Weekday-Weekend Pollutant Studies of the Los Angeles Basin

Pollutant data from the Los Angeles Basin were analyzed for weekday-weekend differences for the smog months of June through September 1972 and 1973. The pollutants investigated were oxidant, NO, NO₂, total hydrocarbons (HC), CO, and particulates. In order to maintain the diurnal variation, the concentration percentiles were calculated for each weekday and weekend hour.     

Turbulent Plume in a Turbulent Cross Flow: Comparison of Wind Tunnel Tests with Field Observations

Plume rise downwind of a large stationary gas turbine was measured in the field and the conditions were then scaled in the laboratory. For the laboratory, the plume exit conditions, wind velocity and temperature profiles, and wind direction were matched. It was found that for high temperature exhaust, the buoyancy is best matched by calculating a dimensionless density difference. With properly calculated buoyancy length scales, the plume trajectories were compared and were found to agree quite well. The probability distributions of the entrainment constant and the average values of the entrapment constant with downwind distance were compared. The field data showed about 15% greater plume rise. The median entrainment constant was about 10% greater for the lab test and the shape of the probability distribution matched very closely.     

Studies on the Effects of Saline Aerosols of Cooling Tower Origin on Plants

A research program was undertaken to develop information that could be used to estimate the risk of adverse effects of saline cooling tower drift on native and cultivated flora in the Indian Point, New York area. Eleven species of woody plants were exposed at 85 % relative humidity to a saline mist with 95% of the particles between 50 and 150 nm in diameter. Three biological factors—stage of development, species, and phenotype—determined the susceptibility of plants to saline aerosols when the occurrence of any lesion on the foliage was used as a measure of response. The effects of stage of development on the incidence and severity of foliar lesions depended upon the kind of plant. In deciduous woody species, the youngest leaves were most susceptible, but in conifers, the year-old needles were most susceptible. Canadian hemlock was the most susceptible species and witch hazel was the least susceptible. Median effective doses for these two species, although undetermined, could be more than 100-fold different (less than 2.4, the lowest used, and greater than 264 ng CI cm^-2, respectively). Other species, ranked in decreasing order of susceptibility were: white ash, white flowering dogwood, forsythia, chestnut oak, silk tree, black locust, red maple, eastern white pine, and golden rain free. Phenofypic variation within a species was not so great—within a 10 to 20-fold increase in dose the incidence of injury went from 0 to 100%. Exposures with bush bean showed that the relative humidity (RH) during or after the exposure period affected the incidence of saline induced foliar injury. A change from 50 to 85% RH doubled the effectiveness of the saline mist. It was also found that compared to particles between 50 and 150 jum in diameter, an increase in the fraction of particles above 150 /xm increased the toxicity of the mist.     

Effect of Oxidizing and Reducing Conditions on the Reaction of Water with Sulfur Bearing Blast Furnace Slags

The evolution of H₂S and SO₂ from hot blast furnace slags by reaction with H₂O has been found to be dependent upon the presence of O₂ or H₂ in the reaction zone as well as on the temperature. H₂ has been found to produce a small increase in H₂S and a small decrease in SO₂ emission, while O₂ has been found to produce a very great inhibiting effect on H₂S emission and only a small increase in SO₂ emission. The total emission of sulfur bearing gases is much less when H₂O + air is blown at the slag than when H₂O + Ar is blown at the slag, particularly at 1200°C and above. These effects may be useful in attempts to design systems for slag quenching which will produce less pollution.     

A Microprocessor-Based Air Quality Monitoring System

Portable air quality monitoring systems may be required to supplement fixed installations or to provide for quick response to a transient situation, possibly at a remote location. A microprocessor-based monitoring unit has been developed for use with existing sensors. The unit is portable and its operational sequence can be programmed to adapt it to any unique requirements existing at the deployment site. Selectable on-site calculations are performed on raw data, and a hard copy or tape record of results can be produced.     

Results of Field Measurements of Industrial Particulate Sources and Electrostatic Precipitator Performance

This paper presents results of source size distribution measurements over the size range from 0.1 μm to 5 μm for six classes of particulate sources and fractional efficiency measurements on five full scale electrostatic precipitators and one pilot scale precipitator. The precipitators all showed moderately high to high particulate collection efficiencies for particles having diameters larger than a few micrometers or smaller than a few hundredths of a micrometer and a minimum in collection efficiency for particles having diameters of a few tenths of a micrometer.     

Some Recent Experience with Fabric Filters for Paniculate Collection

EPA's “Third Symposium on Fabric Filters for Particle Collection,” held in Tucson December 5 and 6, 1977, emphasized the results obtained from both laboratory and field experience. Data from selected new and/or continuing research programs as well as from new pilot and field applications are reviewed.