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DOE OSTI2021

Selective volatile organic compound gas sensor based on carbon nanotubes functionalized with ZnO nanoparticles

Here this paper describes the theory and results for a new class of low-cost chemoresistive gas sensors designed for selective hydrocarbon gas detection. The sensors utilize a multiwalled carbon nanotube (MWCNT) backbone functionalized with metal oxide nanocrystals. Specifically, nanoparticles were grown on the surface of the MWCNTs using atomic layer deposition. The crystallinity of the ZnO-MWCNTs' heterostructure was examined by using a high-resolution transmission electron microscope. The structure of the ZnO/MWCNTs was analyzed using a scanning electron microscope and energy dispersive x ray. The Hall effect measurement shows p-type characteristics of the MWCNTs, supporting the typical PN junction formation with n-type ZnO nanocrystals. The electron-donating ability of ZnO provided a strong response to the ppm levels of toluene at room temperature (25 °C) and showed strong selectivity with other volatile organic compound gases such as benzene, methane, and formaldehyde.

47 OTHER INSTRUMENTATION↗

DOE OSTI2025

Versatile & Intelligent Biodetection via Environmental Sensing (VIBES)

Reactive health monitoring strategies during events like the COVID-19 pandemic highlighted the need for predictive, threat-agnostic diagnostics that can detect both known diseases and novel chemical or biological threats. To address this, we investigated an optical biosensor as a breath volatile organic compound (VOC) analyzer, aiming to emulate biological olfaction. We assembled and validated the device with thin film metal coated substrate-based sensors. We immobilized small biological recognition elements on the substrates and delivered controlled concentrations of target VOCs. The sensor was irradiated with a visible laser and the sensor signal was recorded. We characterized the laser performance and tested 3 recognition elements for 2 VOCs with varying concentrations (1-100 ppm). We also evaluated enhancement of the signal using nanostructures on the metal film in comparison with planar film substrate. We demonstrated detecting ethanol reliably at concentrations as low as ~2 ppm along with preliminary detection of acetone (<100 ppm). We also found several unexpected factors that influence the sensor behavior that should be addressed to further refine the device’s performance. The nanostructures were, as expected, found to amplify the sensor signals. These findings demonstrate the feasibility of the optical bio-sensing modality for breath VOC monitoring at physiologically relevant levels. This positions LLNL to develop a low-cost, scalable, broad-spectrum health monitoring capability aligned with the Early Detection thrust of the Bioresilience Mission Focus Area and attract external funding.

47 OTHER INSTRUMENTATION↗

DOE OSTI2022

Intrahost SARS-CoV-2 k-mer Identification Method (iSKIM) for Rapid Detection of Mutations of Concern Reveals Emergence of Global Mutation Patterns

Despite unprecedented global sequencing and surveillance of SARS-CoV-2, timely identification of the emergence and spread of novel variants of concern (VoCs) remains a challenge. Several million raw genome sequencing runs are now publicly available. We sought to survey these datasets for intrahost variation to study emerging mutations of concern. We developed iSKIM (“intrahost SARS-CoV-2 k-mer identification method”) to relatively quickly and efficiently screen the many SARS-CoV-2 datasets to identify intrahost mutations belonging to lineages of concern. Certain mutations surged in frequency as intrahost minor variants just prior to, or while lineages of concern arose. The Spike N501Y change common to several VoCs was found as a minor variant in 834 samples as early as October 2020. This coincides with the timing of the first detected samples with this mutation in the Alpha/B.1.1.7 and Beta/B.1.351 lineages. Using iSKIM, we also found that Spike L452R was detected as an intrahost minor variant as early as September 2020, prior to the observed rise of the Epsilon/B.1.429/B.1.427 lineages in late 2020. iSKIM rapidly screens for mutations of interest in raw data, prior to genome assembly, and can be used to detect increases in intrahost variants, potentially providing an early indication of novel variant spread.

60 APPLIED LIFE SCIENCES↗

NASA NTRS2003

Environmentally Compatible Vapor-Phase Corrosion Inhibitor for Space Shuttle Hardware

USA-SRB Element is responsible for the assembly and refurbishment of the non-motor components of the SRB as part of Space Shuttle. Thrust Vector Control (TVC) frames structurally support components of the TVC system located in the aft skirt of the SRB. TVC frames are exposed to the seacoast environment after refurbishment and, also, to seawater immersion after splashdown, and during tow-back to CCAFS-Hangar AF refurbishment facilities. During refurbishment operations it was found that numerous TVC frames were experiencing internal corrosion and coating failures, both from salt air and seawater intrusions. Inspectors using borescopes would visually examine the internal cavities of the complicated aluminum alloy welded tubular structure. It was very difficult for inspectors to examine cavity corners and tubing intersections and particularly, to determine the extent of the corrosion and coating anomalies. Physical access to TVC frame internal cavities for corrosion removal and coating repair was virtually impossible, and an improved method using a Liquid (water based) Vapor-phase Corrosion Inhibitor (LVCI) for preventing initiation of new corrosion, and mitigating and/or stopping existing corrosion growth was recommended in lieu of hazardous paint solvents and high VOC / solvent based corrosion inhibitors. In addition, the borescopic inspection method used to detect corrosion, and/or coating anomalies had severe limitations because of part geometry, and an improved non-destructive inspection (NDI) method using Neutron Radiography (N-Ray) was also recommended.

Novak, Howard L.↗

NASA NTRS2021

Wilson Corners SWMU 001 2019-2020 Annual Long-Term Monitoring Report Kennedy Space Center, Florida

This report presents a summary of the long-term monitoring (LTM) activities that occurred in 2019 and 2020 at Wilson Corners, Solid Waste Management Unit 001, at the John F. Kennedy Space Center (KSC), Florida. The site is monitored under KSC’s Resource Conservation and Recovery Act Corrective Action Program. Adaptive site management is being utilized through ongoing assessment, design, and interim measures. This approach also meets the requirements of Chapter 62-780, Florida Administrative Code. The goal of LTM at this site is threefold: to determine groundwater flow characteristics, monitor the downgradient concentration trends, and monitor select locations internal to the groundwater plume. Every 5 years, upgradient and side-gradient monitoring wells are sampled to verify delineation. The last time this was performed was in 2015. Sampling of these wells in 2020 was replaced with the direct push technology investigations in October 2020 and April 2021. The activities presented in this report include three field events: (1) December 2019 -groundwater gauging of 38 monitoring wells and sampling of 36 monitoring wells; (2) May 2020 - groundwater sampling of 7 monitoring wells; and (3) December 2020 - groundwater gauging of 49 monitoring wells and sampling of 43 monitoring wells. During the December 2019 and May 2020 events, monitoring wells were sampled using passive diffusion bags and were analyzed for a “full list” of volatile organic compounds (VOCs), including Freon 113. During the December 2020 event, the low flow sampling method was used, and samples were analyzed for a “select list” of VOCs, including Freon 113. The following conclusions can be made based on the 2019 and 2020 LTM results: •In December 2019 and December 2020, groundwater flow for the site was generally to the west with the individual zones only varying by occasional northerly and southerly components. This is generally consistent with historical observations at the site. •The GCTL plume continues to extend both horizontally and vertically beyond our current monitoring well network. •The vertical extent of VOCs was historically generally delineated by monitoring wells screened greater than 48 feet bls. The results from the two vertical extent monitoring wells WILC-MW0078 and WILC-MW0130 that were sampled during the 2019 and 2020 LTM indicate that groundwater VOC concentrations in both wells were greater than the GCTL. •Freon 113 was not detected above GCTLs during the 2019 and 2020 LTM events. Based on groundwater sampling activities performed during this reporting period, including recent DPT groundwater sampling conducted for the implementation of an air sparge system, the following recommendations are provided: •Install 10 new monitoring wells, which will be sampled along with 49 existing monitoring wells, to assist with delineation of the low concentration plume. The wells are listed inTable 4-1, and the proposed locations are presented on Figures4 -1 through 4-5. (Figures 4-1, 4-2, 4-3, and 4-5 also show updated plumes and proposed performance monitoring well locations. This information will be discussed and presented under a separate cover.) •Modify the annual LTM sampling plan as presented inTable 4-1. •Sampling for future events at the site will be conducted using low flow pumping methods. The next annual LTM sampling event is currently planned for December 2021. Please note the 10 new monitoring wells will not be installed before this event but will be installed as part of the upcoming IM construction and will be sampled during baseline sampling, along with the 49 existing monitoring wells. Following this sampling event, it is recommended that the Annual LTM be combined with the performance monitoring under the IM implementation, and LTM be temporarily discontinued. Objectives of the 2021 LTM are to: (i) evaluate groundwater gradient and flow direction by collecting depth to water measurements from LTM wells; (ii) continue monitoring the peripheral VOC trends in the northern, southern, and western portions of the site by monitoring existing wells and installing and monitoring new wells as recommended; and (iii) monitor select internal plume wells.

Jennifer Lynn Joyal↗

NASA NTRS2001

Analysis of Volatile Organic Compounds in a Controlled Environment: Ethylene Gas Measurement Studies on Radish

Volatile organic compound(VOC), ethylene gas, was characterized and quantified by GC/FID. 20-50 ppb levels were detected during the growth stages of radish. SPME could be a good analytical tool for the purpose. Low temperature trapping method using dry ice/diethyl ether and liquid nitrogen bath was recommended for the sampling process for GC/PID and GC/MS analysis.

Kong, Suk Bin↗

NASA NTRS2015

Wilson Corners SWMU 001 2014 Annual Long Term Monitoring Report Kennedy Space Center, Florida

This document presents the findings of the 2014 Long Term Monitoring (LTM) that was completed at the Wilson Corners site, located at the National Aeronautics and Space Administration (NASA) John F. Kennedy Space Center (KSC), Florida. The goals of the 2014 annual LTM event were to evaluate the groundwater flow direction and gradient and to monitor the vertical and downgradient horizontal extent of the volatile organic compounds (VOCs) in groundwater at the site. The LTM activities consisted of an annual groundwater sampling event in December 2014, which included the collection of water levels from the LTM wells. During the annual groundwater sampling event, depth to groundwater was measured and VOC samples were collected using passive diffusion bags (PDBs) from 30 monitoring wells. In addition to the LTM sampling, additional assessment sampling was performed at the site using low-flow techniques based on previous LTM results and assessment activities. Assessment of monitoring well MW0052DD was performed by collecting VOC samples using low-flow techniques before and after purging 100 gallons from the well. Monitoring well MW0064 was sampled to supplement shallow VOC data north of Hot Spot 2 and east of Hot Spot 4. Monitoring well MW0089 was sampled due to its proximity to MW0090. MW0090 is screened in a deeper interval and had an unexpected detection of trichloroethene (TCE) during the 2013 LTM, which was corroborated during the March 2014 verification sampling. Monitoring well MW0130 was sampled to provide additional VOC data beneath the semi-confining clay layer in the Hot Spot 2 area.

Monitoring↗

DOE OSTI2019

Signaling from below: rodents select for deeper fruiting truffles with stronger volatile emissions

Many plant and fungal species use volatile organic compounds (VOCs) as chemical signals to convey information about the location or quality of their fruits or fruiting bodies to animal dispersers. Identifying the environmental factors and biotic interactions that shape fruit selection by animals is key to understanding the evolutionary processes that underpin chemical signaling. Using four Elaphomyces truffle species, we explored the role of fruiting depth, VOC emissions, and protein content in selection by five rodent species. We used stable isotope analysis of nitrogen (δ15N) in truffles to estimate fruiting depth, proton-transfer-reaction mass spectrometry to determine volatile emission composition, and nitrogen concentrations to calculate digestible protein of truffles. We coupled field surveys of truffle availability with truffle spore loads in rodent scat to determine selection by rodents. Despite presumably easier access to the shallow fruiting species, E. americanus (0.5-cm depth) and E. verruculosus (2.5-cm depth), most rodents selected for truffles fruiting deeper in the soil, E. macrosporus (4.1-cm depth) and E. bartlettii (5.0-cm depth). The deeper fruiting species had distinct VOC profiles and produced significantly higher quantities of odiferous compounds. Myodes gapperi (southern red-backed vole), a fungal specialist, also selected for truffles with high levels of digestible protein, E. verruculosus and E. macrosporus. Our results highlight the importance of chemical signals in truffle selection by rodents and suggest that VOCs are under strong selective pressures relative to protein rewards. Strong chemical signals likely allow detection of truffles deep within the soil and reduce foraging effort by rodents. Finally, for rodents that depend on fungi as a major food source, protein content may also be important in selecting truffles.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1996

Volatile organic compounds detected in the atmosphere of NASA's Biomass Production Chamber

Atmospheres of enclosed environments in which 20 m2 stands of wheat, potato, and lettuce were grown were characterized and quantified by gas chromatography-mass spectrometry. A large number (in excess of 90) of volatile organic compounds (VOCs) were identified in the chambers. Twenty eight VOC's were assumed to be of biogenic origin for these were not found in the chamber atmosphere when air samples were analyzed in the absence of plants. Some of the compounds found were unique to a single crop. For example, only 35% of the biogenic compounds detected in the wheat atmosphere were unique to wheat, while 36% were unique to potato and 26% were unique to lettuce. The number of compounds detected in the wheat (20 compounds) atmosphere was greater than that of potato (11) and lettuce (15) and concentration levels of biogenic and non-biogenic VOC's were similar.

NASA Discipline Number 61-20↗

DOE OSTI2025

TRACER-MAP_2022_volatile_organic_compounds_PTRMS

VOCs collected by quadrupole proton transfer reaction mass spectrometry for July-August 2022. A description of this instrument is included in the related publication. The location of the measurement is indicated by latitude and longitude coordinates; TRACER-MAP included time at the AMF site in La Porte and additional sites around Houston. Data below the minimum detection limit are not included here.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2022

Nafion Passivation of c-Si Surface and Edge for Electron Paramagnetic Resonance

Effective surface passivation of crystalline silicon (c-Si) surface by reducing the carrier recombination rate has led to modern c-Si solar cells with efficiencies > 25% in both laboratory and industrial settings. Typical mainstream surface passivation techniques include high-temperature silicon oxide (SiOx), amorphous silicon (a-Si:H), hydrogen-rich silicon nitride (SiNx), and aluminum oxide (Al2O3) [1]. They have demonstrated excellent surface recombination velocity of < 1 cm/s owing to both chemical passivation (via the hydrogen saturation of Si dangling bonds at the c-Si surface), and field-effect passivation (via the band bending from the fixed charge of the dielectric layers). Recently, several groups have studied solution-based organic materials for c-Si passivation, including bis(trifluoromethane)sulfonimide (TFSI), polystyrenesulfonate, and Nafion [2, 3] via spin or dip coating. All films were processed at ambient room temperature, and a high lifetime of 12 ms, as well as a low saturation current density (J0) of 16 fA/cm2, have been demonstrated using Nafion passivation [2]. However, despite the air instability, Nafion has several advantages when introduced to PV applications: (a) Wafer quality can be measured at high throughput after several process stages. (b) It is compatible with PL mapping, compared to HF liquid passivation which cannot be performed in room ambient. (c) Nafion process is fast and poses fewer constraints on process complexity, and cleanness, compared to Al2O3 and a-Si:H passivation. (d) Nafion is the ideal room temperature passivation, which can be applied onto a small fragment of a degraded module to investigate microscopic mechanisms when studying degradation mechanisms. Edge passivation is needed for advanced characterization tests such as Electron Paramagnetic Resonance (EPR), Electrically Detected Magnetic Resonance (EDMR), Deep Level Transient Spectroscopy (DLTS), local cell current-voltage (J-V), and Suns-Voc. In such cases, the laser-damaged minicell edges will obscure the true degradation mechanisms, and Nafion can effectively passivate them without causing further degradation through elevated-temperature processes. In this contribution, we show the passivation results of Nafion on bare nCz and compare it with a Al2O3 witness. We highlight the importance of edge pre-treatment before Nafion to achieve good passivation. We show that Nafion can reach decent passivation without undergoing high-temperature processes. We also explore the temperature dependency of Nafion through photoluminescence (PL) study and demonstrate the application of Nafion under cryogenic temperature (~6 K) through EPR. Our results reveal that Nafion can reduce surface and edge Si dangling bonds at low temperatures. Thus, it can be used as an effective room temperature passivation technique for advanced characterization methods.

c-Si↗

DOE OSTI2020

Chemical changes in thirdhand smoke associated with remediation using an ozone generator

Ozonation is a common remediation approach to eliminate odors from mold, tobacco and fire damage in buildings. Little information exists to: 1) assess its effectiveness; 2) provide guidance on operation conditions; and 3) identify potential risks associated with the presence of indoor ozone and ozonation byproducts. The goal of this study is to evaluate chemical changes in thirdhand smoke (THS) aerosols induced by high levels of ozone, in comparison with THS aerosols aged under similar conditions in the absence of ozone. Samples representing different stages of smoke aging in the absence of ozone, including freshly emitted secondhand smoke (SHS) and THS, were collected inside an 18-m 3 room-sized chamber over a period of 42 h after six cigarettes were consumed. The experiments involved collection and analysis of gas phase species including volatile organic compounds (VOCs), volatile carbonyls, semivolatile organic compounds (SVOCs), and particulate matter. VOC analysis was carried out by gas chromatography/mass spectrometry with a thermal desorption inlet (TD-GC/MS), and volatile carbonyls were analyzed by on-line derivatization with dinitrophenylhydrazine (DNPH), followed by liquid chromatography with UV/VIS detection. SVOCs were extracted from XAD-coated denuders and Teflon-coated fiberglass filters in the absence of ozone. In those extracts, tobacco-specific nitrosamines (TSNAs) and other SVOCs were analyzed by gas chromatography with positive chemical ionization-triple quadrupole mass spectrometric detection (GC/PCI-QQQ-MS), and polycyclic aromatic hydrocarbons (PAHs) were quantified by gas chromatography with ion trap mass spectrometric detection (GC/IT-MS) in selected ion monitoring mode. Particulate matter concentration was determined gravimetrically. In a second experiment, a 300 mg h -1 commercial ozone generator was operated during 1 h, one day after smoke was generated, to evaluate the remediation of THS by ozonation. VOCs and volatile carbonyls were analyzed before and after ozonation. Extracts from fabrics that were exposed in the chamber before and after ozonation as surrogates for indoor furnishings were analyzed by GC/IT-MS, and aerosol size distribution was studied with a scanning mobility particle sizer. Ozone concentration was measured with a photometric detector. An estimated 175 mg ozone reacted with THS after 1 h of treatment, corresponding to 58% of the total O 3 released during that period. Fabric-bound nicotine was depleted after ozonation, and the surface concentration of PAHs adsorbed to fabric specimens decreased by an order of magnitude due to reaction with ozone, reaching pre-smoking levels. These results suggest that ozonation has the potential to remove harmful THS chemicals from indoor surfaces. However, gas phase concentrations of volatile carbonyls, including formaldehyde, acetaldehyde and acetone were higher immediately after ozonation. Ultrafine particles (UFP, in most cases with size <60 nm) were a major ozonation byproduct. UFP number concentrations peaked shortly after ozonation ended, and remained at higher-than background levels for several hours. Based on these results, minimum re-entry times after ozone treatment were predicted for different indoor scenarios. Clearly defining re-entry times can serve as a practical measure to prevent acute exposures to ozone and harmful ozonation byproducts after treatment. This study evaluated potential benefits and risks associated with THS remediation using ozone, providing insights into this technology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS2016

Airborne In-Situ Measurements of Formaldehyde Over California: First Results from the Compact Formaldehyde Fluorescence Experiment (COFFEE) Instrument

Formaldehyde (HCHO) is one of the most abundant oxygenated volatile organic compounds (VOCs) in the atmosphere, playing a role multiple atmospheric processes. Measurements of HCHO can be used to help quantify convective transport, the abundance of VOCs, and ozone production in urban environments. The Compact Formaldehyde FluorescencE Experiment (COFFEE) instrument uses Non-Resonant Laser Induced Fluorescence (NR-LIF) to detect trace concentrations of HCHO as part of the Alpha Jet Atmospheric eXperiment (AJAX) payload. Developed at NASA GSFC, COFFEE is a small, low maintenance instrument with a sensitivity of 100 pptv and a quick response time (1 sec). The COFFEE instrument has been customized to fit in an external wing pod on the Alpha Jet aircraft based at NASA ARC. The instrument can operate over a broad range of altitudes, from boundary layer to lower stratosphere, making it well suited for the Alpha Jet, which can access altitudes from the surface up to 40,000 ft. Results of the first COFFEE science flights preformed over the California's Central Valley will be presented. Boundary layer measurements and vertical profiles in the tropospheric column will both be included. This region is of particular interest, due to its elevated levels of HCHO, revealed in satellite images, as well as its high ozone concentrations. In addition to HCHO, the AJAX payload includes measurements of atmospheric ozone, methane, and carbon dioxide. Formaldehyde is one of the few urban pollutants that can be measured from space. Plans to compare in-situ COFFEE data with satellite-based HCHO observations such as those from OMI (Aura) and OMPS (SuomiNPP) will also be presented.

ozone↗

NASA NTRS2016

Airborne In-Situ Measurements of Formaldehyde over California: First Results from the Compact Formaldehyde Fluorescence Experiment (COFFEE) Instrument

coffee↗

NASA NTRS2024

Launch Complex 39A, SWMU 008 2023 Long-Term Monitoring Report Kennedy Space Center, Florida

The 2023 Long-Term Monitoring (LTM) Report (LTMR) presents the annual and semi-annual groundwater monitoring results for Launch Complex 39A (LC39A), Solid Waste Management Unit (SWMU) 008, at Kennedy Space Center (KSC), Florida. The reporting period covered under this LTMR is from January to December 2023, and represents the first year of site-wide monitoring following Air Sparge (AS) system shutdown at the end of 2022. AS system operation at LC39A began operation in 2015. The AS system consisted of a total of 173 AS wells ranging in depth from 11 to 37 feet below land surface. The overall remedial objective for the AS Interim Measure was to actively decrease concentrations of COCs to less than their respective Florida Department of Environmental Protection Natural Attenuation Default Concentrations, so that LC39A can transition into an LTM program. This objective was achieved in 2022, with 2023 marking Year 1 of the LTM program to monitor the residual groundwater plume. VOC results indicate that COC concentrations have continued to decrease or stabilize, with no rebound observed since AS system shutdown. Vinyl chloride was the only COC detected above its GCTL, with the highest concentration detected at 8.0 μg/L. PFAS results detected 15 different PFAS compounds (out of 32 analyzed) between the six monitoring wells sampled. Two PFAS compounds, perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), currently have FDEP Provisional GCTLs of 70 nanograms per liter (ng/L). PFOS was detected in one of the six samples above the FDEP Provisional GCTL at a concentration of 200 ng/L. PFOA was not detected above the FDEP Provisional GCTL in any of the six samples. PFOS and PFOA also currently have United States Environmental Protection Agency (USEPA) Maximum Contaminant Levels (MCLs) of 4 ng/L. PFOS was detected in all six samples above the USEPA MCL. PFOA was detected in three of the six samples above the USEPA MCL. Three other PFAS compounds, perfluorohexanesulfonic acid (PFHxS), perfluoro-n-nonanoic acid (PFNA), and hexafluoropropylene oxide dimer acid (GenX), currently have USEPA MCLs of 10 ng/L. PFHxS, PFNA, and GenX were not detected at concentrations greater than their respective USEPA MCLs in any of the six wells. Additional PFAS sampling will occur as part of a PFAS Site Assessment to be conducted in the future. Based on Year 1 LC39A LTM results, recommendations for 2024 are to continue with the second year of LTM in 2024 with the same monitoring well network as Year 1 (18 wells). The three wells that were on a semi-annual schedule will transition to an annual schedule to align with the remaining wells. The next annual event is scheduled for May 2024. The three wells that were found to be inadvertently destroyed will be properly abandoned and a replacement well in the vicinity of former monitoring well 21ST-MW0030I will be installed. This new well will be added to the LTM sampling plan upon installation.

Deborah M. Wilson↗

NASA NTRSDate not supplied

Effects of Ambient Alcohol Levels on the Real-time Monitoring of the Atmosphere of the International Space Station

Effects of Ambient Alcohol Levels on the Real-time Monitoring of the Atmosphere of the International Space StationWilliam T. Wallace,1 Thomas F. Limero,1 Kenneth W. Clark,2 and Daniel B. Gazda31KBR, 2400 NASA Pkwy., Houston, TX 770582JES Tech, 16870 Royal Crest Dr., Houston, TX 770583NASA Lyndon B. Johnson Space Center, 2101 NASA Pkwy., Houston, TX 77058Monitoring of the spacecraft environment is required to ensure the safety of the crew and the health of the vehicle systems. For the ISS atmosphere, routine monitoring has been performed for many years by the Major Constituent Analyzer (MCA) and two Air Quality Monitors (AQMs), which, together, are used to monitor for trace (ppb) levels of 22 volatile organic compounds (VOCs). The target compounds measured by the AQMs include three types of chemicals: 1) those compounds that would be harmful to crew, 2) those compounds that have been detected regularly in archival samples, and 3) compounds that, while not necessarily harmful to crew health, could present problems for Environmental Control and Life Support Systems (ECLSS).In March 2019, following the docking of SpaceX-Demo1 (SpX-DM1), the on-board AQMs began to report extremely high levels of isopropyl alcohol (IPA). While elevated IPA is not abnormal following the docking of visiting vehicles (due to cleaning of the cargo prior to flight), the level measured by the AQM, and its continued presence following multiple days of scrubbing, caused concerns regarding the U.S. Water Recovery System. Following the departure of SpX-DM1, the IPA levels decreased to nominal levels, allowing the team to investigate the cause of the elevated measurements. Initially, based on the changes in the shape of the gas chromatograph (GC) traces in the IPA region during docked operations, it appeared that some unknown coeluting species was causing problems with quantification. However, with the docking of Northrup-Grumman-11 (NG-11), the elevated IPA concentrations returned, as well as the changes in GC traces. In contrast to the SpX-DM1 results, though, the AQM IPA results did not return to nominal levels following the departure of NG-11, suggesting that the changes could not be tied directly to the visiting vehicle.In this paper, we will discuss a number of potential causes for both the genuine (measured in archival samples) increases in IPA as well as the much higher levels measured by the AQM. Additionally, we will discuss methods being explored to decrease the potential for a reoccurrence in the future.

William T Wallace↗

DOE OSTI2022

Versatile soil gas concentration and isotope monitoring: optimization and integration of novel soil gas probes with online trace gas detection

Abstract. Gas concentrations and isotopic signatures can unveil microbial metabolisms and their responses to environmental changes in soil. Currently, few methods measure in situ soil trace gases such as the products of nitrogen and carbon cycling or volatile organic compounds (VOCs) that constrain microbial biochemical processes like nitrification, methanogenesis, respiration, and microbial communication. Versatile trace gas sampling systems that integrate soil probes with sensitive trace gas analyzers could fill this gap with in situ soil gas measurements that resolve spatial (centimeters) and temporal (minutes) patterns. We developed a system that integrates new porous and hydrophobic sintered polytetrafluoroethylene (sPTFE) diffusive soil gas probes that non-disruptively collect soil gas samples with a transfer system to direct gas from multiple probes to one or more central gas analyzer(s) such as laser and mass spectrometers. Here, we demonstrate the feasibility and versatility of this automated multiprobe system for soil gas measurements of isotopic ratios of nitrous oxide (δ18O, δ15N, and the 15N site preference of N2O), methane, carbon dioxide (δ13C), and VOCs. First, we used an inert silica matrix to challenge probe measurements under controlled gas conditions. By changing and controlling system flow parameters, including the probe flow rate, we optimized recovery of representative soil gas samples while reducing sampling artifacts on subsurface concentrations. Second, we used this system to provide a real-time window into the impact of environmental manipulation of irrigation and soil redox conditions on in situ N2O and VOC concentrations. Moreover, to reveal the dynamics in the stable isotope ratios of N2O (i.e., 14N14N16O, 14N15N16O, 15N14N16O, and 14N14N18O), we developed a new high-precision laser spectrometer with a reduced sample volume demand. Our integrated system – a tunable infrared laser direct absorption spectrometry (TILDAS) in parallel with Vocus proton transfer reaction mass spectrometry (PTR-MS), in line with sPTFE soil gas probes – successfully quantified isotopic signatures for N2O, CO2, and VOCs in real time as responses to changes in the dry–wetting cycle and redox conditions. Broadening the collection of trace gases that can be monitored in the subsurface is critical for monitoring biogeochemical cycles, ecosystem health, and management practices at scales relevant to the soil system.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS2002

Regulatory and Technical Issues Concerning the Detection and Treatment of NDMA-Contaminated Groundwater at NASA WSTF

The National Aeronautics and Space Administration (NASA) White Sands Test Facility (WSTF) was established in 1963 primarily to provide rocket engine testing services for several NASA programs. The groundwater underlying the site has been contaminated as a result of historical operations. Groundwater contaminants include several volatile organic compounds (VOCs) and two semi-volatile compounds: N-nitrosodimethylamine (NDMA) and N-nitrodimethylamine (DMN). This paper discusses some of the technical, analytical, regulatory, and health risk issues associated with the contaminant plume. The plume has moved approximately 2.5 miles downgradient of the facility industrial boundary, with evidence of continued migration. As a result, NASA has proposed a pump and treat system using air strippers and ultraviolet (UV) oxidation to stabilize future movement of the contaminant plume. The system has been designed to treat 1,076 gallons (4,073 liters) per minute, with provisions for future expansion. The UV oxidation process was selected to treat NDMA-contaminated groundwater based on successes at other NDMA-contaminated sites. Bench- and pilot-scale testing of WSTF groundwater confirmed the ability of UV oxidation to destroy NDMA and generated sufficient data to design the proposed full-scale treatment system. NDMA is acutely toxic and is a probable human carcinogen. EPA-recommended health risk criteria for the residential consumption of NDMA/DMN-contaminated groundwater was used to determine that a 1.0 x 10(exp -6) excess cancer risk corresponds to 1.7 parts per trillion (ppt). EPA analytical methods are unable to detect NDMA and DMN in the low ppt range. EPA's current Appendix IX analytical method used to screen for NDMA, Method 8270, can detect NDMA only at levels that are orders of magnitude greater than the recommended health risk level. Additionally, EPA Method 607, the most sensitive EPA approved method, has a detection limit of 150 ppt. This corresponds to an excess cancer risk of 9.0 x 10(exp -5), which exceeds the State of New Mexico's water quality standard of a cancer risk less than 1 x 10(exp -5). The treatment system has been engineered to treat contaminated groundwater to levels significantly below the New Mexico standard. However, the inability of EPA-approved analytical methods to detect NDMA and DMN at low ppt levels, and to provide verification of compliance with the 1 x 10(exp -5) cancer risk, introduces a notable risk to the long-term operation of the system. WSTF has been working with Southwest Research Institute to develop a non-EPA analytical method that can achieve a reporting limit of 1 ppt, which corresponds to an excess cancer risk of 7.6 x 10(exp -7). WSTF is currently developing a proposal to obtain approval from the New Mexico Environment Department (NMED) of this non-EPA method.

Wiebe, D. T.↗