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openCC0Oct 2021View details →

Nitrogen and oxygen stable isotopes of nitrate from CalCOFI lines 80 and 93 plus station 081.8 046.9. Collected on cruises from 2010 to 2016.

Stable isotopes of nitrate were measured on CalCOFI cruises from 2010-2016 from lines 80 and 93 plus station 081.8 046.9. Samples were filtered directly from the CTD and then frozen until analysis. Samples collected from 2010-2012 were analyzed in the Sigman Lab at Princeton University. Samples collected from 2013-2016 were analyzed in the Wankel Lab at Woods Hole Oceanographic Insititution. Five samples from station 081.8 046.9 (the Santa Barbara Basin) were further analyzed for nitrogen isotopes of nitrite in the Wankel Lab.

openCC0Feb 2018View details →

Plant Nitrogen Isotopes: BioCON : Biodiversity, Elevated CO2, and N Enrichment

BioCON (Biodiversity, CO2, and Nitrogen) is an ecological experiment started in 1997 at the University of Minnesota's Cedar Creek Ecosystem Science Reserve. BioCON's goal is to explore the ways in which plant communities will respond to three environmental changes that are known to be occurring on a global scale: increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity. Why Biodiversity, CO2, and Nitrogen? While there are many uncertainties in global change biology, there are also some well documented facts. Some of these are: 1. The amount of carbon dioxide (CO2) in the atmosphere is rising. Since the industrial revolution, the CO2 concentration in the atmosphere has increased from approximately 275 parts per million (ppm) to about 378 ppm today. This has been largely the result of fossil fuel burning. It is expected that CO2 levels will continue to rise, and that by the year 2050 these levels will be approximately 550 ppm. CO2 is the raw material for photosynthesis and is known to affect plant growth and development. 2. The amount of nitrogen moving through terrestrial ecosystems has increased in the recent past. While natural "background" levels of nitrogen fixation have remained constant, human additions to the system through fertilizer production and fossil fuel use have increased dramatically. Nitrogen is a key nutrient for plant growth and plays a critical role in plant community structure and composition in many environments. 3. Biodiversity levels are falling. While the research and data are not as complete as they are for CO2 and nitrogen, data indicate that the number of species globally, is being reduced. Perhaps more important for ecosystem function, diversity levels on local to regional scales have fallen due to land use change, biotic invasion and many other drivers. While much is known about how each of these factors affects ecosystem functioning, many questions remain. There is also little data on how these issues affe

openCC (other)Jun 2020View details →

Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Forest: Foliar Nitrogen and Natural Abundance Nitrogen Isotopic Composition

Foliar nitrogen and natural abundance stable isotopes of nitrogen in foliage were measured on all Climate Change Across Seasons Experiment (CCASE) plots. There are six plots total (each 11 x 14 m). Two are warmed 5 degrees C throughout the growing season (Plots 3 and 4). Two others are warmed 5 degrees C in the growing season and have snow removed during winter to induce soil freezing and then warming cables turn on to create thaws; each soil freeze/thaw cycle includes 72-hours of soil freezing followed by 72-hours of thaw (Plots 5 and 6). Four kilometers (2.5 mi) of heating cable are buried in the soil to warm these four plots. Two additional plots serve as controls for our experiment (Plots 1 and 2). This data set includes foliar nitrogen and natural abundance stable isotopes of nitrogen in foliage from 2012 to 2018. 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.

openOpenJan 2020View details →

SGS-LTER CO2 Elevation Study: Leaf carbon isotope, nitrogen, carbon and Ci/Ca means from the SGS Open Top Chamber experiment on the Central Plains Experimental Range, Nunn, Colorado, USA 1997 - 2001

This data package was produced by researchers working on the Shortgrass Steppe Long Term Ecological Research (SGS-LTER) Project, administered at Colorado State University. Long-term datasets and background information (proposals, reports, photographs, etc.) on the SGS-LTER project are contained in a comprehensive project collection within the Digital Collections of Colorado (http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429). The data table and associated metadata document, which is generated in Ecological Metadata Language, may be available through other repositories serving the ecological research community and represent components of the larger SGS-LTER project collection. Additional information and referenced materials can be found: http://hdl.handle.net/10217/82454. Carbon isotopes of elevated and ambient OTC plants were measured for use in isotope labeling and plant water-use-efficiency measures. Leaf N and C are associated parameters were also measured. This research was conducted at the Central Plains Experimental Range, near Nunn, CO; lat.40degrees 40 minutes N; long. 104 degrees 45 minutes W in the shortgrass steppe region of NE Colorado, USA and as a collaboration between SGS-LTER and USDA-ARS researchers.

opencc-zeroSep 2020View details →

A non‐steady state model based on dual nitrogen and oxygen isotopes to constrain moss nitrate uptake and reduction

Epilithic mosses are early colonizers of the terrestrial biosphere, constitute a special ecosystem regulating rock-atmosphere interactions, and may be more restricted in their nitrogen (N) supply than other mosses. Terrestrial mosses can take up nitrate (NO3-), a major form of bioavailable N, from soil substrates. However, the importance of substrate NO3- relative to atmospheric NO3- remains unclear in moss NO3- utilization. This has prevented the understanding of moss NO3- dynamics and its responses to environmental N loadings. Here we investigated the monthly concentrations, δ15N, and δ18O of NO3- in four epilithic moss species from August, 2006 to August, 2007 in Guiyang, southwestern China. We developed a non-steady state isotope mass-balance model based on dual N and O isotopes to evaluate fractional contributions of atmospheric NO3- (Фatm) and soil NO3- (Фsoil), moss NO3- uptake flux (Finflux), moss NO3- reduction flux (Freduction), and the percentage of NO3- reduction in total NO3- uptake of mosses (expressed as freduced). Monthly Фsoil values averaged 53 ± 13% and monthly freduced values averaged 50 ± 35%. Both monthly Freduction and freduced values increased with monthly Finflux values, particularly when Фsoil values were higher than Фatm values. However, the amount of annual NO3- reduction (219.7 ± 30.5 μg-N/g, dw) accounted for only 1.0 ± 0.2% in bulk N of mosses. We conclude that half of NO3- in epilithic mosses is derived from soil NO3- and that NO3- uptake from soil induces moss NO3- reduction, but the total NO3- assimilation contributed a low fraction to total N of study mosses. These findings are important for understanding N sources and dynamics in terrestrial mosses.

opencc-zeroDec 2020View details →

Quality control for modern bone collagen stable carbon and nitrogen isotope measurements

(1) Isotopic analyses of collagen, the main protein preserved in sub fossil bone and tooth, has long provided a powerful tool for the reconstruction of ancient diets and environments. Although isotopic studies of contemporary ecosystems have typically focused on more accessible tissues (e.g., muscle, hair), there is growing interest in the potential for analyses of collagen because it is often available in hard tissue archives (e.g., scales, skin, bone, tooth), allowing for enhanced long-term retrospective studies. The quality of measurements of the stable carbon and nitrogen isotopic compositions of ancient samples are subject to robust and well-established criteria for detection of contaminants and digenesis. Among these quality control (QC) criteria, the most widely utilized is the atomic C:N ratio (C:NAtomic), which for ancient samples has an acceptable range between 2.9 and 3.6. While this QC criterion was developed for ancient materials, it has increasingly being applied to collagen from modern tissues. (2) Here we use a large survey of published collagen amino acid compositions (n = 436) from 193 vertebrate species as well as recent experimental isotopic evidence from 413 modern collagen extracts to demonstrate that the C:NAtomic range used for ancient samples is not suitable for assessing collagen quality of modern and archived historical samples. (3) For modern tissues, collagen C:NAtomic falling outside 3.00–3.30 for fish and 3.00–3.28 for mammals and birds can produce systematically skewed isotopic compositions and may lead to significant interpretative errors. These findings are followed by a review of protocols for improving C:NAtomic criteria for modern collagen extracts. (4) Given the tremendous conservation and environmental policy-informing potential that retrospective isotopic analyses of collagen from contemporary and archived vertebrate tissues have for addressing pressing questions about long-term environmental conditions and species behaviours, it is critical that QC criteria tailored to modern tissues are established.

opencc-zeroJan 2023View details →

An isotope study on Nitrogen and Phosphorus use efficiency and movement in soil in a mimicked vermicompost-based organo-mineral fertilizer

Vermicompost (VC), a stabilized organic material with high organic and humic carbon, and favorable aggregation properties, was tested as a fraction of organo-mineral fertilizers (OMFs), where organic and mineral fractions interact in hotspot areas with surrounding soil. Solutions containing 33P radioisotope and 15N labeled mineral fertilizers were combined with vermicompost at two ratios of organic carbon (Corg) to mineral nitrogen (N) and phosphorus (P) (OMF7.5C and OMF15C) to simulate OMF granules. Control treatments included unfertilized soil (N0P0), mineral fertilizer (MFNP), and sole vermicompost at 2 rates (OF7.5C and OF15C). Nitrogen and P uptake by Italian ryegrass (Lolium multiflorum) were measured over in 8 weeks. Furthermore, MFNP, OMF7.5C, and OMF15C treatments were incubated for 10 days without plant to measure atom% 15N excess and 33P radioactivity, as indicators of N and P movement from two soil layers (surrounding fertilizer hotspot and below it). In the pot study, OMF15C caused 24% lower biomass and less nutrient recovery derived from fertilizer (N -11%, P –8.5%), compared to MFNP. In the incubation study, OMF15C exhibited +19% atom% 15N excess in the combined two soil layers, relative to MFNP, and +28% 33P radioactivity in the soil surrounding the hotspot, and –89 % in the soil below it. We interpreted this as a reduction in nutrient availability of the combined vermicompost+mineral fertilizers, due to lower P mobility in soil. The combination of vermicompost with mineral fertilizers can reduce P movement in soil. A higher Corg:N:P ratio resulted in lower nutrient use efficiency in two months.

opencc-zeroFeb 2024View details →

Bulk Carbon and Amino Acid nitrogen isotope data from Baltic cod (Gadus morhua) and European flounder (Platichthys flesus) muscle tissue samples from the western and central Baltic Sea

Eutrophication, increased temperatures and stratification can lead to massive, filamentous, N2-fixing cyanobacterial (FNC) blooms in coastal ecosystems with largely unresolved consequences for the mass and energy supply in pelagic and benthic food webs. Mesozooplankton adapt to not top-down controlled FNC blooms by switching diets from phytoplankton to microzooplankton, resulting in a directly quantifiable increase in its trophic position (TP) from 2.0 (herbivore) to as high as 3.0 (carnivore). If this process in mesozooplankton, we call trophic lengthening, was transferred up to higher trophic levels of a food web, a large loss of energy could result in massive declines of fish biomass. We used compound-specific nitrogen stable isotope data of amino acids (CSIA) to estimate and compare the nitrogen (N) sources and TPs of cod and flounder (mesopredators) from areas with influence of FNC blooms (central Baltic Sea) and without it (western Baltic Sea). We tested if FNC-caused trophic lengthening in mesozooplankton is carried over to fish. The TP of cod from the western Baltic, feeding mainly on decapods, was equal to the global mean value (4.1, secondary carnivore). Only cod from the central Baltic, mainly feeding on zooplanktivorous pelagics, had a higher TP (4.8, near-tertiary carnivore), indicating a strong carry-over effect of FNC-caused trophic lengthening from mesozooplankton. In contrast, the TP of molluscivorous flounder (3.2 ± 0.2 in both areas), associated with the benthic food web, was unaffected by trophic lengthening. This suggests that FNC blooms cause a large loss of energy in zooplanktivorous but not in molluscivorous mesopredators. If FNC blooms continue to detour energy at the base of the pelagic food web, the TP of cod will not return to global mean values and the fish stock not recover. Monitoring the TP of key species can identify fundamental changes in ecosystems and provide useful information for resource management.

opencc-by-4.0Jul 2022View details →

Laboratory Assessment of the Impact of Chemical Oxidation, Mineral Dissolution, and Heating on the Nitrogen Isotopic Composition of Fossil-bound Organic Matter

Results of laboratory experiments reported in the manuscript "Laboratory Assessment of the Impact of Chemical Oxidation, Mineral Dissolution, and Heating on the Nitrogen Isotopic Composition of Fossil-bound Organic Matter", published in the journal Geochemistry, Geophysics, Geosystems

opencc-by-4.0Jun 2024View details →

Data from: Dissolved nitrogen uptake versus nitrogen fixation: Mode of nitrogen acquisition affects stable isotope signatures of a diazotrophic cyanobacterium and its grazer

Field studies suggest that changes in the stable isotope ratios of phytoplankton communities can be used to track changes in the utilization of different nitrogen sources, i.e., to detect shifts from dissolved inorganic nitrogen (DIN) uptake to atmospheric nitrogen (N2) fixation by diazotrophic cyanobacteria as an indication of nitrogen limitation. We explored changes in the stable isotope signature of the diazotrophic cyanobacterium Trichormus variabilis in response to increasing nitrate (NO3-) concentrations (0 to 170 mg L-1) under controlled laboratory conditions. In addition, we explored the influence of nitrogen utilization at the primary producer level on trophic fractionation by studying potential changes in isotope ratios in the freshwater model Daphnia magna feeding on the differently grown cyanobacteria. We show that δ15N values of the cyanobacterium increase asymptotically with DIN availability, from -0.7 &permil; in the absence of DIN (suggesting N2 fixation) to 2.9 &permil; at the highest DIN concentration (exclusive DIN uptake). In contrast, δ13C values of the cyanobacterium did not show a clear relationship with DIN availability. The stable isotope ratios of the consumer reflected those of the differently grown cyanobacteria but also revealed significant trophic fractionation in response to nitrogen utilization at the primary producer level. Nitrogen isotope turnover rates of Daphnia were highest in the absence of DIN as a consequence of N2 fixation and resulting depletion in 15N at the primary producer level. Our results highlight the potential of stable isotopes to assess nitrogen limitation and to explore diazotrophy in aquatic food webs.

opencc-by-4.0Jun 2024View details →

Nitrogen in the Orgueil meteorite: abundant ammonium among other reservoirs of variable isotopic compositions

These data are relative to the paper "Nitrogen in the Orgueil meteorite: abundant ammonium among other reservoirs of variable isotopic compositions" The dataset consists in 20 Excel files that represent the data presented in the Figures and Tables of this paper. Note: <ul> <li>Data from Table S5 of the paper were obtained from the data shown in Table S1, whose data file is provided here</li> <li>Data from Table S6 of the paper were obtained from the data shown in Figure S5, whose data file is provided here</li> </ul>

opencc-zeroJul 2024View details →

Lipid extraction alters amino acid composition and bulk, but not amino acid, carbon and nitrogen isotope values

Rationale: Concerns exist over observed shifts in value and variance of nitrogen isotopes following physicochemical extraction of lipids from organic matter. The mechanisms behind these apparent changes in bulk tissue δ15N values are not fully understood yet have major implications for analytical costs and integrity of data interpretations. Methods: Changes in proximate analysis, amino acid composition, C:N ratios, bulk tissue and amino acid δ13C and δ15N values, and resulting isotope‐based food web metrics were compared between lipid‐intact and lipid‐extracted muscle tissue of fishes spanning <1% to >20% muscle fat content to identify mechanisms of nitrogen isotope fractionation associated with physicochemical lipid extraction. Results: Bulk δ13C and δ15N values increased and %N, C:N ratios and crude protein content decreased following lipid extraction. Resulting bulk isotope niche spacing and overlap varied significantly between lipid‐intact and lipid‐extracted tissues. While amino acid composition significantly changed during lipid extraction, particularly for lipid‐associated amino acids (e.g., Glu, Lys, Ser), individual amino acid δ13C and δ15N values, and their associated compound‐specific isotope analysis of amino acids (CSIA‐AA)‐based food web metrics, did not. Conclusions: Physicochemical lipid extraction caused significant tissue composition changes (e.g., leaching of amino acids and 15N‐deplete nitrogenous waste) that affected δ13C and δ15N values and tissue %C and %N beyond simply removing lipids. However, lipid extraction did not alter individual amino acid δ13C or δ15N values or their associated CSIA‐AA‐based food web metrics.

opencc-zeroSep 2021View details →

Seasonal dynamics of sinking organic matter in the Pacific Arctic Ocean revealed by nitrogen isotope ratios of amino acids

The Pacific Arctic Ocean has experienced a rapidly changing climate, sea-ice retreat, and enhanced primary production over the past few decades. The export production generated by photoautotrophs and heterotrophs has been characterized in the Arctic Ocean, but their seasonal variations in relative proportion are largely unknown due to the limited access in the ice-covered season. We measured the concentration and nitrogen isotope ratio of individual amino acids from sinking particles in the northern east Siberian Sea (KAMS1), northern Chukchi Sea (KAMS2), and Northwind Ridge (KAMS4) from August 2017 to July 2019. The average trophic position, based on differences in the nitrogen isotope ratios of glutamic acid and phenylalanine, can indicate the relative proportions of biogenic organic matters derived from photoautotrophs and heterotrophs in sinking particles. Decreasing values (close to 1.0) in summer at KAMS2 in 2018 suggest that primary producers are responsible for most of the downward flux of sinking particles. However, the average trophic position at KAMS1 in 2017 increased to > 1.5 in autumn and was maintained at approximately 1.7 during ice-covered winter periods, likely due to greater contributions from heterotrophic organisms. Exceptionally high average trophic positions (close to 2.0) of sinking particles in summer at KAMS1 in 2017 and KAMS4 in 2018 were likely due to small export of photoautotrophs due to the surface seawater stratification and limited pelagic production. The average trophic position in sinking particles should reflect the spatiotemporal variation in export particle composition in the Pacific Arctic Ocean.

opencc-zeroOct 2022View details →

Occurrence patterns of crop-foraging sika deer distribution in an agriculture-forest landscape revealed by nitrogen stable isotopes

Conflicts arising from the consumption of anthropogenic foods by wildlife are increasing worldwide. Conventional tools for evaluating the spatial distribution pattern of large terrestrial mammals that consume anthropogenic foods have various limitations, despite their importance in management to mitigate conflicts. In this study, we examined the spatial distribution pattern of crop-foraging sika deer by performing nitrogen stable isotope analyses of bone collagen. We evaluated whether crop-foraging deer lived closer to agricultural crop fields during the winter and spring, when crop production decreases. We found that female deer in proximity to agricultural crop fields during the winter and spring were more likely to be crop-foraging individuals. Furthermore, the likelihood of crop consumption by females decreased by half as the distance to agricultural crop fields increased to 5-10 km. We did not detect a significant trend in the spatial distribution of crop-foraging male deer. The findings of spatial distribution patterns of crop-foraging female deer will be useful for the establishment of management areas, such as zonation, for efficient removal of them.

opencc-zeroDec 2022View details →

Isotopic evidence for increased carbon and nitrogen exchanges between peatland plants and their symbiotic microbes with rising atmospheric CO2 concentrations since 15000 cal. yr BP

Whether nitrogen (N) availability will limit plant growth and removal of atmospheric CO2 this century is controversial. Studies have suggested that N could progressively limit plant growth, as trees and soils accumulate N in slowly cycling biomass pools in response to increases in carbon sequestration. However, a question remains over the longer-term (decadal to century) feedbacks between climate, CO2 and plant N uptake. The symbiosis between plants and microbes can help plants with mycorrhizal N uptake or biological N2 fixation – the pathway through which N can be rapidly brought into ecosystems and thereby partially or completely alleviate N limitation on plant productivity. Here we present results for plant N isotope composition (δ15N) in a peat core that dates to 15000 cal. yr BP to ascertain ecosystem-level N cycling responses to rising atmospheric CO2 concentrations in the past. We found that an increase in atmospheric CO2 concentration happened with a decrease in δ15N values of both Sphagnum moss and Ericaceae over this time period when constrained for climatic factors. A modern experiment demonstrated that δ15N of Sphagnum mosses decreased with increasing N2 fixation rates. These findings suggested that N2 fixation in Sphagnum moss by symbiosis with cyanobacteria and N uptake in Ericaceae by symbiosis with mycorrhizal fungi both likely increased with rising atmospheric CO2 concentrations, highlighting a longer-term feedback mechanism whereby N constraints on terrestrial carbon storage can be overcome.

opencc-by-4.0Oct 2023View details →

Supplementary Data to: "Organic Phases in Bivalve (Arctica islandica) Shells: Their Bulk and Amino Acid Nitrogen Stable Isotope Compositions" in Geochemistry, Geophysics, Geosystems

This dataset contains the data generated for publication "Organic Phases in Bivalve (Arctica islandica) Shells: Their Bulk and Amino Acid Nitrogen Stable Isotope Compositions", including the following files: Specimen_ID_shell_morphology_measurement: Description of locality of collection, shell ID, shell working ID and the shell morphology measurement which can be referred to Section 2.1 of the manuscript. EA_IRMS_raw_error_propagate: This file contains data showing the m/z 28 signal intensities of all measurements and the error propagation that mentioned in Section 2.3 of the manuscript. It also includes the calculation of analytical accuracy and precision.  Statistics: The file contains the summary of statistical analyses performed in this manuscript. Refer to Section 2.7 and 3.3. Recovery: It contains the recovery of the total nitrogen contents or amino acid concentrations after different treatments and this was mentioned in Section 4.1 of the manucript. Mass_balance: The computation procedure that showed in Section 3.4 and discussed in Section 4.3 can be traced in this file. GC-C-IRMS_long_term_sd: The file shows the long-term precision of GC-C-IRMS computed from the mixed standard of amino acids  BSIA_d15N: The file contains all the bulk d15N data that used in this manuscript. CSIA_d15N: The file contains all the amino acid d15N data that used in this manuscript. AA_Composition: The file shows AA percent data that used in this manuscript. For details see main text of the manuscript.

publicJun 2025View details →

Feather nitrogen and carbon stable isotope (d15N and d13C) values for Golden-crowned Sparrows

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publicFeb 2024View details →

Bulk Carbon and Amino Acid nitrogen isotope data from Baltic cod (Gadus morhua) and European flounder (Platichthys flesus) muscle tissue samples from the western and central Baltic Sea

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publicJul 2024View details →

Lipid extraction alters amino acid composition and bulk, but not amino acid, carbon and nitrogen isotope values

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