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At least 1,495 records · Page 83
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Concentration Variations in Particulate Matter in Seoul Associated with Asian Dust and Smog Episodes

In this study, particulate species were measured in April–May 2003 at two sites, one in the megacity of Seoul and the other in the Deokjeok Island to the west of Seoul, to examine the effects of long-range transport under the influence of prevailing westerlies. The effects of Asian dust were observed in April, and a severe smog episode occurred in late May. During May, all air pollutants showed negative correlations with wind speed at Seoul, particularly for NO 2 and CO, a large proportion of which result from vehicle emissions. SO 4 2– continued to increase in association with an inflow of air pollutants from China with heavy use of coal, with fluctuations depending on wind speed. The smog episode in late May occurred as emissions from Siberian forest fires were superimposed on pollutant inflows from China that had persisted since early May and local emissions accumulated under stagnant conditions. During the episode, Siberian forest fires increased K + while local emissions primarily from vehicles increased NO 3 – , OC, and EC. The effects of an inflow of air pollutants from the outside were significant at Deokjeok, with small local emissions, resulting in substantial increases in Ca 2+ during the Asian dust event and SO 4 2– during the smog episode, compared to those at Seoul. Because both sites were strongly influenced by the effects of long-range transport in May, PM 2.5 along with SO 4 2– and K + exhibited a strong correlation between Seoul and Deokjeok.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Impact of isoprene and HONO chemistry on ozone and OVOC formation in a semirural South Korean forest

Rapid urbanization and economic development in East Asia in past decades has led to photochemical air pollution problems such as excess photochemical ozone and aerosol formation. Asian megacities such as Seoul, Tokyo, Shanghai, Guangzhou, and Beijing are surrounded by densely forested areas, and recent research has consistently demonstrated the importance of biogenic volatile organic compounds (VOCs) from vegetation in determining oxidation capacity in the suburban Asian megacity regions. Uncertainties in constraining tropospheric oxidation capacity, dominated by hydroxyl radical, undermine our ability to assess regional photochemical air pollution problems. We present an observational data set of CO, NO x , SO 2 , ozone, HONO, and VOCs (anthropogenic and biogenic) from Taehwa research forest (TRF) near the Seoul metropolitan area in early June 2012. The data show that TRF is influenced both by aged pollution and fresh biogenic volatile organic compound emissions. With the data set, we diagnose HO x (OH, HO 2 , and RO 2 ) distributions calculated using the University of Washington chemical box model (UWCM v2.1) with near-explicit VOC oxidation mechanisms from MCM v3.2 (Master Chemical Mechanism). Uncertainty from unconstrained HONO sources and radical recycling processes highlighted in recent studies is examined using multiple model simulations with different model constraints. The results suggest that (1) different model simulation scenarios cause systematic differences in HO x distributions, especially OH levels (up to 2.5 times), and (2) radical destruction (HO 2 + HO 2 or HO 2 + RO 2 ) could be more efficient than radical recycling (RO 2 + NO), especially in the afternoon. Implications of the uncertainties in radical chemistry are discussed with respect to ozone–VOC–NO x sensitivity and VOC oxidation product formation rates. Overall, the NO x limited regime is assessed except for the morning hours (8 a.m. to 12 p.m. local standard time), but the degree of sensitivity can significantly vary depending on the model scenarios. The model results also suggest that RO 2 levels are positively correlated with oxygenated VOCs (OVOCs) production that is not routinely constrained by observations. These unconstrained OVOCs can cause higher-than-expected OH loss rates (missing OH reactivity) and secondary organic aerosol formation. The series of modeling experiments constrained by observations strongly urge observational constraint of the radical pool to enable precise understanding of regional photochemical pollution problems in the East Asian megacity region.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Aerosol-induced changes in the vertical structure of precipitation: a perspective of TRMM precipitation radar

Our knowledge is still poor regarding the response of the precipitation vertical structure to aerosols, partly due to the ignorance of precipitation occurring at different spatial scales. A total of 6 years of collocated ground-based PM 10 and satellite-based (Tropical Rainfall Measuring Mission, TRMM) radar data, along with ERA-Interim reanalysis, are used in this study to investigate the aerosol effects on three localized rain regimes (shallow, stratiform, and convective rain) over the Pearl River Delta region of China. A subjective analysis method is proposed to discriminate between the localized and synoptic-scale precipitations based on weather composite charts where daily averaged wind field at 850 hPa is overlaid with the geopotential height at 500 hPa. In general, average rain rate tends to be greater under polluted conditions than under clean conditions. But such potential aerosol effects are regime dependent: as the atmosphere becomes slightly polluted (PM 10 ≤38 µg m -3 ), the top 1 % radar reflectivity (Z) for all regimes initially increases, followed by continued increases and weak decreases for convective and stratiform/shallow rain regimes, respectively. As the atmosphere becomes much more polluted, such regime dependences of aerosol effects are more significant. From a perspective of the vertical Z structure, comparisons between polluted conditions (days with the highest third of PM 10 concentration) and clean conditions (days with the lowest third of PM 10 concentration) show that the convective rain regime exhibits a deeper and stronger Z pattern, whereas a much shallower and weaker Z pattern is observed for stratiform and shallow precipitation regimes. In particular, the top height of the 30 dBZ rain echo increases by ~29 % (~1.27 km) for the convective regime, but decreases by ~10.8 % (~0.47 km) for the stratiform regime. However, no noticeable changes are observed for the shallow precipitation regime. Impacts of meteorological factors are further studied on both rain top height (RTH) and the center of gravity of Z, including vertical velocity, vertical wind shear, convection available potential energy, and vertically integrated moisture flux divergence (MFD). The possible invigoration effect on convective precipitation seems dependent on wind shear, in good agreement with previous findings. Overall, the observed dependence of the precipitation vertical structure on ground-based PM 10 supports the notion of aerosol invigoration or suppression effect on cold or warm rain and adds new insights into the nature of the complex interactions between aerosol and various localized precipitation regimes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Process-based and observation-constrained SOA simulations in China: the role of semivolatile and intermediate-volatility organic compounds and OH levels

Organic aerosol (OA) is a major component of tropospheric submicron aerosol that contributes to air pollution and causes adverse effects on human health. Chemical transport models have difficulties in reproducing the variability in OA concentrations in polluted areas, hindering understanding of the OA budget and sources. Herein, we apply both process-based and observation-constrained schemes to simulate OA in GEOS-Chem. Comprehensive data sets of surface OA, OA components, secondary organic aerosol (SOA) precursors, and oxidants were used for model–observation comparisons. The base models generally underestimate the SOA concentrations in China. In the revised schemes, updates were made on the emissions, volatility distributions, and SOA yields of semivolatile and intermediate-volatility organic compounds (SVOCs and IVOCs) and additional nitrous acid sources. With all the model improvements, both the process-based and observation-constrained SOA schemes can reproduce the observed mass concentrations of SOA and show spatial and seasonal consistency with each other. Our best model simulations suggest that anthropogenic SVOCs and IVOCs are the dominant source of SOA, with a contribution of over 50% in most of China, which should be considered for pollution mitigation in the future. The residential sector may be the predominant source of SVOCs and IVOCs in winter, despite large uncertainty remaining in the emissions of IVOCs from the residential sector in northern China. The industry sector is also an important source of IVOCs, especially in summer. More SVOC and IVOC measurements are needed to constrain their emissions. Besides, the results highlight the sensitivity of SOA to hydroxyl radical (OH) levels in winter in polluted environments. The addition of nitrous acid sources can lead to over 30% greater SOA mass concentrations in winter in northern China. It is important to have good OH simulations in air quality models.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

The diurnal susceptibility of subtropical clouds to aerosols

The diurnal susceptibility of clouds and their radiative properties to aerosols is examined during their Lagrangian transition from subtropical stratocumulus to shallow cumulus regimes. Using large-eddy simulations, we analyze the six-day evolution of an air mass along a 3800 km observed trajectory from the coast of Peru toward the equator. Pristine and polluted scenarios are simulated with forcing imposed from weather reanalysis. The polluted scenario exhibits stronger diurnal variations in cloud water, cloud fraction, and albedo, with enhanced nighttime entrainment and suppressed precipitation. The overall response of cloud properties and outgoing shortwave radiation to droplet number concentration follows a distinct diurnal pattern: strong positive cloud adjustments dominate at night and in the morning, while weak negative adjustments prevail in the afternoon. This cycle is driven by the competition between precipitation suppression, which enhances cloud water and coverage, and entrainment drying, which depletes them. In polluted conditions, enhanced entrainment leads to a deeper and more decoupled boundary layer that cannot be sustained by surface fluxes in the afternoon, resulting in negative cloud adjustments. The enhanced entrainment rate under polluted conditions is caused by the reduced sedimentation of cloud and precipitation water from the entrainment zone. While the Twomey effect dominates the diurnal average albedo response, the diurnal variation in the competing cloud adjustments lead to a near-neutral net susceptibility in the afternoon, highlighting the critical role of diurnally varying processes in aerosol-cloud interactions.

Geosciences↗
DOE OSTI2014

Impact of isoprene and HONO chemistry on ozone and OVOC formation in a semirural South Korean forest

Rapid urbanization and economic development in East Asia in past decades has led to photochemical air pollution problems such as excess photochemical ozone and aerosol formation. Asian megacities such as Seoul, Tokyo, Shanghai, Gangzhou, and Beijing are surrounded by densely forested areas and recent research has consistently demonstrated the importance of biogenic volatile organic compounds from vegetation in determining oxidation capacity in the suburban Asian megacity regions. Uncertainties in constraining tropospheric oxidation capacity, dominated by hydroxyl radical concentrations, undermine our ability to assess regional photochemical air pollution problems. We present an observational dataset of CO, NOX, SO2, ozone, HONO, and VOCs (anthropogenic and biogenic) from Taehwa Research Forest (TRF) near the Seoul Metropolitan Area (SMA) in early June 2012. The data show that TRF is influenced both by aged pollution and fresh BVOC emissions. With the dataset, we diagnose HOx (OH, HO2, and RO2) distributions calculated with the University of Washington Chemical Box Model (UWCM v 2.1). Uncertainty from unconstrained HONO sources and radical recycling processes highlighted in recent studies is examined using multiple model simulations with different model constraints. The results suggest that 1) different model simulation scenarios cause systematic differences in HOX distributions especially OH levels (up to 2.5 times) and 2) radical destruction (HO2+HO2 or HO2+RO2) could be more efficient than radical recycling (HO2+NO) especially in the afternoon. Implications of the uncertainties in radical chemistry are discussed with respect to ozone-VOC-NOX sensitivity and oxidation product formation rates. Overall, the VOC limited regime in ozone photochemistry is predicted but the degree of sensitivity can significantly vary depending on the model scenarios. The model results also suggest that RO2 levels are positively correlated with OVOCs production that is not routinely constrained by observations. These unconstrained OVOCs can cause higher than expected OH loss rates (missing OH reactivity) and secondary organic aerosol formation. The series of modeling experiments constrained by observations strongly urge observational constraint of the radical pool to enable precise understanding of regional photochemical pollution problems in the East Asian megacity region.

Kim, Saewung↗
DOE OSTI2018

Long-term evaluation of air sensor technology under ambient conditions in Denver, Colorado

Air pollution sensors are quickly proliferating for use in a wide variety of applications, with a low price point that supports use in high-density networks, citizen science, and individual consumer use. This emerging technology motivates the assessment under real-world conditions, including varying pollution levels and environmental conditions. A seven-month, systematic field evaluation of low-cost air pollution sensors was performed in Denver, Colorado, over 2015–2016; the location was chosen to evaluate the sensors in a high-altitude, cool, and dry climate. A suite of particulate matter (PM), ozone (O 3 ), and nitrogen dioxide (NO 2 ) sensors were deployed in triplicate and were collocated with federal equivalent method (FEM) monitors at an urban regulatory site. Sensors were evaluated for their data completeness, correlation with reference monitors, and ability to reproduce trends in pollution data, such as daily concentration values and wind-direction patterns. Most sensors showed high data completeness when dataloggers were functioning properly. The sensors displayed a range of correlations with reference instruments, from poor to very high (e.g., hourly-average PM Pearson correlations with reference measurements varied from 0.01 to 0.86). Some sensors showed a change in response to laboratory audits/testing from before the sampling campaign to afterwards, such as Aeroqual, where the O 3 response slope changed from about 1.2 to 0.6. Some PM sensors measured wind-direction and time-of-day trends similar to those measured by reference monitors, while others did not. This study showed different results for sensor performance than previous studies performed by the U.S. EPA and others, which could be due to different geographic location, meteorology, and aerosol properties. These results imply that continued field testing is necessary to understand emerging air sensing technology.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1970

Thermodynamics of the internal combustion engine

The ubiquitous automobile has played both the role of hero and villain during the course of its history. At the present time it is being cast as the villain with increasing frequency because it has been indicted as a major source of air pollution. It is just this characterization that is responsible for our renewed interest in the automobile. When we speak of the automobile as a source of air pollution, we really mean the heart of the automobile, the internal combustion engine. The prototype of the modern internal combustion engine was first successfully operated by Nicholas August Otto in 1876. In spite of its long history, the internal combustion engine is still poorly understood in terms of the details of the physical processes that take place during its operations. The internal combustion engine operates on what is known as the Otto cycle, and Otto cycle calculations have been with us for many years. The emphasis in earlier calculations was usually on the performance rather than on the pollution aspects. Performance characteristics can often be estimated reasonably accurately even with a considerable degree of simplification. We are interested in the pollution aspects of the internal combustion engine, and therefore the calculations must be performed with more care. Our extensive experience with equilibrium calculations places us in a position to carry out such careful calculations. We have just recently begun such an analysis, and its objective is the prediction of exhaust gas properties. I will describe our progress by first reviewing the Otto cycle, and then I will illustrate the effect of various assumptions on the calculated results.

Frank J. Zeleznik↗
NASA NTRS1971

Final Environmental Impact Statement for Langley

The Langley Research Center is described, together with the nature of its activities, from which it can be seen that the Center is basically not a major pollution source. Geographical, geological, and climatic charateristics of the site are also described. inasmuch as they influence both the choice of disposal methods and the environmental effects of the pollutants. The known or probable pollution sources at the Center are described. Where the intensities of these sources might exceed the recommended guide-lines, the corrective actions that have been taken or are being taken are described. The entire inventory of pollution sources and control methods is summarized in an appendix.

Source record↗
NASA NTRS1973

Environment Surveys

The applications of ERTS-1 in the investigation of environmental quality and pollution are reviewed. Problem areas discussed are: (1) air pollution; (2) water pollution; (3) land pollution; and (4) aesthetics.

Walter, L. S.↗
NASA NTRS1974

The experimental clean combustor program: Description and status

The objectives, program plan, schedule, pollution and performance goals, program approaches to pollution reduction, and status of the project are presented. Advanced supersonic transport and combustion noise programs are also discussed. The phases of the program consist of the following: (1) screening of low pollutant combustors, (2) refinement of the best combustors, and (3) engine demonstration of the best combustors. It is stated that all combustor designs investigated appear capable of achieving the idle pollutant goals with additional development effort.

Niedzwiecki, R. W.↗
NASA NTRS1973

Investigation of the environmental change pattern of Japan

The author has identified the following significant results. ERTS-1 imagery clearly identifies the relationships between the status of erosion, effluent patterns affected by the coastal current, and the cultural construction activities. Simple photographic techniques can be used for detecting water mass distribution separately from cloud cover and also noise caused by reflected sunlight from wave surfaces. Polluted water does not diffuse continuously into the oceanic water, but forms masses in the water in the Kuroshio area. The polluted or turbid water in the area just north of the Tomogashima Channel, the south outlet of the Osaka Bay, shows that the northward tidal current runs in a clockwise eddy at the tidal period when the imagery was taken. Such an eddy-like pattern of tidal current had never been revealed by conventional oceanographic data. A front between an oceanic water mass and a polluted water mass runs in a NW-SE direction in the central part of the Osaka Bay. The patterns of turbid water discharged from the Kii River and Yoshino River show a northward tidal current in the North Kii Straits. The pattern of lighter turbid or polluted water located in the northwest region of the North Kii straits suggests the existence of a clockwise eddy in the straits.

Maruyasu, T.↗
NASA NTRS1975

The experimental clean combustor program: Description and status to November 1975

The generation of technology was studied for the development of advanced commercial CTOL aircraft engines with lower exhaust emissions than current aircraft. The program is in three phases. Phase 1, already completed, consisted of screening tests of low pollution combustor concepts. Phase 2, currently in progress, consists of test rig refinement of the most promising combustor concepts. Phase 2 test results are reported. Phase 3, also currently in progress, consists of incorporating and evaluating the best combustors as part of a complete engine. Engine test plans and pollution sampling techniques are described in this report. Program pollution goals, specified at engine idle and take-off conditions, are idle emission index value of 20 and 4 for carbon monoxide (CO) and total unburned hydrocarbons (THC), respectively, and at take-off are an oxides of nitrogen (NOx) emission index level of 10 and a smoke number of 15. Pollution data were obtained at all engine operating conditions. Results are presented in terms of emission index and also in terms of the Environmental Protection Agency's 1979 Standards Parameter.

Niedzwiecki, R. W.↗
NASA NTRS1975

Application of thermal scanning to the study of transverse mixing in rivers

Remote sensing has shown itself to be a valuable research tool in the study of transverse mixing in rivers. It is desirable, for a number of reasons, to study and predict the two-dimensional movement of pollutants in the region just downstream of a pollutant discharge point. While many of the more common pollutants do not exhibit a spectral signature, it was shown that the temperature difference between the pollutant and the receiving water could be successfully exploited by applying a mathematical model of mass transport processes to heat transport, and testing and calibrating it with thermal scanning data.

Eheart, J. W.↗
NASA NTRS1992

Water quality modeling using geographic information system (GIS) data

Protection of the environment and natural resources at the Kennedy Space Center (KSC) is of great concern. The potential for surface and ground water quality problems resulting from non-point sources of pollution was examined using models. Since spatial variation of parameters required was important, geographic information systems (GIS) and their data were used. The potential for groundwater contamination was examined using the SEEPAGE (System for Early Evaluation of the Pollution Potential of Agricultural Groundwater Environments) model. A watershed near the VAB was selected to examine potential for surface water pollution and erosion using the AGNPS (Agricultural Non-Point Source Pollution) model.

Engel, Bernard A↗
NASA NTRS1994

CFD assessment of the carbon monoxide and nitric oxide formation from RD-170 hot-fire testing at MSFC

Computational Fluid Dynamics (CFD) technology has been used to assess the exhaust plume pollutant environment of the RD-170 engine hot-firing on the F1 Test Stand at Marshall Space Flight Center. Researchers know that rocket engine hot-firing has the potential for forming thermal nitric oxides (NOx), as well as producing carbon monoxide (CO) when hydrocarbon fuels are used. Because of the complicated physics involved, however, little attempt has been made to predict the pollutant emissions from ground-based engine testing, except for simplified methods which can grossly underpredict and/or overpredict the pollutant formations in a test environment. The objective of this work, therefore, has been to develop a technology using CFD to describe the underlying pollutant emission physics from ground-based rocket engine testing. This resultant technology is based on a three-dimensional, viscous flow, pressure-based CFD formulation, where wet CO and thermal NOx finite-rate chemistry mechanisms are solved with a Penalty function method.

Wang, Ten-See↗
NASA NTRS2000

Toxicological Assessment of the International Space Station Atmosphere

Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on the standards that define acceptable air quality, measurements of pollutant levels during the flight, and reports from the crew on their in-flight perceptions of air quality. Air samples from ISS flight 2A showed that contaminants in the Zarya module were at higher concentrations than the Unity module. At the crew's first entry, the amount of non-methane volatile organic compounds (NMVOCs) in Zarya was 23 Mg/cubic meter, whereas in the amount of NMVOCs in Unity was 5.3 mg/cubic meter. Approximately 26 hours later at egress from the modules, the NMVOCs were comparable indicating good mixing of the atmospheres. The 2A crew reported no adverse health effects related to air pollution during their flight. Ingress air samples from 2A.1, which was flown more than 5 months after 2A, again showed that the Zarya had accumulated more unscrubbed pollutants than Unity. The NMVOCs in Unity were 3.5 mg/cubic meter, whereas the were 20 mg/cubic meter in Zarya. After almost 80 hours of ISS operations, the NMVOCs were 7.5 and 12 mg/cubic meter in Unity and Zarya, respectively. This suggests that the atmospheres in the modules were not mixing very well. The 2A.1 crew felt that the air quality in Zarya deteriorated when they were working in a group at close quarters, when the panels had been removed, and after they had worked in an area for some time. The weight of evidence suggests that human metabolic products (carbon dioxide, water vapor, heat) were not being effectively removed from the crew's work area, and these caused their symptoms. Additional local measurements of pollutants are planned for the 2A.2 mission to the ISS.

James, John T.↗
NASA NTRS1996

Compositional Evolution of Saturn's Ring: Ice, Tholin, and 'CHIRON'-Dust

We address compositional evolution in planetary ring systems subsequent to meteoroid bombardment. The huge surface area to mass ratio of planetary rings ensures the importance of this process, given currently expected values of meteoroid flux. We developed a model which includes both direct deposition of extrinsic meteoritic 'pollutants', and ballistic transport of the increasingly polluted ring material as impact ejecta. Certain aspects of the observed regional variations in ring color and albedo can be understood in terms of such a process. We conclude that the regional scale color and albedo differences between the C ring and B ring can be understood if all ring material began with the same composition (primarily water ice, based on other data, but colored by tiny amounts of non-icy, reddish absorber) and then evolved entirely by addition and mixing of extrinsic, neutrally colored, highly absorbing material. This conclusion is readily extended to the Cassini Division and its surroundings as well. Typical silicates are unable to satisfy the ring color, spectroscopic, and microwave absorption constraints either as intrinsic or extrinsic non-icy constituents. However, 'Titan Tholin' provides a satisfactory match for the inferred refractive indices of the 'pre-pollution' nonicy ring material. The extrinsic bombarding material is compatible with the properties of Halley or Chiron, but not with the properties of other 'red' primitive objects such as Pholus. We further demonstrate that the detailed radial profile of color across the abrupt B ring - C ring boundary is quite compatible with such a 'pollution transport' process, and that the shape of the profile can constrain key parameters in the model. We use the model to estimate the 'exposure age' of Saturn's rings to extrinsic meteoroid flux. We obtain a geologically young 'age' which is compatible with timescales estimated independently based on the evolution of ring structure due to ballistic transport, and also with other 'short timescales' estimated on the grounds of gravitational torques.

Cuzzi, Jeffrey N.↗