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395 results for “carbon to nitrogen”
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.
Data from: Nitrogen and chlorine co-doped carbon dots as probe for sensing and imaging in biological samples
A facile one step hydrothermal synthesis approach was proposed to prepare nitrogen and chlorine co-doped carbon dots using l-ornithine hydrochloride as the sole precursor. The configuration and component of carbon dots were characterized by TEM, XPS, and FTIR. The obtained CDs (Orn-CDs) with a mean diameter of 2.1 nm were well monodispersed in aqueous solutions. The as-prepared CDs exhibited a bright blue fluorescence with a high yield of 60%, good photostability and low cytotoxicity. The emission of Orn-CDs could be selectively and effectively suppressed by Fe3+. Thus, a quantitative assay of Fe3+ was realized by this nanoprobe with a detection limit of 95.6 nmol L-1 in the range of 0.3-50 µmol L-1. Furthermore, ascorbic acid could recover the fluorescence of Orn-CDs suppressed by Fe3+, owing to the transformation of Fe3+ to Fe2+ by ascorbic acid. The limit of detection for ascorbic acid was 137 nmol L-1 in the range of 0.5-10 µmol L-1. In addition, the established method was successfully applied for Fe3+ and ascorbic acid sensing in human serum and urine specimans and for imaging of Fe3+ in living cells. With merits of low economic cost, easy to scale up, without additional functionalized and sample pretreatment, Orn-CDs based sensing platform showed its potential to be used for biomedical related study.
Herbivore grazing mitigates the negative effects of nitrogen deposition on soil organic carbon in low-diversity grassland
<p>1. Changes in soil carbon (C) sequestration in grassland ecosystems have important impacts on the global C cycle. As such, it is important that researchers better understand the underlying mechanisms affecting soil C. Increasing evidence has shown that atmospheric nitrogen (N) deposition can cause dramatic changes in grassland soil C. It remains unclear whether herbivore grazing, a primary means to manage and utilize grassland resources, can regulate the effects of N deposition on soil C, and whether these effects are dependent on plant community diversity.</p> <p>2. Here, we examined the joint effects of herbivore grazing and N-addition on soil organic C (SOC) stocks in two types of communities with low and high plant diversity, respectively.</p> <p>3. Our results showed that the effects of N-addition and its combination with herbivore grazing on grassland SOC were inconsistent in the two types of communities. In the low-diversity community, N-addition greatly decreased SOC stocks, while grazing significantly increased it. Additionally, the grazing-induced increase in soil C stocks in presence of N-addition was so great that it completely counteracted the significant decline in SOC induced by N-addition. However, in the high-diversity community, we observed no effects of N-addition on SOC and grazing increased SOC only in the absence of N-addition and had no significant effect in presence of N-addition.</p> <p>4. Synthesis and applications. Our study suggests that increased N deposition can trigger a remarkable reduction in soil C sequestration in grasslands with low plant diversity, but that herbivore grazing can offset this decline, which may help to mitigate greenhouse gas emissions caused by atmospheric N deposition. As a result, we suggest that moderate herbivore grazing should be considered as an effective grassland management measure for maintaining and improving grassland soil C sequestration as the increasing global change such as elevated atmospheric carbon dioxide, N deposition, and biodiversity losses threat.</p>
Data from: Strong interactive effects of warming and insect herbivory on soil carbon and nitrogen dynamics at Subarctic tree line
<p>Warming will likely stimulate Arctic primary production, but also soil C and N mineralization, and it remains uncertain whether the Arctic will become a sink or a source for CO<sub>2</sub>. Increasing insect herbivory may also dampen the positive response of plant production and soil C input to warming. We conducted an open-air warming experiment with Subarctic field layer vegetation in North Finland to explore the effects of warming (+3°C) and reduced insect herbivory (67% reduction in leaf damage using an insecticide) on soil C and N dynamics. We found that plant root growth, soil C and N concentrations, microbial biomass C, microbial activity, and soil NH<sub>4</sub><sup>+</sup> availability were increased by both warming and reduced herbivory when applied alone, but not when combined. Soil NO<sub>3</sub><sup>-</sup> availability increased by warming only and in-situ soil respiration by reduced herbivory only. Our results suggest that increasing C input from vegetation under climate warming increases soil C concentration, but also stimulates soil C turnover. On the other hand, it appears that insect herbivores can significantly reduce plant growth. If their abundance increases with warming as predicted, they may curtail the positive effect of warming on soil C concentration. Moreover, our results suggest that temperature and herbivory effects on root growth and soil variables interact strongly, which probably arises from a combination of N demand increasing under lower herbivory and soil mineral N supply increasing under higher temperature. This may further complicate the effects of rising temperatures on Subarctic soil C dynamics.</p>
Periphyton carbon and nitrogen stable isotopes detect agricultural stressors in low-order streams
<p>Shifts in the stable isotope signatures of carbon (C) and nitrogen (N) in ecological materials have the potential to indicate environmental disturbances. This study examined the δ<sup>13</sup>C‰ and δ<sup>15</sup>N‰ ratios of stream water and periphyton from low-order streams in a landscape influenced by agricultural activities. Our key purpose was to assess the influence of best management practice (BMP) presence and age on C and N isotope values as a potential water-quality assessment. We collected stream water and periphyton from 19 streams within the Upper Delaware River watershed in New York, USA, in each of 4 management categories: 1) recently applied BMP treatments, 2) long-standing BMPs, 3) streams lacking BMPs, and 4) minimally disturbed reference streams. We sampled and analyzed water and periphyton for δ<sup>13</sup>C‰ and δ<sup>15</sup>N‰ in a repeated-measures design (BMP category ´ time) from April to November 2013. There were large seasonal differences in stream water δ<sup>13</sup>C-dissolved organic C (DIC)‰ and δ<sup>15</sup>NO<sub>3</sub>-N‰, with strong differences between reference and agricultural streams. Periphyton δ<sup>13</sup>C‰ and δ<sup>15</sup>N‰ values also differed strongly across streams draining land with agricultural activities, with 85% higher periphyton δ<sup>15</sup>N‰ signals in all agricultural categories vs reference streams. Periphyton diatom and chlorophyte taxonomic proportions showed the strongest relationship with periphyton δ<sup>13</sup>C‰ values, where diatoms were negatively associated with increasing δ<sup>13</sup>C‰. These results suggest that aqueous and periphytic stable isotopes were sensitive in detecting persistent effects of agriculture on these streams despite BMP mitigation, where nutrient (orthosphosphate, nitrite, and ammonia) levels were non-indicative. These results also suggest that BMPs may not have fully eliminated the negative impacts of agricultural stressors on water quality in impacted streams.</p>
Application of sulfur and nitrogen doped carbon quantum dots as sensitive fluorescent nanosensors for the determination of saxagliptin and gliclazide
<p>In this study, highly fluorescent sulfur and nitrogen doped carbon quantum dots (S,N-CQDs) were used as fluorescent nanosensors for direct spectrofluorimetric estimation of each of gliclazide and saxagliptin without any pre-derivatization steps for the first time. S,N-CQDs were synthesized employing a simple hydrothermal technique using citric acid and thiosemicarbazide. The produced S,N-CQDs were characterized using different techniques including fluorescence emission spectroscopy, UV spectrophotometry, high resolution transmission electron microscopy, and FT-IR spectroscopy. Following excitation at 360 nm, S,N-CQDs exhibited a strong emission peak at 430 nm. The native fluorescence of S,N-CQDs was quantitatively enhanced by addition of increased concentrations of the studied drugs. The fluorescence enhancement of S,N-CQDs and the concentrations of the studied drugs revealed a wide linear relationship in the range of 30.0-500.0 μM and 75.0-600.0 µM with limits of detection of 5.0 μM and 10.15 µM for gliclazide and saxagliptin, respectively. The proposed method was efficiently utilized for determination of cited drugs in their commercial tablets with % recoveries ranging from 98.6 to 101.2% and low % RSD values (less than 2%). The mechanism of interaction between S,N-CQDs and the two drugs was studied. Validation of the proposed method was carried out in accordance with ICH guidelines.</p>
Cold Nitrogen Plasma: A Groundbreaking Eco-Friendly Technique for Surface Modification of Activated Carbon Aimed at Elevating Its CO2 Adsorption Capacity
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Data from: The decline in plant biodiversity slows down soil carbon turnover under increasing nitrogen deposition in a temperate steppe
1. Nitrogen (N) deposition not only alters the physiological processes of individual plant, but also leads to worldwide biodiversity loss. However, little is known about how the hierarchical responses from individual physiological processes to plant community structure would have cascading effects on soil carbon (C) cycling. 2. Here, we assessed whether changes in plant chemistry and community composition under increasing N input would affect the turnover rate of litter layer and soil C loss via heterotrophic respiration (Rh) in a temperate grassland. 3. We showed that more than a decade's N addition significantly decreased plant species richness, litter layer turnover rate and Rh. The 13C-NMR results showed that, for individual species, N addition either increased the abundance of recalcitrant C groups such as Alkyl and Methoxyl, or decreased labile C groups such as Carbohydrate, resulting in decreases in Carbohydrate C to Methoxyl C ratio (CC/MC) for most species. Our data also showed that with the increase in N deposition, the abundance of relatively high degradable dominant species, such as A. cristatum and A. frigida declined rapidly, and the relatively recalcitrant species such as P. bifurca and L. chinensis become dominate. Changes in individual species' chemistry and plant community composition significantly decreased litter quality at community level, as indicated by the lower community level CC/MC at higher N addition rates. 4. The result of step-AIC model selection further found that plant diversity loss and the decrease in community level CC/MC jointly best explained the decrease in Rh after N addition, and further relative importance partition result showed that these two factors respectively contributed 65.1% and 34.9% of the explained variation. 5. Overall, we demonstrated that changes in plant chemistry and diversity loss due to N addition reduced the quality of plant C input to soil, which further slowed down litter layer turnover rate and inhibited soil heterotrophic respiration. Our study complements the intermediate links of how shifts in plant community structure regulates soil C cycle under global changes.
Data from: A novel adenine-based-MOF derived nitrogen-doped nanoporous carbon for flexible solid-state supercapacitor
In this article, we have synthesized a series of nitrogen-doped nanoporous carbon (NPC) from metal organic framework (MOF) of UiO-66 with different ratio of adenine and coated on carbon nanotube film (CNTF) to obtain a flexible porous electrode (NPC/CNTF). It is worth noting that the introduction of adenine at different ratio did not change the structure of UiO-66. We also investigated the effect of carbonization temperature from 800 to 1000 °C on the electrochemical properties of the NPC. The ratio (1, 4-benzendicarboxylate: adenine) 9:1 and the NPC carbonized at 900 °C (noted as NPC-1-900) exhibits better electrochemical properties. The results show that NPC-1-900/CNTF electrode exhibits an exceptionally areal capacitance of 121.5 mF cm-2 than that of PC-900/CNTF electrode (22.8 mF cm-2) at 5 mV s-1 in a three-electrode system, indicating that the incorporation of nitrogen is beneficial to the electrochemical properties of nanoporous carbon. A symmetric flexible solid-state supercapacitor of NPC-1-900/CNTF has also been assembled and tested. Electrochemical date shows that the device exhibited superior areal capacitance (43.2 mF cm-2) at the scan rate of 5 mV s-1, the volumetric energy density is 57.3 µWh cm-3 and the volumetric power density is 2.4 mW cm-3 at the current density of 0.5 mA cm-2 based on PVA/H3PO4 gel electrolyte. For practical application, we have also studied the bending tests of the device, which show that the device exhibits the outstanding mechanical stability under different bending angles. Furthermore, the flexible device shows excellent cyclic stability, which can retain 91.5% of the initial capacitance after 2000 cycles.
Data from: Starvation effects on nitrogen and carbon stable isotopes of animals: an insight from meta-analysis of fasting experiments
Nitrogen and carbon stable isotopic compositions (δ15N and δ13C) of consumers have been used for physiological and food web studies. Previous studies have shown δ15N and δ13C values are affected by several biological and environmental factors during starvation, but the generality of the effect of starvation on δ15N and δ13C values has not yet been tested. Here, we performed a meta-analysis to evaluate the effects of starvation on δ15N and δ13C values of consumers, and the underlying factors that may explain the observed variation. The δ15N and δ13C values were calculated as the differences between the final δ15N and δ13C values of consumers (post-starvation) and the pre-starvation values on each experiment. Our meta-analysis showed a large variation in the δ15N and δ13C values of consumers (δ15N range: –0.82 to 4.30‰; mean: 0.47‰ and δ13C range: –1.92 to 2.62‰; mean: 0.01‰). The δ15N values of most consumers increased along the length of the starvation period and were influenced by nitrogen excretion and thermoregulation types, probably because differences in nitrogen metabolism and thermoregulation affect nitrogen processing and excretion rates. None of our predictor variables accounted for the variation in δ13C values, which showed both increases and decreases due to fasting. Our findings suggest that starvation results in changes in consumer δ15N values which are mainly explained by the length of the fasting period and by nitrogen and energy metabolism, but the underlying mechanisms of the starvation effects on δ13C values seem to be more complex than previously thought.
Figure 1 from: Máguas C, Pinho P, Branquinho C, Hartard B, Lakatos M (2013) Carbon-Water-Nitrogen relationships between lichens and the atmosphere: Tools to understand metabolism and ecosystem change. MycoKeys 6: 95-106. https://doi.org/10.3897/mycokeys.6.4814
Figure 1 - Schematic illustration of a cross-section through a lichen thallus with distinctive cortex, algal layer and medulla and the main factors contributing to thallus CO2 exchange and the consequence for carbon d13C fractionation that affects organic matter in lichens.
Supplementary material 1 from: Balestrini R, Delconte C, Buffagni A, Fumagalli A, Freppaz M, Calvo E, Buzzetti I (2019) Dynamic of nitrogen and dissolved organic carbon in an alpine forested catchment: atmospheric deposition and soil solution trends. In: Mazzocchi MG, Capotondi L, Freppaz M, Lugliè A, Campanaro A (Eds) Italian Long-Term Ecological Research for understanding ecosystem diversity and functioning. Case studies from aquatic, terrestrial and transitional domains. Nature Conservation 34: 41-66. https://doi.org/10.3897/natureconservation.34.30738
: Data type: statistical data
Periphyton carbon and nitrogen stable isotopes detect agricultural stressors in low-order streams
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Data from: Forest defoliator pests alter carbon and nitrogen cycles
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Data from: Nitrogen and chlorine co-doped carbon dots as probe for sensing and imaging in biological samples
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Maps of northern peatland extent, depth, carbon storage and nitrogen storage
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Data from: A novel adenine-based-MOF derived nitrogen-doped nanoporous carbon for flexible solid-state supercapacitor
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Application of sulfur and nitrogen doped carbon quantum dots as sensitive fluorescent nanosensors for the determination of saxagliptin and gliclazide
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Data from: Disentangling plant and soil microbial controls on carbon and nitrogen loss in grassland mesocosms
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Data from: The direction of carbon and nitrogen fluxes between ramets changes during ontogeny under simulated competition for light
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Allen Brain Atlas
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