The Effect of Oxygen Deprivation on Inorganic Nitrogen Uptake in an Antarctic Macrolichen

1996 ◽  
Vol 28 (4) ◽  
pp. 347-354 ◽  
Author(s):  
P. D. Crittenden
Keyword(s):  
Nitrogen Uptake ◽  
Initial Rate ◽  
Inorganic Nitrogen ◽  
Oxygen Deprivation ◽  
Rate Of Decline ◽  
Effect Of Oxygen

AbstractSnow meltwater containing 36 ng ml−1 NO3−−N (raised here to between 95–101 ng ml−1 NO3−−N) and 112 ng ml−1 NH4+ −N was sprayed onto illuminated Usnea sphacelata at 2°C in a 2−1 capacity transparent perspex chamber force-ventilated with either air or O2− (and CO2−) free N2. The NO3-concentration in meltwater recirculated through a layer of U. sphacelata fell to c. 8 ng ml−1 after 1.25 h. Although the pattern of decline was broadly comparable in both air and N2, the initial rate of decline was lower in N2. When undepleted meltwater was continuously sprayed onto the lichen and the effluent collected for analysis, the lichen was found to retain 55% of the wet deposited NO3− in air but only 27% under N2. Up to 90%) of NH4+ supplied in a continuous spray of meltwater was retained by the lichen but this was affected little by O2 and CO2 deprivation.

scholarly journals Soil Nitrogen Dynamics in a Managed Temperate Grassland Under Changed Climatic Conditions

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 931
Author(s):  
Mona Giraud ◽  
Jannis Groh ◽  
Horst H. Gerke ◽  
Nicolas Brüggemann ◽  
Harry Vereecken ◽  
...  
Keyword(s):  
Nitrogen Uptake ◽  
Inorganic Nitrogen ◽  
Nitrogen Concentration ◽  
Nitrogen Dynamics ◽  
Climatic Conditions ◽  
Undisturbed Soil ◽  
Nitrogen Emissions ◽  
Growing Period ◽  
Grassland Type ◽  
Wide Range

Grasslands are one of the most common biomes in the world with a wide range of ecosystem services. Nevertheless, quantitative data on the change in nitrogen dynamics in extensively managed temperate grasslands caused by a shift from energy- to water-limited climatic conditions have not yet been reported. In this study, we experimentally studied this shift by translocating undisturbed soil monoliths from an energy-limited site (Rollesbroich) to a water-limited site (Selhausen). The soil monoliths were contained in weighable lysimeters and monitored for their water and nitrogen balance in the period between 2012 and 2018. At the water-limited site (Selhausen), annual plant nitrogen uptake decreased due to water stress compared to the energy-limited site (Rollesbroich), while nitrogen uptake was higher at the beginning of the growing period. Possibly because of this lower plant uptake, the lysimeters at the water-limited site showed an increased inorganic nitrogen concentration in the soil solution, indicating a higher net mineralization rate. The N2O gas emissions and nitrogen leaching remained low at both sites. Our findings suggest that in the short term, fertilizer should consequently be applied early in the growing period to increase nitrogen uptake and decrease nitrogen losses. Moreover, a shift from energy-limited to water-limited conditions will have a limited effect on gaseous nitrogen emissions and nitrate concentrations in the groundwater in the grassland type of this study because higher nitrogen concentrations are (over-) compensated by lower leaching rates.

Effect of Oxygen Deprivation and Reoxygenation on Endothelin-Induced Contractions of Porcine Coronary Artery1

2015 ◽  
pp. 221-231
Author(s):  
David J. Schmidt ◽  
Denise Koth ◽  
Denise Jubenville ◽  
Robert F. Highsmith
Keyword(s):  
Oxygen Deprivation ◽  
Effect Of Oxygen

scholarly journals Evidence for efficient regenerated production and dinitrogen fixation in nitrogen-deficient waters of the South Pacific Ocean: impact on new and export production estimates

2008 ◽  
Vol 5 (2) ◽  
pp. 323-338 ◽  
Author(s):  
P. Raimbault ◽  
N. Garcia
Keyword(s):  
Pacific Ocean ◽  
Nitrogen Uptake ◽  
N2 Fixation ◽  
Inorganic Nitrogen ◽  
South Pacific ◽  
Dinitrogen Fixation ◽  
The South ◽  
New Production ◽  
Marquesas Islands ◽  
South Pacific Ocean

Abstract. One of the major objectives of the BIOSOPE cruise, carried out on the R/V Atalante from October-November 2004 in the South Pacific Ocean, was to establish productivity rates along a zonal section traversing the oligotrophic South Pacific Gyre (SPG). These results were then compared to measurements obtained from the nutrient – replete waters in the Chilean upwelling and around the Marquesas Islands. A dual 13C/15N isotope technique was used to estimate the carbon fixation rates, inorganic nitrogen uptake (including dinitrogen fixation), ammonium (NH4) and nitrate (NO3) regeneration and release of dissolved organic nitrogen (DON). The SPG exhibited the lowest primary production rates (0.15 g C m−2 d−1), while rates were 7 to 20 times higher around the Marquesas Islands and in the Chilean upwelling, respectively. In the very low productive area of the SPG, most of the primary production was sustained by active regeneration processes that fuelled up to 95% of the biological nitrogen demand. Nitrification was active in the surface layer and often balanced the biological demand for nitrate, especially in the SPG. The percentage of nitrogen released as DON represented a large proportion of the inorganic nitrogen uptake (13–15% in average), reaching 26–41% in the SPG, where DON production played a major role in nitrogen cycling. Dinitrogen fixation was detectable over the whole study area; even in the Chilean upwelling, where rates as high as 3 nmoles l−1 d−1 were measured. In these nutrient-replete waters new production was very high (0.69±0.49 g C m−2 d−1) and essentially sustained by nitrate levels. In the SPG, dinitrogen fixation, although occurring at much lower daily rates (≈1–2 nmoles l−1 d−1), sustained up to 100% of the new production (0.008±0.007 g C m−2 d−1) which was two orders of magnitude lower than that measured in the upwelling. The annual N2-fixation of the South Pacific is estimated to 21×1012g, of which 1.34×1012g is for the SPG only. Even if our "snapshot" estimates of N2-fixation rates were lower than that expected from a recent ocean circulation model, these data confirm that the N-deficiency South Pacific Ocean would provide an ideal ecological niche for the proliferation of N2-fixers which are not yet identified.

scholarly journals Modelling the ecosystem effects of nitrogen deposition: Model of Ecosystem Retention and Loss of Inorganic Nitrogen (MERLIN

1997 ◽  
Vol 1 (1) ◽  
pp. 137-158 ◽  
Author(s):  
B. J. Cosby ◽  
R. C. Ferrier ◽  
A. Jenkins ◽  
B. A. Emmett ◽  
R. F. Wright ◽  
...  
Keyword(s):  
Nitrogen Deposition ◽  
Soil Solution ◽  
Nitrogen Uptake ◽  
Inorganic Nitrogen ◽  
Balance Model ◽  
Litter Production ◽  
Catchment Scale ◽  
Exchange Constants ◽  
External Sources ◽  
Carbon Productivity

Abstract. A catchment-scale mass-balance model of linked carbon and nitrogen cycling in ecosystems has been developed for simulating leaching losses of inorganic nitrogen. The model (MERLIN) considers linked biotic and abiotic processes affecting the cycling and storage of nitrogen. The model is aggregated in space and time and contains compartments intended to be observable and/or interpretable at the plot or catchment scale. The structure of the model includes the inorganic soil, a plant compartment and two soil organic compartments. Fluxes in and out of the ecosystem and between compartments are regulated by atmospheric deposition, hydrological discharge, plant uptake, litter production, wood production, microbial immobilization, mineralization, nitrification, and denitrification. Nitrogen fluxes are controlled by carbon productivity, the C:N ratios of organic compartments and inorganic nitrogen in soil solution. Inputs required are: 1) temporal sequences of carbon fluxes and pools- 2) time series of hydrological discharge through the soils, 3) historical and current external sources of inorganic nitrogen; 4) current amounts of nitrogen in the plant and soil organic compartments; 5) constants specifying the nitrogen uptake and immobilization characteristics of the plant and soil organic compartments; and 6) soil characteristics such as depth, porosity, bulk density, and anion/cation exchange constants. Outputs include: 1) concentrations and fluxes of NO3 and NH4 in soil solution and runoff; 2) total nitrogen contents of the organic and inorganic compartments; 3) C:N ratios of the aggregated plant and soil organic compartments; and 4) rates of nitrogen uptake and immobilization and nitrogen mineralization. The behaviour of the model is assessed for a combination of land-use change and nitrogen deposition scenarios in a series of speculative simulations. The results of the simulations are in broad agreement with observed and hypothesized behaviour of nitrogen dynamics in growing forests receiving nitrogen deposition.

Effect of oxygen deprivation on soil hydrophobicity during heating

2005 ◽  
Vol 14 (4) ◽  
pp. 449 ◽  
Author(s):  
R. Bryant ◽  
S. H. Doerr ◽  
M. Helbig
Keyword(s):  
Heat Source ◽  
Forest Soils ◽  
Water Droplet ◽  
Oxygen Deprivation ◽  
Eucalypt Forest ◽  
Soil Hydrophobicity ◽  
Effect Of Oxygen ◽  
Penetration Time ◽  
Droplet Penetration ◽  
Heating Duration

Previous studies of the effects of heating on soil hydrophobicity have been conducted under free availability of oxygen. Under fire, however, soils may be deprived of oxygen due to its consumption at the heat source and inadequate replenishment in the soil. In the present study, effects of heating on soil hydrophobicity are examined for three initially hydrophobic Australian eucalypt forest soils under standard and oxygen-deprived atmospheres for temperatures (T) of 250–600°C and durations (tE) 2–180 min. Hydrophobicity assessments using water droplet penetration time (WDPT) tests indicate substantial differences between the absence and presence of oxygen. Heating to 250–300°C enhanced hydrophobicity from initial respective WDPTs of 2029 s, 361 s and 15 s to > 18 000 s for all samples under both atmospheres. Depending on heating duration, hydrophobicity was eliminated (WDPTs ~0 s) in air between 210 and 340°C, but under oxygen-deprived conditions between 400 and 510°C. Relationships between the destruction temperature for hydrophobicity TD and tE provide temperature–duration thresholds below which hydrophobicity persists under oxygen concentrations <21%. As established temperature–duration thresholds for hydrophobicity destruction are based on the free availability of oxygen, caution is advised in their applicability to field situations where heating under burning may occur in oxygen-depleted conditions.

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