EFFECTS OF TEMPERATURE ON NO3− AND NO2− REDUCTION, NITROGENOUS GAS PRODUCTION, AND REDOX POTENTIAL IN A SATURATED SOIL

1973 ◽  
Vol 53 (2) ◽  
pp. 213-218 ◽  
Author(s):  
L. D. BAILEY ◽  
E. G. BEAUCHAMP
Keyword(s):  
Redox Potential ◽  
Nitrogen Source ◽  
Low Temperatures ◽  
Slow Rate ◽  
Gas Production ◽  
Saturated Soil ◽  
Anaerobic Conditions ◽  
Ap Horizon ◽  
Effects Of Temperature ◽  
No2 Reduction

Samples of the Ap horizon of a Huron soil were used to investigate the effects of temperature on NO3− and NO2− reduction, nitrogenous gas production, and redox potential under anaerobic conditions in the laboratory. NO3− and NO2− reduction occurred at redox potential (Eh) values of 200 and 180 mV, respectively. The rate of NO3− and NO2− reduction decreased with decreasing temperatures (30–5 C). At 5 C, NO3− reduction was completely inhibited but NO2− reduction continued at a slow rate. Gas chromatographic analyses showed that the denitrification gas was composed of N2, N2O, and NO. Decreasing the temperature decreased the production of N2, increased the production of NO, and did not significantly affect the production of N2O. The increased production of NO at low temperatures when NO2− was the nitrogen source is attributed to chemodenitrification processes.

EFFECTS OF TEMPERATURE AND ROOT ON DENITRIFICATION IN A SOIL

1976 ◽  
Vol 56 (2) ◽  
pp. 79-87 ◽  
Author(s):  
L. D. BAILEY
Keyword(s):  
Relative Proportion ◽  
Gas Production ◽  
Soil Samples ◽  
No Production ◽  
Soil System ◽  
Ap Horizon ◽  
Effects Of Temperature ◽  
Nitrogenous Gases ◽  
Crop System

The effects of temperature on denitrification were studied in a soil system with a root in situ and one without a root. Soil samples of the Ap horizon of a Huron soil were used in the laboratory study. Germinated corn seedlings were planted and grown in cylinders for 84 h. At the end of this time the cylinders were cut horizontally so that the bottom 8.8-cm portion contained one root. Other cylinders were left unplanted. The soil in the cylinders was saturated with 5 ml of distilled water or 5 ml of a KNO3 solution. The rate of denitrification, both in terms of NO3− reduction and nitrogenous gas production, was more rapid in the system containing a root than in the fallowed system. Qualitatively, nitrogenous gases (N2, N2O and NO) were produced by both systems. At 30, 15 and 10 C there were no significant differences in the total quantity of gases produced by both systems. However, at all temperatures the crop system produced the larger quantities of NO, and also accumulated the larger quantities of NO2− and exchangeable NH4+. The root initially absorbed a portion of the added NO3−; however, with time the NO3− concentration of the root decreased to zero. The amount of NO3− taken up by the root and the rate at which the NO3− content of the root decreased was greatest at the high temperatures. At 5 C there was uptake of NO3− by the root but no decrease in the NO3− concentration of the root. Decreasing the temperature decreased the rate of denitrification, both in terms of NO3− reduction and nitrogenous gas production. At 5 C, denitrification was completely inhibited. Decreasing the temperature also changed the relative proportion of the nitrogenous gases produced. The quantity of N2 produced decreased as the temperature was decreased from 30 to 6–8 C. The decrease in temperature resulted in an increase in NO production; this was the principal gas produced at 6–8 C. Nitrous oxide (N2O) production, like NO, increased as the temperature decreased from 30 C to 10 C where it was the principal gas produced. At 30 to 15 C and 6–8 C, N2O production was secondary in quantity to N2 and NO, respectively.

scholarly journals Electrochemically Induced Metal- vs. Ligand-Based Redox Changes in Mackinawite: Identification of a Fe3+- and Polysulfide-Containing Intermediate

2021 ◽  
Author(s):  
Sebastian Sanden ◽  
Robert Szilagyi ◽  
Yamei Li ◽  
Norio Kitadai ◽  
Samuel M Webb ◽  
...  
Keyword(s):  
Redox Potential ◽  
Ferrous Iron ◽  
Maturation Process ◽  
Anaerobic Conditions ◽  
Ph Dependent

Under anaerobic conditions, ferrous iron reacts with sulfide producing FeS, which can then undergo a temperature, redox potential, and pH dependent maturation process resulting in the formation of oxidized mineral...

Versatile Cryostated Optically Transparent Thin-Layer Electrochemical (OTTLE) Cell for Variable-Temperature UV-Vis/IR Spectroelectrochemical Studies

1994 ◽  
Vol 48 (12) ◽  
pp. 1522-1528 ◽  
Author(s):  
F. Hartl ◽  
H. Luyten ◽  
H. A. Nieuwenhuis ◽  
G. C. Schoemaker
Keyword(s):  
Thin Layer ◽  
Low Temperatures ◽  
Variable Temperature ◽  
Experimental Setup ◽  
Strictly Anaerobic ◽  
Carbonyl Complexes ◽  
Anaerobic Conditions ◽  
Optically Transparent ◽  
Solution Layer ◽  
Preset Temperature

This article describes the construction of a novel optically transparent thin-layer electrochemical (OTTLE) cell for IR and UV-Vis spectroelectrochemical experiments at variable temperature. The cell has a three-electrode set melt-sealed into a smooth polyethylene spacer which is sandwiched between two CaF2 windows. The width of this spacer (0.18–0.20 mm) defines the thickness of the thin solution layer. The whole electrode assembly is housed in a thermostated Cu block of the OTTLE cell which fits into a double-walled nitrogen-bath cryostat. The experimental setup permits relatively fast electrolysis within the tested temperature range of 295 to 173 K under strictly anaerobic conditions and protection of light-sensitive compounds. Other important merits of the cell design include lack of leakage, facile cleaning, almost negligible variation of the preset temperature, and facile manipulation in the course of the experiments. The applicability of the variable-temperature IR/UV-Vis OTTLE cell is demonstrated by stabilization of a few electrogenerated carbonyl complexes of Mn(I) and Ru(II) with 3,5-di- tert. butyl-1,2-benzo(semi)quinone (DB(S)Q) and N, N′-diisopropyl-1,4-diaza-1,3-butadiene (iPr-DAB) ligands, respectively, at appropriately low temperatures.

scholarly journals Self-Synchronized Oscillatory Metabolism of Clostridium pasteurianum in Continuous Culture

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 137 ◽  
Author(s):  
Erin E Johnson ◽  
Lars Rehmann
Keyword(s):  
Redox Potential ◽  
Continuous Culture ◽  
H2 Production ◽  
Gas Production ◽  
Glycerol Metabolism ◽  
Clostridium Pasteurianum ◽  
Continuous Stirred Tank Reactor ◽  
Industrial Fermentation ◽  
Oxidative Pathway ◽  
Product Profile

By monitoring the real-time gas production (CO2 and H2) and redox potential at high sampling frequency in continuous culture of Clostridium pasteurianum on glycerol as sole carbohydrate, the self-synchronized oscillatory metabolism was revealed and studied. The oscillations in CO2 and H2 production were in sync with each other and with both redox potential and glycerol in the continuous stirred tank reactor (CSTR). There is strong evidence that the mechanism for this is in the regulation of the oxidative pathway of glycerol metabolism, including glycolysis, and points toward complex, concerted cycles of enzyme inhibition and activation by pathway intermediates and/or redox equivalents. The importance of understanding such an “oscillatory metabolism” is for developing a stable and highly productive industrial fermentation process for butanol production, as unstable oscillations are unproductive. It is shown that the oscillatory metabolism can be eradicated and reinstated and that the period of oscillations can be altered by modification of the operating parameters. Synchronized oscillatory metabolism impacted the product profile such that it lowered the selectivity for butanol and increased the selectivity for ethanol. This elucidates a possible cause for the variability in the product profile of C. pasteurianum that has been reported in many previous studies.

Temperature acclimation of the caudal photoreceptor response in the crayfish Orconectes rusticus (Girard)

1988 ◽  
Vol 66 (5) ◽  
pp. 1168-1171 ◽  
Author(s):  
Jim H. Belanger
Keyword(s):  
Stimulus Intensity ◽  
Low Temperatures ◽  
Temperature Acclimation ◽  
Thermal Capacity ◽  
Maximum Frequency ◽  
Orconectes Rusticus ◽  
Temperature Dependent ◽  
Caudal Photoreceptor ◽  
Effects Of Temperature ◽  
Nerve Cords

Crayfish (Orconectes rusticus (Girard)) were acclimated for 3 weeks at 5 and 25 °C. The effects of temperature and temperature acclimation on the latency, maximum frequency, and sensitivity to stimulus intensity of the caudal photoreceptor response were examined in isolated abdominal nerve cords. Each of these components was temperature dependent. The maximum frequency of the response showed thermal capacity acclimation but latency did not. Caudal photoreceptor response was insensitive to stimulus intensity at low temperatures but acclimation improved sensitivity.

EAR LENGTH AND SPIKELET NUMBER OF WHEAT GROWN AT DIFFERENT TEMPERATURES AND LIGHT INTENSITIES

1965 ◽  
Vol 43 (3) ◽  
pp. 345-353 ◽  
Author(s):  
D. J. C. Friend
Keyword(s):  
Light Intensity ◽  
Low Temperatures ◽  
Dry Weight ◽  
High Light ◽  
Morphological Development ◽  
Spikelet Number ◽  
Light Intensities ◽  
Different Temperatures ◽  
Total Plant ◽  
Effects Of Temperature

The number of spikelets on the differentiating inflorescence and the ear at anthesis was highest at high light intensities and at low temperatures. The length of the developing inflorescence and the ear, the height of the main stem, and the total plant dry weight at the time of anthesis were also greatest under these conditions.These results are related to differential effects of temperature and light intensity on the rates and duration of apical elongation, morphological development of the ear, and spikelet formation.

Effects of Temperature on Responses of the Gonads of Green Sunfish (Lepomis cyanellus) to Treatment with Carp Pituitaries and Testosterone Propionate

1973 ◽  
Vol 30 (7) ◽  
pp. 905-912 ◽  
Author(s):  
Calvin M. Kaya
Keyword(s):  
Low Temperatures ◽  
Elevated Temperatures ◽  
Testosterone Propionate ◽  
Lepomis Cyanellus ◽  
Pituitary Glands ◽  
Effects Of Temperature ◽  
Gonadal Recrudescence ◽  
Green Sunfish ◽  
The Brain ◽  
Stimulation Of

Previous investigations have demonstrated that stimulation of gonadal recrudescence in the green sunfish (Lepomis cyanellus) depends on the concurrent presence of long photoperiods (15 hr) and elevated temperatures (> 15 C). The present investigation indicates that recrudescence can be stimulated in seasonally regressed ovaries and testes by injections of a crude extract of fish pituitary glands, and in testes by testosterone propionate, but only under elevated temperature. The low temperatures that block gonadal responses to long photoperiods also effectively prevent gonadal responses to administered hormones. These observations indicate that the responsiveness of the gonads of this species to stimulating hormones is markedly modified by temperature; however, the results do not obviate the possibility that secretion of gonadotropins by the brain–pituitary system may also be affected.

Sign in / Sign up

Export Citation Format

Share Document