Chemical composition of fine particles in the Tennessee Valley region

Fine particles in the atmosphere have elicited new national ambient air quality standards (NAAQS) because of their potential role in health effects and visibility-reducing haze. Since April 1997, Tennessee Valley Authority (TVA) has measured fine particles (PM2.5) in the Tennessee Valley region using prototype Federal Reference Method (FRM) samplers, and results indicate that the new NAAQS annual standard will be difficult to meet in this region. The composition of many of these fine particle samples has been determined using analytical methods for elements, soluble ions, and organic and elemental carbon. The results indicate that about one-third of the measured mass is SO4(-2), one-third is organic aerosol, and the remainder is other materials. The fraction of SO4(-2) is highest at rural sites and during summer conditions, with greater proportions of organic aerosol in urban areas throughout the year. Additional measurements of fine particle mass and composition have been made to obtain the short-term variability of fine mass as it pertains to human exposure. Measurements to account for semi-volatile constituents of fine mass (nitrates, semi-volatile organics) indicate that the FRM may significantly under-measure organic constituents. The potentially controllable anthropogenic fraction of organic aerosols is still largely unknown.     

Crop loss due to ambient ozone in the Tennessee Valley

Rural and urban ozone (O3) monitoring data for the Tennessee Valley and crop loss models developed under the National Crop Loss Assessment Network (NCLAN) were used to estimate potential yield reductions for winter wheat, corn, soybean, cotton, and tobacco during the 1982 to 1984 growing seasons. Reductions from 0 to 20% of potential crop yields were estimated due to ambient O3. Rural O3 exposures measured in the Tennessee Valley were significantly higher than the measured urban exposures, suggesting that spatial interpolation from urban O3 records may underestimate rural O3 and thereby potential crop loss. Seasonal mean O3 exposures were highest in summer 1983, and similar in 1982 and 1984. Although a consistent inverse relationship was found between measured crop yields in the Tennessee Valley and seasonal O3 exposures, annual variation in yields was much greater than attributable to the annual variation in O3. Moisture stress, as indicated by the Palmer Drought Severity Indices, is likely the major determinant for yields of nonirrigated crops. This is consistent with field studies that demonstrate that ambient O3 levels can reduce crop yields under ideal soil moisture conditions, but cause little to no detectable yield reduction for nonirrigated crops. These models could be improved if crop response to O3 were allowed to vary as a function of environmental factors such as moisture stress.     

Outdoor/Indoor/Personal ozone exposures of children in Nashville, Tennessee

An ozone (O3) exposure study was conducted in Nashville, TN, using passive O3 samplers to measure six weekly outdoor, indoor, and personal O3 exposure estimates for a group of 10- to 12-yr-old elementary school children. Thirty-six children from two Nashville area communities (Inglewood and Hendersonville) participated in the O3 sampling program, and 99 children provided additional time-activity information by telephone interview. By design, this study coincided with the 1994 Nashville/Middle Tennessee Ozone Study conducted by the Southern Oxidants Study, which provided enhanced continuous ambient O3 monitoring across the Nashville area. Passive sampling estimated weekly average outdoor O3 concentrations from 0.011 to 0.O30 ppm in the urban Inglewood community and from 0.015 to 0.042 ppm in suburban Hendersonville. The maximum 1- and 8-hr ambient concentrations encountered at the Hendersonville continuous monitor exceeded the levels of the 1- and 8-hr metrics for the O3 National Ambient Air Quality Standard. Weekly average personal O3 exposures ranged from 0.0013 to 0.0064 ppm (7-31% of outdoor levels). Personal O3 exposures reflected the proportional amount of time spent in indoor and outdoor environments. Air-conditioned homes displayed very low indoor O3 concentrations, and homes using open windows and fans for ventilation displayed much higher concentrations.     

Residues of organochlorine pesticides in Alabama soils

A survey was made of 36 Alabama agricultural soils to assess residues of formerly used organochlorine pesticides. Compounds determined comprised alpha- and gamma-hexachlorocyclohexane, heptachlor, heptachlor-exo-epoxide, trans- and cis-chlordane, trans-nonachlor, dieldrin, toxaphene, DDT and DDE. Concentrations varied by several orders of magnitude among farms and appeared to be log-normally distributed. Highest concentrations (ng g(-1) dry soil, arithmetic means) were found for toxaphene (285+/-390) and DDTs (p,p'-DDE, 22.7+/-21.4; p,p'-DDT, 24.6+/-30.5; o,p'-DDT, 4.00+/-5.86; p,p'-DDD, 2.40+/-2.41) which were once heavily used in the southern USA. Pesticide residues were not proportional to soil organic carbon content indicating that residue concentrations were a reflection of pesticide application history and dissipation rates rather than air-soil equilibrium. Mean ratios of DDT/DDE in six regions of the state ranged from 0.39 to 1.5, and compound ratios for chlordanes and toxaphene were different from those in the technical mixtures.     

Comparative toxicity of solid waste leachates to Daphnia magna

The comparative acute and chronic toxicities of municipal, industrial, coal-fired power plant, and synthetic fuel solid waste leachates to the aquatic invertebrate Daphnia magna were determined. Seventeen leachates were laboratory-derived by extraction with 0.5 N acetic acid, and one, an arsenic-contaminated groundwater, was naturally derived. The acute toxicity 48-h LC₅₀ estimates (concentrations of the test materials that killed 50% of the test organisms in 48 h) ranged from 0.0005% for a dye waste leachate to > 100% (i.e., undiluted) for a coal gasification waste leachate. The most toxic leachates were derived from a dye waste, a plater's waste, and the arsenic-contaminated groundwater, and the least toxic were from a soybean process cake waste and a coal gasification waste. Of the 16 leachates used in the 28 day chronic toxicity tests, only the arsenic-contaminated groundwater and a municipal sewage sludge significantly affected D. magna reproduction. The former material at 1.0% concentration and the sludge at 0.1% caused about an 88% reduction in the numbers of young produced by exposed females compared with controls. Generally, the industrial waste leachates were more toxic than those from the power plant and synthetic fuel wastes. Because its presence in the test materials interfered with interpretation of the results, acetic acid may not be an appropriate extraction medium for preparation of leachates.     

Chemical Composition of Fine Particles in the Tennessee Valley Region

ABSTRACT

Fine particles in the atmosphere have elicited new national ambient air quality standards (NAAQS) because of their potential role in health effects and visibility-reducing haze. Since April 1997, Tennessee Valley Authority (TVA) has measured fine particles (PM_2.5) in the Tennessee Valley region using prototype Federal Reference Method (FRM) samplers, and results indicate that the new NAAQS annual standard will be difficult to meet in this region. The composition of many of these fine particle samples has been determined using analytical methods for elements, soluble ions, and organic and elemental carbon. The results indicate that about one-third of the measured mass is SO₄ ^-2, one-third is organic aerosol, and the remainder is other materials. The fraction of SO₄ ^-2 is highest at rural sites and during summer conditions, with greater proportions of organic aerosol in urban areas throughout the year. Additional measurements of fine particle mass and composition have been made to obtain the short-term variability of fine mass as it pertains to human exposure. Measurements to account for semi-volatile constituents of fine mass (nitrates, semi-volatile organics) indicate that the FRM may significantly under-measure organic constituents. The potentially controllable anthropogenic fraction of organic aerosols is still largely unknown.     

Improving road transport-related air quality in England through joint working between Environmental Health Officers and Transport Planners

In this paper the necessity for effective joint working arrangements between Environmental Health Officers and Transport Planners is demonstrated as a fundamental prerequisite for successful management of traffic-related air quality in English local government areas. Current approach to joint working and collaboration between the officers was examined based on the evidence from a three-year study which involved questionnaire surveys and case study interviews. The findings show that despite good administrative devolution and policy integration, the chance of improving specific local air quality situations through the Local Transport Planning process is dependent on other overriding factors which influence the capabilities of the authorities to integrate policies across departments and tiers of governments. Implicit in these findings is the need for a shared paradigm of continuous engagement by all the policy actors and stakeholders if proper integration and the possibility of tangible results in future policy development are to be achieved. The paper proposes a new framework through which such collaborations can be developed and within which solutions to the issues identified can be evaluated.     

Impact of the 1998 Central American fires on PM2.5 mass and composition in the southeastern United States

The impact of the Central American fires on PM_2.5 mass concentration and composition in the Tennessee Valley region during portions of May, 1998, has been quantified. Elevated concentrations of smoke aerosol tracers—fine potassium, (and to a lesser extent, calcium and silicon) and, where available, organic and elemental carbon—were observed in the region during times in which satellite imagery (TOMS and GOES-8) showed regional transport of hazy, smoky airmasses from southern Mexico and adjacent areas of Central America. Back-trajectories from network sites in the Tennessee Valley network were consistent with this regional transport. The extent of transport of extra-regional fine particle mass during May, 1998, is discussed relative to the new US fine particle mass-based standards for fine particulate matter.     

A Strategy for the Evaluation of Sensory and Pulmonary Irritation Due to Chemical Emissions from Indoor Sources

Abstract

Sensory and pulmonary irritation are physiological responses to chemical exposure which result in characteristic, measurable changes in respiratory activity in mice. A standard method has been applied to the estimation of sensory irritation associated with a specific chemical exposure. This method has been correlated with human responses to these chemicals. Symptoms associated with chemical irritants are consistent with complaints due to problems with indoor air quality, which may include eye and upper respiratory tract irritation, headaches, and nausea. A stepwise strategy for assessing the contribution of indoor products to sensory and pulmonary irritation is discussed in the current paper. The strategy includes product emissions testing using dynamic environmental chambers, the selection of suspected irritants for respiratory irritation testing, respiratory irritation testing of individual compounds and representative mixtures using synthesized atmospheres, and the evaluation of test data to determine those compounds which may contribute to sensory and pulmonary irritation in humans. The current strategy is being applied to evaluate carpet system materials and their constituent chemicals.