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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Microbial community shifts correspond with suppression of decomposition 25 years after liming of acidic forest soils

Microbial community structure and function regularly covary with soil pH, yet effects of these interactions on soil carbon are rarely tested experimentally within natural ecosystems. We investigated the enduring (25 year) impacts of liming on microbial community structure and decomposition at an acidic northern hardwood forest, where experimental liming increased pH one unit and surprisingly doubled the organic carbon stocks of the forest floor. Here we show that this increase in carbon storage corresponded with restructuring of the bacterial and fungal communities that drive decomposition. In the Oe horizon, liming reduced the activities of five extracellular enzymes that mediate decomposition, while the Oa horizon showed an especially large (64%) reduction in the activity of a sixth, peroxidase, which is an oxidative enzyme central to lignocellulose degradation. Decreased enzyme activities corresponded with loss of microbial taxa important for lignocellulose decay, including large reductions in the dominant ectomycorrhizal genera Russula and Cenococcum, saprotrophic and wood decaying fungi, and Actinobacteria (Thermomonosporaceae). These results demonstrate the importance of pH as a dominant regulator of microbial community structure and illustrate how changes to this structure can produce large, otherwise unexpected increases in carbon storage in forest soils.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Final Technical Report: Role of Methanotrophs in Metal Mobilization, Metal Immobilization and Mineral Weathering: Effects on the In Situ Microbial Community and the Sustainability of Subsurface Water Systems

Activities from this DOE sponsored project can be divided into four broad areas: (1) investigations into the potential of methanobactin, a biogenic metal-binding agent produced by methanotrophs, in mitigating mercury toxicity; (2) elucidation of the genetic basis for methanobactin synthesis from methanotrophs; (3) examination of differential gene expression of M. trichosporium OB3b when grown in the presence of varying amounts of copper and/or cerium, and (4) collection and characterization of soil cores from Savannah River Test Site to determine the ubiquity of methanobactin producing methanotrophs. From these efforts, we have conclusively shown that methanobactin can strongly bind mercury as Hg[II], and in so doing significantly reduce the toxicity of this metal to microbes. Further, we have deduced the genetic basis of methanobactin production in methanotrophs, enabling us to construct mutants such that we can now ascribe function to different genes as well as propose a pathway for methanobactin biosynthesis. We have also clear evidence that copper and cerium (as an example of a rare earth element) dramatically affect gene expression in methanotrophs, and thus have an important impact on the activity and application of these microbes to a variety of environmental and industrial issues. Finally, we successfully isolated one methanotroph from the deep subsurface of the Savannah River Test Site and characterized the ability of different forms of methanobactin to mobilize copper and mercury from these soils.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1983

A microwave systems approach to measuring root zone soil moisture

Computer microwave satellite simulation models were developed and the program was used to test the ability of a coarse resolution passive microwave sensor to measure soil moisture over large areas, and to evaluate the effect of heterogeneous ground covers with the resolution cell on the accuracy of the soil moisture estimate. The use of realistic scenes containing only 10% to 15% bare soil and significant vegetation made it possible to observe a 60% K decrease in brightness temperature from a 5% soil moisture to a 35% soil moisture at a 21 cm microwave wavelength, providing a 1.5 K to 2 K per percent soil moisture sensitivity to soil moisture. It was shown that resolution does not affect the basic ability to measure soil moisture with a microwave radiometer system. Experimental microwave and ground field data were acquired for developing and testing a root zone soil moisture prediction algorithm. The experimental measurements demonstrated that the depth of penetration at a 21 cm microwave wavelength is not greater than 5 cm.

Newton, R. W.↗
NASA NTRS1974

Enzyme activity in terrestrial soil in relation to exploration of the Martian surface

Sensitive tests for the detection of extracellular enzyme activity in Martian soil was investigated using simulated Martian soil. Enzyme action at solid-liquid water interfaces and at low humidity were studied, and a kinetic scheme was devised and tested based on the growth of microorganisms and the oxidation of ammonium nitrite.

Mclaren, A. D.↗
DOE OSTI2019

Genomics of Energy Sorghum's Water Use Efficiency/Drought Resilience

The overall goal of the proposed research is to increase the biomass yield of C4 bioenergy grasses such as sorghum that are often grown in water limited environments by improving the water use efficiency, soil water extraction, and drought resilience of these crops. High biomass yield is strongly correlated with long duration of vegetative growth, however, insufficient rainfall during long growing seasons is a primary factor limiting biomass yield. To minimize this yield constraint, the proposed project will identify sorghum genotypes and traits/QTL that improve water use efficiency, soil water extraction by roots, and drought resilience. The specific objectives of the proposed research are to; (1) Screen diverse energy sorghum accessions and RIL populations for variation in traits that affect soil water extraction, water use efficiency, and drought resilience using lysimeters, aeroponics, and field experiments, (2) identify QTL/alleles and gene regulatory networks that modify expression of traits that impact soil water extraction and water use efficiency, and (3) test the utility of traits/alleles that affect soil water extraction, water use efficiency, and drought resilience in field plots under irrigated and water deficit conditions.

09 BIOMASS FUELS↗
DOE OSTI2021

Development of energetic and enzymatic limitations on microbial carbon cycling in soils

Soil organic carbon (SOC) constitutes an important reservoir in the global carbon cycle that is vulnerable to transformation and loss from land use and climate change. Anoxic conditions protect SOC from microbial degradation through limiting the energetics of respiration and inhibiting extracellular oxidative enzymes. Given growing evidence of prevalent anaerobic microsites in upland soils, we designed an experiment testing the development of dissolved organic carbon (DOC) signatures of energetic and enzymatic limitations on microbial carbon utilization across simulated soil aggregates or peds. Reactors comprised a soil column “aggregate” underlying an advective “macropore” channel. Soils received downward diffusive inputs of aerated porewater media with added nitrate, sulfate, or no amendment—where native ferrihydrite served as dominant anaerobic terminal electron acceptor (TEA). After 40 days, added nitrate resulted in highest bulk respiration and DOC production while sulfate did not differ from the control. Nominal oxidation state of carbon (NOSC) was higher (more favorable) with added TEAs at soil surfaces and decreased with depth, while NOSC in the non-amended soil remained lower and constant with depth. DOC generally increased with depth, which along with decreasing NOSC values indicates joint electron-donor and acceptor control over respiration energetics. Of all organic compound classes, only the relative abundance of phenolics increased between 0 and 0.5 cm depth, which aligns with the oxic-anoxic transition and suggests oxidative enzyme inhibition. Furthermore, our results suggest that oxygen limitation within upland soil aggregates may preserve SOC via both energetic and enzymatic C protection mechanisms, which are vulnerable upon exposure to oxygen.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Animals Exposed to Leptospira Serogroups Not Included in Bacterins in the United States and Puerto Rico

Leptospirosis is a worldwide zoonotic disease. Pathogenic leptospires colonize the renal tubules and genital tract of animals and are excreted via urine. Transmission occurs via direct contact or through contaminated water or soil. The microscopic agglutination test (MAT) is the gold standard for the serodiagnosis of leptospirosis. The present study aims to evaluate animal exposure to Leptospira in the U.S. and Puerto Rico during the period 2018–2020. The presence of antibodies against pathogenic Leptospira spp. was assessed with the MAT according to the standards of the World Organisation for Animal Health. A total of 568 sera were submitted for diagnostic, surveillance, or import/export testing from the U.S. and Puerto Rico. Seropositivity (≥1:100) was 51.8% (294/568) with agglutinating antibodies found in 115 (39.1%) cattle, 84 (28.6%) exotic animals, 38 (12.9%) horses, 22 (7.5%) goats, 15 (5.1%) dogs, 11 (3.7%) swine, and 9 (3.1%) sheep. The most detected serogroups were Australis, Grippotyphosa, and Ballum. The results showed that animals were exposed to serogroups/serovars not included in commercial bacterins such as Ballum, Bratislava (only in swine vaccine), and Tarassovi. Our findings suggest that more studies should include culture and concomitant genotyping to reduce animal disease and zoonotic risk through efficacious vaccine and diagnostic strategies.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1969

Desert soil collection at the JPL soil science laboratory

Collection contains desert soils and other geologic materials collected from sites in the United States and foreign countries. Soils are useful for test purposes in research related to extraterrestrial life detection, sampling, harsh environmental studies, and determining suitable areas for training astronauts for lunar exploration.

Blank, G. B.↗
NASA NTRS1971

Study and interpretation of lunar close-up stereo photography

The lunar close-up steroscopic camera was used successfully on Apollo 11, 12, and 14 flights. It functioned without any technical faults and was judged convenient to use by all three crews. It recorded a variety of surface textures in the lunar soil, both disturbed and undisturbed, a number of rock surfaces in the undisturbed condition, and a number of surface samples of materials brought to the moon whose interaction with the lunar soil was to be tested. A resolution of approximately 80 microns was aimed for in the design of the camera and was indeed obtained on all pictures. Stereoscopy played a major part in interpreting surface textures and small scale structure.

Gold, T.↗
NASA NTRS1973

Site alteration effects from rocket exhaust impingment during a simulated Viking Mars landing. Part 1: Nozzle development and physical site alternation

A potential interference problem for the Viking '75 scientific investigation of the Martian surface resulting from retrorocket exhaust plume impingement of the surface was investigated experimentally and analytically. It was discovered that the conventional bell nozzle originally planned for the Viking Lander retrorockets would produce an unacceptably large amount of physical disturbance to the landing site. An experimental program was subsequently undertaken to find and/or develop a nozzle configuration which would significantly reduce the site alteration. A multiple nozzle configuration, consisting of 18 small bell nozzles, was shown to produce a level of disturbance that was considered by the Viking Lander Science Teams to be acceptable on the basis of results from full-scale tests on simulated Martian soils.

Romine, G. L.↗
NASA NTRS1974

Remote sensing of soil moisture by Skylab radiometer and scatterometer sensors

A Skylab experiment was designed to evaluate the feasibility of monitoring the moisture content of the soil from space. Data from various Skylab sensors were collected across two test sites while direct measurements of soil moisture were being made at the surface depths of soil. Correlations were obtained between the moisture content of the soil and radiometer sensors (S193 and S194) and the scatterometer instrument (S193). The high correlations obtained indicate that microwave sensors may be quite useful for such measurements in the future.-

Eagleman, J. R.↗
NASA NTRS1976

Lineaments on Skylab photographs: Detection, mapping, and hydrologic significance in central Tennessee

The author has identified the following significant results. Lineaments were detected on Skylab photographs by stereo viewing, projection viewing, and composite viewing. Sixty-nine percent more lineaments were found by stereo viewing than by projection, but segments of projection lineaments are longer; total length of lineaments found by these two methods is nearly the same. Most Skylab lineaments consist of topographic depression: stream channel alinements, straight valley walls, elongated swales, and belts where sinkholes are abundant. Most of the remainder are vegetation alinements. Lineaments are most common in dissected areas having a thin soil cover. Results of test drilling show: (1) the median yield of test wells on Skylab lineaments is about six times the median yield of all existing wells; (2) three out of seven wells on Skylab lineaments yield more than 6.3 1/s (110 gal/min): (3) low yields are possible on lineaments as well as in other favorable locations; and (4) the largest well yields can be obtained at well locations of Skylab lineaments that also are favorably located with respect to topography and geologic structure, and are in the vicinity of wells with large yields.

Moore, G. K.↗
NASA NTRS1975

Remote sensing of soil moisture by Skylab radiometer and scatterometer sensors

A Skylab experiment was designed to evaluate the feasibility of monitoring the moisture content of the soil from space. Data from various Skylab sensors were collected across two test sites while direct measurements of soil moisture were being made at the surface depths of soil. Correlations were obtained between the moisture content of the soil and radiometer sensors (S193 and S194) and the scatterometer instrument (S193). The high correlations obtained indicate that microwave sensors may be quite useful for such measurements in the future.-

Eagleman, J. R.↗
NASA NTRS1977

Electrostatic dust transport and Apollo 17 LEAM experiment

The Lunar Ejecta and Meteorite (LEAM) experiment has been in operation since December 1973 when it was deployed in the Taurus-Littrow region of the moon by the Apollo 17 crew. A specialized analysis based on more than twenty-two lunations of the impact data shows that all of the events recorded by the sensors during the terminator passages are essentially lunar surface microparticles carrying a high electrostatic charge. Charged lunar fines held in place by adhesive forces can be ejected into space if the electrostatic stress exceeds the adhesive strength. A simple laboratory test demonstrated that this soil transport can indeed take place at the lunar terminator and in the vicinity of it.

Rhee, J. W.↗
NASA NTRS1979

Mars ultraviolet simulation facility

A facility was established for long-duration ultraviolet (UV) radiation exposure of natural and synthetic materials in order to test hypotheses concerning Martian soil chemistry observed by the Viking Mars landers. The system utilized a 2500 watt xenon lamp as the radiation source, with the beam passing through a heat-dissipating water filter before impinging upon an exposure chamber containing the samples to be irradiated. The chamber was designed to allow for continuous tumbling of the samples, maintenance of temperatures below 0 C during exposure, and monitoring of beam intensity. The facility also provided for sample preparation under a variety of atmospheric conditions, in addition to the Mars nominal. As many as 33 sealed sample ampules have been irradiated in a single exposure. Over 100 samples have been irradiated for approximately 100 to 700 h. The facility has performed well in providing continuous UV irradiation of multiple samples for long periods of time under simulated Mars atmospheric and thermal conditions.

Zill, L. P.↗
NASA NTRS1988

The prospects for detecting spectral shifts due to satellite sensor aging

Along with responsivity changes due to sensor aging, there may be concurrent spectral changes. A field-measurement approach for detecting postlaunch spectral changes is described. For illustration, one hypothetical model of change (spectral band shift) is explored through simulation for five satellite sensors. Two different types of natural terrain - vegetation and bare soil - are used as test targets.

Suits, G.↗
NASA NTRS1991

Rock fraction effects on the interpretation of microwave emission from soils

The effects of rock fraction on the relationship between microwave emission and surface soil moisture were investigated through a combination of laboratory dielectric measurements and field observation of emissivity. Field measurements were conducted which included soils with and without rocks. Microwave brightness temperature was measured at L and C band using a truck-mounted radiometer. Dielectric measurements were made at L band. Field observations of emissivity showed that the presence of rocks decreases the range of the measurements. At 21 cm this decrease was relatively small; however, at 6 cm almost all sensitivity to soil moisture was eliminated by the presence of 35 percent rocks. Comparisons between observed and predicted data showed that the effects of rock fraction are not significant in estimating the sample soil moisture for the tested conditions.

Jackson, Thomas J.↗