Gaseous Pollutants in St. Louis and Other Cities

During the fall of 1972, a study was undertaken to characterize gaseous air pollutants in the St. Louis metropolitan area. Information obtained in this study will be used in planning air pollution modeling studies to be carried out over the next 4 or 5 years under the Regional Air Pollution Study (RAPS) of the Environmental Protection Agency. From analyses of roadway samples, it was found that certain compounds in automotive emissions such as acetylene, carbon monoxide, o-xylene, ethylene, and 2-methylpentane occur in consistent proportions to other compounds. The concentrations of these indicator compounds in atmospheric samples were used to estimate the amounts of other hydrocarbons present that are attributable to automotive related emissions. Methane, ethane, and propane were found to originate principally from nonautomotive sources, both at St. Louis University and the St. Louis CAMP station. Similar concentrations were found in urban and non-urban areas. A comparison of ethylene-CO and propyl-ene-CO ratios in urban and non-urban areas indicates that CO can serve as an indicator of transport of urban pollutants. Sunlight irradiations of captured air samples showed increasing ozone production with increasing initial concentrations of hydrocarbons and nitrogen oxides. Substantial ozone and peroxyacetyl nitrate were formed from a total non-methane hydrocarbon concentration of only ¹/₄ ppm C.     

Aerosol ion characteristics during the Big Bend Regional Aerosol and Visibility Observational study

The ionic compositions of particulate matter with aerodynamic diameter < or = 2.5 microm (PM2.5) and size-resolved aerosol particles were measured in Big Bend National Park, Texas, during the 1999 Big Bend Regional Aerosol and Visibility Observational study. The ionic composition of PM2.5 aerosol was dominated by sulfate (SO4(2-)) and ammonium (NH4+). Daily average SO4(2-) and NH4+ concentrations were strongly correlated (R2 = 0.94). The molar ratio of NH4+ to SO4(2-) averaged 1.54, consistent with concurrent measurements of aerosol acidity. The aerosol was observed to be comprised of a submicron fine mode consisting primarily of ammoniated SO4(2-) and a coarse particle mode containing nitrate (NO3-). The NO3- appears to be primarily associated with sea salt particles where chloride has been replaced by NO3-, although formation of calcium nitrate (Ca(NO3)2) is important, too, on several days. Size-resolved aerosol composition results reveal that a size cut in particulate matter with aerodynamic diameter < or = 1 microm would have provided a much better separation of fine and coarse aerosol modes than the standard PM2.5 size cut utilized for the study. Although considerable nitric acid exists in the gas phase at Big Bend, the aerosol is sufficiently acidic and temperatures sufficiently high that even significant future reductions in PM2.5 SO4(2-) are unlikely to be offset by formation of particulate ammonium nitrate in summer or fall.     

Heavy Metals in Urban Soils of East St. Louis,IL Part II: Leaching Characteristics and Modeling

ABSTRACT

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produced organic and inorganic chemicals, and petroleum refineries. Following a gross assessment of heavy metals in the community soils (see Part I of this two-part series), leaching tests were performed on specific soils to elucidate heavy metal-associated mineral fractions and general leachability. Leaching experiments, including the Toxicity Characteristic Leaching Procedure (TLCP) and column tests, and sequential extractions, illustrated the low leachability of metals in East St. Louis soils. The column leachate results were modeled using a formulation developed for fly ash leaching. The importance of instantaneous dissolution was evident from the model. By incorporating desorption/adsorption terms into the source term, the model was adapted very well to the time-dependent heavy metal leachate concentrations. The results demonstrate the utility of a simple model to describe heavy metal leaching from contaminated soils.     

Characteristics of regional nucleation events in urban East St. Louis

Continuous measurements of aerosol size distributions (3 nm–2 μm) were carried out over a 26 month period (1 April 2001–31 May 2003; 650 days with valid data) in urban East St. Louis, IL, as a part of the US Environmental Protection Agency's Supersite program. This paper analyzes data for the 155 days on which “regional nucleation events” were observed during this study. Such events were observed during every month of the study except January 2003. We observed some differences, however, between events in the summer (defined here as April–September) and winter (December–February). Regional nucleation events were observed more frequently in summer months (36±13% of days) than in winter (8±7%), and nucleated particles grew faster in the summer (6.7±4.8 nm h⁻¹) than in winter (1.8±1.9 nm h⁻¹). The daily maximum in the number concentration of nanoparticles formed by nucleation (4.8±3.5×10⁴ cm⁻³) was highly variable and showed no clear seasonal dependence. Particle formation increased particle concentrations by an average factor of 3.1±2.8. Maximum daily rates of 3 nm particle production (17±20 cm⁻³ s⁻¹) were also highly variable and without a clear seasonal dependence. During these events, particle formation rates were typically near their maxima at 08:00–09:00 a.m., but particle production sometimes persisted at diminishing rates until late in the afternoon (15:00–16:00 p.m.).     

Day of the week variations of photochemical pollutants in the St. Louis area

As part of the Environmental Protection Agency's Regional Air Pollution Study (RAPS) a network of 25 stations continuously recorded aeromatic data in the Greater St. Louis area. Various photochemical pollutants (O₃, NO, NO₂ and total hydrocarbons) and some selected meteorological variables (wind speed, temperature, and solar radiation) were analyzed with respect to the day of the week using 11 months of data collected during the warm months of the year — periods during which high ozone concentrations were common in St. Louis. The results reveal that the sign (±) of the workday to Sunday differences in the concentration of ozone depends to a large extent on the distance of the measurement from the major emission area of the metropolitan area of St. Louis. The data suggest that this is due to the impact of nitric oxide on the ambient ozone concentrations. This appears to offer at least a partial explanation for some of the contrasting results reported by various investigators regarding the differences in ozone concentrations between weekends and weekdays.     

Estimates of Particle Hygroscopicity during the Southeastern Aerosol and Visibility Study

ABSTRACT

Aerosol water content was determined from relative humidity controlled optical particle counter (ASASP-X) size distribution measurements made during the Southeastern Aerosol and Visibility Study (SEAVS) in the Great Smoky Mountains National Park during summer 1995. Since the scattering response function of the ASASP-X is sensitive to particle refractive index, a technique for calibrating the ASASP-X for any real refractive index was developed. A new iterative process was employed to calculate water mass concentration and wet refractive index as functions of relative humidity. Experimental water mass concentrations were compared to theoretically predicted values assuming only ammonium sulfate compounds were hygroscopic. These comparisons agreed within experimental uncertainty. Estimates of particle hygroscopicity using a rural aerosol model of refractive index as a function of relative humidity demonstrated no significant differences from those made with daily varying refractive index estimates. Although aerosol size parameters were affected by the assumed chemical composition, forming ratios of these parameters nearly canceled these effects.     

Public Awareness and Concern with Air Pollution in the St. Louis Metropolitan Area

The public attitudes survey involving St. Louis City, St. Louis County, and Madison and St. Clair Counties, Illinois, was completed and published in the fall of 1964. A total of 1002 respondents gave needed information for the development of an acceptable abatement program. Substantial proportions from the study area expressed the view that they have had some negative reaction to the quality of the air. These respondents indicated that air pollution meant, primarily, odor and smoke with residents of some localities indicating other significant elements. The interviewed persons felt that factories and businesses were the prime causal agents in the existence of air pollution. Over 90 percent of all respondents felt that some governmental agency should do something about air pollution in the St. Louis area, with some bi-state metropolitan agency being the principal choice. The residents also expressed a willingness to pay minimal tax support for such a program. Indications as to the significance of air pollution in a general problems context, difference in attitudes between sub-sections of the study area, and more detailed analysis of the problem, its causes, and possible cures are contained in the study r     

Estimates of particle hygroscopicity during the Southeastern Aerosol and Visibility Study

Aerosol water content was determined from relative humidity controlled optical particle counter (ASASP-X) size distribution measurements made during the Southeastern Aerosol and Visibility Study (SEAVS) in the Great Smoky Mountains National Park during summer 1995. Since the scattering response function of the ASASP-X is sensitive to particle refractive index, a technique for calibrating the ASASP-X for any real refractive index was developed. A new iterative process was employed to calculate water mass concentration and wet refractive index as functions of relative humidity. Experimental water mass concentrations were compared to theoretically predicted values assuming only ammonium sulfate compounds were hygroscopic. These comparisons agreed within experimental uncertainty. Estimates of particle hygroscopicity using a rural aerosol model of refractive index as a function of relative humidity demonstrated no significant differences from those made with daily varying refractive index estimates. Although aerosol size parameters were affected by the assumed chemical composition, forming ratios of these parameters nearly canceled these effects.     

A Critical Assessment of Atmospheric Visibility and Aerosol Measurements in the Eastern United States

As part of a study examining the technical basis for a secondary national ambient air quality standard for fine particulate matter to protect visibility, we reviewed available data on atmospheric aerosol and visibility in the eastern U.S. This paper presents the results of that visibility and aerosol characterization.

Analysis of airport visibility data indicates that the annual median visual ranges in the East are in the 16-25 km range. In the absence of a "reference method," limited measurements of visibility using various types of instruments provide data generally in agreement with the airport visibility estimates when a contrast threshold of 0.05 is assumed in calculating visual range from the instrumental measurements.

Both long- and short-term aerosol measurements have yielded consistent results; however, because of the differences in instrumentation and laboratory analytical techniques among various studies, data often are not directly comparable. The measured annual average fine particulate matter mass concentration is about 18 μg/m³ in the rural East; during summer it increases to about 23 μg/m³. If all the sulfur in the fine mass is assumed to exist as ammonium sulfate, it would constitute 46 percent of the annual mean and about 60 percent of the summer mean fine mass concentrations. Carbon and volatiles, including water, are believed to constitute significant fractions of the fine mass; however, there are little data quantifying their contributions to fine mass and visibility impairment. Additional long-term measurements of visibility and fine aerosol and its various components are necessary to completely characterize visibility and aerosol in the East.     

Heavy Metals in Urban Soils of East St. Louis,IL, Part I: Total Concentration of Heavy Metals in Soils

ABSTRACT

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produce organic and inorganic chemicals, and petroleum refineries. A protocol for soil analysis was developed to produce sufficient information on the extent of heavy metal contamination in East St. Louis soils. Soil cores representing every borough of East St. Louis were analyzed for heavy metals—As, Cd, Cu, Cr, Hg, Ni, Pb, Sb, Sn, and Zn. The topsoil contained heavy metal concentrations as high as 12.5 ppm Cd, 14,400 ppm Cu, ppm quantities of Hg, 1860 ppm Pb, 40 ppm Sb, 1130 ppm Sn, and 10,360 ppm Zn. Concentrations of Sb, Cu, and Cd were well correlated with Zn concentrations, suggesting a similar primary industrial source. In a sandy loam soil from a vacated rail depot near the bank of the Mississippi River, the metals were evenly distributed down to a 38-cm depth. The clay soils within a half-mile downwind of the Zn smelter and Cu products company contained elevated Cd (81 ppm), Cu (340 ppm), Pb (700 ppm), and Zn (6000 ppm) and displayed a systematic drop in concentration of these metals with depth. This study demonstrates the often high concentration of heavy metals heterogeneously distributed in the soil and provides baseline data for continuing studies of heavy metal soil leachability.     

Effects of Aerosol Species on Atmospheric Visibility in Kaohsiung City,Taiwan

Abstract

Visibility data collected from Kaohsiung City, Taiwan, for the past two decades indicated that the air pollutants have significantly degraded visibility in recent years. During our study period, the seasonal mean visibilities in spring, summer, fall, and winter were only 5.4, 9.1, 8.2, and 3.4 km, respectively. To ascertain how urban aerosols influence the visibility, we conducted concurrent visibility monitoring and aerosol sampling in 1999 to identify the principal causes of visibility impairments in the region. In this study, ambient aerosols were sampled and analyzed for 11 constituents, including water-soluble ions and carbon materials, to investigate the chemical composition of Kaohsiung aerosols. Stepwise regression method was used to correlate the impact of aerosol species on visibility impairments. Both seasonal and diurnal variation patterns were found from the monitoring of visibility. Our results showed that light scattering was attributed primarily to aerosols with sizes that range from 0.26 to 0.90 μm, corresponding with the wavelength region of visible light, which accounted for ～72% of the light scattering coefficient. Sulfate was a dominant component that affected both the light scattering coefficient and the visibility in the region. On average, (NH₄)₂SO₄, NH₄NO₃, total carbon, and fine particulate matter (PM_2.5)-remainder contributed 53%, 17%, 16%, and 14% to total light scattering, respectively. An empirical regression model of visibility based on sulfate, elemental carbon, and humidity was developed, and the comparison indicated that visibility in an urban area could be properly simulated by the equation derived herein.     

Characterization of ambient aerosol particulate samples from the St. Louis area by X-ray powder diffractometry

Direct X-ray powder diffraction analysis of airborne particulate material collected in the St. Louis area on cellulose ester membrane filters has given results for both fine and coarse particle fractions which are consistent with elemental data, and which are also in keeping with expectations based on the anthropogenic and natural sources of particles in the area. The most frequently observed compounds in the fine fraction samples were (NH₄)₂SO₄ and the double salts (NH₄)₂SO₄PbSO₄ and 3(NH₄)₂SO₄H₂SO₄. The occurrence of (NH₄)₂SO₄PbSO₄ appears to be mainly associated with discrete source activity although the formation of this compound by the interaction of automotive PbBrCl with atmospheric (NH₄)₂SO₄ cannot be ruled out. The minerals calcite (CaCO₃) and α-quartz (SiO₂) are present as major components in almost all coarse fraction samples as expected from the composition of surface rocks in the region. Some coarse fraction samples also contain compounds apparently emitted by nearby industrial sources.     

The Evolution of Particles in the Plume from a Large Coal-Fired Boiler with Flue Gas Desulfurization

ABSTRACT

Airborne measurements were made of gaseous and particulate species in the plume of a large coal-fired power plant after flue gas desulfurization (FGD) controls were installed. These measurements were compared with measurements made before the controls were installed. The light scattering and number and volume distributions of plume excess particles were determined by nephelometry and optical particle counting techniques. The plume impact based on optical techniques was much lower than that observed in earlier measurements. Indeed, plume excess volumes as a function of particle size were of the same magnitude as the variability of the background volume distribution. In situ excess plume scattering actually decreased with distance from the source, in contrast to pre-FGD conditions. The upper limit for the dry rate of SO₂-to-SO₄ ^2- conversion was estimated from plume excess volume measurements to be about 4% lir¹. This is slightly greater than the upper limit, 3.5% lir¹, estimated by earlier researchers, but the same as that estimated using the present technique with the earlier data. The cross-plume profile of volume suggests SO₂-to-SO₄ ^2- conversion is highest at the plume edges. The greatest benefit of SO₂ reduction on plume excess volume and visibility appears to occur far downwind of the source.     

Aerosol composition and sources in Urban areas in India

The elemental composition of aerosols over four cities in India was determined by EDXRF over a 1-year period and the results are presented. The crustal element levels in air in all the cities are found to be similar to those reported for urban areas elsewhere in the world while that of anthropogenic elements are lower. The aerosol compositions show a seasonal variation. The levels of crustal elements are higher during summer and decrease with rainfall. The anthropogenic elements are generally higher during winter. The lead levels are essentially from non-auto exhaust sources such as refuse burning, smelter etc., and in three of the cities they are strongly correlated to zinc. The crustal elements are from local soils and no significant crust-air fractionation is seen. Factor analysis of the data suggests between four and six aerosol source types for the four cities. Soil dust accounts for the major fraction of the measured mass. About 68–80 % of the aerosol mass comprising the residuals seems to consist of C, O₂ and N, in particular, which were not measured.     

Comparison of RAM model estimates with 1976 St. Louis RAPS measurements of sulfur dioxide

Comparisons of model estimates from the model RAM with SO₂ measurements from 13 Regional Air Pollution Study sites in St. Louis for the year 1976 were made with emphasis on 2nd highest concentrations for the 1-h, 3-h and 24-h averaging times, and also the top 5% of the distribution for 24-h concentrations. Although there is considerable scatter in the comparison of the 2nd highest concentrations, only 9 of 39 data points are outside the bounds of a factor of two and no overall bias is seen, although as the averaging time increases there is more underestimation by the model. Exponential distribution fit the top 5 % of the 24-h concentration distributions for all stations for both estimated and measured concentrations. The distributions for estimated and measured concentrations were judged to match at eight of the thirteen sites.     

Heavy metals in urban soils of East St. Louis, IL. Part II: Leaching characteristics and modeling

The city of East St. Louis, IL, has a history of abundant industrial activities including smelters of ferrous and non-ferrous metals, a coal-fired power plant, companies that produced organic and inorganic chemicals, and petroleum refineries. Following a gross assessment of heavy metals in the community soils (see Part I of this two-part series), leaching tests were performed on specific soils to elucidate heavy metal-associated mineral fractions and general leachability. Leaching experiments, including the Toxicity Characteristic Leaching Procedure (TLCP) and column tests, and sequential extractions, illustrated the low leachability of metals in East St. Louis soils. The column leachate results were modeled using a formulation developed for fly ash leaching. The importance of instantaneous dissolution was evident from the model. By incorporating desorption/adsorption terms into the source term, the model was adapted very well to the time-dependent heavy metal leachate concentrations. The results demonstrate the utility of a simple model to describe heavy metal leaching from contaminated soils.