to 8.7‰ with no significant trend as the reaction proceeded. Values of δ18O increased with N2O production (slope of δ18O against [−f ln f/(1 – f)] = −19.9 ± 1.9‰). We present implications for the mechanism of N2O production from cNOR based on our data.

This study screens microorganisms that have genetic potential for extracellular electron transfer capabilities in anaerobic wastewater treatment.

In mainstream wastewater treatment, the potential coupling between ammonia-oxidizing archaea (AOA) and anaerobic ammonium-oxidizing bacteria (AnAOB) t…

Intermittent rivers and ephemeral streams (IRES), which represent more than half of the global river network, remain largely understudied as potential…

Deciphering the adaptive mechanisms of anaerobic ammonium-oxidizing (anammox) bacteria to redox dynamics is pivotal for overcoming critical bottleneck…

In this study, bioelectrochemical technology was used to investigate the enrichment effect on anaerobic ammonium oxidation (anammox) sludge of three b…

Coastal salt marshes are highly valuable ecosystems that function as significant methane (CH4) sources. CH4 emissions in salt marsh ecosystems result …

A 165 Myr record of N and Corg isotopes show that the N-cycle responds to feedbacks associated with productivity and the location of upwelling centers changing due to continental meander.

Nitrification and denitrification are two important biological processes producing N2O in soils, but their contributions to N2O emissions are not well understood, hindering precise mitigation measures. Here, we developed process-based models (PBM) with and without transport (T) to partition N2O sources by tracking nitrogen flows (NF) through different reaction pathways. The model with transport (PBM-T-NF) well predicted N2O production from nitrification and denitrification in two different repacked soils with a shallow depth of 8 mm under moisture conditions ranging from 40 to 100% water-filled pore space (WFPS), demonstrating its robustness and reliability. In comparison, the model without transport (PBM-NF) failed to capture the N2O dynamics and the relative contribution of denitrification to N2O production ( $${C}_{D}$$ C D ), highlighting the need of including mass transport in predicting N2O dynamics. The PBM-T-NF model was further employed to investigate the effects of soil properties on N2O emissions and sources. Increased NH4+ concentration significantly decreased $${C}_{D}$$ C D under relatively low moisture conditions, while increased NO3− slightly promoted $${C}_{D}$$ C D over different moisture contents, emphasizing the importance of substrate availability and moisture conditions in controlling $${C}_{D}$$ C D . Furthermore, the PBM-T-NF model was used to quantify N2O sources from an artificial soil core of 80 mm depth. Soil depth was shown to be important in mediating $${C}_{D}$$ C D by controlling O2 diffusivity, which is highly dependent on moisture content. Given the long-standing challenge in experimental quantification of N2O sources from soils, our developed model provides a novel way to estimate N2O production from different nitrogen processes, which is key for accurately targeting mitigation of N2O emissions from soils.

How do we mentor, teach, and do stats when AI can do so much of the work?

Loretan and colleagues present a low-cost smartphone-based microscope capable of detecting single-molecule fluorescence. This approach opens doors to personalised and widely distributed applications in diagnostics, biosensing, and science education.

Vacancy at Department of Biology - Microbiology, Aarhus University