Temporal variation of particle scattering coefficients at Brookhaven National Laboratory,New York

Real-time measurements of scattering coefficients of particles in the atmospheric boundary layer were continuously measured during 1975 and 1976 at a height of 106 m at Brookhaven National Laboratory. Long Island, New York to study their variations with meteorological parameters and in relation to upwind source regions. Short and long time scales of fluctuations, frequency distributions, stagnation periods, and effects on incoming solar radiation were investigated. Results indicate seasonal dependence and variations due to the upwind location of sources.     

An analysis of particulate sulfur and lead gradient data collected at Argonne National Laboratory

Two automatic aerosol particle samplers were operated at heights of 11.5 and 34.5 m on the meteorological tower at Argonne National Laboratory (about 40 km southwest of Chicago) during the summer of 1976. Data obtained during one week of intensive study permit evaluation of the horizontal transport of both particulate sulfur and lead; sulfur was found to be associated with south-westerly flow, while lead appeared to originate in Chicago. By combining measurements of particle concentration gradients with wind and temperature gradients, deposition velocities of particulate sulfur have been computed for a range of atmospheric conditions. The resulting evaluations show a strong dependence on atmospheric stability and on wind speed. Although larger than values normally associated with particulate sulfur, the deposition velocities, averaging about 1.4cm s⁻¹, compare favorably with both the momentum transfer velocity and some recently reported results obtained by application of eddy correlation methods.     

New and Improved Procedures for Gas Sampling and Analysis in the National Air Sampling Network

The NASN sampler for the collection of gaseous pollutants has been modified to increase its versatility and efficiency. Oxides of nitrogen are collected in bubblers employing a 70-100 μ frit with a collection efficiency of approximately 50% depending upon the frit porosity. Included in the sampler is a bubbler for the collection of aldehydes in which the aldehyde-MBTH complex is stable at least two weeks. This inert bubbler, which is constructed of polypropylene and Teflon, makes it possible for samples to be collected over the network and analyzed at a central laboratory. In addition, gaseous ammonia is collected in 0.1N H₂SO₄. This collecting system has an efficiency of greater than 85%. Low-level samples are analyzed automatically employing Nesslerization, whereas high-level samples from source emissions may be collected in indicating boric acid and titrated with 0.02N H₂SO₄. The sampler will accommodate either 50 or 100 ml polypropylene collecting tubes.     

Sampling atmospheric pesticides with SPME: Laboratory developments and field study

To estimate the atmospheric exposure of the greenhouse workers to pesticides, solid phase microextraction (SPME) was used under non-equilibrium conditions. Using Fick's law of diffusion, the concentrations of pesticides in the greenhouse can be calculated using pre-determined sampling rates (SRs). Thus the sampling rates (SRs) of two modes of SPME in the lab and in the field were determined and compared. The SRs for six pesticides in the lab were 20.4-48.3 mL min⁻¹ for the exposed fiber and 0.166-0.929 mL min⁻¹ for the retracted fiber. In field sampling, two pesticides, dichlorvos and cyprodinil were detected with exposed SPME. SR with exposed SPME for dichlorvos in the field (32.4 mL min^-1) was consistent with that in the lab (34.5 mL min^-1). SR for dichlorvos in the field (32.4 mL min⁻¹) was consistent with that in the lab (34.5 mL min⁻¹). The trends of temporal concentration and the inhalation exposure were also obtained.     

国家标准环境监测实验室建设的思考

围绕环境监测现代化建设目标，提出了实现实验室标准化管理的必要性，阐述了实验室认可的发展及认可的内容，探讨了创建标准化实验室实施的要点。     

Gas and Particle Emissions from Automobile Tires in Laboratory and Field Studies

This paper is directed to air pollution scientists interested in special mobile emission sources. The purpose was to determine the contribution which automobile tires make to air pollution. The gaseous hydrocarbon and sulfur compounds emitted in laboratory tests were identified. Although these hydrocarbons can participate in smog reactions, their mass emission rate is less than 0.1 % of the current exhaust hydrocarbon emission rate. Hydrocarbons from tires are not measurable near a freeway. The particulate emitted from tires ranges in size from 0.01 μm to more than 30 μm, with the larger particles dominating the total mass. Measurements along a California freeway showed that most of the tire debris had settled within 5 m of the pavement edge. Airborne rubber concentrations were less than 0.5 μg/m³, or less than 5% of the total tire wear. These field measurements confirm the indoor emission pattern and verify that tire wear products are not a significant air pollution problem.     

Planning and Conducting Sampling Surveys of Hazardous Wastes at Industrial Facilities

Many organizations and their consultants are involved in sampling programs to characterize waste streams and materials at industrial facilities. Due to financial limitations, calendar deadlines, or other practical restrictions, a short-term, survey-type sampling plan (“sampling survey”) may need to he implemented. Survey results can he used to determine if the wastes are hazardous or if they are being managed in accordance with applicable regulations. This paper brings together practical experience and diverse information to identify the major concerns in conducting sampling surveys and to suggest methods of approaching these concerns. The paper addresses sampling in time and space, “correct” sampling to minimize bias, selecting equipment to minimize contamination, sample handling, and quality assurance/quality control. Even a quick sampling survey can be a high quality effort with a careful approach to the critical issues.     

Sampling at controlled relative humidity with a cascade impactor

The design and function of a device that regulates the relative humidity of an ambient aerosol sample is described. We use this RH controller upstream of MOUDI impactors to permit sampling at relative humidities in the 70–80% range. Humidity control is achieved by allowing the aerosol to approach equilibrium with a saturated salt solution. Benefits to sampling with impactors in this relative humidity range include greatly reduced bounce of fine, hygroscopic particles, minimal flow-induced sizing errors, and minimization of uncertainties in measured size distributions due to diurnal variations in relative humidity during sampling. Data from field measurements in a humid environment (Look Rock, TN) and arid environments (Las Vegas, NV and Meadview, AZ) are discussed.     

A Rainfall Simulator for Laboratory Use in Acidic Precipitation Studies

A rainfall simulator, developed on the principle of droplet formation from needle tips, is described. The simulator is designed for laboratory experimentation to examine the effects of acidic precipitation on terrestrial plants. Droplet diameter can be varied from 2.5 to 3.4 mm with different gauge needles, and rainfall intensities from 0.50 to 1.25 cm h^-1 can be attained by a variable speed peristaltic pump. Uniform distribution of rainfall was achieved by rotating the target area and by spacing needles, using an empirical cumulative probability distribution function, along eight radial tubular arms. Variation in rainfall distribution across a 1.2 m diameter circular target area was < 5 % . Integrity of solution chemistry was maintained upon passage through the simulator with variations in cation concentrations <10%, anion concentrations <5 % and pH <0.2. The system offers sufficient flexibility to simulate a range of rainfall characteristics by varying needle diameter, changing pump speed and/or altering the number of radial arms on each unit.     

A Method for Checking Instrument Performance at Remote Sampling Sites

This paper describes a quality control technique used by the central headquarters operation of the Continuous Air Monitoring Program in an ejjort to insure valid data production from instruments located at remote sampling stations.

The procedure consists of preparation of 0.10 to 2.00 ppm mixtures of SO₂ or NO₂ in duplicate Mylar bags, each encased in a corrugated paper box.

These mixtures are analyzed during make-up to insure duplication. One box is shipped to the field station where it is analyzed on-site. The control mixture is analyzed in the central lab at the same time. Correlation between measurements indicates the usefulness of this dynamic calibration check.

The techniques used are described and results of the program are presented.     

A Movable Laboratory for Controlled Clinical Studies of Air Pollution Exposure

The cause of the Yokkaichi asthma episode (1960-1969) has been analyzed. It Is concluded that the respiratory diseases were due not to sulfur dioxide but to concentrated sulfuric acid mists emitted from stacks of calciners of a titanium oxide manufacturing plant located windward of the residential area.     

Laboratory Scale Thermal Plasma Arc Vitrification Studies of Heavy Metal-Laden Waste

Abstract

Plasma processing has been identified as a useful tool for immobilizing heavy metal-contaminated wastes into safe, leach-resistant slag. Although much effort has gone into developing this technology on a pilot scale, not much information has been published on basic research topics. A laboratory-scale plasma arc furnace located at the University of Illinois was operated in cooperation with the U.S. Army Construction Engineering Research Laboratories in an effort to establish an understanding of the chemical and physical processes (such as metal volatilization and resultant gas evolution) that occur during thermal plasma treatment of metal-spiked samples. Experiments were conducted on nickel and chromium using a highly instrumented furnace equipped with a 75 kW transferred arc plasma torch. The volatility of nickel and chromium was examined as a function of varying oxygen partial pressures. Oxidizing conditions reduced the total dust gathered for both the nickel and chromium samples, although each dust sample was found to be metal-enriched. Plasma treating increased the leach-resistance of the slags by at least one order of magnitude when compared to unprocessed specimens. The leach- resistance of the nickel-containing slags increased in the presence of oxygen, whereas chromium samples remained relatively constant.     

Current Research on Aerosols at Pacific Northwest Laboratory1

Construction of a new bridge span over San Francisco Bay in the summer of 1967 made feasible for the first time continuous measurement of oxidant levels at a mid-bay site. Hypotheses of higher or lower oxidant levels over a central body of water in an urban complex could thus be evaluated. No significant bay effect, positive or negative, was found in the mean data, but analysis on a case basis showed that conditions favoring adverse oxidant development over the region favored even higher levels over the bay itself. Patterns of oxidant concentration reinforced by the mid-bay data show a broadly distributed community air pollution level, and they support the mixing of oxidant precursors from area-wide sources so that the bay and the surrounding land are equally involved as sites for the photochemical process of oxidant formation.     

Laboratory Wind Tunnel and Model Studies to Improve Gas Velocity Distribution in Cottrell Precipitators

Corrosion of flue gas desulfurization (FGD) scrubbing equipment is one of several critical problems facing both the power industry operating these units and the engineering firms that have to select materials of construction for the specific processes. The various processes and the status of flue-gas desulfurization technology were discussed at the 68th annual meeting of the Air Pollution Control Association.¹     

A Laboratory Method for the Simulation of Automobile Exhaust and Studies of Catalyst Poisoning

The expected use of catalytic converters on automobiles to meet the legislated automotive emission standards makes desirable a laboratory method that permits realistic testing of these catalysts. Such a method should be versatile enough to simulate a wide range of conditions which are applicable for catalysts designed to oxidize hydrocarbons and carbon monoxide, or to reduce nitric oxide, as the case may be. For this purpose, we have modified a pulse-flame combustor, based on a design by Meguerian. The output of this simulator very closely resembles engine exhaust with respect to composition, space velocity, and contaminants. The durability of a monolithic or pelleted catalyst can be evaluated by long term exposure to the simulated exhaust and by periodic measurement of the catalyst activity as a function of temperature. The apparatus and the range of conditions that can be achieved are described in detail. Poisoning of a Pt catalyst by fuels containing low concentrations of lead was studied with this exhaust simulator and compared with results obtained in engine dynamometer tests; a satisfactory correlation of catalyst deterioration was established.     

Dispersion modeling to compare alternative technologies for odor remediation at swine facilities

The effectiveness of 18 alternative technologies for reducing odor dispersion at and beyond the boundary of swine facilities was assessed in conjunction with an initiative sponsored through agreements between the Attorney General of North Carolina and Smithfield Foods, Premium Standard Farms, and Frontline Farmers. The trajectory and spatial distribution of odor emitted at each facility were modeled at 200 and 400 m downwind from each site under two meteorological conditions (daytime and nighttime) using a Eulerian-Lagrangian model. To predict the dispersion of odor downwind, the geographical area containing the odorant sources at each facility was partitioned into 10-m2 grids on the basis of satellite photographs and architectural drawings. Relative odorant concentrations were assigned to each grid point on the basis of intensity measurements made by the trained odor panel at each facility using a 9-point rating scale. The results of the modeling indicated that odor did not extend significantly beyond 400 m downwind of any of the test sites during the daytime when the layer of air above the earth's surface is usually turbulent. However, modeling indicated that odor from all full-scale farms extended beyond 400 m onto neighboring property in the evenings when deep surface cooling through long-wave radiation to space produces a stable (nocturnal) boundary layer. The results also indicated that swine housing, independent of waste management type, plays a significant role in odor downwind, as do odor sources of moderate to moderately high intensity that emanate from a large surface area such as a lagoon. Human odor assessments were utilized for modeling rather than instrument measurements of volatile organic compounds (VOCs), hydrogen sulfide, ammonia, or particulates less than 10 microm in diameter (PM10) because these physical measurements obtained simultaneously with human panel ratings were not found to accurately predict human odor intensity in the field.