Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

and discusses the issues and research needs for improving the methodology of modeling human exposures to mobile source emissions.
NTIS
Carbon Monoxide; Concentration (Composition); Atmospheric Composition; Air Pollution; Pollution Monitoring; Air Quality
20000063514 Environmental Protection Agency, National Exposure Research Lab., Research Triangle Park, NC USA
Characterization of Emissions from Handheld Two-Stroke Engines
Gabele, P. A.; 2000; 16p; In English
Report No.(s): PB2000-105753; EPA/600/A-00/012; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche
Results reported in this paper were obtained using a facility that shares exhaust emission sampling and analytical systems
with an adjacent automotive emissions test laboratory with an adjacent automotive emissions test laboratory. This enabled a comprehensive
examination of emissions from three hand-held, two stroke, engines. In addition to the determination of routine regulated
pollutant emission rates, organic emissions are speciated and particulate matter emission rates are measured. Each engine
was tested using two fuels: 1990 Baseline Gasoline and a reformulated gasoline. One engine was run for an extended period to
assess durability effects on exhaust emissions, and another was operated at a leaner air-fuel ratio setting to examine enleanment
effects.
NTIS
Exhaust Emission; Variable Cycle Engines
20000063519 Georgia Inst. of Tech., School of Earth and Atmospheric Sciences, Atlanta, GA USA
Modeling and Data Analysis of SONEX Observations
Liu, Shaw C., Georgia Inst. of Tech., USA; [1997]; 3p; In English
Contract(s)/Grant(s): NAG2-1103; No Copyright; Avail: CASI; A01, Hardcopy; A01, Microfiche
Primary focus of the study is on the sources, photochemistry and transport of reactive nitrogen species, O3, as well as other
O3 precursors such as NMHC and CO. Major objectives are: (1) Identify the major sources of NO(x) and quantify the contribution
of each source to the NO(x) distribution in the free troposphere, particularly in the upper troposphere. (2) Understand the odd
hydrogen photochemistry and the recycling of NO(x) in the free troposphere. (3) Evaluate the photochemical production and
destruction of O3. A combination of modeling and data analysis/interpretation approach is used. We use a three-dimensional
model and a box model to simulate, analyze, and interpret the observations. Both models are needed because they are complementary
and each has its advantages and limitations. Proven analytical techniques, including correlation of NOx with various tracers
and with different air masses, are applied to both observations and model results to deduce useful information toward accomplishing
the objectives. In addition, the SONEX observations are compared and analyzed in a systematic way against other airborne
experiments conducted over remote atmosphere, especially those from NASA GTE experiments, AASE 1 and 2, and SUCCESS.
Author
Data Processing; Models; Nitrogen Oxides; Troposphere; Hydrogen; Photochemical Reactions
20000064548 Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA USA
Monitoring of Volcanogenic CO2-Induced Tree Kills with AVIRIS Image Data at Mammoth Mountain, California
Hausback, Brian P., California State Univ., USA; Strong, Mel, California State Univ., USA; Farrar, Chris, Geological Survey,
USA; Pieri, David, Jet Propulsion Lab., California Inst. of Tech., USA; Summaries of the Seventh JPL Airborne Earth Science
Workshop January 12-16, 1998; Dec. 19, 1998; Volume 1, pp. 221-222; In English; See also 20000064520; No Copyright; Abstract
Only; Available from CASI only as part of the entire parent document
Elevated cold CO2 emissions from the flank of Mammoth Mountain volcano on the southwest rim of the Long Valley Caldera,
eastern California, have been the cause of over 100 acres of dead trees in that area since 1990. The source of the CO2 gas is thought
to be from one or more magmatic intrusion(s) beneath Mammoth Mountain and is probably related to a period of seismic unrest
that began in 1989. The gas rises to the surface probably from depths of a few kilometers, along faults and fracture zones. The
gas is at ambient temperature and diffuses from the soil rather than discharging from distinct vents. Typically, soil gas concentrations
in tree-kill areas range from 10% to over 90% CO2 by volume, as compared to normal background of is less than 1% in
healthy forest. The gas composition is predominantly CO2 mixed with air (sulfur gases are not elevated), and C and He isotopic
ratios are consistent with a magmatic origin for the gas. The total CO2 emission has been estimated at 1200 tons/day, comparable
to the emissions at Kilauea. Some of the dead trees are as old as 250 years, suggesting that similar anomalous gas discharge has
not occurred over the previous few hundred years. The delta C-13/12 ratio in the Mammoth Mountain CO2 emission averages
about -4.5 (PDB standard). This is consistent with a mantle source for the carbon. However, the large volume of the emission suggests
that not all of the CO2 is necessarily being generated from the 1989 intrusion. The voluminous gas could be leaking from
125