James W. Butler

AMBIENT SULFATE MEASUREMENTS ON ALLEGHENY MOUNTAIN AND THE QUESTION OF ATMOSPHERIC SULFATE IN THE NORTHEASTERN UNITED STATES

An experimental study is described in which atmospheric aerosol measurements at Allegheny Mountain in southwestern Pennsylvania were used to search for interrelationships of SO/sub 4/(-), percentage SO/sub 2/-SO/sub 4/(-) conversion, meteorological properties, rainfall, visibility, light scattering, SO/sub 2/, aerosol mass, H(+), NO/sub 3/, various trace elements, and rainfall H(+) and SO/sub 4/(-). The selected woodland location is in the area of maximum SO/sub 4/(-) concentration in the northestern U.S. The results obtained show that aerosol H(+) and SO/sub 4/(-) were uniquely correlated with each other and with light scattering, that the light scattering was entirely attributable to SO/sub 4/(-), and that SO/sub 2/ is evidently not related to any other parameter. It is concluded that the SO/sub 4/(-) at Allegheny Mountain stemmed from transport, with or without SO/sub 2/ oxidation, from westward nonurban sources of some kind that were sources of very little else in the aerosol.

Artifact Formation of Sulfate, Nitrate, and Hydrogen Ion on Backup Filters: Allegheny Mountain Experiment

Artifact sulfate formation in ambient conditions on filters of several types was evaluated by comparison between upstream and downstream tandem filters and also by comparison between filters operated in parallel. Some evaluation of artifact H+ and NO3 − was also performed. The experimental site was a tower on the top of Allegheny Mountain in southwestern Pennsylvania. Artifact SO4 = on backup filters was observed to be directly related to filter alkalinity, relative humidity, and cumulative exposure to SO2 with the more alkaline types converting ≥ 10% of the SO2 to which they were exposed, even after very long exposure. On the quartz-fiber backup filters, which gave relatively little artifact, the artifact SO4 = and NO3 − precursors seem to have the same origin as the atmospheric SO2. Artifact H+ was also related to atmospheric SO2, though not clearly to artifact SO4 =; on a mole basis, H+ was a leading, if not the major, artifact species on quartz-fiber backup filters. However, the backup filter method g...

Hydrocarbon and Aldehyde Emissions From an Engine Fueled With Ethyl-t-Butyl Ether

Organic exhaust emissions (including formaldehyde) from a small-displacement, single-cylinder, spark-ignition engine fueled on either ethyl-t-butyl ether of 2,2,4-trimethylpentane show differences that are less than {plus minus}20 percent from the mean of repeat measurements for all non-fuel species except propylene. Such differences are within the data scatter observed upon repetitive measurements with a single fuel and should not be regarded as significant in these experiments. The factor of 3.5 reduction in propylene when the engine is fueled on ETBE is significant and can be rationalized based on the differences in the molecular structures of the two fuels. These preliminary results suggest that the nonfuel organic exhaust species emissions and total organic mass emissions from ETBE fuel are similar to those from a typical branched alkane to within the {plus minus}20% data uncertainty.

FTIR: fundamentals and applications in the analysis of dilute vehicle exhaust

FTIR spectroscopy has been shown to be a valuable tool in the analysis of complex gas phase mixtures, such a dilute vehicle exhaust. Regulated and non-regulated vehicle emissions have been routinely sampled and analyzed using prototype instrumentation developed in this laboratory, and in several other laboratories over the last decade. More recently, commercial versions of these FTIR analyzers have become available through several manufacturers. This paper reviews the data acquisition and processing techniques utilized by the FTIR analyzer developed in this laboratory. The statistical detection limits for 22 of the components analyzed by the system are presented. In addition, the linearity of the carbon monoxide (CO) analysis is demonstrated over several orders of magnitude. Experiments designed to study the effects of environmental parameters on the accuracy and the sensitivity of the system are also described.

Sulfate emissions from vehicles on the road

Experiments have been conducted to measure vehicle sulfate emissions, by vehicle type, at two tunnels on the Pennsylvania Turnpike. A satisfactory balance between estimated fuel sulfur consumption and observed emissions of sulfur compounds corrected for ambient-air contributions was obtained. This work started in 1974 before the introduction of catalyst-equipped automobiles and continued into 1976. The sulfate contributed by vehicles even in the tunnels was found to be generally modest relative to rural ambient sulfate levels. Average sulfate emission rates were found to be approximately 30 mg/km (50 mg/mi) from heavy-duty Diesel trucks, ..SO/sub 4//sup -2/ conversion of the vehicle emissions was 2%.

Methylcyclopentadienyl Manganese Tricarbonyl: Effect on Manganese Emissions from Vehicles on the Road

The paper describes some measurements of manganese concentrations and manganese emission rates, categorized as to vehicle type, from cars and trucks at two tunnels on the Pennsylvania Turnpike. These measurements were made during the period that methylcyclopentadienyl manganese tricarbonyl came into use as an alternative to organo-lead compounds for improving combustion in gasoline engines. /EI/

Acid Enhancement of Zinc and Lead Atomic Absorption Signals

We have been measuring atmospheric particulate Pb and Zn concentrations by atomic absorption. Samples are collected on membrane filters and dissolved in HNO3-HClO4 prior to comparison with aqueous standards, using an Instrumentation Laboratories model 153 dual beam dual channel atomic absorption spectrophotometer equipped with background correction, operating with a stoichiometric air-acetylene flame. The absorption lines are 217.0 nm for Pb and 213.9 nm for Zn.

Nitrate and Nitric Acid Emissions from Catalyst-Equipped Automotive Systems

Abstract We have performed experiments to assess nitrate and HNO3 emissions from the diluted exhaust of a dynamometer-mounted engine at simulated 60 mph speed and road load. The amount of nitrate and/or HNO3 found is very small, 0.0003 grams per mile at most, without a catalyst. There is evidence that even this small amount is spurious in part, that is, does not represent nitrate or HNO3 actually present in the exhaust. A noble-metal monolithic oxidation catalyst caused no perceptible increase in this figure. We conclude that catalyst-induced nitrate and HNO3 emissions are inconsequential at the conditions described.

FAST-RESPONSE ZIRCONIA SENSOR-BASED INSTRUMENT FOR MEASUREMENT OF THE AIR/FUEL RATIO OF COMBUSTION EXHAUST

A fast-response zirconia sensor-based instrument has been developed to measure the air/fuel ratio (A/F) of combustion exhaust. This instrument uses a reduced-pressure sampling system which improves instrument response time (due to faster diffusion at lower pressures) and eliminates the need for a heated sample line. The measured response time of the described instrument is 170 ms (0-90%) for a step-change in oxygen concentration. The prototype instrument is easily calibrated in less than 2 min, requiring only nitrogen and room air for calibration. A complete description of the instrument is given. Results of tests comparing the instrument accuracy to a chemical balance technique are given. Also, a comparison study was conducted with the prototype instrument and a conventional zirconia sensor-based A/F monitor (Lamdascan, Sensors, Inc., Ann Arbor, Michigan) with respect to accuracy and response time.