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106 results for “organic nitrogen”
Deep sea dissolved organic nitrogen and phosphorus (DON and DOP) at Station ALOHA in the North Pacific Subtropical Gyre
<p>Data on organic and inorganic nutrients in unfiltered seawater that was sampled at and around Station ALOHA, north of Oahu, Hawaii, in the North Pacific Subtropical Gyre. Seawater was collected into HDPE or polypropylene bottles and immediately frozen. Silicate, phosphate and nitrate+nitrite are determined colormetrically on a SEAL Analytical Autoanalyzer (AA3 with HR detectors), with the exception of nitrate+nitrite that is <0.5umol/L, which is analyzed by high-sensitivity chemiluminescence. Total phosphorus (TP) and total nitrogen (TN) are determined by analysis of phosphate and nitrate, respectively, after oxidation by high-intensity ultraviolet light. Total organic phosphorus and total organic nitrogen are determined by subtracting background PO4 and NO3+NO2 from TP and TN, respectively. Total organic carbon is determined by combustion on a Shimadzu TOC-V analyzer. This dataset was originally published in the following article, in which additional details and interpretations of the data can be found:</p> <p>R. K. Foreman, K. M. Björkman, C. A. Carlson, K. Opalk, D. M. Karl, (2019). Improved ultraviolet photo‐oxidation system yields estimates for deep‐sea dissolved organic nitrogen and phosphorus, Limnol. Oceanogr. Methods, <a href="https://doi.org/10.1002/lom3.10312">doi.org/10.1002/lom3.10312</a> <br> </p>
Data from: Feedbacks between nitrogen fixation and soil organic matter increase ecosystem functions in diversified agroecosystems
Nitrogen (N) losses from intensified agriculture are a major cause of global change, due to nitrate (NO3-) export and the eutrophication of aquatic systems as well as emissions of nitrous oxide (N2O) into the atmosphere. Diversified agroecosystems with legume cover crops couple N and carbon (C) inputs to soil and reduce N pollution, but there is a need to identify controls on legume N2 fixation across ecosystems with variable soil conditions. Here, I tested the hypothesis that N mineralization from turnover of soil organic matter (SOM) regulates legume N2 fixation across 10 farms that spanned a gradient of SOM levels. I separated soil samples into two SOM fractions, based on size and density, which are indicators of soil nutrient cycling and N availability (free particulate organic matter and intra-aggregate particulate organic matter (POM)). This study indicates downregulation of legume N2 fixation in diversified agroecosystems with increasing N availability in intra-aggregate POM and increasing N mineralization. Intercropping the legume with a grass weakened the relationship between N in POM and N2 fixation due to N assimilation by the grass. Further, mean rates of N and C mineralization across sites increased with two seasons of a legume-grass cover crop mixture, which could enhance this stabilizing feedback between soil N availability and N2 fixation over time. These results suggest a potential mechanism for the diversity-ecosystem function relationships measured in long-term studies of agroecosystems, in which regular use of legume cover crops increases total soil organic C and N and reduces the environmental costs of crop production.
Data and analysis process for Microbiome processing of organic nitrogen input supports growth and cyanotoxin production of Microcystis aeruginosa cultures
<p>Data and analysis process for manuscript titled "Microbiome processing of organic nitrogen input supports the growth and cyanotoxin production of Microcystis aeruginosa cultures"</p>
Metagenome-assembled genomes for "Impacts of beaver ponds on biogeochemical cycling of organic nitrogen within a fire-impacted watershed"
<p>This dataset includes all of the metagenome-assembled genomes (MAGs) used in Roth et al.: "Impacts of beaver ponds on biogeochemical cycling of organic nitrogen within a fire-impacted watershed" (in prep.). The metagenomic sequencing was completed on a suite of sediment samples collected from the sediment-water interface of beaver ponds within wildfire burn scars.</p>
Data used to generate figures in 'Autotrophic Dissolved Organic Phosphorus Uptake Stimulates Nitrogen Fixation in Subtropical Gyres'
<p>Data used to generate figures in '<strong><span>Autotrophic Dissolved Organic Phosphorus Uptake Stimulates Nitrogen Fixation in Subtropical Gyres</span></strong>' by Shen and Wang</p> <p> </p> <p><span>Figure2.mat</span></p> <p><span>up2d: Integrated Euphotic Zone’s DOP uptake rate (mmol P m^{-2} yr^{-1}) (Fig. 2a)</span></p> <p><span>per: Contribution percentage of DOP uptake to net primary production(NPP) (Fig. 2b)</span></p> <p><span> </span></p> <p><span>Figure3.mat</span></p> <p><span>NFtmp: Global distribution of microbial N<sub>2</sub> fixation rate (mmol N m^{-2} yr^{-1}) (Fig. 3a)</span></p> <p><span>fn2p: </span><span>N:P of exported material from euphotic zone (Fig. 3b)</span></p> <p><span>NFdif: N<sub>2</sub> fixation anomaly (mmol N m^{-2} yr^{-1}) (Fig. 3c)</span></p> <p><span>difper: N<sub>2</sub> fixation anomaly in percentage (Fig. 3d)</span></p> <p><span> </span></p> <p><span>Figure4.mat</span></p> <p><span>rdop: </span><span>Contribution of newly fixed N to export production (Fig. 4a)</span></p> <p><span>dif: Anomaly of contributions of newly fixed N to export production (Fig. 4b)</span></p> <p><span>mass2d: </span><span>Annual Net Community Production (mg C m^{-2} day^{-1}) (Fig.4c)</span></p>
Bulk and amino acid nitrogen specific isotope data from particulate organic matter and mesozooplankton (1000-2000 µm) from the Mekong River plume and southern South China Sea
<p><strong><span><span>The mean trophic position (TP) of mesozooplankton largely determines how much mass and energy is available for higher trophic levels like fish. Unfortunately, the ratio of herbivores to carnivores in mesozooplankton is difficult to identify in field samples. Here we investigated changes in the mean TP of mesozooplankton in a highly dynamic environment encompassing four distinct habitats in </span></span></strong>the southern South China Sea:<strong> </strong><span>the </span>Mekong River plume, coastal upwelling region, shelf waters, and offshore oceanic waters<strong><span>. </span></strong><span>We used a set of parameters derived from bulk and amino acid nitrogen stable isotopes from particulate organic matter (POM) and four mesozooplankton size fractions to identify changes in the nitrogen source and structure of the planktonic food web across these habitats.</span> We found clear indications of a shift in N sources for biological production from nitrate in near-coastal waters towards an increase in diazotroph-N inputs in oceanic waters where diazotrophs shaped the phytoplankton community. The shift in N source was accompanied by a lengthening of the food chain (increase in the TP), which may provide further support for the connection between diazotrophy and the indirect routing of N through the marine food web. Our combined bulk and amino acid δ<sup>15</sup>N approach also allowed us to estimate the trophic enrichment (TE) of mesozooplankton across the entire regional ecosystem. When put in the context of literature values, our high TE of 5.1‰ suggested a link between ecosystem heterogeneity and the less efficient transfer of mass and energy across trophic levels.</p>
Climate and geology overwrite land use effects on soil organic nitrogen cycling on a continental scale
<p><strong>Abstract.</strong> Soil fertility and plant productivity are globally constrained by N availability. Proteins are the largest N reservoir in soils and the cleavage of proteins into small peptides and amino acids has been shown to be the rate limiting step in the terrestrial N cycle. However, we are still lacking a profound understanding of the environmental controls of this process. Here we show that integrated effects of climate and soil geochemistry drive protein cleavage across large scales. We measured gross protein depolymerization rates in mineral and organic soils sampled across a 4000-km-long European transect covering a wide range of climates, geologies and land uses. Based on structural equation models we identified that soil organic N cycling was strongly controlled by substrate availability, e.g. by soil protein content. Soil geochemistry was a secondary predictor, by controlling protein stabilization mechanisms and protein availability. Precipitation was identified as the main climatic control on protein depolymerization, by affecting soil weathering and soil organic matter accumulation. In contrast, land use was a poor predictor of protein depolymerization. Our results highlight the need to consider geology and precipitation effects on soil geochemistry when estimating and predicting soil N cycling at large scales.</p>
On the Contributions of Nitrogen from Different Sources to Exported Organic Nitrogen from the East China Sea
<p>Processed model data for "On the Contributions of Nitrogen from Different Sources to Exported Organic Nitrogen from the East China Sea" submitted to Geophysical Research Letters. Detailed information is described in readme.txt.</p>
Nine years of warming and nitrogen addition in the Tibetan grassland promoted loss of soil organic carbon but did not alter the bulk change of chemical structure
<p>Understanding the changes in soil organic carbon (SOC) storage and chemical stabilization dynamics is important for accurately predicting ecosystem C sequestration and/or potential C loss, but the relevant information, especially for the intervention of environmental controls on grassland soil is limited in Tibetan plateau regions. Here we used a 9-year two-way factorial experiment involving warming with open top chambers (+1.80 °C in the daytime and +0.77 °C in the nighttime at the soil surface) and multilevel nitrogen (N) enrichment treatments (0, 5, 10, and 15 g m<sup>-2</sup> year<sup>-1</sup>) in the Tibetan plateau to investigate the changes in SOC pool size and chemical structure. 9-year warming treatment significantly decreased SOC stock in the Tibetan grassland. We observed decreasing SOC concentrations which may be related to changes in the C degrading enzymes. Surprisingly, the SOC molecular structure remained unchanged in all N enrichment and warmed plots, suggesting that both treatments had affected all forms of SOC, from simple and complex polymeric in a similar way. Our results suggest that long-term warming stimulates soil C loss but no preference in SOC loss with different chemical structure.</p>
Data from: Effect of organic matters on anammox coupled denitrification system: when nitrite nitrogen was sufficient
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Data from: Tree species rather than type of mycorrhizal association drives inorganic and organic nitrogen acquisition in tree-tree interactions
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Data from: Feedbacks between nitrogen fixation and soil organic matter increase ecosystem functions in diversified agroecosystems
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Bulk and amino acid nitrogen specific isotope data from particulate organic matter and mesozooplankton (1000-2000 µm) from the Mekong River plume and southern South China Sea
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Data from: Concentrations and ratios of particulate organic carbon, nitrogen, and phosphorus in the global ocean
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Soil Organisms:BioCON: Biodiversity, CO2, and Nitrogen
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
Soil organic matter, total nitrogen and pH:Microbial composition and function across an old-field chronosequence
As mediators of biogeochemical cycles, understanding the ecological forces structuring soil microbial communities is of ecosystem-level significance. Due to gradual shifts in plant species composition and litter addition through time, succession can be used as a model to understand how plant communities shape microbial community composition and function in soil. Numerous studies have investigated microbial biomass and diversity along successional gradients, yet few have quantified changes in microbial communities. Using the established successional dynamics experiment at Cedar Creek, principal investigators Lauren C. Cline and Donald R. Zak investigated the influence of plant community composition in structuring microbial community composition and function. Specifically, their research addressed the following questions: 1. Do shifts in saprotrophic microbial communities correlate to changes in plant community composition through successional time? 2. What is the relative influence of soil properties and plant community characteristics in determining microbial community dynamics? Cline and Zak sampled soils from 8 established abandoned agricultural fields (e054), as well as three adjacent forests representing potential late-successional ecosystems, to investigate microbial dynamics using three complementary approaches: targeted sequencing of fungal and bacterial communities, quantitative PCR, and shotgun metagenomics. Further, the characterization of soil properties across the chronosequence will enable us to disentangle the impact of abiotic factors in structuring microbial communities.
Particulate organic carbon and nitrogen measurements from Go-Flo bottles sampling the water column from a zodiac during Palmer LTER station seasons at Palmer Station Antarctica, 1991 - 2012.
All organisms are composed of organic matter. Organic matter is synthesized from dissolved inorganic carbon (dissolved CO2) and inorganic nutrients by phytoplankton photosynthesis, and consumed (oxidized) by respiration by heterotrophs (zooplankton and bacteria). The organic matter in seawater is a variable mixture of dissolved and particulate organic matter (DOM and POM). Typically DOM predominates over POM by an order of magnitude, but the relative amount of POM can be highly enhanced during large phytoplankton blooms. The principal elemental components of POM include organic carbon (POC), organic nitrogen (PN), there is no particulate inorganic N) and phosphorus (POP). These elements exist in a relatively stable, characteristic ratio of 106:6:1 (C:N:P) in seawater, known as the Redfield Ratio. Marine particulate matter is a complex mixture of live and dead plankton and detritus, and of carbohydrates, proteins, lipids and nucleic acids. POC and PN are enhanced in the euphoric zone, reflecting their origin by photosynthesis. The particulate pool is also a complex assemblage of particles of different sizes, shapes and densities. A simplified scheme divides the particles into large, rapidly sinking particles (10s - 100s of meters per day) and smaller, suspended particles. The transition between small particles and dissolved organic matter is typically specified by filtration through GF/F filters. POC and PN are analyzed for all samples in the upper 50 meters at Palmer Station B (75 m depth) and the upper 65 m at Station E (200 m depth). There is a gradient of POM from higher values inshore to much lower values in deep ocean water beyond the continental shelf break (sampled on the annual cruise).
Data from: Nitrogen loads influence trophic organization of estuarine fish assemblages
Nutrient (N and P) loading may affect functioning in aquatic ecosystems by restructuring producer assemblages with flow-on effects to consumers. Trophic niche occupancy and trophic organization of consumers are key components of ecosystem function that have been increasingly investigated using quantitative isotopic niche indices. These indices are based on the premise that the isotopic values of consumer tissues indicate their assimilated diet. Typically, isotopic niche indices are calculated using only consumer isotope data, which limit their application for spatial and temporal comparisons because consumer isotopic niches depend on isotopic variability of available autotrophs. We used measures of isotopic variability of autotrophs to standardize isotopic niche indices, which enabled us to compare trophic organization of fish assemblages in nine estuaries spanning a broad range of nutrient loading. We related standardized isotopic niche indices of fish assemblages to nitrogen and phosphorous loads and hydrological flushing of the estuaries in autumn and spring. The estuarine fish assemblages studied here showed greater trophic diversity and less redundancy given moderate to high inorganic nitrogen loading. Taxonomic richness partly influenced three isotopic niche indices measuring trophic diversity, but not measures of redundancy. Similar patterns may occur in other systems in which nitrogen loads have increased but the diversity of primary producers has not been reduced to a single dominant source. Our results demonstrate bottom-up controls of estuarine food webs. Effects of inorganic nitrogen loading were transmitted upwards through the food web to affect the trophic organization of higher trophic levels, demonstrating the crucial role of nitrogen for estuarine trophic dynamics.
Data from: Direct and indirect effects of nitrogen enrichment on soil organisms and carbon and nitrogen mineralization in a semi‐arid grassland
1. Semi-arid grasslands on the Mongolian Plateau are expected to experience high inputs of anthropogenic reactive nitrogen in this century. It remains unclear, however, how soil organisms and nutrient cycling are directly affected by N enrichment (i.e., without mediation by plant input to soil) vs. indirectly affected via changes in plant-related inputs to soils resulting from N enrichment. 2. To test the direct and indirect effects of N enrichment on soil organisms (bacteria, fungi, and nematodes) and their associated C and N mineralization, in 2010 we designated two subplots (with plants and without plants) in every plot of a six-level N-enrichment experiment established in 1999 in a semi-arid grassland. 3. In 2014, 4 years after subplots with and without plant were established, N enrichment had substantially altered the soil bacterial, fungal, and nematode community structures due to declines in biomass or abundance whether plants had been removed or not. N enrichment also reduced the diversity of these groups (except for fungi) and the soil C mineralization rate and induced a hump-shaped response of soil N mineralization. As expected, plant removal decreased the biomass or abundance of soil organisms and C and N mineralization rates due to declines in soil substrates or food resources. 4. Analyses of plant removal-induced changes (ratios of without- to with-plant subplots) showed that microorganisms and C and N mineralization rates were not enhanced as N enrichment increased but that nematodes were enhanced as N enrichment increased, indicating that the effects of plant removal on soil organisms and mineralization depended on trophic level and nutrient status.5. Surprisingly, there was no statistical interaction between N enrichment and plant removal for most variables, indicating that plant-related inputs did not qualitatively change the effects of N enrichment on soil organisms or mineralization. Structural equation modeling confirmed that changes in soil communities and mineralization rates were more affected by the direct effects of N enrichment (via soil acidification and increased N availability) than by plant-related indirect effects. Our results provide insight into how future changes in N-deposition and vegetation may modify below-ground communities and processes in grassland ecosystems.
Ultrafast Charge Dynamics in Nitrogen-Rich Covalent Organic Frameworks for Hydrogen Peroxide Photosynthesis
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