Interplay between temperature and redox conditions regulates wetland biogeochemistry and greenhouse gas emissions.

Wetlands play a crucial role in global greenhouse gas (GHG) dynamics, yet their response to climate change is not yet fully understood. Here, we investigate how increasing temperature and oxygen availability interact to regulate wetland GHG emissions through combined analysis of biogeochemical and functional gene measurements. We found distinct temperature-dependent shifts in carbon emission pathways, with CO emissions unexpectedly declining as temperature rose from 15 to 25 °C, while increasing consistently at higher temperatures (25-35 °C), reflecting a transition to more thermally-driven processes.

Unravelling spatiotemporal NO dynamics in an urbanized estuary system using natural abundance isotopes.

Estuaries are strong sources of NO to the atmosphere; yet we still lack insights into the impact of their biogeochemical dynamics on the emissions of this powerful greenhouse gas. Here, we investigated the spatiotemporal dynamics of the N cycle in an estuary with a focus on the emission mechanisms and pathways of NO. By coupling NO isotopocule analysis and substrate NO isotope analysis, we found that nutrient availability, oxygen level, salinity gradient and temperature variation were major drivers of the NO emissions from the Scheldt Estuary.

Regulating greenhouse gas dynamics in tidal wetlands: Impacts of salinity gradients and water pollution.

Tidal wetlands play a critical role in emitting greenhouse gases (GHGs) into the atmosphere; our understanding of the intricate interplay between natural processes and human activities shaping their biogeochemistry and GHG emissions remains lacking. In this study, we delve into the spatiotemporal dynamics and key drivers of the GHG emissions from five tidal wetlands in the Scheldt Estuary by focusing on the interactive impacts of salinity and water pollution, two factors exhibiting contrasting gradients in this estuarine system: pollution escalates as salinity declines. Our findings reveal a marked escalation in GHG emissions when moving upstream, primarily attributed to increased concentrations of organic matter and nutrients, coupled with reduced levels of dissolved oxygen and pH.

Drug discovery-based approach identifies new nitrification inhibitors.

Nitrogen (N) fertilization is crucial to sustain global food security, but fertilizer N production is energy-demanding and subsequent environmental N losses contribute to biodiversity loss and climate change. N losses can be mitigated be interfering with microbial nitrification, and therefore the use of nitrification inhibitors in enhanced efficiency fertilizers (EEFs) is an important N management strategy to increase N use efficiency and reduce N pollution. However, currently applied nitrification inhibitors have limitations and do not target all nitrifying microorganisms.

Impact of salinity gradient, water pollution and land use types on greenhouse gas emissions from an urbanized estuary.

Estuaries have been recognized as one of the major sources of greenhouse gases (GHGs) in aquatic systems; yet we still lack insights into the impact of both anthropogenic and natural factors on the dynamics of GHG emissions. Here, we assessed the spatiotemporal dynamics and underlying drivers of the GHG emissions from the Scheldt Estuary with a focus on the effects of salinity gradient, water pollution, and land use types, together with their interaction. Overall, we found a negative impact of salinity on carbon dioxide (CO) and nitrous oxide (NO) emissions which can be due to the decrease of both salinity and water quality when moving upstream.

Carbon isotope composition of respired CO2 in woody stems and leafy shoots of three tree species along the growing season: physiological drivers for respiratory fractionation.

The carbon isotope composition of respired CO2 (δ13CR) and bulk organic matter (δ13CB) of various plant compartments informs about the isotopic fractionation and substrate of respiratory processes, which are crucial to advance the understanding of carbon allocation in plants. Nevertheless, the variation across organs, species and seasons remains poorly understood. Cavity Ring-Down Laser Spectroscopy was applied to measure δ13CR in leafy shoots and woody stems of maple (Acer platanoides L.

Patterns of free amino acids in tundra soils reflect mycorrhizal type, shrubification, and warming.

The soil nitrogen (N) cycle in cold terrestrial ecosystems is slow and organically bound N is an important source of N for plants in these ecosystems. Many plant species can take up free amino acids from these infertile soils, either directly or indirectly via their mycorrhizal fungi. We hypothesized that plant community changes and local plant community differences will alter the soil free amino acid pool and composition; and that long-term warming could enhance this effect.

Isotopically characterised N O reference materials for use as community standards.

Rationale: Information on the isotopic composition of nitrous oxide (N O) at natural abundance supports the identification of its source and sink processes. In recent years, a number of mass spectrometric and laser spectroscopic techniques have been developed and are increasingly used by the research community. Advances in this active research area, however, critically depend on the availability of suitable N O isotope Reference Materials (RMs).

Observing the water handling in humans to resolve the role of the interstitium: preliminary results of the usability of deuterium oxide and bio-impedance analysis - a pilot analysis.

The aim of this research was to evaluate the relevance of using deuterium oxide (HO) and bio-impedance analysis (BIA) to assess size and function of the interstitium for urological research. Nineteen volunteers were recruited to this prospective trial combining ingestion of HO and BIA. Blood samples were obtained every 10 min after ingestion of HO.

Greenhouse gas dynamics in an urbanized river system: influence of water quality and land use.

Rivers act as a natural source of greenhouse gases (GHGs). However, anthropogenic activities can largely alter the chemical composition and microbial communities of rivers, consequently affecting their GHG production. To investigate these impacts, we assessed the accumulation of CO, CH, and NO in an urban river system (Cuenca, Ecuador).

Fire-derived phosphorus fertilization of African tropical forests.

Central African tropical forests face increasing anthropogenic pressures, particularly in the form of deforestation and land-use conversion to agriculture. The long-term effects of this transformation of pristine forests to fallow-based agroecosystems and secondary forests on biogeochemical cycles that drive forest functioning are poorly understood. Here, we show that biomass burning on the African continent results in high phosphorus (P) deposition on an equatorial forest via fire-derived atmospheric emissions.

Efflux and assimilation of xylem-transported CO in stems and leaves of tree species with different wood anatomy.

Determining the fate of CO respired in woody tissues is necessary to understand plant respiratory physiology and to evaluate CO recycling mechanisms. An aqueous C-enriched CO solution was infused into the stem of 3-4 m tall trees to estimate efflux and assimilation of xylem-transported CO via cavity ring-down laser spectroscopy and isotope ratio mass spectrometry, respectively. Different tree locations (lower stem, upper stem and leafy shoots) and tissues (xylem, bark and leaves) were monitored in species with tracheid, diffuse- and ring-porous wood anatomy (cedar, maple and oak, respectively).

Legacy of historic land cover changes on sediment provenance tracked with isotopic tracers in a Mediterranean agroforestry catchment.

A Compound Specific Stable Isotope (CSSI) sediment tracing approach is applied for the first time in a Mediterranean mountain agroforestry catchment subjected to intense land use changes in the past decades. Many Mediterranean mountain environments underwent conversion of rangelands into croplands during the previous centuries to increase agricultural production. Converted land has increased the risk of erosion and in some cases has led to loss of the entire fertile topsoil.

Spatial and temporal variations of greenhouse gas emissions from a waste stabilization pond: Effects of sludge distribution and accumulation.

Due to regular influx of organic matter and nutrients, waste stabilization ponds (WSPs) can release considerable quantities of greenhouse gases (GHGs). To investigate the spatiotemporal variations of GHG emissions from WSPs with a focus on the effects of sludge accumulation and distribution, we conducted a bathymetry survey and two sampling campaigns in Ucubamba WSP (Cuenca, Ecuador). The results indicated that spatial variation of GHG emissions was strongly dependent on sludge distribution.

Century-long apparent decrease in intrinsic water-use efficiency with no evidence of progressive nutrient limitation in African tropical forests.

Forests exhibit leaf- and ecosystem-level responses to environmental changes. Specifically, rising carbon dioxide (CO ) levels over the past century are expected to have increased the intrinsic water-use efficiency (iWUE) of tropical trees while the ecosystem is gradually pushed into progressive nutrient limitation. Due to the long-term character of these changes, however, observational datasets to validate both paradigms are limited in space and time.

C Incorporation as a Tool to Estimate Biomass Yields in Thermophilic and Mesophilic Nitrifying Communities.

Current methods determining biomass yield require sophisticated sensors for measurements or multiple steady-state reactor runs. Determining the yield of specific groups of organisms in mixed cultures in a fast and easy manner remains challenging. This study describes a fast method to estimate the maximum biomass yield (Y), based on C incorporation during activity measurements.

Isotope ratio laser spectroscopy to disentangle xylem-transported from locally respired CO2 in stem CO2 efflux.

Respired CO2 in woody tissues radially diffuses to the atmosphere or it is transported upward with the transpiration stream, making the origin of CO2 in stem CO2 efflux (EA) uncertain, which may confound stem respiration (RS) estimates. An aqueous 13C-enriched solution was infused into stems of Populus tremula L. trees, and real-time measurements of 13C-CO2 and 12C-CO2 in EA were performed via Cavity Ring Down Laser Spectroscopy (CRDS).

A deconvolutional Bayesian mixing model approach for river basin sediment source apportionment.

Increasing complexity in human-environment interactions at multiple watershed scales presents major challenges to sediment source apportionment data acquisition and analysis. Herein, we present a step-change in the application of Bayesian mixing models: Deconvolutional-MixSIAR (D-MIXSIAR) to underpin sustainable management of soil and sediment. This new mixing model approach allows users to directly account for the 'structural hierarchy' of a river basin in terms of sub-watershed distribution.

Community managed forests dominate the catchment sediment cascade in the mid-hills of Nepal: A compound-specific stable isotope analysis.

Soil erosion by water is critical for soil, lake and reservoir degradation in the mid-hills of Nepal. Identification of the nature and relative contribution of sediment sources in rivers is important to mitigate water erosion within catchments and siltation problems in lakes and reservoirs. We estimated the relative contribution of land uses (i.

High fire-derived nitrogen deposition on central African forests.

Atmospheric nitrogen (N) deposition is an important determinant of N availability for natural ecosystems worldwide. Increased anthropogenic N deposition shifts the stoichiometric equilibrium of ecosystems, with direct and indirect impacts on ecosystem functioning and biogeochemical cycles. Current simulation data suggest that remote tropical forests still receive low atmospheric N deposition due to a lack of proximate industry, low rates of fossil fuel combustion, and absence of intensive agriculture.

Measuring C-enriched CO in air with a cavity ring-down spectroscopy gas analyser: Evaluation and calibration.

Rationale: Cavity ring-down spectroscopy (CRDS) is becoming increasingly popular for δ C-CO analysis of air. However, little is known about the effect of high C abundances on the performance of CRDS. Overlap between CO and CO spectral lines may adversely affect isotopic-CO CRDS measurements of C-enriched samples.

Phosphorus resource partitioning shapes phosphorus acquisition and plant species abundance in grasslands.

Species diversity is commonly hypothesized to result from trade-offs for different limiting resources, providing separate niches for coexisting species. As soil nutrients occur in multiple chemical forms, plant differences in acquisition of the same element derived from different compounds may represent unique niche dimensions. Because plant productivity of ecosystems is often limited by phosphorus, and because plants have evolved diverse adaptations to acquire soil phosphorus, a promising yet untested hypothesis is phosphorus resource partitioning.

A robust nitrifying community in a bioreactor at 50 °C opens up the path for thermophilic nitrogen removal.

The increasing production of nitrogen-containing fertilizers is crucial to meet the global food demand, yet high losses of reactive nitrogen associated with the food production/consumption chain progressively deteriorate the natural environment. Currently, mesophilic nitrogen-removing microbes eliminate nitrogen from wastewaters. Although thermophilic nitrifiers have been separately enriched from natural environments, no bioreactors are described that couple these processes for the treatment of nitrogen in hot wastewaters.

Nitrogen deposition promotes the production of new fungal residues but retards the decomposition of old residues in forest soil fractions.

Atmospheric nitrogen (N) deposition has frequently been observed to increase soil carbon (C) storage in forests, but the underlying mechanisms still remain unclear. Changes in microbial community composition and substrate use are hypothesized to be one of the key mechanisms affected by N inputs. Here, we investigated the effects of N deposition on amino sugars, which are used as biomarkers for fungal- and bacterial-derived microbial residues in soil.