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At least 1,027 records · Page 57
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

On the emergent scale of bedrock groundwater contribution to headwater mountain streams

We investigated the contribution of bedrock groundwater to streamflow as a function of catchment scale in a headwater stream. Synoptic surveys were conducted during hydrologically important periods of the year using multiple environmental tracers in stream water, soil water, and bedrock groundwater, along a first-order montane stream, in west-central Montana. Sampled analytes included 222 Rn, used to constrain total subsurface flux, and major and minor elements, used in end-member mixing analysis (EMMA) to identify the contributions of soil and bedrock groundwater to the stream. Partitioning between soil-derived and bedrock-derived groundwater was then analyzed as a function of the incremental and accumulated sub-catchment sizes. Radon results indicated that subsurface water contributions accounted for the majority of streamflow at all surveyed times. EMMA results revealed that the bedrock groundwater contribution to streamflow varied between 26% during peak snowmelt and 44% during late summer. Streamflow generation was dominated by soil groundwater contribution along the entire reach, but the bedrock groundwater contribution increased consistently with accumulated sub-catchment size. However, groundwater contributions were not well-correlated with incremental sub-catchment size. The scale at which increased bedrock groundwater discharge can be correlated with sub-catchment size appears to be >1 km 2 for our study. Our results are consistent with a conceptual model where streamflow is predominantly generated by a 3D subsurface nested flow system. Local subsurface heterogeneities control the stream source at local scales but begin to average out at scales >2 km 2 . Our study indicates that, while soil groundwater is the dominant source, bedrock groundwater remains an important and predictable contributor to streamflow throughout the year, even in a snow-dominated, mountainous headwater catchment.

environmental tracers↗
DOE OSTI2020

Regional climate change projections from NA-CORDEX and their relation to climate sensitivity

Abstract The climate sensitivity of global climate models (GCMs) strongly influences projected climate change due to increased atmospheric carbon dioxide. Reasonably, the climate sensitivity of a GCM may be expected to affect dynamically downscaled projections. However, there has been little examination of the effect of the climate sensitivity of GCMs on regional climate model (RCM) ensembles. Therefore, we present projections of temperature and precipitation from the ensemble of projections produced as a part of the North American branch of the international Coordinated Regional Downscaling Experiment (NA-CORDEX) in the context of their relationship to the climate sensitivity of their parent GCMs. NA-CORDEX simulations were produced at 50-km and 25-km resolutions with multiple RCMs which downscaled multiple GCMs that spanned nearly the full range of climate sensitivity available in the CMIP5 archive. We show that climate sensitivity is a very important source of spread in the NA-CORDEX ensemble, particularly for temperature. Temperature projections correlate with driving GCM climate sensitivity annually and seasonally across North America not only at a continental scale but also at a local-to-regional scale. Importantly, the spread in temperature projections would be reduced if only low, mid, or high climate sensitivity simulations were considered, or if only the ensemble mean were considered. Precipitation projections correlate with climate sensitivity, but only at a continental scale during the cold season, due to the increasing influence of other processes at finer scales. Additionally, it is shown that the RCMs do alter the projection space sampled by their driving GCMs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Automated processing of environmental transmission electron microscopy images for quantification of thin film dewetting and carbon nanotube nucleation dynamics

We report scalable production of carbon nanotubes (CNTs) requires catalysts and reaction conditions that provide high nucleation efficiency. In situ characterization methods such as environmental transmission electron microscopy (ETEM) can reveal fundamental mechanisms of synthesis, but to date have primarily provided qualitative observations on small sample sizes. Here, quantitative analysis is performed using high-resolution, high-rate video capture of ETEM experimentation coupled with automated image processing, involving computer vision algorithms and convolutional neural networks. By this approach, we detect distinct nanoparticle formation from an alumina-supported iron thin film and subsequent CNT nucleation from the nanoparticles. The statistical summary of particles in each video shows that, compared to a H 2 -only atmosphere, pretreatment of the catalyst with carbon added to the H 2 atmosphere results in a smaller average particle diameter, a 2-fold increase in particle density (to 5300 particles/μm 2 ), a 3-fold increase in CNT nucleation efficiency (to 92%), and more than a 5-fold increase in CNT density (to 4800/μm 2 ). Addition of carbon during exposure to H 2 is also more effective than NH 3 at dewetting the catalyst film and increasing the CNT nucleation efficiency, in spite of NH 3 being a stronger reducing agent for iron. Insights from this study are applicable to improving CNT yield and productivity in both batch-style and continuous processes.

25 ENERGY STORAGE↗
DOE OSTI2023

Earthworms Exposed to Polyethylene and Biodegradable Microplastics in Soil: Microplastic Characterization and Microbial Community Analysis

While much is known about microplastics in aquatic environments, only few studies have focused on how microplastics interact with terrestrial organisms. The objective of our study was to investigate the interactions of earthworms with microplastics in a natural environment with environmentally realistic plastic concentrations. Here we investigated whether earthworms would ingest microplastics and incorporate them into their bodies and cast, and whether microplastics would alter the intestinal and soil microbiome. Lumbricus terrestris was exposed to two types of mi croplastics, biodegradable polybutylene adipate terephthalate (PBAT) and low-density polyethylene (LDPE) in mesocosoms filled with natural soil. Microplastics were mixed with poplar leaves and earthworms were allowed to forage for food for 20 days. Surface and bulk soil, earthworm cast, and earthworms themselves were sampled and analyzed for plastic content and microbial communities. Earthworms did not show macroscopic health deterioration (weight loss, vitality). We observed microplastics particles in earthworm casts and guts. Raman spectroscopy indicated that PBAT in guts and cast had degraded to some extent; however, LDPE remained unchanged among the different samples. Microbial analysis showed that soil and casts has similar microbial communities; however, they were signicantly different from the guts samples. Microplastic treatments did not result in a statistically signicant change in bacterial richness, diversity or community composition compared to controls. Taken together, our results suggest that, at environmentally realistic concentrations and short exposure times, PBAT and LDPE microplastics do not have adverse effects on Lumbricus terrestris earthworms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Origins of glycan selectivity in streptococcal Siglec-like adhesins suggest mechanisms of receptor adaptation

Bacterial binding to host receptors underlies both commensalism and pathogenesis. Many streptococci adhere to protein-attached carbohydrates expressed on cell surfaces using Siglec-like binding regions (SLBRs). The precise glycan repertoire recognized may dictate whether the organism is a strict commensal versus a pathogen. However, it is currently not clear what drives receptor selectivity. Here, we use five representative SLBRs and identify regions of the receptor binding site that are hypervariable in sequence and structure. We show that these regions control the identity of the preferred carbohydrate ligand using chimeragenesis and single amino acid substitutions. We further evaluate how the identity of the preferred ligand affects the interaction with glycoprotein receptors in human saliva and plasma samples. As point mutations can change the preferred human receptor, these studies suggest how streptococci may adapt to changes in the environmental glycan repertoire.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

Development of Testing Methods to Predict Cracking in Photovoltaic Backsheets

In recent years there have been some significant failures of photovoltaic backsheets resulting from inadequacies of design that are not detected in current versions of the qualification standards. In some cases, this has resulted in catastrophic failure in less than 5 y of deployment. In this work, we develop a test sample construction and evaluate accelerated exposure conditions necessary to duplicate the cracking field failure of backsheets using a small and manageable coupon. This sample uses a piece of solder wire to put some controlled topology and stress into the backsheet. Through exposure to different environmental stressors it was found that the application of thermal cycling stresses, after ultraviolet radiation exposure, is of primary importance to duplicate field failures.

14 SOLAR ENERGY↗
DOE OSTI2022

Leaf demography spectra, February 2017, PA-SLZ: Panama

This dataset contains leaf reflectance spectra of sunlit canopy leaves from trees at the San Lorenzo Protected Area (PA-SLZ), Panama. Spectra were measured with a full-spectrum (350 -2500 nm) spectroradiometer with a leaf clip attachment. Leaves previously documented in a demography survey were targeted, and each leaf spectrum is paired with species identification, relative leaf position on each branch and estimated leaf age in days. Leaves were measured from the following species: Apeiba membranacea, Carapa guianensis, Guatteria dumetorum, Miconia borealis, Tachigali versicolor, Terminalia amazonia, Tocoyena pittieri and Vochysia ferruginea Unprocessed spectral data are included as SVC *.sig files, and metadata, including sample details, are presented in *.xlsx files. Leaf reflectance spectra of sunlit canopy leaves from trees at the San Lorenzo Protected Area (PA-SLZ), Panama. Spectra were measured with a full-spectrum (350 -2500 nm) spectroradiometer with a leaf clip attachment. Leaves previously documented in a demography survey were targeted, and each leaf spectrum is paired with species identification, relative leaf position on each branch and estimated leaf age in days. Leaves were measured from the following species: Apeiba membranacea, Carapa guianensis, Guatteria dumetorum, Miconia borealis, Tachigali versicolor, Terminalia amazonia, Tocoyena pittieri and Vochysia ferruginea Unprocessed spectral data are included as SVC *.sig files, and metadata, including sample details, are presented in *.xlsx files.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

ExINP-ENA Ice-Nucleating Particle Concentrations - PINE

This data set comprises cumulative ambient ice-nucleating particle (INP) concentrations measured at the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Eastern North Atlantic (ENA) observatory on Graciosa Island, Azores (39.0916° N, 28.0257° W). Our INP data were generated using a combination of online instruments, the Portable Ice Nucleation Experiment chamber (PINE), and an offline assay instrument, the West Texas Cryogenic Refrigerator Applied to Freezing Test system (WT-CRAFT), for aerosol particle samples collected on polycarbonate filters (with 0.2-micron diameter pores).

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1972

Petrographic and electron microprobe study of the Monturaqui impactite.

Investigation of the type of shock features present in Monturaqui impactites aimed at determining the shock intensities, type of meteorite projectile, and environmental conditions that might have been at the origin of the formation of these impactites. Following a description of the impactite samples, their shock features, and chemistry, a discussion is presented of the procedures, results, and interpretation of the impactite-formation simulating experiments performed.

Bunch, T. E.↗
NASA NTRS1976

Environmental parameters of the Tennessee River in Alabama. 1: Thermal stratification

Thermal stratification data of a transect across Wheeler Reservoir are correlated with the climatological data at the time of sampling. This portion of the Tennessee River is used as a heat sink for the effluent from the three reactor Browns Ferry Nuclear Power Plant. The transect sampling line is 1.3 miles below this point of effluence. Data are presented by weekly samplings for one year prior to plant operations. Post-operational data are presented with one reactor in operation and with two reactors in partial operation. Data gathering was terminated when the plant ceased operations. The results indicate that the effluent for partial plant operation were inconclusive. As a result, recommendations include continuing the sampling when the plant resumes operation at full capacity. Recommendations also include developing math models with the presented thermal and climatological data to be used for predicting the effluent impact in the river with varying climatological conditions and also to predict the effectiveness of the cooling towers.

Rosing, L. M.↗
NASA NTRS2000

Assessment of Thermal Control and Protective Coatings

This final report is concerned with the tasks performed during the contract period which included spacecraft coating development, testing, and applications. Five marker coatings consisting of a bright yellow handrail coating, protective overcoat for ceramic coatings, and specialized primers for composites (or polymer) surfaces were developed and commercialized by AZ Technology during this program. Most of the coatings have passed space environmental stability requirements via ground tests and/or flight verification. Marker coatings and protective overcoats were successfully flown on the Passive Optical Sample Assembly (POSA) and the Optical Properties Monitor (OPM) experiments flown on the Russian space station MIR. To date, most of the coatings developed and/or modified during this program have been utilized on the International Space Station and other spacecraft. For ISS, AZ Technology manufactured the 'UNITY' emblem now being flown on the NASA UNITY node (Node 1) that is docked to the Russian Zarya (FGB) utilizing the colored marker coatings (white, blue, red) developed by AZ Technology. The UNITY emblem included the US American flag, the Unity logo, and NASA logo on a white background, applied to a Beta cloth substrate.

Mell, Richard J.↗
NASA NTRS2004

Classifying Terrestrial Volcanic Alteration Processes and Defining Alteration Processes they Represent on Mars

Characterizing alteration of the rocks on Mars is difficult, but some guidelines can be made through comparison with terrestrial volcanic alteration. Subaerial volcanic activity on the Hawaiian islands and subglacial volcanic activity on Iceland have led to the formation of a variety of silicate and iron oxide-rich alteration products that may serve as models for chemical alteration on Mars. Multiple samples have been collected from palagonitized tuffs, altered pillow lavas, altered tephra, and S-rich vents for study in the lab. Variations in the kinds of alteration products have been observed depending on the sample environment. We are defining associations between the alteration products and formation conditions that can be used to provide information about environmental conditions on Mars. In particular, we are providing definitions for palagonitic, pedogenic and solfataric alteration that can be used to characterize these alteration processes.

Bishop, J. L.↗
NASA NTRS2005

Autonomy Software Architecture for LORAX (Life On ice Robotic Antarctic eXplorer)

LORAX is a robotic astrobiological study of the ice field surrounding the Carapace Nunatak near the Allan Hills in Antarctica. The study culminates in a l00km traverse, sampling the ice at various depths (from surface to 10cm) at over 100 sites to survey microbial ecology and to record environmental parameters. The autonomy requirements from LORAX are shared by many robotic exploration tasks. Consequently, the LORAX autonomy architecture is a general architecture for on-board planning and execution in environments where science return is to be maximized against resource limitations and other constraints.

Jonsson, Ari↗
NASA NTRS2014

Detection of Nitric Oxide by the Sample Analysis at Mars (SAM) Instrument Implications for the Presence of Nitrates

One of the main goals of the Mars Science Laboratory is to determine whether the planet ever had environmental conditions able to support microbial life. Nitrogen is a fundamental element for life, and is present in structural (e.g., proteins), catalytic (e.g., enzymes and ribozymes), energy transfer (e.g., ATP) and information storage (RNA and DNA) biomolecules. Planetary models suggest that molecular nitrogen was abundant in the early Martian atmosphere, but was rapidly lost to space by photochemistry, sputtering impact erosion, and oxidized and deposited to the surface as nitrate. Nitrates are a fundamental source for nitrogen to terrestrial microorganisms. Therefore, the detection of nitrates in soils and rocks is important to assess the habitability of a Martian environment. SAM is capable of detecting nitrates by their thermal decomposition into nitric oxide, NO. Here we analyze the release of NO from soils and rocks examined by the SAM instrument at Gale crater, and discuss its origin.

Navarro-Gonzalez, R.↗
NASA NTRS2017

Cyclic Fatigue Durability of Uncoated and EBC Coated 3D SiC/SiC Composites Under Thermal Gradient Conditions at 2700F in Air

Ceramic matrix composites (CMCs) such as SiC/SiC are currently being designed and implemented in high temperature sections of aerospace turbine engines. Such components will be subject to through-thickness thermal gradients, which may affect the durability. In this study, SiC/SiC CMCs with a hybrid chemical vapor infiltrated (CVI) and polymer infiltration and pyrolysis (PIP) matrix were loaded in tension while one surface was heated with a laser and the opposite surface was cooled. Issues associated with laser testing will be discussed, along with initial results for coated and uncoated samples.

Ceramic matrix composite↗
NASA NTRS2021

Empirical Model of 10 – 130 MeV Solar Energetic Particle Spectra at 1 AU Based on Coronal Mass Ejection Speed and Direction

We present a new empirical model to predict solar energetic particle (SEP) event integrated and peak intensity spectra between 10 and 130 MeV at 1 AU, based on multi-point spacecraft measurements from the Solar TErrestrial RElations Observatory (STEREO), the Geostationary Operational Environmental Satellites (GOES), and the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) satellite experiment. The analyzed data sample includes 32 SEP events occurring between 2010 and 2014, with a statistically significant proton signal at energies in excess of a few tens of MeV, unambiguously recorded at three spacecraft locations. The spatial distributions of SEP intensities are reconstructed by assuming an energy-dependent 2D Gaussian functional form, and accounting for the correlation between the intensity and the speed of the parent coronal mass ejection (CME), and the magnetic-field-line connection angle. The CME measurements used are from the Space Weather Database Of Notifications, Knowledge, Information (DONKI). The model performance, including its extrapolations to lower/higher energies, is tested by comparing with the spectra of 20 SEP events not used to derive the model parameters. Despite the simplicity of the model, the observed and predicted event-integrated and peak intensities at Earth and at the STEREO spacecraft for these events show remarkable agreement, both in the spectral shapes and their absolute values.

Alessandro Bruno↗
NASA NTRS2023

Space Environmental Effects on Additively Manufactured Materials – Results from MISSE-9 and MISSE-10

The NASA Marshall Space Flight Center (MSFC) Space Environmental Effects (SEE) and Contamination Control (CC) teams prepared and characterized MISSE-9 and MISSE-10’s additively manufactured (AM) materials samples to investigate the effect of ultraviolet (UV) radiation, thermal cycling, outgassing, and temperature and provide data on the durability of these samples. Materials studied were polyetherimide (Ultem 1010 and 9085), electrostatic dissipative polyetherketoneketone (ESD-PEKK), also known commercially as Antero 840CN03, polycarbonate biocompatible per ISO 10993 USP Class VI (PC-ISO), and Inconel 718. Some samples were manufactured at MSFC, while 3D printer manufacturers Stratasys and Made In Space, Inc. (MIS) (now Redwire) participated in this effort to compare different vendors and printing setups. Results from nondestructive analyses and tensile testing are presented.

additive manufacturing↗
DOE OSTI2022

FTICR-MS, Sensor, and Environmental Data from 5 Streams Impacted by the 2020 Holiday Farm Fire Associated with: "Spatiotemporal controls on the delivery of dissolved organic matter to streams following a wildfire"

This data package is associated with the publication "Spatiotemporal Controls on the Delivery of Dissolved Organic Matter to Streams Following a Wildfire" submitted to Geophysical Research Letters (Roebuck et al., 2022). The study aims to understand storm induced transport of pyrogenic materials to streams impacted by varying degrees of burn severity. Time series samples (24 samples in 1-hour intervals) were collected at 5 sites within the McKenzie River Watershed (Oregon, USA) whose catchment were each completely engulfed by the 2020 Holiday Farm Fire. The samples were collected in November 2020 during the first major storm pulse following the conclusion of the wildfire. Samples were characterized for dissolved organic carbon, total dissolved nitrogen, and by ultra-high resolution mass spectrometry. In situ turbidity data also collected.This data package contains 4 primary folders that include the following: 1) Metadata, 2) EnvData (Environmental Data), 3) SensorData, and 4) FTICR_SupportingData. The package contains a single file-level metadata (flmd) file. Each primary folder also contains individual data dictionaries (dd) to define and provide descriptors of column/row headers and data flags. The FTICR_SupportingData, folder 4, contains raw, unprocessed FTICR-MS Data files in addition to a csv containing processed FTICR-MS data. This package contains the following file types: csv, xml, pdf.

54 ENVIRONMENTAL SCIENCES↗