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  • Geophysics  (12)
  • OCEANOGRAPHY  (6)
  • INSTRUMENTATION AND PHOTOGRAPHY  (3)
  • mineral-N flush  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Soil restoration under pasture after topsoil removal: Some factors influencing C and N mineralization and measurements of microbial biomass (1990)
    Springer
    Plant and soil 127 (1990), S. 49-59 
    Details
    ISSN: 1573-5036
    Keywords: microbial biomass ; mineral-N flush ; nitrogen mineralization ; pasture plants ; soil respiration ; soil restoration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Factors influencing rates of C and N mineralization of soil and plant materials, and the reliability of different procedures for estimating microbial biomass, were measured in a soil (Typic Dystrochrept) that had been restored under grazed pasture in a temperate environment for 10–11 years after 20 cm of the original topsoil had been removed by stripping. Rates of net N mineralization were appreciably lower, but CO2-C production higher, in the stripped than in the unstripped soil. These activities were not influenced directly by levels of soil mineral-N, but they were influenced by differences in plant composition. Herbage and litter, and roots, from the stripped plots were generally mineralized more readily to CO2-C, but more slowly to net mineral-N, than were the corresponding materials from the unstripped plots. Rates of mineralization of herbage and litter, or roots, were mainly indistinguishable in stripped and unstripped soil, whereas rates of mineralization of all standing dead material were lower in stripped soil. Measurements of extractable-C flush, and of CO2-C flush (using a fumigated soil control) and mineral-N flush by fumigation-incubation procedures, indicated that microbial biomass in stripped soil had recovered to at least 88 percent of the levels in unstripped soil. Substrate-induced respiration also generally indicated high levels of recovery of microbial biomass. The fumigation-incubation procedure appeared to under-estimate microbial biomass markedly in stripped soil when unfumigated soil controls were used; the used of a large soil inoculum (20 percent w/w) only sometimes overcame this problem. Possible reasons for apparent anomalies in estimation of microbial C are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010836
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Microbial contributions to the increased nitrogen mineralization after air-drying of soils (1988)
    Springer
    Plant and soil 105 (1988), S. 163-167 
    Details
    ISSN: 1573-5036
    Keywords: air-drying ; nitrogen mineralization ; microbial-N ; mineral-N flush ; soil biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The amounts of mineral-nitrogen (NH4−N+NO3−N) extracted by 2MKCL and the net amounts of N mineralized (δ Min-N) during a 10-day incubation of field-moist soils, air-dried then rewetted samples, and chloroform-fumigated samples, were measured in a range of 20 topsoils from grasslands. Air-drying generally increased extractable-N and the δ Min-N of the remoistened soils, but decreased the Min-N flush after fumigation. The C∶N ratios (CO2−C production: net Min-N production) over 10 days decreased significantly from an average of 25 to 12 after initial air-drying, suggesting that substrates of low C∶N ratio, such as microbial cells, were contributiong to the extra N mineralized after the air-drying treatment. A procedure to quantify the contribution from microbial-N to the increased δ Min-N after air-drying was only partially successful, but indicated a large proportion of this increase was derived from microbial cells killed by desccation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02376779
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Microbial biomass and bacteria in two pasture soils: An assessment of measurement procedures, temporal variations, and the influence of P fertility status (1991)
    Springer
    Plant and soil 132 (1991), S. 233-241 
    Details
    ISSN: 1573-5036
    Keywords: ATP ; mineral-N flush ; pasture soils ; seasonal effects ; soil bacteria ; soil fertility ; soil microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The reliability of three methods (microbial C and mineral-N flush by fumigation-incubation, and ATP) for measuring soil microbial biomass was assessed on two silt-loam soils of different P fertility status under grazed perennial pastures. The mineral-N flush and ATP methods provided a reasonably reliable index of microbial biomass, but the fumigation-incubation procedure for CO2-C flush, using preincubated samples and an unfumigated 0–10 day control, was inappropriate for these soils. The numbers of bacteria (direct microscopy) and the percentage metabolically active were also measured. Generally, in both soils, total microbial biomass and the numbers, mass and metabolic activity of bacteria were influenced more by temporal factors in samples taken monthly than by the fertility status. Temporal fluctuations were greater in the high-fertility (Waikanae) soil, but no consistent seasonal trends in mineral-N flush and ATP values were apparent. In both soils, numbers and biomass of bacteria were at a minimum in spring. Values of two biomass indices (mineral-N flush and ATP contents) were similar in the high- and low-fertility (Pomare) soil, and comprised similar percentages of organic-matter contents. The percentages of metabolically active bacteria, however, tended to be higher in Pomare than in Waikanae soil, and, therefore, did not reflect soil fertility status. Methodological and field aspects of these results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00010404
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  • 4
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    Synthetic aperture radar imaging of ocean waves - Comparison with wave measurements (1980)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: Synthetic aperture radar images of ocean waves were obtained in conjunction with reference wave data near Marineland, Florida, December 14, 1975. Each of the various types of measurements were processed into a form that allowed direct comparisons with the others. Maxima of radar spectra occurred at the same frequencies as the maxima of reference wave height spectra. In a comparison of a radar spectrum with observed spectra of wave height, wave orbital velocity, and surface slope the high-frequency portion of the radar spectrum lay near and between the wave height and the orbital velocity spectra but differed significantly from the surface slope spectrum. The radar-derived mean directions and model-fitted directional spreads of wave energy were close to the values from a directional wave buoy and indicated the accuracy of radar measurements of wave direction. However, a directional plot of a radar spectrum near shore at the frequency of the maximum showed a sharper peak than such a plot of a fitted spectrum derived from reference data.
    Keywords: OCEANOGRAPHY
    Type: Journal of Geophysical Research; 85; Sept. 20
    Format: text
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  • 5
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    Comparison of in situ and remotely sensed ocean waves off Marineland, Florida (1978)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Comparison between X-band and L-band radar imagery of sea waves is made. Sea truth was obtained by in situ pitch-and-roll buoy measurements. Under the low wind and wave conditions of the tests, superior wave imagery and more useful Fourier transforms were obtained with X-band SAR as compared to L-band with equivalent signal-to-noise ratio and synthetic aperture resolution. A comparison between X-band wave images and the in situ measurements shows agreement in the dominant wave direction to within a few degrees. The normalized spectra show a striking resemblance in spectral shape.
    Keywords: OCEANOGRAPHY
    Format: text
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  • 6
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    On the relationship of radar backscatter to wind speed and fetch (1978)
    In:  Other Sources
    Details
    Publication Date: 2011-08-17
    Description: The physics of the interaction of electromagnetic waves with the ocean surface has been an active area of research for a number of years. This paper contains the results of satellite and aircraft experiments to investigate the ability of active microwave radars to infer surface wind speeds remotely. Data obtained from the recent National Aeronautics and Space Administration (NASA) Skylab experiment are compared with surface wind speeds measured by low-flying aircraft and ships-of-opportunity and found to give useful estimates of the ocean wind field. Also investigated was the influence of varying wave height on radar measurements of wind speed by measuring the backscattering cross-section for constant wind speed but variable wave conditions. It is found that this effect is of little importance.
    Keywords: OCEANOGRAPHY
    Format: text
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  • 7
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    Spectral characteristics of the microwave emission from a wind-driven foam-covered sea (1976)
    In:  Other Sources
    Details
    Publication Date: 2011-08-16
    Description: Aircraft observations of the microwave emission from the wind-driven foam-covered Bering Sea substantiate earlier results and show that the combination of surface roughness and white water yields a significant microwave brightness temperature dependence on wind speed over a wide range of microwave wavelengths, with a decreasing dependence for wavelengths above 6 cm. The spectral characteristic of brightness temperature as a function of wind speed is consistent with a foam model in which the bubbles give rise to a cusped surface between the foam and the sea. In the fetch-limited situation the contribution of the wave structure at the surface appears to increase as the foam coverage decreases. Although the data show that the thin streaks are the most important part of the white water signature, there is some evidence for the contribution of whitecaps.
    Keywords: OCEANOGRAPHY
    Type: Journal of Geophysical Research; 81; June 20
    Format: text
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  • 8
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    Practical utility of the blue spectral region (1972)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Some aspects of multispectral photography in the blue region are discussed briefly, and sample images are submitted to demonstrate the potential utility of the blue multispectral record for oceanography.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: NASA. Manned Spacecraft Center 4th Ann. Earth Resources Program Rev., Vol. 4; 29 p
    Format: application/pdf
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  • 9
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    A unique method of leak-rate measurements. (1973)
    In:  Other Sources
    Details
    Publication Date: 2019-06-27
    Description: Description of an acceptable method for precision helium leak-rate measurement, for rather large pressurized vessels. Precise leakage rates of gaseous helium were measured by adapting a nominal helium leak detector in such a way that the gas load of the vacuum system plus the test vessel could be handled by the augmented pumping equipment while still being traced through the incorporated mass spectrometer. The vacuum chamber used for this experiment was maintained in 100 ntorr pressure range with a foreline pressure of 4 microns. Although sensitivity of the leak detector was diminished by reason of the larger pumping system, this did not affect the overall result in the capture and measurement of a complete leakage rate.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Journal of Environmental Sciences; 16; May-June
    Format: text
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  • 10
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    Soft X-ray and XUV imaging with a charge-coupled device /CCD/-based detector (1981)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: A soft X-ray/XUV imaging camera which uses a thinned, back-illuminated, all-buried channel RCA CCD for radiation sensing has been built and tested. The camera is a slow-scan device which makes possible frame integration if necessary. The detection characteristics of the device have been tested over the 15-1500 eV range. The response was linear with exposure up to 0.2-0.4 erg/sq cm; saturation occurred at greater exposures. Attention is given to attempts to resolve single photons with energies of 1.5 keV.
    Keywords: INSTRUMENTATION AND PHOTOGRAPHY
    Type: Solid state imagers for astronomy; June 10, 11, 1981; Cambridge, MA
    Format: text
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