Biodiversity loss threatens ecosystem functions, including decomposition and nutrient cycling. We investigated whether Collembola (springtails), key s…

Cryoconite holes are among the most biologically active and diverse limnic habitats on glacier surfaces. The apex cryoconite consumers, tardigrades and rotifers, are known to contribute significan...

Sulfur-based denitrification offers unique advantages in nitrogen removal in low-carbon environments. Despite its importance, the prevalence, controlling factors, and microbial mediators of sulfur-based denitrification in aquifers remain largely unknown. By integrating multiple stable isotopes and genome-resolved metagenomics, we investigated the coupling of nitrogen and sulfur cycling along the groundwater flowpath from unconfined to confined alluvial-lacustrine aquifers in the Poyang Lake Plain, China. Isotope (i.e., δ15N–NO3–, δ18O–NO3–, δ34S–SO42–, δ18O–SO42–, δ18O–H2O, δ13C-DIC, and δ13C-DOC) fractionation and hydrogeochemical trends indicated a transition from nitrification-dominated processes in the unconfined aquifer to denitrification, sulfide oxidation, and sulfate reduction in the confined aquifer. A significant negative correlation between δ34S–SO42– and δ15N–NO3–, along with a significant positive correlation between genes involved in sulfide oxidation and nitrate reduction, suggested cryptic coupling between sulfide oxidation and nitrate reduction. Sulfur-autotrophic denitrifying metagenome assembly genomes encoding Calvin–Benson–Bassham carbon fixation and rTCA pathways, such as Burkholderiales, Rhodocyclaceae, and Sulfurimonas, were enriched in the confined aquifer and co-occurred with sulfate reducers (Pseudomonadota and Desulfobacterota). These results highlighted sulfur cycling consortia when sulfate was reduced to facilitate removal of nitrate via sulfur-based denitrification. These findings reveal the role of cryptic sulfur cycling in sustaining denitrification in aquifers, offering new insights into nitrogen–sulfur interactions in subsurface ecosystems.

Microcystis forms harmful cyanobacterial algal blooms around the world, including regions with low inorganic nitrogen (N) concentrations. Here, we measured the N2 fixation rates of isolated Microcystis colonies, free-living plankton, and the whole plankton community during dense Microcystis blooms over a three year period in six diverse lakes across eastern North America including Lake Erie. For five of six lakes, rates within the colony fraction were greater than the rates measured for free-living plankton (p < 0.05). N2 fixation rates were inversely correlated with the rates of ammonium uptake by the colony fraction (p < 0.05), and in experiments, ammonium significantly reduced N2 fixation rates within the colony fraction by 50–85% (p < 0.001). In several lakes, the δ15N of isolated colonies was lower (p < 0.05) than that of free-living plankton presumably due to the preferential use of 14N2 by diazotrophic, colony-associated plankton. Cyanobacterial and noncyanobacterial nifH sequences were associated with the Microcystis colonies with the nifH-based diversity of both groups being lower in colonies compared to free-living plankton. Compared to nitrate, ammonium, and urea uptake, N2 fixation rates accounted for 1–76% of total N assimilation by the Microcystis colony fraction and averaged 18% across systems, suggesting this process could support the proliferation of Microcystis blooms.

Ammonium (NH₄⁺) and nitrous oxide (N₂O) are key reactive nitrogen species in aquatic systems, with implications for water quality and greenhouse gas e…

Lipids are structurally diverse and functionally critical biomolecules playing key roles in energy storage, signal transduction, and membrane formatio…

Well-preserved amino acid δ15N tracks isotopic changes in upper ocean nutrient and the trophic structure of the western equatorial Pacific The grazing proportion exhibits distinct precessional va...

Anthropogenic nitrogen (N) deposition comprising reduced (NHx) and oxidized (NOy) forms, differentially influences ecosystem processes. However, th...

Stable carbon isotopic compositions of amino acids (δ13CAA) in organisms potentially record information on carbon sources and flow in food webs. In this study, we report δ13C values of 16 proteinogeni...

Environmental pollution in stream networks is a major concern. In this study, the effects of land-use and geological characteristics on basin-scale sulfate and nitrate dynamics in the Chikusa River ba...

We compiled data from 15N tracer studies across forests in China to examine nitrogen (N) retention and its contribution to carbon (C) sequestration. On average, forests retain about 65% of deposited ...

Partitioning autochthonous and allochthonous organic matter (OM) contributions to reservoir sediments is essential for accurately estimating the magni…

The oxygen isotopes of nitrate (NO3−), specifically δ18O(NO3−) and Δ17O(NO3−), provide insights into the oxidation mechanisms responsible for NO3− for…

Stable isotope data has broad applicability across multiple science domains. As more datasets are published and stable isotope data systems are built,…

Understanding the mechanisms shaping food chain length (FCL) has long been central to food web ecology. FCL is a key determinant of stability, energy flow efficiency, and biodiversity maintenance, bu....

Sulfur isotopes in ice cores quantify how much sulfate over the Southern Ocean comes from passive volcanic degassing versus phytoplankton A global chemical transport model underestimates the volc...

Distributions of carbon and nitrogen stable isotope ratios of primate hairs from Kalinzu Forest Reserve, Uganda.

The intra-annual distribution of precipitation has a significant impact on vegetation growth in arid and semi-arid regions. Intra-annual variations in…

Scleractinian coral evolved under nitrogen (N)-limited conditions. The increase in N flux from anthropogenic activities to these otherwise N-depleted environments is threatening coral health and cora....

The astronomical impact on marine organic carbon cycling and resulting environmental changes are evaluated in a 3D Earth system model At eccentricity maxima, marine carbon burial is promoted by s...

We compare alkenone sea-surface temperatures records with new clumped-isotope and δ18 ${\delta }^{18}$O carbonate data from a southern California upwelling site over 4.2 Myr Clumped-isotope and δ...

Oxygen content was lower than modern throughout much of the glacial Atlantic Ocean Changes in preformed δ13C and oxygen were critical components of the observed difference between the last glacia...

Modern water data is used to fit an orographic precipitation isotope model for the Himalaya and Tibetan Plateau region Model predictions for primary water isotopes are paired with leaf wax hydrog...

Continental weathering and shelf-basin carbonate partitioning regulate Oligocene-Miocene carbon cycling on orbital timescales.

Fire severity is key in shaping soil organic matter (SOM) composition, affecting biogeochemical cycles and post-fire recovery. However, accurately ass…