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56 results for “Denitrification”
Salt River Wetlands denitrification rate, dissimilatory nitrate reduction to ammonium rate, dissolved organic carbon concentration in June 2016 as well as soil porosity and bulk density
Raw and derived data used to calculate denitrification and dissimilatory nitrate to ammonium (DNRA) from push-pull experiments with added isotopically labelled nitrate. Experiments were conducted in 2016 in the Salt River Accidental Wetlands in three different patch types: Unvegetated, dominated by Ludwigia peploides, and dominated by Typha species (T. domingensis and T. latifolia). Data include start and end of incubation concentration of nitrate, ammonium, atom percent 15N in ammonium, dissolved organic carbon, excess mass 29-N2, and excess mass 30-N2. Soil data was collected from the same patch types including soil moisture, porosity, and bulk density.
Nitrogen fixation (acetylene reduction) and denitrification (acetylene block) data from streams across ecoclimatic domains in the United States, 2017-2019
We conducted a cross-ecoregion study to test the hypothesis that N-fixation and denitrification would co-occur in streams and rivers across a range of reactive N concentrations. Between 2017 and 2019, we sampled 30 streams in 13 ecoregions, using chambers to quantify N-fixation using acetylene reduction and denitrification using acetylene block. 25 of the study streams were part of the National Ecological Observatory Network or the StreamPULSE network, which provided data on water temperature, light, nutrients, discharge and metabolism. Although N-fixation and denitrification occur under contrasting environmental conditions, we found that they co-occurred in ca. 40% of stream ecosystems surveyed, and microbes capable of carrying out each process were found in all surveyed streams. This dataset includes the chamber data used to calculate nitrogen fixation and denitrification rates, stream substrate information used to scale rates from substrate to whole-reach scale, and a variety of reach-to-landscape scale covariates used to evaluate predictors of rates across the study streams.
Denitrification, nitrogen fixation, and physio-chemical data for Pilgrim River from May 2017 to May 2019
Rates of nutrient cycling processes, as well as the drivers and mechanisms of variation in those rates, may change at different time scales. Although seasonal patterns in these process rates have been studied, it's unclear how they may respond to shifting seasonal dynamics (i.e., earlier snowmelt and extreme weather events), and we know little about how rates may vary at shorter daily and weekly timescales. Understanding this variation across temporal scales is essential to understand how nutrient cycling processes operate in aquatic ecosystems and predict how they may respond to global change. This study quantified denitrification and nitrogen (N) fixation rates seasonally and daily in a northern temperate river, and explored how environmental conditions such as discharge, light, and nutrients were related to that variation at different time scales in the Pilgrim River, tributary of Lake Superior located in the Upper Peninsula of Michigan, USA. This dataset includes denitrification and nitrogen fixation rates measured from May 2017- May 2019 on rock and sediment substrates as well as physical and chemical properties of the river measured during each sampling event.
Data from: Heterogeneity in habitat and nutrient availability facilitate the co-occurrence of N2 fixation and denitrification across wetland - stream - lake ecotones of Lakes Superior and Huron
Great Lakes coastlines are mosaics of wetland, stream, and lake habitats, characterized by a high degree of spatial heterogeneity that may facilitate the co-occurrence of seemingly incompatible biogeochemical processes due to variation in environmental factors that favor each process. We measured nutrient limitation and rates of N2 fixation and denitrification along transects in 5 wetland - stream - lake ecotones with different nutrient loading in Lakes Superior and Huron and hypothesized that rates of both processes would be related to nutrient limitation status, habitat type, and environmental characteristics including temperature, nutrient concentrations, and organic matter quality. This data package includes information on sampling sites, dates and locations; rates of N fixation and denitrification measured at each site, date and transect location; and biomass information from nutrient diffusing substrates deployed on the study transects.
Patch-level rates of nitrogen fixation and denitrification and environmental covariates from seven streams in Idaho and Michigan
We hypothesized that environmental variation at the patch scale (1 - 10’s m) would facilitate the co-occurrence of N2 fixation and denitrification through the formation of hot spots in streams. We measured rates of N2 fixation and denitrification and relative abundances of the genes nifH and nirS in patches determined by channel geomorphic units and substrate type in 4 Idaho and 3 Michigan streams encompassing a gradient of N and P concentrations. This data package includes patch-level measurements of N2 fixation and denitrification rates, relative gene abundances of nifH and nirS, and environmental covariates (nutrient concentrations, water temperature, surface and subsurface dissolved oxygen concentrations, organic matter content) that were used to explore the factors that could predict process rates and relative gene abundances across patches and streams.
Baltimore Ecosystem Study: Denitrification potential in riparian zones and streams
Denitrification potential and a series of ancillary variables (inorganic nitrogen concentrations, moisture content, organic matter content, microbial biomass carbon and nitrogen content, potential net nitrogen mineralization and nitrification, microbial respiration, root biomass) has been measured in riparian zone soils and stream geomorphic features by a series of undergraduate and graduate student researchers as part of the Baltimore Ecosystem Study since the early 2000s. These studies often center on the series of sites where there has been long-term monitoring (since 2000) of riparian water tables and groundwater chemistry along four first or second order steams in and around the Gwynns Falls watershed in Baltimore City and County, MD (https://doi.org/10.6073/pasta/f7721ec5a4fab5b031f8056824e07e7d). One site is in the completely forested Pond Branch catchment that serves as a "reference" study area for the Baltimore LTER (BES). Two sites (Glyndon, Gwynbrook) are in suburban areas of the watershed; one just upstream from the Glyndon BES long-term stream monitoring site in the headwaters of the Gwynns Falls, and one along a tributary that enters the Gwynns Falls just above the Gwynnbrook BES long-term stream monitoring site farther downstream. The final, urban site (Cahill) is along a tributary to the Gwynns Falls in Leakin Park in the urban core of the watershed. Other sites were used in different studies as described in the publications associated with each study. The different studies also varied in just which ancillary variables were measured.
Denitrification and N2O potential of streams, lakes and uplands in boreal Alaska
Includes: denitrification enzymatic activity (denitrate), N2O production potential, relative production of N2O (fN2O), AFDM, extractable, stream water and pore water NO3, NH4, DOC, thaw depth of upland sites, bulk density. A warming climate causes permafrost to thaw, especially in the region of discontinuous permafrost, where soil temperatures may only be a few degrees below 0 degC. Permafrost thaw may be exacerbated by more frequent and severe fires that remove insulating organic layers above permafrost. Soil thaw releases carbon and nitrogen (N) into the actively cycling pools, and whereas carbon emissions following permafrost thaw are well documented, the fates of N remain unclear. Denitrification could release thawed N as nitrous oxide (N2O) or nitrogen gas (N2), but the contributions of these processes to the high-latitude N cycle remain uncertain. We quantified microbial capacity for denitrification and N2O production in boreal soils, lakes, and streams, and assessed correlates of denitrifying enzyme activity (DEA) in Interior Alaska. Across all landscape positions, DEA under anoxia and nitrate and organic carbon amendment was 4.15 microgram N2O-N /kg dry soil*h (range -6.39 to 479.94). Riparian soils and stream sediments supported the highest potential rates of denitrification, upland soils were intermediate, and lakes supported lower rates, whereas deep permafrost soils supported little denitrification. Time-since-fire had no effect on denitrification potential in upland soils. Across all landscape positions, DEA was negatively correlated with ammonium pools. Within each landscape position, potential rate of denitrification increased with soil or sediment organic matter content. Widespread N loss to denitrification in the boreal forest could constrain the capacity for N-limited primary producers to maintain carbon stocks in soils following permafrost thaw.
Nitrogen cycling in accidental urban wetlands in the Salt River (central Arizona, USA): the effects of season, inundation and plants on denitrification (2013-2014)
This project sought to understand the spatial and temporal patterns and drivers of denitrification in nine accidental wetlands in the Salt River in Phoenix, AZ. Accidental urban wetlands are the result from human activities but are not designed nor managed for any specific purpose; thus, they are useful for examining the effects of both human and non-human drivers of ecosystem processes. For this study, we examined how seasonal monsoon and winter floods affected denitrification in different plant patch types at wetlands with different inundation regimes. Inundation regimes of the study wetlands are driven by storm drains that supply urban baseflow to the wetlands; however, the timing and frequency of discharges differ among storm drains resulting in different durations of inundation. Some storm drains provide enough baseflow that wetlands remain inundated year-round (perennially inundated) while others provide very little baseflow, so inundation is largely in response to rain events (ephemerally inundated). Intermittently inundated wetlands receive enough baseflow to remain inundated for part of the year. At each study wetland, we identified 2-4 dominant plant patch types, including one unvegetated patch. We took 2-4 soil samples from each patch type at each site in each season (pre-monsoon, post-monsoon and winter rainy seasons). We measured denitrification potential, soil organic matter, soil moisture, soil nitrate, soil texture, and water depth. In addition to soil characteristics, we also collected data on plant traits for each patch type. Plant functional traits provide one method to examine mechanistic links between plants and ecosystem processes. Measured plant traits were above- and belowground biomass, above- and belowground C:N ratios, and rooting depth.
Universal temperature sensitivity of denitrification nitrogen losses in forest soils
<p><span>Soil nitrous oxide (N<sub>2</sub>O) and dinitrogen (N<sub>2</sub>) emissions from denitrification are crucial to the global nitrogen (N) cycle. </span><span>However, the temperature sensitivities of gaseous N losses in forest soils are poorly understood, limiting our ability to predict N cycling responses to global warming. We quantified temperature sensitivities (Q10) of denitrification-derived potential N<sub>2</sub>O and N2 production ex-situ for 18 forest soils across China.</span><span> N<sub>2</sub>O</span><span> and N<sub>2</sub> production rates increased exponentially with temperature, showing large variation among soils. By contrast, the Q10 values for N<sub>2</sub>O (</span><span>2.1±0.5</span><span>) and N<sub>2 </sub>(</span><span>2.6±0.6</span><span>) were surprisingly similar across soils. N<sub>2</sub> was more sensitive to temperature than N<sub>2</sub>O, suggesting warming could promote complete denitrification. The Q10 values for denitrification (</span><span>2.3±0.5)</span><span> were similar to those reported for aquatic sediments. Collectively, our results indicate a universal temperature sensitivity of gaseous N losses from denitrification, which will facilitate modelling N losses in response to warming on the global scale<a>.</a></span><span> </span></p>
Electronic appendix to: Spectral Induced Polarization (SIP) of Denitrification-Driven Microbial Activity in Column Experiments Packed with Calcareous Aquifer Sediments
<p>This is the electronic appendix of the publication <br> C. Strobel, S. Abramov, J. A. Huisman, O.A. Cirpka, A. Mellage (2022): Spectral Induced Polarization (SIP) of Denitrification-Driven Microbial Activity in Column Experiments Packed with Calcareous Aquifer Sediments (submitted)</p>
Rates of greenhouse gas (carbon dioxide, methane and nitrous oxide) fluxes, denitrification-derived N2O and N2 fluxes and nitrification-derived N2O fluxes from salt marsh soils in Quebec, Canada and Louisiana, U.S. under ambient and elevated temperature and nutrient loading.
<p>Dataset used in <a href="https://link.springer.com/article/10.1007/s10533-023-01104-0?utm_source=rct_congratemailt&utm_medium=email&utm_campaign=oa_20231214&utm_content=10.1007/s10533-023-01104-0#citeas">Elevated temperature and nutrients lead to increased N<sub>2</sub>O emissions from salt marsh soils from cold and warm climates</a>.</p> <p>The dataset contains fluxes calculated from headspace gas samples taken over a 24 hour period from intact soil cores, as well as corresponding environmental data. Intact soil cores (0-15 cm depth, 2.5 cm diameter) were taken at five sampling locations along a 20 m transect using a soil auger or piston corer. Samples were collected along a transect in four marsh sites in Quebec, Canada (La Pocatière: 47°22'24.7"N 70°03'26.3"W) and Louisiana, U.S. (Barataria Basin: 29°33'47.3"N 90°04'22.8"W and 29°29'52.2"N 89°55'00.2"W) from two vegetation types (<em>Sporobolus alterniflorus</em> formerly known as <em>Spartina alterniflora </em>and<em> Sporobolus pumilus</em> formerly known as<em> Spartina patens</em>). In Quebec, the two vegetation zones were in the same marsh whereas in Louisiana two separate marshes, dominated by the relevant vegetation, were chosen. Soil samples were collected on the 20-21<sup>st</sup> July 2021 from Louisiana and the 9-10<sup>th</sup> August 2021 from Quebec. Environmental data was collected including <em>in-situ</em> soil temperature and salinity, and gravimetric soil moisture, extractable soil dissolved organic carbon (DOC), extractable soil total dissolved nitrogen (TDN), extractable soil nitrate, extractable soil ammonium, extractable soil soluble reactive phosphate, soil total carbon, soil total nitrogen, soil carbon to nitrogen ratio, soil d<sup>13</sup>C and soil d<sup>15</sup>N determined from additional 0-15 cm core samples. This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement no. 838296, a NSERC Discovery Grant and a Natural Environment Research Council grant number (NE/T012323/1).</p> <p>Stable <sup>15</sup>N tracers were added to the intact soil cores so that at each location, at each treatment level (ambient and elevated, described below), there was one core receiving no tracer for greenhouse gas fluxes, one core receiving <sup>15</sup>N-NO<sub>3</sub><sup>‑ </sup>for denitrification rates and one core receiving <sup>15</sup>N-NH<sub>4</sub><sup>+</sup> for nitrification rates. The cores were incubated at ambient temperature (16 ℃ and 28.1 ℃ for Quebec and Louisiana, respectively) and nutrient concentrations (3.2 NO<sub>3</sub><sup>-</sup>, 2.0 NH<sub>4</sub><sup>+</sup>; 2.9 NO<sub>3</sub><sup>-</sup>, 2.5 NH<sub>4</sub><sup>+</sup>; 0.5 NO<sub>3</sub><sup>-</sup>, 7.3 NH<sub>4</sub><sup>+ </sup>and 5.7 NO<sub>3</sub><sup>-</sup>, 2.8 NH<sub>4</sub><sup>+</sup> mg g wet soil<sup>-1</sup> for Quebec <em>S. alterniflorus</em>, Quebec <em>S. pumilus</em>, Louisiana <em>S. alterniflorus</em> and Louisiana <em>S. pumilus</em>, respectively), and elevated temperature (ambient temperature +5 ℃) and nutrient concentration (double ambient concentration). Gas samples were collected from the headspace of 0-15 cm intact cores in a 20 cm high PVC pipe, capped at the top and bottom to create a 5 cm headspace. Gas samples were analysed for greenhouse gases (GHGs: N<sub>2</sub>O, CH<sub>4</sub>, CO<sub>2</sub>) and <sup>15</sup>N in denitrification-derived N<sub>2</sub>O, denitrification-derived N<sub>2</sub> and nitrification-derived N­<sub>2</sub>O.</p> <p>Soil temperature (YSI 30, Baton Rouge, USA or DeltaTrak 11050, Pleasanton, USA) and porewater salinity (YSI 30, Baton Rouge, USA or portable ATC refractometer) were measured in-situ or in the laboratory using the portable refactometer. Additional soil samples were used for multiple analyses; one subsample was extracted with ultrapure water (18.2 MΩ) for DOC and TDN analysis, one subsample was extracted with 2M KCl for NO<sub>3</sub><sup>-</sup> and NH<sub>4</sub><sup>+</sup>, one subsample was extracted with Olsen-P solution (0.5 M NaHCO<sub>3</sub>, pH 8.5), for soluble reactive phosphate analysis and one subsample was weighed and dried for soil moisture and then finely ground and analysed for total carbon, total nitrogen, d<sup>13</sup>C and d<sup>15</sup>N.</p> <p>N<sub>2</sub>O, CH<sub>4</sub> and CO<sub>2</sub> concentrations were measured in the gas samples using a gas chromatograph interfaced with a PAL3 autosampler (Agilent 7890A, Agilent Technologies Ltd, USA) fitted with a flame ionisation detector (FID) for CH<sub>4</sub> analysis and a micro electron capture detector (mECD) for N<sub>2</sub>O analysis. CO<sub>2</sub> was methanised to CH<sub>4</sub> before analysis on the FID. The instrument precision as the relative standard deviation was < 5 % for all of the gases, while the minimum detectable concentration difference (MDCD) was 9 ppb N<sub>2</sub>O, 72 ppb CH<sub>4 </sub>and 31 ppm CO<sub>2</sub>. Potential GHG fluxes were calculated from the linear portion or where the highest production was observed in the concentration-time series ( https://doi.org/10.2134/jeq2003.2436). If fluxes were below the MDCD they were set to zero see (https://doi.org/10.1002/2017JG003783). The <sup>15</sup>N content of the N<sub>2</sub> and N<sub>2</sub>O was determined using a continuous flow isotope ratio mass spectrometer (Elementar Isoprime PrecisION; Elementar Analysensysteme GmbH, Hanau, Germany) coupled with a trace-gas pre-concentrator inlet with autosampler (isoFLOW GHG; Elementar Analysensysteme GmbH, Hanau, Germany), with a standard deviation of d<sup>15</sup>N < 0.05 %. Extractable dissolved organic carbon and total dissolved nitrogen were analysed in soil extractant (ultrapure water 18.2 MΩ, 7:1 of extractant to soil) on a TOC/TDN analyser (TOC VCSn + TMN-1, Shimadzu, Kyoto, Japan), with 50 mg C l<sup>-1</sup> and 10 mg l<sup>-1</sup> standards resulting in accuracy and precision of 0.3 and ±0.3 mg C l<sup>-1</sup>, and 0.5 and ±0.3 mg N l<sup>-1</sup>, respectively. Extractable nitrate+nitrite (assumed to be nitrate) and ammonium were analysed in soil extractant (2M KCl, 5:1 of extractant to soil) using a microplate reader and methods in Sims et al., 1995 (<a href="https://doi.org/10.1080/00103629509369298">https://doi.org/10.1080/00103629509369298</a>) with a limit of detection of 0.1 ppm and accuracy of ±5 %. Extractable phosphate was analysed in soil extractant (Olsen-P solution 0.5M NaHCO­<sub>3</sub>, pH 8.5, 10:1 of extractant to dry soil) using a microplate reader and methods in Jeannotte et al., 2004 (https://doi.org/10.1007/s00374-004-0760-4) with a limit of detection of 1 mg P l<sup>-1</sup> and accuracy of ±6 %. Soil total carbon, total nitrogen, d<sup>13</sup>C and d<sup>15</sup>N analysis was performed using a continuous flow isotope ratio mass spectrometer (Elementar Isoprime PrecisION; Elementar Analysensysteme GmbH, Hanau, Germany) coupled with an elemental analyser (EA) inlet (vario PYRO cube; Elementar Analysensysteme GmbH, Hanau, Germany). The precision was < 5 % for both C and N and the precision as a standard deviation was < 0.06 % for both d<sup>13</sup>C and d<sup>15</sup>N. Results from the experiments were entered into an Excel spreadsheet for ingestion into the Zenodo data repository.</p>
Nitrification and denitrification in the Community Land Model compared to observations at Hubbard Brook Forest
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Universal temperature sensitivity of denitrification nitrogen losses in forest soils
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Denitrification losses in response to N fertiliser rates - integrating high temporal resolution N2O, in-situ 15N2O and 15N2 measurements and fertiliser 15N recoveries in intensive sugarcane systems
Denitrification is a key process in the global nitrogen (N) cycle, causing both nitrous oxide (N2O) and dinitrogen (N2) emissions. However, estimates of seasonal denitrification losses (N2O+N2) are scarce, reflecting methodological difficulties in measuring soil-borne N2 emissions against the high atmospheric N2 background and challenges regarding their spatio-temporal upscaling. This study investigated N2O+N2 losses in response to N fertiliser rates (0, 100, 150, 200 and 250 kg N ha-1) on two intensively managed tropical sugarcane farms in Australia, by combining automated N2O monitoring, in-situ N2 and N2O measurements using the 15N gas flux method and fertiliser 15N recoveries at harvest. Dynamic changes in the N2O/(N2O+N2) ratio (< 0.01 to 0.768) were explained by fitting generalised additive mixed models (GAMMs) with soil factors to upscale high temporal-resolution N2O data to daily N2 emissions over the season. Cumulative N2O+N2 losses ranged from 12 to 87 kg N ha-1, increasing non-linearly with increasing N fertiliser rates. Emissions of N2O+N2 accounted for 31–78% of fertiliser 15N losses and were dominated by environmentally benign N2 emissions. The contribution of denitrification to N fertiliser loss decreased with increasing N rates, suggesting increasing significance of other N loss pathways including leaching and runoff at higher N rates. This study delivers a blueprint approach to extrapolate denitrification measurements at both temporal and spatial scales, which can be applied in fertilised agroecosystems. Robust estimates of denitrification losses determined using this method will help to improve cropping system modelling approaches, advancing our understanding of the N cycle across scales.
Co-occurrence of in-stream nitrogen fixation and denitrification across a nitrogen gradient in a western U.S. watershed, 2015 - 2016
This data was collected as part of the NSF CAREER Grant DEB 14-51919 to Amy Marcarelli to evaluate if nitrogen fixation and denitrification co-occur in streams across a gradient of nitrate concentrations. This data was collected during summer 2015 and 2016 in the Portneuf River watershed near Pocatello, ID. In summer 2015, rates of nitrogen fixation were only measured on rock substrate and denitrification only on sediment substrate. In summer 2016, both process rates were measured on both rock and sediment substrate to more accurately capture variation in rates.
In situ Denitrification Rates in the Riparian Zone of Caribou-Poker Creeks Research Watershed, Alaska, 2002 - 2004
Prior to this investigation, denitrification had not been intensively measured in headwater catchments of interior Alaska. The primary purpose of this database was to estimate the importance of denitrification as a mechanism of nitrogen retention in the riparian zone of watersheds underlain by discontinuous permafrost.
Determinative factors of denitrification in a urban, arid wash of central Arizona (2012-2013)
Although the absence of nitrogen (N) can be detrimental to many biological processes, in large quantities certain forms of N can be harmful to the environment. N deposits can leak down through the soil and accumulate in groundwater stores, lakes, and other bodies of water. In arid, residential watersheds, N accumulates by fertilization, atmospheric deposition, and litter from residents and is transported to washes during storms. The main goal of this research is to ascertain how geochemical and hydrological factors limit denitrification and, therefore, affect the quantities of N exported from such a wash. In this study, we evaluate the effects of factors including moisture content, soil texture, and N concentrations on denitrification in a residential, desert wash. In order to carry out our research, we sampled soil from a wash in Scottsdale, AZ during summer 2012. Although there were no strong geochemical correlations with denitrification, it was found that there was a strong relationship between denitrification and distance between inlets and sites.
Hubbard Brook Experimental Forest: Stream sediment denitrification potential assays, Watershed 1 and Bear Brook
In early September 2015, we sampled five debris dams in both the stream draining W1 and Bear Brook, immediately downstream of W6. This dataset contains laboratory analysis of potential denitrification enzyme activity assays from these sediment cores. Details of the analysis method are reported in the supporting information of Marinos et al. 2018. These data are being published only in the interest of full data transparency. These data have very important limitations, discussed in the supporting information of Marinos et al. 2018, and the authors advise anybody considering reusing this data to be appropriately cautious. Marinos, R. E., Campbell, J. L., Driscoll, C. T., Likens, G. E., McDowell, W. H., Rosi, E. J., Rustad, L. E., & Bernhardt, E. S. (2018). Give and Take: A Watershed Acid Rain Mitigation Experiment Increases Baseflow Nitrogen Retention but Increases Stormflow Nitrogen Export. Environmental Science & Technology, 52(22), 13155–13165. https://doi.org/10.1021/acs.est.8b03553 These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.
Denitrification rates in lake sediments of mountains affected by high atmospheric nitrogen deposition
<p>During the last decades, atmospheric nitrogen loading in mountain ranges of the Northern Hemisphere has increased substantially, resulting in high nitrate concentrations in many lakes. Yet, how increased nitrogen has affected denitrification, a key process for nitrogen removal, is poorly understood. We measured actual and potential (nitrate and carbon amended) denitrification rates in sediments of several lake types and habitats in the Pyrenees during the ice-free season. Actual denitrification rates ranged from 0 to 9 μmol N<sub>2</sub>O m<sup>−2</sup> h<sup>−1</sup> (mean, 1.5 ± 1.6 SD), whereas potential rates were about 10-times higher. The highest actual rates occurred in warmer sediments with more nitrate available in the overlying water. Consequently, littoral habitats showed, on average, 3-fold higher rates than the deep zone. The highest denitrification potentials were found in more productive lakes located at relatively low altitude and small catchments, with warmer sediments, high relative abundance of denitrification nitrite reductase genes, and sulphate-rich waters. We conclude that increased nitrogen deposition has resulted in elevated denitrification rates, but not sufficiently to compensate for the atmospheric nitrogen loading in most of the highly oligotrophic lakes. However, there is potential for high rates, especially in the more productive lakes and landscape features largely govern this.</p>
Relative importance between nitrification and denitrification to N2O from a global perspective
<p><span>Nitrous oxide (N<sub>2</sub>O) is a potent greenhouse gas and its mitigation is a pressing task in the coming decade. However, it remains unclear which specific process between concurrent nitrification and denitrification dominates worldwide N<sub>2</sub>O emission. We snagged an opportunity to ascertain whence the N<sub>2</sub>O came and which were the controlling factors on the basis of 1315 soil N<sub>2</sub>O observations from 74 peer-reviewed articles. The average N<sub>2</sub>O emission derived from nitrification (N<sub>2</sub>O<sub>n</sub>) was higher than that from denitrification (N<sub>2</sub>O<sub>d</sub>) worldwide. The ratios of nitrification-derived N<sub>2</sub>O to denitrification-derived N<sub>2</sub>O, hereof N<sub>2</sub>O<sub>n</sub>:N<sub>2</sub>O<sub>d</sub>, exhibited large variations across terrestrial ecosystems.<strong> </strong>Although soil carbon and nitrogen content, pH, moisture, and clay content accounted for a part of the geographical variations in the N<sub>2</sub>O<sub>n</sub>:N<sub>2</sub>O<sub>d</sub> ratio, ammonia-oxidizing microorganisms (AOM):denitrifier ratio was the pivotal driver for the N<sub>2</sub>O<sub>n</sub>:N<sub>2</sub>O<sub>d</sub> ratios, since the AOM:denitrifier ratio accounted for 53.7% of geographical variations in N<sub>2</sub>O<sub>n</sub>:N<sub>2</sub>O<sub>d</sub> ratios. Compared with natural ecosystems, soil pH exerted a more remarkable role in dictating the N<sub>2</sub>O<sub>n</sub>:N<sub>2</sub>O<sub>d</sub> ratio in croplands. This study emphasizes the vital role of functional soil microorganisms in geographical variations of N<sub>2</sub>O<sub>n</sub>:N<sub>2</sub>O<sub>d</sub> ratio, and lays the foundation for the incorporation of soil AOM:denitrfier ratio into models to better predict N<sub>2</sub>O<sub>n</sub>:N<sub>2</sub>O<sub>d</sub> ratio. Identifying soil N<sub>2</sub>O derivation will provide a global potential benchmark for N<sub>2</sub>O mitigation by manipulating the nitrification or denitrification.</span></p>
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Allen Brain Atlas
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Annotated Behaviour and Observability Dataset (ABODe)
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DANDI Archive for NWB datasets
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OpenNeuro
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