Spatial patterns of aerobic limit depth and oxygen diffusion rate at two peatlands drained for forestry in Alberta

1999 ◽  
Vol 29 (1) ◽  
pp. 53-61 ◽  
Author(s):  
U Silins ◽  
R L Rothwell
Keyword(s):  
Spatial Variability ◽  
Water Table ◽  
Spatial Patterns ◽  
Oxygen Diffusion ◽  
Diffusion Rate ◽  
Drainage Ditches ◽  
Soil Aeration ◽  
Rooting Zone ◽  
Capillary Zone ◽  
Oxygen Diffusion Rate

The spatial variability of soil aeration (aerobic limit depth and oxygen diffusion rate (ODR)) among different drainage ditch spacings and at various distances from drainage ditches was examined at two peatlands drained for forestry in north-central Alberta. Drainage lowered mean water table levels (p < 0.001) at both peatlands. Lower water table levels within drained areas were associated with greater aerobic limit depths (p < 0.001) and greater ODR (p < 0.001 at Saulteaux River; p < 0.027 at Wolf Creek) compared with undrained areas of both peatlands. Spatial patterns of aerobic limit depth and ODR indicated strong spatial variability of soil aeration in the immediate vicinity of drainage ditches. However, little sensitivity of soil aeration to different ditch spacings was evident. Potential effects of post-drainage subsidence on soil aeration was evident as increased distance of both the aerobic limit, and near-zero oxygen diffusion rates above the water table surface at both peatlands. One effect of post-drainage peatland subsidence may be to increase the thickness of the capillary zone above the water table. However, reduction of aeration within the rooting zone of peatland trees due to subsidence was not observed because of low water tables within the drained areas of both peatlands.

Low-temperature annealing of YBa2Cu3O7-x

1992 ◽  
Vol 50 (1) ◽  
pp. 88-89
Author(s):  
R.L. Sabatini ◽  
Yimei Zhu ◽  
Masaki Suenaga ◽  
A.R. Moodenbaugh
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Low Temperature ◽  
Oxygen Diffusion ◽  
Diffusion Rate ◽  
Oxygen Depletion ◽  
Low Temperature Annealing ◽  
Transmission Electron ◽  
Microstructural Effects ◽  
Oxygen Diffusion Rate

Low temperature annealing (<400°C) of YBa2Cu3O7x in a ozone containing oxygen atmosphere is sometimes carried out to oxygenate oxygen deficient thin films. Also, this technique can be used to fully oxygenate thinned TEM specimens when oxygen depletion in thin regions is suspected. However, the effects on the microstructure nor the extent of oxygenation of specimens has not been documented for specimens exposed to an ozone atmosphere. A particular concern is the fact that the ozone gas is so reactive and the oxygen diffusion rate at these temperatures is so slow that it may damage the specimen by an over-reaction. Thus we report here the results of an investigation on the microstructural effects of exposing a thinned YBa2Cu3O7-x specimen in an ozone atmosphere using transmission electron microscopy and energy loss spectroscopy techniques.

INFLUENCE OF MOISTURE STRESS, RELATIVE HUMIDITY AND OXYGEN DIFFUSION RATE ON SEED SET AND YIELD OF WHEAT

1969 ◽  
Vol 49 (1) ◽  
pp. 29-37 ◽  
Author(s):  
C. A. Campbell ◽  
D. S. McBean ◽  
D. G. Green
Keyword(s):  
Soil Moisture ◽  
Relative Humidity ◽  
Oxygen Diffusion ◽  
Seed Set ◽  
Diffusion Rate ◽  
Moisture Stress ◽  
Morphological Examination ◽  
Hand Pollination ◽  
Growth Chamber Studies ◽  
Oxygen Diffusion Rate

The influence of oxygen diffusion rate (ODR) and relative humidity (RH) on seed set and yield of wheat was investigated in two growth chamber studies. In one study, plants grown at 80% RH were compared with those grown at 60%. In the other, plants grown in pots without supplemental aeration were compared with plants grown in aerated pots.Wheat grown at low soil moisture stress (between 25 and 16%) produced significantly poorer seed set and grain yield than those grown at higher stress (between 25 and 10%). Seed set was less severely reduced in Manitou than in Chinook. Plants grown at low moisture stress and 60% RH gave better seed set than those grown at 80%. However, even at 60% RH, seed set was less than 65%.The oxygen diffusion rates in unaerated pots were 28 × 10−8, 100 × 10−8 and 200 × 10−8 g cm−2min−1 at 25%, 16% and 10% soil moisture (by weight). In aerated pots, ODR at 25% and 16% soil moisture were 82 × 10−8 and 180 × 10−8 g cm−2min−1, respectively.Seed set and grain yields of Chinook wheat grown at low moisture stress were increased from 54 to 82% and from 11.5 to 26.7 g/pot by improving the soil aeration.The anthers, especially the pollen, were the main reproductive components damaged by poor aeration. This was demonstrated by morphological examination and by hand-pollination experiments. Poor seed set was confined primarily to the top two-thirds of the head.

Relationships between Oxygen Diffusion Rate and Corn Growth 1

1965 ◽  
Vol 57 (1) ◽  
pp. 91-92 ◽  
Author(s):  
J. Letey ◽  
L. H. Stolzy ◽  
N. Valoras
Keyword(s):  
Oxygen Diffusion ◽  
Diffusion Rate ◽  
Oxygen Diffusion Rate
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