In the context of the ecological sustainability of phosphorus, the ubiquitous presence of polyphosphate-accumulating bacteria in natural environments invites efforts to reveal their unknown roles in the biogeochemical cycle of phosphorus. In this study, we evaluated the potential of combining the staining of intracellular polyphosphate granules and their subsequent detection by flow cytometry for the detection, quantification and cell sorting of polyphosphate-accumulating bacteria.

The solubility characteristics of soil humic acids (HAs), fulvic acids (FAs), and protein-like substances (PLSs) at varying pH levels remain unclear. The key findings include the following: HA solubility increases with increasing pH and decreases with decreasing pH; HA_pH6 and HA_pH1 contribute to 39.1–49.2% and 3.1–24.1% of dissolved organic carbon, respectively; and HA_pH2, FA, and PLSs are highly soluble at acidic pHs and are transported by ambient water. These issues are crucial for sustainable soil management.

We present a novel method for quantifying N₂ fixation by cyanobacteria, which is crucial in Baltic Sea eutrophication. Our Gas Equilibrium – Membrane-Inlet Mass Spectrometer (GE-MIMS), designed for operation on voluntary observing ships (VOSs), enables large-scale monitoring of surface water N₂ depletion caused by N₂ fixation. Laboratory tests confirm the device’s accuracy and precision, ensuring that it can complement current methods and contribute valuable data for better understanding N₂ fixation in the Baltic Sea.

Climate change has the potential to influence the carbon sequestration potential of terrestrial ecosystems, and here the nitrogen cycle is also important. We used the terrestrial biosphere model QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system) in a mixed deciduous forest in Canada. We investigated the usefulness of using the leaf area index and leaf chlorophyll content to improve the parameterization of the model. This work paves the way for using spaceborne observations in model parameterizations, also including information on the nitrogen cycle.