SEARCH · Engineering Papers

Results for “Soil Sample Processing”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20

All sources NASA NTRS DOE OSTI

NASA NTRS1979

Regolith layering processes based on studies of low-temperature volatile elements in Apollo core samples

The concentrations of Hg released at at the most 130 C increase with depth in near-surface samples from cores. This is in response to a daytime thermal gradient with temperatures of approximately 400 K at the surface decreasing to approximately 250 K at greater than 10 cm depth (Keihm and Langseth, 1973). The steepness of the slopes and the depths to which the concentration gradients extend appear to be determined by the color, density and possibly the grain size of the soils. Earlier surface layers can be identified and, in general, are in agreement with other indicators of such layers. Low temperature volatilized Br exhibits trends that parallel those of Hg in a number of cases. This is also true of Br and Hg fractions released in stepwise heating experiments at higher temperatures. The coherence, especially in higher temperature fractions, between these chemically dissimilar elements implies a common physical process of entrapment; possibly one related to the presence of vapor deposits on surfaces and to opening and closing of microcracks and pores.

Jovanovic, S.↗

DOE OSTI2019

Tonopah Test Range Air Monitoring: CY2018 Meteorological, Radiological, and Wind Transported Particulate Observations

In 1963, the U.S. Department of Energy (DOE) (formerly the Atomic Energy Commission [AEC]), implemented Operation Roller Coaster on the Tonopah Test Range (TTR) and an adjacent area of the Nevada Test and Training Range (NTTR) (formerly the Nellis Air Force Range). This operation resulted in radionuclide-contaminated soils at the Double Tracks site and Clean Slate I, II, and III sites. This report documents observations made during ongoing monitoring of radiological, meteorological, and dust conditions at stations installed adjacent to the Clean Slate sites and at the TTR Sandia National Laboratories (SNL) Range Operations Center (ROC). The primary objective of the monitoring effort is to support the DOE Environmental Management Nevada Program (EM NV) in the safe remediation of the environmental legacy of nuclear device development and testing by determining if wind blowing across the Clean Slate sites is transporting particles of radionuclide-contaminated soil beyond the physical and administrative boundaries of the sites, and to provide information for designing long-term monitoring of the sites. The monitoring program in 2018 included five stations. Station 400, located within TTR Area 3 and near the ROC, monitors conditions near the local workforce center. Stations 401 and 403 are located on the northern and southeastern perimeter fence lines, respectively, of the Clean Slate III site. Stations 404 and 405 are along the northern and eastern boundary fence, respectively, at Clean Slate II. The stations are generally downwind of the contaminated areas during either northwesterly or southerly winds, which are the predominant wind directions. The stations—which are similar in design to the Community Environmental Monitoring Program (CEMP) stations operating at locations surrounding the Nevada National Security Site and TTR—include meteorological instruments and continuous-flow, low-volume air samplers. Three pressurized ionization chambers for measuring gamma energy are in use at Stations 400, 401, and 403. Saltation sensors and saltation traps are deployed at the stations adjacent to the Clean Slate sites. Detailed meteorological data are recorded on data loggers, with periodic uploads via a satellite system to the Western Regional Climate Center (WRCC) at Desert Research Institute (DRI), to monitor instrument and site conditions. Air filter samples are collected every two weeks and the deposits in the saltation traps are collected when a sufficient sample mass for analysis has accumulated (generally a six- to eight-month interval). Monitoring at TTR in calendar year (CY) 2018 provided surveillance of both ambient conditions, and ground disturbance associated with remediation activities at Clean Slate II and III. The first half of CY2018 data from Stations 404 and 405 at Clean Slate II were collected during remediation activities at that site, and data collected during the final third of the year at Stations 401 and 403 at Clean Slate III coincided with remediation work at the site. Ambient conditions prevailed at Station 400 throughout the year. Dust transport by suspension and saltation is strongly dependent on wind speed. Concentrations of PM 10 (particulate matter of aerodynamic diameter ≤10 micrometers [μm], a size fraction of small particles that are suspended in the air and can be easily inhaled) remain low until winds exceed approximately 32 kilometers per hour (km/hr) (20 miles per hour [mph]). Saltation particle counts also increase above the same general threshold wind speed. Wind speeds in excess of 32 km/hr (20 mph) occur less than three percent of the time at the sites. Ground disturbing remediation activities were carried out at Clean Slate II from October 31, 2017, until July 26, 2018. Station 404 is located closest to the remediation area and is downwind of the area when winds are from the south. By late November, analysis of dust from the air sampler at Station 404 registered increases in plutonium-239+240 ( 239+240 Pu) concentrations. Peak plutonium concentrations, accompanied by elevated gross alpha concentrations and the detection of americium-241 ( 241 Am) by gamma spectroscopy, occurred between March and May 2018. During spring and early summer of 2018, elevated radionuclide concentrations were also measured in dust collected from the air sampler at Station 405, which is more than twice the distance from the remediation activity as Station 404. A minor but sustained increase in gross alpha concentration of suspended dust collected at Stations 400, 401, and 403 was also observed starting in May 2018 and continuing into August. Stations 401 and 403 are approximately 4.8 to 6.4 km (three to four miles) from Clean Slate II and Station 400 is approximately 13 km (eight miles) from that site. The radionuclide content of material that saltated into the passive Big Spring Number Eight (BSNE) traps during the Clean Slate II remediation period increased in both the traps facing toward and away from the fenced contamination area at Station 404, with the largest increases in concentration (almost five times the previous 239+240 Pu concentration) observed in the traps facing the fenced area. The radionuclide concentration in material in the trap facing away from the fence more than doubled from that measured in 2017. A similar increase was observed for the saltation trap facing away from the fenced area at Station 405, although no increase was observed for material captured in the trap facing the fenced area. Particles ranging in size from 50 to 500 µm generally move by saltation processes and are not expected to significantly contribute to dose for someone breathing in the standard respiratory zone for adult humans (1.5 to 1.7 m [4.9 to 5.6 ft] above ground level) because they are too large to be entrained in the air as suspended dust. Remediation activities at Clean Slate III began on September 5, 2018, and continued until a brief hiatus started on December 20, 2018. Although Station 401 is much closer to the remediation area than Station 403, the first increase in gross alpha and 239+240 Pu concentrations was noted in dust from filters collected at Station 403 in early November 2018. The highest radionuclide concentrations of 2018 at the Clean Slate III stations were recorded in air samples taken from Stations 401 and 403 in late December 2018 and these concentrations were comparable between the two station locations. Gamma rate data measured by the PICs was slightly higher than the annual average at Stations 401 and 403 after remediation activities began, but no single measurement was outside of the range observed in 2018 prior to remediation activities. No increase in radionuclide concentration was observed for the Clean Slate III remediation time period on air filters collected from the other stations. Radiological monitoring at Station 400—which is located at the ROC, and therefore the closest regularly staffed work location to the Clean Slate sites—recorded a higher mean gross alpha activity from dust collected on air sampler filters than in previous years. The individual biweekly air filters yielded measurements of gross alpha that were at or below the mean plus one standard deviation measured in CY2017, except for the period from April 25, 2018, through September 12, 2018. Nonetheless, gamma spectroscopy of all air filters from Station 400 identified only naturally occurring radionuclides, with no detection of americium-241 ( 241 Am) (which is used as an indicator of plutonium-241[ 241 Pu]). Alpha spectroscopy of selected air filters collected at Station 400 did not detect plutonium-238 ( 238 Pu) or 239+240 Pu above the analytical detection limit. Gross beta and gamma exposure rate data were comparable to data from regional CEMP stations. No saltation traps are deployed at Station 400. Considering the ambient monitoring periods during CY2018, the monitoring stations adjacent to the Clean Slate sites recorded above-background 238 Pu and 239+240 Pu concentrations (SNL, 1998; Turner et al., 2003) in samples collected by passive saltation traps and on selected air filters. These observations were consistent with previous years and indicated that radionuclide movement occurred under ambient conditions by processes of both saltation and suspension. The presence of radionuclides in all saltation traps, both upwind and downwind of the fenced contamination areas, was consistent with previous radiological survey results (EG&G, 1979) that show lower concentration radiologically contaminated material dispersed outside the fenced area. Although 239+240 Pu concentrations in the air filter samples were sometimes orders of magnitude higher than background, the concentrations were below risk-based action levels defined for an industrial area worker scenario (U.S. DOE, 2014). The interception of airborne dust with above-background radionuclide concentrations demonstrates that dispersal processes are continuing. Strong winds are the driver for both suspension and saltation of dust and soil. The recorded wind speed and PM10 during remediation activities at Clean Slate II and III identified discrete wind events lasting approximately five to eight hours each, which accounted for the greatest PM 10 concentrations at the monitoring stations. These events captured the effect of winds from the northwest and from the south. The observed differences in dust loading and radionuclide concentrations for the monitoring stations when they were either upwind or downwind of the contamination area identify the remediation area as a source of plutonium contaminated dust. The increase in concentration of radionuclides in airborne dust during the remediation activities, compared with measurements under previous ambient conditions (mean 239+240 Pu concentrations during remediation activities are approximately nine to 40 times higher compared to pre-remediation concentrations, depending on monitoring station), highlights the impact of land disturbance on wind-borne contaminant transport from the Clean Slate test areas. The meteorological and particulate matter monitoring indicated that conditions for wind-borne contaminant movement exist at the Clean Slate sites, and that transport of radionuclide-contaminated soil by both suspension and saltation occurred under ambient conditions and accelerated when the sites were disturbed. The 239+240 Pu alpha spectroscopy results indicated that airborne concentrations during remediation activities ranged from 2 × 10-16 to 380 × 10-16 µCi/ml. These results can be compared to the derived air concentration limit for 239 Pu of 6 × 10-11 µCi/ml for occupational workers contained in Code of Federal Regulations 10 CFR 835, Occupational Radiation Protection. Even though the air sampling results document an increase in concentration during remediation activities, the observed concentrations are less than 0.06 percent of the occupational limit. The Corrective Action Unit (CAU) closure strategy uses a risk-based approach, whereby acceptable contaminant concentrations are determined as a function of anticipated human exposure.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2018

A critical review of ferrate(VI)-based remediation of soil and groundwater

Highlights: • Ferrate(VI) has exhibited promising behavior towards the oxidation of inorganic/organic impurities. • It has unique properties of strong oxidizing potential and generation of ferric coagulating species. • It can degrade and/or oxidize organic and inorganic impurities (at least partially). • It can also disinfect microorganisms and remove suspended/colloidal particulate materials. • We reviewed on the preparation, properties, and role of ferrate to resolve multifaceted challenges. Over the past few decades, diverse chemicals and materials such as mono- and bimetallic nanoparticles, metal oxides, and zeolites have been used for soil and groundwater remediation. Ferrate (Fe{sup VI}O{sub 4}{sup 2-}) has been widely employed due to its high-valent iron (VI) oxo compound with high oxidation/reduction potentials. Ferrate has received attention for wide environmental applications including water purification and sewage sludge treatment. Ferrate provides great potential for diverse environmental applications without any environmental problems. Therefore, this paper provides comprehensive information on the recent progress on the use of (Fe{sup VI}O{sub 4}{sup 2-}) as a green material for use in sustainable treatment processes, especially for soil and water remediation. We reviewed diverse synthesis recipes for ferrates (Fe{sup VI}O{sub 4}{sup 2-}) and their associated physicochemical properties as oxidants, coagulants, and disinfectants for the elimination of a diverse range of chemical and biological species from water/wastewater samples. A summary of the eco-sustainable performance of ferrate(VI) in water remediation is also provided and the future of ferrate(VI) is discussed in this review.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1974

Grain size and the evolution of lunar soils

Grain-size data are presented for Apollo-17 soils, and the relationship is considered between grain-size distribution and the processes which pulverize the soil, reconstitute it as agglutinates, and replenish it with fresh material. It is shown that a strong inverse correlation exists between mean grain size and standard deviation and that there is a correlation between grain size and agglutinate content whereby the finest samples have the highest agglutinate content. Two evolutionary sequences are described for the soils in which (1) reworking by micrometeorites predominates over mixing with other soils and (2) mixing predominates over reworking. It is shown that the final result of soil evolution may be a steady-state soil where pulverization by micrometeorites is balanced by agglutination and replenishment of coarser grains. A model is presented for such a soil, and it is argued that its grain-size distribution may depend on regolith thickness.-

Mckay, D. S.↗

DOE OSTI2024

Linking Dissolved Organic Matter Composition to Landscape Properties in Wetlands Across the United States of America

Abstract Wetlands are integral to the global carbon cycle, serving as both a source and a sink for organic carbon. Their potential for carbon storage will likely change in the coming decades in response to higher temperatures and variable precipitation patterns. We characterized the dissolved organic carbon (DOC) and dissolved organic matter (DOM) composition from 12 different wetland sites across the USA spanning gradients in climate, landcover, sampling depth, and hydroperiod for comparison to DOM in other inland waters. Using absorption spectroscopy, parallel factor analysis modeling, and ultra‐high resolution mass spectroscopy, we identified differences in DOM sourcing and processing by geographic site. Wetland DOM composition was driven primarily by differences in landcover where forested sites contained greater aromatic and oxygenated DOM content compared to grassland/herbaceous sites which were more aliphatic and enriched in N and S molecular formulae. Furthermore, surface and porewater DOM was also influenced by properties such as soil type, organic matter content, and precipitation. Surface water DOM was relatively enriched in oxygenated higher molecular weight formulae representing HUP High O/C compounds than porewaters, whose DOM composition suggests abiotic sulfurization from dissolved inorganic sulfide. Finally, we identified a group of persistent molecular formulae (3,489) present across all sites and sampling depths (i.e., the signature of wetland DOM) that are likely important for riverine‐to‐coastal DOM transport. As anthropogenic disturbances continue to impact temperate wetlands, this study highlights drivers of DOM composition fundamental for understanding how wetland organic carbon will change, and thus its role in biogeochemical cycling.

Environmental Sciences & Ecology↗

NASA NTRS1979

A system for processing Landsat and other georeferenced data for resource management applications

The NASA Earth Resources Laboratory has developed a transferrable system for processing Landsat and disparate data with capabilities for digital data classification, georeferencing, overlaying, and data base management. This system is known as the Earth Resources Data Analysis System. The versatility of the system has been demonstrated with applications in several disciplines. A description is given of a low-cost data system concept that is suitable for transfer to one's available in-house minicomputer or to a low-cost computer purchased for this purpose. Software packages are described that process Landsat data to produce surface cover classifications and that geographically reference the data to the UTM projection. Programs are also described that incorporate several sets of Landsat derived information, topographic information, soils information, rainfall information, etc., into a data base. Selected application algorithms are discussed and sample products are presented. The types of computers on which the low-cost data system concept has been implemented are identified, typical implementation costs are given, and the source where the software may be obtained is identified.

Whitley, S. L.↗

NASA NTRS1992

Plot-scale field experiment of surface hydrologic processes with EOS implications

Plot-scale hydrologic field studies were initiated at NASA Marshall Space Flight Center to a) investigate the spatial and temporal variability of surface and subsurface hydrologic processes, particularly as affected by vegetation, and b) develop experimental techniques and associated instrumentation methodology to study hydrologic processes at increasingly large spatial scales. About 150 instruments, most of which are remotely operated, have been installed at the field site to monitor ground atmospheric conditions, precipitation, interception, soil-water status, and energy flux. This paper describes the nature of the field experiment, instrumentation and sampling rationale, and presents preliminary findings.

Laymon, Charles A.↗

NASA NTRS1974

Stabilization of lunar core samples

Processing of lunar cores includes: (1) careful dissection for study of loose fines, and (2) stabilization of the residue by peeling and impregnation. The newly developed technique for preparing thin peels of lunar cores requires application of the methacrylate adhesive to a backing strip, before taking the peel. To ensure complete impregnation of the very fine, dry lunar soil, the low-viscosity epoxy, Araldite 506, is gently flowed onto the core, under vacuum.

Nagle, J. S.↗

DOE OSTI2021

Soil organic carbon is not just for soil scientists: measurement recommendations for diverse practitioners

Soil organic carbon (SOC) regulates terrestrial ecosystem functioning, provides diverse energy sources for soil microorganisms, governs soil structure, and regulates the availability of organically bound nutrients. Investigators in increasingly diverse disciplines recognize how quantifying SOC attributes can provide insight about ecological states and processes. Today, multiple research networks collect and provide SOC data, and robust, new technologies are available for managing, sharing, and analyzing large data sets. Here, we advocate that the scientific community capitalize on these developments to augment SOC data sets via standardized protocols. We describe why such efforts are important and the breadth of disciplines for which it will be helpful, and outline a tiered approach for standardized sampling of SOC and ancillary variables that ranges from simple to more complex. We target scientists ranging from those with little to no background in soil science to those with more soil-related expertise, and offer examples of the ways in which the resulting data can be organized, shared, and discoverable.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2024

Response of soil bacteria to PUREX chemicals suggests biomarker utility and bioremediation potential

Chemicals involved in plutonium uranium reduction extraction (PUREX) can be released from nuclear reprocessing facilities and accumulate in the environment. We exposed chemically diverse soils to a range of concentrations of key chemicals used in the PUREX process. The responses of soil microbial communities are dependent on soil type, and tributyl phosphate exposure generates the most reproducible changes in microbial communities. We reconstructed the genomes of key bacteria and find several phosphotriesterase genes found only in Rhizobiaceae. The abundance of phosphotriesterase genes is significantly higher in samples exposed to tributyl phosphate. In conclusion, these phosphotriesterase genes may be involved in breakdown of tributyl phosphate, and a means of accessing phosphate for these bacteria.

Bioremediation↗

NASA NTRS1997

Moessbauer Mineralogy on the Moon: The Lunar Regolith

A first-order requirement for spacecraft missions that land on solid planetary objects is instrumentation for mineralogical analyses. For purposes of providing diagnostic information about naturally-occurring materials, the element iron is particularly important because it is abundant and multivalent. Knowledge of the oxidation state of iron and its distribution among iron-bearing mineralogies tightly constrains the types of materials present and provides information about formation and modification (weathering) processes. Because Moessbauer spectroscopy is sensitive to both the valence of iron and its local chemical environment, the technique is unique in providing information about both the relative abundance of iron-bearing phases and oxidation state of the iron. The Moessbauer mineralogy of lunar regolith samples (primarily soils from the Apollo 16 and 17 missions to the Moon) were measured in the laboratory to demonstrate the strength of the technique for in situ mineralogical exploration of the Moon. The regolith samples were modeled as mixtures of five iron-bearing phases: olivine, pyroxene, glass, ilmenite, and metal. Based on differences in relative proportions of iron associated with these phases, volcanic ash regolith can be distinguished from impact-derived regolith, impact-derived soils of different geologic affinity (e.g., highlands, maria) can be distinguished on the basis of their constituent minerals, and soil maturity can be estimated. The total resonant absorption area of the Moessbauer spectrum can be used to estimate total FeO concentrations.

Morris, Richard V.↗

NASA NTRS2006

The Effects of Space Weathering at UV Wavelengths: S-Class Asteroids

We present evidence that space weathering manifests itself at near-UV wavelengths as a bluing of the spectrum, in contrast with the spectral reddening that has been seen at visible-near-IR wavelengths. Furthermore, the effects of space weathering at UV wavelengths tend to appear with less weathering than do the longer wavelength effects, suggesting that the UV wavelength range is a more sensitive indicator of weathering, and thus age. We report results from analysis of existing near-UV (approx.220-350 nm) measurements of S-type asteroids from the International Ultraviolet Explorer and the Hubble Space Telescope and comparisons with laboratory measurements of meteorites to support this hypothesis. Composite spectra of S asteroids are produced by combining UV spacecraft data with ground-based longer wavelength data. At visible-near-IR wavelengths, S-type asteroids are generally spectrally redder (and darker) than ordinary chondrite meteorites, whereas the opposite is generally true at near-UV wavelengths. Similarly, laboratory measurements of lunar samples show that lunar soils (presumably more weathered) are spectrally redder at longer wavelengths, and spectrally bluer at near-UV wavelengths, than less weathered crushed lunar rocks. The UV spectral bluing may be a result of the addition of nanophase iron to the regolith through the weathering process. The UV bluing is most prominent in the 300-400 nm range, where the strong UV absorption edge is degraded with weathering.

Moon↗

NASA NTRS2010

The Epiregolith

The physical properties of the lunar regolith were originally inferred from remotely sensed data, first from the Earth and later from orbiting spacecraft. The Surveyor landings and the Apollo surface explorations produced a more concrete characterization of the macroscopic properties. In general, the upper regolith consists of a loosely consolidated layer centimeters thick underlain by a particulate but extremely compacted layer to depths of meters or tens of meters. The median particle size as determined by mechanical sieving in terrestrial laboratories is several tens of micrometers. However, the comminuting processes that form the layer produce particles in all sizes down to manometers. The smallest particles, having a high surface to volume ratio, tend to be electrostatically bound to larger particles and are quite difficult to separate mechanically in the laboratory. Particle size distributions determined from lunar soil samples often group particles smaller than 10 micrometers.

Mendell, Wendell W.↗

NASA NTRS2013

Soil Moisture Active Passive (SMAP) observer power system architecture

The Soil Moisture Active and Passive (SMAP) observer is scheduled for launch in 2014. The primary science objective of SMAP is the high-resolution mapping of earth’s soil moisture. These measurements will be used to enhance understanding of processes that link the water, energy and carbon cycles, and to extend the capabilities of weather and climate prediction models. The SMAP orbit, sun-synchronous with an altitude of 680 km, was chosen to optimize the sampling characteristics of the instruments while ensuring that the resolution requirements are met. The combined active radar and passive radiometer measurement approach takes advantage of the spatial resolutions of the radar (3 km x 1000 km) and the radiometer (39 km x 47 km).

Carr, Gregory↗

DOE OSTI2018

The Fifth International Workshop on Ice Nucleation phase 2 (FIN-02): laboratory intercomparison of ice nucleation measurements

Abstract. The second phase of the Fifth International Ice Nucleation Workshop (FIN-02)involved the gathering of a large number of researchers at the KarlsruheInstitute of Technology's Aerosol Interactions and Dynamics of the Atmosphere(AIDA) facility to promote characterization and understanding of icenucleation measurements made by a variety of methods used worldwide.Compared to the previous workshop in 2007, participation was doubled,reflecting a vibrant research area. Experimental methods involved sampling ofaerosol particles by direct processing ice nucleation measuring systems fromthe same volume of air in separate experiments using different ice nucleatingparticle (INP) types, and collections of aerosol particle samples ontofilters or into liquid for sharing amongst measurement techniques thatpost-process these samples. In this manner, any errors introduced bydifferences in generation methods when samples are shared across laboratorieswere mitigated. Furthermore, as much as possible, aerosol particle sizedistribution was controlled so that the size limitations of different methodswere minimized. The results presented here use data from the workshop toassess the comparability of immersion freezing measurement methods activatingINPs in bulk suspensions, methods that activate INPs in condensation and/orimmersion freezing modes as single particles on a substrate, continuous flowdiffusion chambers (CFDCs) directly sampling and processing particles wellabove water saturation to maximize immersion and subsequent freezing ofaerosol particles, and expansion cloud chamber simulations in which liquidcloud droplets were first activated on aerosol particles prior to freezing.The AIDA expansion chamber measurements are expected to be the closestrepresentation to INP activation in atmospheric cloud parcels in thesecomparisons, due to exposing particles freely to adiabatic cooling. The different particle types used as INPs included the minerals illite NX andpotassium feldspar (K-feldspar), two natural soil dusts representative of arable sandy loam(Argentina) and highly erodible sandy dryland (Tunisia) soils, respectively,and a bacterial INP (Snomax ® ). Consideredtogether, the agreement among post-processed immersion freezing measurementsof the numbers and fractions of particles active at different temperaturesfollowing bulk collection of particles into liquid was excellent, withpossible temperature uncertainties inferred to be a key factor in determiningINP uncertainties. Collection onto filters for rinsing versus directly intoliquid in impingers made little difference. For methods that activatedcollected single particles on a substrate at a controlled humidity at orabove water saturation, agreement with immersion freezing methods was good inmost cases, but was biased low in a few others for reasons that have not beenresolved, but could relate to water vapor competition effects. AmongstCFDC-style instruments, various factors requiring (variable) highersupersaturations to achieve equivalent immersion freezing activation dominatethe uncertainty between these measurements, and for comparison with bulkimmersion freezing methods. When operated above water saturation to includeassessment of immersion freezing, CFDC measurements often measured at orabove the upper bound of immersion freezing device measurements, but oftenunderestimated INP concentration in comparison to an immersion freezingmethod that first activates all particles into liquid droplets prior tocooling (the PIMCA-PINC device, or Portable Immersion Mode Cooling chAmber–Portable Ice Nucleation Chamber), and typically slightly underestimated INPnumber concentrations in comparison to cloud parcel expansions in the AIDAchamber; this can be largely mitigated when it is possible to raise therelative humidity to sufficiently high values in the CFDCs, although this isnot always possible operationally. Correspondence of measurements of INPs among direct sampling andpost-processing systems varied depending on the INP type. Agreement was bestfor Snomax ® particles in the temperature regimecolder than −10 ∘ C, where their ice nucleation activity is nearlymaximized and changes very little with temperature. At temperatures warmer than −10 ∘ C, Snomax ® INP measurements (allvia freezing of suspensions) demonstrated discrepancies consistent withprevious reports of the instability of its protein aggregates that appear tomake it less suitable as a calibration INP at these temperatures. ForArgentinian soil dust particles, there was excellent agreement across allmeasurement methods; measures ranged within 1 order of magnitude for INPnumber concentrations, active fractions and calculated active site densitiesover a 25 to 30 ∘ C range and 5 to 8 orders of correspondingmagnitude change in number concentrations. This was also the case for alltemperatures warmer than −25 ∘ C in Tunisian dust experiments. Incontrast, discrepancies in measurements of INP concentrations or active sitedensities that exceeded 2 orders of magnitude across a broad range of temperaturemeasurements found at temperatures warmer than −25 ∘ C in a previous study werereplicated for illite NX. Discrepancies also exceeded 2 orders of magnitude attemperatures of −20 to −25 ∘ C for potassium feldspar (K-feldspar), but these coincidedwith the range of temperatures at which INP concentrations increase rapidly atapproximately an order of magnitude per 2 ∘ C cooling forK-feldspar. These few discrepancies did not outweigh the overall positive outcomes of theworkshop activity, nor the future utility of this data set or future similarefforts for resolving remaining measurement issues. Measurements of the samematerials were repeatable over the time of the workshop and demonstratedstrong consistency with prior studies, as reflected by agreement of databroadly with parameterizations of different specific or general (e.g., soildust) aerosol types. The divergent measurements of the INP activity of illiteNX by direct versus post-processing methods were not repeated for otherparticle types, and the Snomax ® datademonstrated that, at least for a biological INP type, there is no expectedmeasurement bias between bulk collection and direct immediately processedfreezing methods to as warm as −10 ∘ C. Since particle size rangeswere limited for this workshop, it can be expected that for atmosphericpopulations of INPs, measurement discrepancies will appear due to thedifferent capabilities of methods for sampling the full aerosol sizedistribution, or due to limitations on achieving sufficient watersupersaturations to fully capture immersion freezing in direct processinginstruments. Overall, this workshop presents an improved picture of presentcapabilities for measuring INPs than in past workshops, and providesdirection toward addressing remaining measurement issues.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2017

Spatial variation in microbial processes controlling carbon mineralization within soils and sediments

Soils have a defining role in global carbon cycling, having one of the largest dynamic stocks of C on earth—3300 Pg of C are stored in soils, which is three-times the amount stored in the atmosphere and more than the terrestrial land plants. An important control on soil organic matter (SOM) quantities is the mineralization rate. It is well recognized that the rate and extent of SOM mineralization is affected by climatic factors and mineral-organic matter associations. What remained elusive is to what extent constraints on microbial metabolism induced by the respiratory pathway, and specifically the electron acceptor in respiration, control overall rates of carbon mineralization in soils. Therefore, physical factors limiting oxygen diffusion such as soil texture and aggregate size (soil structure) may therefore be central controls on C mineralization rates. The goal of our research was therefore to determine if variations in microbial metabolic rates induced by anaerobic microsites in soils are a major control on SOM mineralization rates and thus storage. We performed a combination of laboratory experiments and field investigations will be performed to fulfill our research objectives. We used laboratory studies to examine fundamental factors of respiratory constraints (i.e., electron acceptor) on organic matter mineralization rates. We ground our laboratory studies with both manipulation of field samples and in-field measurements. Selection of the field sites is guided by variation in soil texture and structure while having (other environmental/soil factors constant. Our laboratory studies defined redox gradients and variations in microbial metabolism operating at the aggregate-scale (cm-scale) within soils using a novel constructed diffusion reactor. We further examined micro-scale variation in terminal electron accepting processes and resulting C mineralization rates within re-packed soils. A major outcome of our research is the ability to quantitatively place the importance of aggregate-based heterogeneity in microbial redox processes and the resulting lack of oxygen on the rate of carbon mineralization. Collectively, our research shows that anaerobic microsites are prevalent in soils and are important regulators of soil carbon persistence, shifting microbial metabolism to less efficient anaerobic respiration and selectively protecting otherwise bioavailable, reduced organic compounds such as lipids and waxes from decomposition. Further, shifting from anaerobic to aerobic conditions leads to a 10-fold increase in volume-specific mineralization rate, illustrating the sensitivity of anaerobically protected carbon to disturbance. Vulnerability of anaerobically protected carbon to future climate or land use change thus constitutes a yet unrecognized soil carbon-climate feedback that should be incorporated into terrestrial ecosystem models.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2020

3-D Radiological Data Acquisition, Visualization and Modeling - 20211

The U.S. Army Corps of Engineers (USACE) was tasked to investigate and remediate low activity radiological contamination from research and production of the nation's first nuclear weapons at the former DuPont Chambers Works Formerly Utilized Sites Remedial Action Program (FUSRAP) site (DuPont). The DuPont site had several buildings used for the Manhattan project that were demolished in the 1940's and 1950's apparently using heavy earthmoving equipment. Some of the contaminated rubble from the demolition appears to have been spread out by this equipment resulting in somewhat random scattering of radiologically contaminated soil and debris along with aqueous spills. Traditional investigative methods such as soil borings, test pits and 2-dimensional gamma walkovers were only partially successful in delineating the radiological contamination at the site. It was feared that even 'chasing' the contamination during remediation would miss contamination if the demolition resulted in discontinuous trails of radiologically contaminated soils. In evaluating the data generated over the interceding decades, the USACE determined that a better method to collect and process the remedial action radiological data was needed to enable the project team to optimize predictive planning and meet documentation expectations. The purpose of this paper is to provide an overview of the effort and progress to combine and organize radiological survey methods into a highly flexible sampling, modeling, and decision analysis approach that emphasizes the quality of decision-making during remediation. This innovative system blends multiple tools to develop a methodology that can extend MARRSIM [1] into the subsurface and provide tools that can be applied to other sites. (authors)

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Rhizosphere Soil Biogeochemical Data and Photosynthetic Data of Vicia Faba in a Rhizobox

Here we share the data in column format via csv files for pH, redox, and dissolved oxygen collected at hourly resolution from microelectrodes. Dissolved organic carbon concentrations collected from TOC are also provided in a similar format but are composited samples from hourly microdialysis collection. This provided resolution of diel rhizosphere dynamics belowground. Plant physiological data was also collected at every 5 min for 24 hr cycles in order to capture diel dynamics aboveground. This data was used to parameterize the reaction transport model eSTOMP-ROOTS, which examines the rhizosphere biogeochemistry of a growing Vicia faba plant. The aim was to investigate plant activity and belowground biogeochemical processes, particularly their impact on mineral-organic associations in the rhizosphere. We combined in-situ rhizosphere microsensor and plant physiological measurements with a 3-D plant-soil reactive transport model to explore the behavior of dissolved organic carbon (DOC) in the rhizosphere. Over several days, microdialysis probes placed at the root-soil interface in live soil showed distinct daily patterns of DOC concentration in the pore water. Spikes in DOC concentrations during the day aligned with peaks in leaf-level photosynthesis, accompanied by decreasing redox potential and dissolved oxygen levels, and increasing pH in the rhizosphere. This new mechanistic modeling framework, which integrates aboveground plant physiological data with non-destructive, high-resolution monitoring of rhizosphere processes, offers significant potential for studying the factors that control carbon storage in soils.

54 ENVIRONMENTAL SCIENCES↗