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

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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1996

Grazing-Activated Production of Dimethyl Sulfide (DMS) by two clones of Emiliania huxleyi

Emiliania huxleyi clones CCMP 370 and CCMP 373 produced similar amounts of dimethylsulfoniopropionate (DMSP) during axenic exponential growth, averaging 109 mM internal DMSP. Both clones had detectable DMSP lyase activity, as measured by production of dimethyl sulfide (DMS) during in vitro assays of crude cell preparations, but activities and conditions differed considerably between clones. Clone 373 had high activity; clone 370 had low activity and required chloride. For both strains, enzyme activity per cell was constant during exponential growth, but little DMS was produced by healthy cells. Rather, DMS production was activated when cells were subjected to physical or chemical stresses that caused cell lysis. We propose that DMSP lyase and DMSP are segregated within these cells and re-action only under conditions that result in cell stress or damage. Such activation occurs during microzooplankton grazing. When these clones were grazed by the dinoflagellate Oxyrrhis marina, DMS was produced; ungrazed cells, as well as those exposed to grazer exudates and associated bacteria, generated no DMS. Grazing of clone 373 produced much more DMS than grazing of clone 370, consistent with their relative in vitro DMSP lyase activities. DMS was only generated when cells were actually being grazed, indicating that ingested cells were responsible for the DMS formation. We suggest that even low levels of grazing can greatly accelerate DMS production.

Wolfe, Gordon V.↗
NASA NTRS1990

Two approaches to determining the sea-to-air flux of dimethyl sulfide - Satellite ocean color and a photochemical model with atmospheric measurements

The feasibility of using remotely sensed data to map the marine sources of a photoreactive trace gas was investigated by comparing satellite ocean color data with result of a photochemical model with atmospheric measurements of dimethyl sulfide (DMS). A mean DMS flux for a region in the tropical North Atlantic for October 1980 was derived, using an empirical relationship between DMS and chlorophyll a data obtained by the CZCS instrument, and was compared with the sea-to-air flux derived from a one-dimensional photochemical model that reproduces boundary layer concentrations of ozone, CO, NO, and hydrocarbons measured by an experimental vessel cruising at the same location and time. Results suggest that surface sensing of DMS sources is feasible but only in regions and seasons where phytoplankton pigment is a meaningful marker for biogenic emissions.

Thompson, Anne M.↗
NASA NTRS1993

Measurements of dimethyl sulfide and H2S over the western North Atlantic and the tropical Atlantic

Airborne measurements of DMS and H2S were made off the east coast of the United States and over the tropical Atlantic off Brazil. Samples were collected through a fluorinated ethylene propylene Teflon inlet manifold. Dimethyl sulfide (DMS) was preconcentrated onto gold wool and analyzed by gas chromatography/flame photometric detection. H2S was collected on AgNO3-impregnated filters and determined by fluorescence quenching. Use of a new scrubber material (cotton) to remove negative interference on DMS measurements was investigated. Comparison with a Na2CO3/Anakrom scrubber gave good overall agreement. Only under extreme conditions, e.g., on flight 9 (continental air mass, low humidity, high O3, and low DMS values) did Na2CO3 show noticeable loss of DMS compared to cotton. On most flights, especially in marine air masses with high humidity and relatively low O3, the results from both scrubbers agreed well with each other and with other instruments used during the intercalibration. Off the U.S. East Coast, DMS levels showed strong dependence on air mass origin with high values (up to 83 ppt) in marine tropical air masses and low values (10-20 ppt) in continental and polar air. Over the tropical Atlantic, DMS ranged over 20-100 ppt in the mixed layer. Nighttime values were a factor of 1.6-2.3 higher than daytime levels. DMS decreased with altitude to less than 1 ppt at 4000 m. H2S in the mixed layer off the U.S. East Coast ranged from 10 to 200 ppt. Significant influence from terrestrial and pollution sources was evident. H2S in air masses originating over the eastern seaboard was much higher than in continental polar air or over the remote tropical continents. In contrast, over the tropical Atlantic, concentrations were very low (5-10 ppt), typical of truly marine air. Night/day ratios were about 1.4. No significant geographical variability was seen in H2S levels over the tropical Atlantic. The correlation of atmospheric Rn-222 and H2S was significant, with both being higher off the U.S. East Coast than over the tropical Atlantic.

Andreae, T. W.↗
NASA NTRS1977

Collection and analysis of organic gases from natural ecosystems - Application to poultry manure

Combined gas chromatography-mass spectrometry was used to identify volatile compounds generated from chicken manure and collected in Poropak QS-Carbosieve B traps. Various alcohols, ketones, esters, and carboxylic acids together with dimethyl sulfide and dimethyl disulfide were detected when the wastes were incubated in an argon atmosphere. Significant amounts of dimethyl sulfide and dimethyl disulfide but few other compounds were found when the manure was incubated in air

Smith, M. S.↗
NASA NTRS1992

Emissions of biogenic sulfur gases from Alaskan tundra

Fluxes of the biogenic sulfur gases carbonyl sulfide (COS), dimethyl sulfide (DMS), methyl mercaptan (MeSH), and carbon disulfide (CS2) were determined for several freshwater and coastal marine tundra habitats using a dynamic enclosure method and gas chromatography. In the freshwater tundra sites, highest emissions, with a mean of 6.0 nmol/m(sup -2)H(sup -1) (1.5-10) occurred in the water-saturated wet meadow areas inhabited by grasses, sedges, and Sphagnum mosses. In the drier upland tundra sites, highest fluxes occurred in areas inhabited by mixed vegetation and labrador tea at 3.0 nmol/m(sup -2)h(sup -1) (0-8.3) and lowest fluxes were from lichen-dominated areas at 0.9 nmol/m(sup -2)h(sup -1). Sulfur emissions from a lake surface were also low at 0.8 nmol/m(sup -2)h(sup -1). Of the compounds measured, DMS was the dominant gas emitted from all of these sites. Sulfure emissions from the marine sites were up to 20-fold greater than fluxes in the freshwater habitats and were also dominated by DMS. Emissions of DMS were highest from intertidal soils inhabited by Carex subspathacea (150-250 nmol/m(sup -2)h(sup -1)). This Carex sp. was grazed thoroughly by geese and DMS fluxes doubled when goose feces were left within the flux chamber. Emissions were much lower from other types of vegetation which were more spatially dominant. Sulfure emissions from tundra were among the lowest reported in the literature. When emission data were extrapolated to include all tundra globally, the global flux of biogenic sulfur from this biome is 2-3 x 10(exp 8) g/yr. This represents less than 0.001 percent of the estimated annual global flux (approximately 50 Tg) of biogenic sulfur and less than 0.01 percent of the estimated terrestrial flux. The low emissions are attributed to the low availability of sulfate, certain hydrological characteristics of tundra, and the tendency for tundra to accumulate organic matter.

Hines, Mark E.↗
NASA NTRS1992

Gas exchange in wetlands: Controls and remote sensing

This project was directed toward the quantification of fluxes of gaseous biogenic sulfur compounds from freshwater wetlands. These compounds (primarily hydrogen sulfide (H2S), dimethyl sulfide (DMS), and carbonyl sulfide (OCS)) have been implicated in the regulation of planetary albedo by the formation of microscopic atmospheric aerosols when they oxidize, and the further role of these aerosols as cloud condensation nuclei (CCN). The role of continental sources and sinks for these compounds is poorly understood. The present study was undertaken to quantify the source and sink strength of high latitude wetlands, and to delineate factors that regulate this flux.

Hines, Mark E.↗
DOE OSTI2024

Contribution of Speciated Monoterpenes to Secondary Aerosol in the Eastern North Atlantic

Extension of laboratory results suggests that monoterpenes, a subset of marine biogenic volatile organic compounds, might play a competitive role in secondary aerosol formation in the remote marine atmosphere, where the oxidation of dimethyl sulfide has traditionally been thought to dominate. However, the current assessment of the role of monoterpenes in secondary aerosol formation in the remote marine atmosphere is limited by the scarcity of speciated monoterpene measurements and the complete absence of collocated measurements of particle chemical composition and monoterpene speciation. Here, in this paper, we present measurements of gas-phase volatile organic compounds, with particular focus on speciated monoterpenes, and commensurate measurements of aerosol chemical composition in the Eastern North Atlantic. The average monoterpene concentration in periods of marine air was 14 ± 10 ppt, and the dominant isomer was β-pinene (46 ± 10%), with other contributions from α-pinene, limonene, and β-ocimene. The total monoterpene concentration in marine air was greater than that of isoprene by a factor of 3.9 on average, in contrast to prior research and potentially due to the large β-pinene contribution. Monoterpenes were significantly smaller in concentration than dimethyl sulfide, which was also highlighted by the substantial contribution of sulfate to non-refractory submicron aerosol. The mean and interquartile range of the sulfate to organic aerosol mass ratio in clean marine air were 2.7 (0.7–3.4). Finally, a simple box model analysis showed that the BVOC precursors, dimethyl sulfide, methanethiol, monoterpenes, and isoprene, could sustain the measured sulfate to organic aerosol ratio in clean marine air.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1992

A preliminary study of the variability and magnitude of the flux of biogenic sulfur gases from a New Hampshire salt marsh

Salt marshes have highly variable spatial and temporal fluxes of hydrogen sulfide, carbonyl sulfide, methane thiol, dimethyl sulfide, and carbon disulfide (H2S, COS, MeSH, DMS, and CS2, respectively). This variability was tested at nine emission sites in a New Hampshire, USA salt marsh: three replicates in each of three vegetation zones, Spartina alterniflora, S. patens, and a transition zone. Three sites were sampled simultaneously, either within or across vegetation zones, using a dynamic flux chamber technique. Difficulties with calibration and field equipment resulted in fluxes with maximum absolute uncertainties of greater than plus or minus 200 percent. However, the relative uncertainty between subsequent samples was closer to plus or minus 20 percent. Chambers are expected to affect the natural flux of gases by altering the humidity, temperature, and composition of the gas inside the chamber. Summertime fluxes are highest for all gases except COS which demonstrated evidence of a springtime peak. A summertime background flux of 5 to 100 x 10(exp -9) g S/m(sup -2) min was observed for all gases, while S alternifora fluxes of MeSH and DMS were approximately 8 fold and approximately 100 fold higher than S. patens, respectively. DMS and MeSH fluxes were higher during the day than at night. Evidence of COS uptake by plants was observed. CS2 appeared to be the quantitatively least important sulfur gas emitted. Improved laboratory and sample collection techniques and further data collection in the field will yield information on the details of salt marsh variability, will improve estimates of the error associated with single flux measurements, and will allow a more accurate estimation of sulfur fluxes from salt marshes based on vegetation and area coverage data. Inability to control the temperature and humidity inside of the chamber remain significant problems with the chamber design.

Morrison, Michael Cope↗
NASA NTRS1985

Some thoughts on GAIA and the sulfur cycle

The data hypothesis states that the composition, oxidation reduction state, and temperature of the troposphere are actively regulated by the biota for the biota. One of the early predictions of the Gaia hypothesis was that there should be a sulfur compound made by the biota in the oceans. It would need to be stable enough against oxidation in water to allow its transfer to the air. Either the sulfur compound itself or its atmospheric oxidation product would have to return sulfur from the sea to the land surfaces. The most likely candidate for this role was dimethyl sulfide. Another sulfur compound of interest from a Gaian viewpoint CS2 (carbon disulfide) is discussed. Theories on the production of dimethyl sulfide and carbon disulfide related to the Gaian hypothesis are examined.

Lovelock, J. E.↗
DOE OSTI2023

Uptake behavior of arsenic and selenium with sulfur-based extraction chromatography resins in HCl and HNO 3 media

Here, the uptake behavior of 73 As and 75 Se was studied in HCl and HNO3 media with CL resin, ethanethiol resin and dimethyl sulfide resin. In HCl solutions, there was high extraction of selenium on CL resin and ethanethiol resin but lower uptake on dimethyl sulfide resin; arsenic was only extracted by CL resin. From HNO 3 , selenium was extracted only by ethanethiol resin and CL resin and there was no uptake of arsenic on any resin. While the sulfur-based resins have high selenium uptake and selectivity, column separations are challenging due to the chemical instability of these resins.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS2003

Emissions of Trace Gases and Particles from Savanna Fires in Southern Africa

Airborne measurements made on initial smoke from 10 savanna fires in southern Africa provide quantitative data on emissions of 50 gaseous and particulate species, including carbon dioxide, carbon monoxide, sulfur dioxide, nitrogen oxides, methane, ammonia, dimethyl sulfide, nonmethane organic compounds, halocarbons, gaseous organic acids, aerosol ionic components, carbonaceous aerosols, and condensation nuclei (CN). Measurements of several of the gaseous species by gas chromatography and Fourier transform infrared spectroscopy are compared. Emission ratios and emission factors are given for eight species that have not been reported previously for biomass burning of savanna in southern Africa (namely, dimethyl sulfide, methyl nitrate, five hydrocarbons, and particles with diameters from 0.1 to 3 microns). The emission factor that we measured for ammonia is lower by a factor of 4, and the emission factors for formaldehyde, hydrogen cyanide, and CN are greater by factors of about 3, 20, and 3 - 15, respectively, than previously reported values. The new emission factors are used to estimate annual emissions of these species from savanna fires in Africa and worldwide.

Sinha, Parikhit↗
NASA NTRS1997

Global Troposphere Experiment Project

For the Global Troposphere Experiment project Pacific Exploratory Measurements West B (PEM West B), we made determinations of sulfur dioxide (SO2) and dimethyl sulfide (DMS) using gas chromatography-mass spectrometry with isotopically labelled internal standards. This technique provides measurements with precision of 1 part-per-trillion by volume below 20 pptv and 1% above 20 pptv. Measurement of DMS and SO2 were performed with a time cycle of 5-6 minutes with intermittent zero checks. The detection limits were about 1 pptv for SO2 and 2 pptv for DMS. Over 700 measurements of each compound were made in flight. Volcanic impacts on the upper troposphere were again found as a result of deep convection in the tropics. Extensive emission of SO2 from the Pacific Rim land masses were primarily observed in the lower well-mixed part of the boundary layer but also in the upper part of the boundary layer. Analyses of the SO2 data with aerosol sulfate, beryllium-7, and lead-210 indicated that SO2, contributed to half or more of the observed total oxidized sulfur (SO2 plus aerosol sulfate) in free tropospheric air. Cloud processing and rain appeared to be responsible for lower SO2 levels between 3 and 8.5 km than above or below this region. During both phases of PEM-West, dimethyl sulfide did not appear to be a major source of sulfur dioxide in the upper free troposphere over the western Pacific Ocean. In 1991 the sources Of SO2 at high altitude appeared to be both anthropogenic and volcanic with an estimated 1% being solely from DMS. The primary difference for the increase in the DMS source was the very low concentration of SO2 at high altitude. In the midlatitude region near the Asian land masses, DMS in the mixed layer was lower than in the tropical region of the western Pacific. Convective cloud systems near volcanoes in the tropical convergence in the western Pacific troposphere were a major source of SO2 at high altitudes during PEM-West B. High levels of SO2 were observed in several instances with large number concentrations of ultrafine CN above 9 km in the tropical convergence zone. Conversion of SO2, by OH to SO3 and subsequently to sulfuric acid may have been enhanced by lightning-produced NO levels exceeding 1 part per billion. Coupling of strong convection and volcanic sources of SO2 apparently is an important source of new particle formation at high altitude in the tropical convergence zone.

Bandy, Alan R.↗