Speciation of Arsenic in Ambient Aerosols Collected in Los Angeles

First-time measurements of the potentially toxic inorganic species of arsenic (arsenite arid arsenate) have been obtained in fine (<2.5 µm AD) and coarse (>2.5 µm AD) atmospheric particles in the Los Angeles area. A recently developed method that includes procedures for sample collection, preparation, and analysis was used in this study. Size-fractlonated aerosol samples were collected with a high-volume dichotomous virtual impactor that employed polytetrafluoroethylene filters. Results were obtained for the recovery of arsenic standards added to unexposed and collected filters. Data from this study, indicated that the recently developed speciation method can be used to determine concentrations of As(lll) and As(V) In atmospheric particulate matter samples.

Size-fractionated aerosol samples were collected in the city of Industry during January and February 1987. In most samples, As(lll) and As( V) were above the detection limit (approximately 1 ng m^-3 of either species) in both aerosol size fractions. A greater portion (about 75 percent) of the two species were observed in the fine particles. The As(lll)/As(V) ratio for both particle sizes was close to 1 (I.e., an equal mixture of both species). Comparison of total suspended particulate arsenic measured by the speciation method to that measured by a routine California Air Resources Board-approved procedure showed good agreement (r = 0.94), indicating both methods were approximately equivalent for the collection and analysis of aerosol arsenic.     

Pulmonary Function Changes Associated with an Air Pollution Episode in January 1987

In January 1987, an air pollution episode occurred In central and western Europe. Levels of SO₂, NO₂, black smoke, sulphates and other components were elevated, with 24 hour average concentrations of SO₂ reaching a maximum of close to 300 μg/m3 In an area In the southeast of the Netherlands. Pulmonary function was measured In a group of children of 6- 12 years old at the end of the episode, and also two and three and a half weeks after the episode. A baseline lung function value was obtained about three months before the episode. Pulmonary function growth between baseline and retest dates was estimated from a simple growth model which was validated using measured pulmonary function growth data from a longitudinal study. A decline of pulmonary function (FVC, FEV₁ and PEF) from predicted baseline levels was observed, starting on the last day of the episode. Two weeks after the episode, FVC, FEV₁ PEF and MMEF were all decreased, and three and a half weeks after the episode, there was still a deficit compared to predicted baseline levels for FVC and FEV₁     

Regional Photochemical Measurement and Modeling Studies: A Summary of the Air & Waste Management Association International Specialty Conference

Abstract

This paper summarizes the Air & Waste Management Association’s International Specialty Conference, "Regional Photochemical Measurement and Modeling Studies," held in San Diego, California, on November 8-12,1993. The purpose of the conference was to facilitate exchange of information and to initiate better communication and interaction among scientists, air quality managers, regulators, and others involved in or applying tools (models and measurements to support the modeling efforts) that can be used to develop equitable and effective emissions management practices for attainment of ozone standards. Attendees heard more than 350 presentations from authors representing nearly 30 air quality and meteorological measurement and modeling studies from 18 countries. While the primary emphasis of the conference was technical, two policy sessions were included (Plenary and Concluding Sessions) to place the technical results in perspective with the policy issues. The technical agenda was divided into three subjects: Analysis of Field Measurements (results and interpretation), Modeling (status and results), and Other Topics. Papers presented at the conference are being published in a variety of journals or books to meet the needs of the scientific and policy communities. A complete bibliographical listing of the papers presented at the conference is included with this paper.

An unexpected outcome of the conference has been the development of an initiative for continuing the intercomparison of goals and scientific findings from regional air quality studies in Europe and North America, entitled “Regional Oxidants Programs Intercomparison” (ROxPIn). This paper will also discuss the goals and objectives of ROxPIn.     

Development of Cleanup Standards at Superfund Sites: An Evaluation of Consistency

The Washington Department of Ecology (WDOE) recently developed a regulatory program for determining cleanup standards at hazardous waste sites. One of WDOE's first tasks in the development of a cleanup standards program was to evaluate how standards have been developed and implemented under Superfund.

The evaluation of cleanup standards revealed: (1) a great deal of variation among sites, both in the magnitude of the standards set for some contaminants and the basis on which they were set, and (2) that there is no consistent decision-making approach for determining how standards should be set. This lack of consistency and guidance has the potential to result in overly stringent or underprotective cleanup requirements and inefficient standard development.

Washington State has adopted an approach that allows for implementing uniform numerical cleanup standards at relatively straightforward sites and provides a process for establishing site-specific cleanup levels at more complex sites. This approach is expected to facilitate development of standards that offer appropriate human health and ecological protection while minimizing private and public sector site management and cleanup costs.     

Carbon Monoxide Exposures Inside an Automobile Traveling on an Urban Arterial Highway

Carbon monoxide (CO) exposures were measured inside a motor vehicle during 88 standardized drives on a major urban arterial highway, El Camino Real (traffic volume of 30,500-45,000 vehicles per day), over a 13-1/2 month period. On each trip (lasting between 31 and 61 minutes), the test vehicle drove the same 5.9-mile segment of roadway in both directions, for a total of 11.8 miles, passing through 20 intersections with traffic lights (10 in each direction) in three California cities (Menlo Park, Palo Alto, and Los Altos). Earlier tests showed that the test vehicle was free of CO intrusion. For the 88 trips, the mean CO concentration was 9.8 ppm, with a standard deviation of 5.8 ppm. Of nine covariates that were examined to explain the variability in the mean CO exposures observed on the 88 trips (ambient CO at two fixed stations, atmospheric stability, seasonal trend function, time of day, average surrounding vehicle count, trip duration, proportion of time stopped at lights, and instrument type), a fairly strong seasonal trend was found. A model consisting of only a single measure of traffic volume and a seasonal trend component had substantial predictive power (R² = 0.68); by contrast, the ambient CO levels, although partially correlated with average exposures, contributed comparatively little predictive power to the model. The CO exposures experienced while drivers waited at the red lights at an intersection ranged from 6.8 to 14.9 ppm and differed considerably from intersection to intersection. A model also was developed to relate the short-term variability of exposures to averaging time for trip times ranging from 1 to 20 minutes using a variogram approach to deal with the serial autocorrelation. This study shows: (1) the mass balance equation can relate exterior CO concentrations as a function of time to interior CO concentrations; (2) CO exposures on urban arterial highways vary seasonally; (3) momentary CO exposures experienced behind red lights vary with the intersection; and (4) an averaging time model can simulate exposures during short trips (20 minutes or less) on urban arterial highways.     

NOx Removal with Combined Selective Catalytic Reduction and Selective Noncatalytic Reduction: Pilot-Scale Test Results

Pilot-scale tests were conducted to develop a combined nitrogen oxide (NO_x) reduction technology using both selective catalytic reduction (SCR) and selective noncatalytic reduction (SNCR). A commercially available vanadium- and titanium-based composite honeycomb catalyst and enhanced urea (NH₂CONH₂) were used with a natural-gas-fired furnace at a NO_x concentration of 110 ppm. Changes in SNCR chemical injection temperature and stoichiometry led to varying levels of post-furnace ammonia (NH₃), which acts as the reductant feed to the downstream SCR catalyst. The urea-based chemical could routinely achieve SNCR plus SCR total NO_x reductions of 85 percent with less than 3 ppm NH₃ slip at reductant/NO_x stoichiometries ranging from about 1.5 to 2.5 and SCR space velocities of 18,000 to 32,000 h^?1. This pilot-scale research has shown that SNCR and SCR can be integrated to achieve high NO_x removal. SNCR provides high temperature reduction of NO_x followed by further removal of NO_x and minimization of NH₃ slip by a significantly downsized (high-space velocity) SCR.     

Determination of Volatile Organic Compounds in the Atmosphere Using Two Complementary Analysis Techniques

ABSTRACT

During a preliminary field campaign of volatile organic compound (VOC) measurements carried out in an urban area, two complementary analysis techniques were applied to establish the technical and scientific bases for a strategy to monitor and control VOCs and photochemical oxidants in the Autonomous Community of the Basque Country. Integrated sampling was conducted using Tenax sorbent tubes and laboratory analysis by gas chromatography, and grab sampling and in situ analysis also were conducted using a portable gas chromatograph. With the first technique, monocyclic aromatic hydrocarbons appeared as the compounds with the higher mean concentrations. The second technique allowed the systematic analysis of eight chlorinated and aromatic hydrocarbons. Results of comparing both techniques, as well as the additional information obtained with the second technique, are included.     

Characterization of Municipal Solid Waste Incineration Residues From Facilities with Different Air Pollution Control Systems

Abstract

Municipal Solid Waste incinerator residues produced in two types of facilities were exhaustively characterized: granulometry, mineralogy, chemical composition, leaching behavior, and elemental distribution as a function of particle size. Air Pollution Control (APC) residues coming from a semi-dry scrubber have shown higher solubility than fly ashes originating in an Electrostatic Precipitator (ESP), as well as higher contents in volatile metals (Cd, Hg). Different metal speciation and distribution as a function of particle size have been found in fly ashes (ESP residues) and APC residues. In APC residues, heavy metals (with the exception of Hg) show a parabolic distribution with maxima in the smallest and largest particles, following the same profile as soluble salts. Metal distribution for APC residues exhibits that metals generally are not associated with silicate aluminate matrix. Results show the effect of adding lime to APC residues in metal speciation and distribution.     

Evaluation of Tire-Derived Fuel for Use in Nitrogen Oxide Reduction by Reburning

ABSTRACT

Tire-derived fuel (TDF) was tested in a small-scale (44 kW or 150,000 Btu/hr) combustor to determine its feasibility as a fuel for use in reburning for control of nitrogen oxide (NO). TDF was gravity-fed into upward flowing combustion gases from a primary natural gas flame doped with ammonia to simulate a high NO combustion process. Emissions of NO, oxygen, carbon dioxide, carbon monoxide, and particulate matter were measured. The tests varied the nominal primary NO level from 600 to 1,200 ppm and the primary stoichiometry from 1.1 to 1.2, and used both natural gas and TDF as reburn fuels. The reburn injection rate was varied to achieve 8–20% of the total heat input from the reburn fuel. NO emissions reductions ranged between 20 and 63% when using TDF, depending upon the rate of TDF injection, primary NO, and primary stoichiometry. NO emission reductions when using natural gas as the reburn fuel were consistently higher than those when using TDF. While additional work remains to optimize the process and evaluate costs, TDF has been shown to have the potential to be a technically viable reburning fuel.     

The 1999 Fresno Particulate Matter Exposure Studies: Comparison of Community,Outdoor, and Residential PM Mass Measurements

ABSTRACT

Two collaborative studies have been conducted by the U.S. Environmental Protection Agency (EPA) National Exposure Research Laboratory (NERL) and National Health and Environmental Effects Research Laboratory to determine personal exposures and physiological responses to par-ticulate matter (PM) of elderly persons living in a retirement facility in Fresno, CA. Measurements of PM and other criteria air pollutants were made inside selected individual residences within the retirement facility and at a central outdoor site on the premises. In addition, personal PM exposure monitoring was conducted for a subset of the participants, and ambient PM monitoring data were available for comparison from the NERL PM research monitoring platform in central Fresno. Both a winter (February 1-28, 1999) and a spring (April 19-May 16, 1999) study were completed so that seasonal effects could be