Jeffrey V. Ryan

Mutagenicity and chemical analysis of emissions from the open burning of scrap rubber tires.

The Salmonella mutagenicity assay and chemical analyses were used to evaluate the emissions from the open burning of scrap rubber tires that had been cut into either of two sizes, CHUNK or SHRED. A wide variety of polycyclic aromatic hydrocarbons was detected in the particulate organics. The mutagenic emission factor for the open burning of scrap rubber tires (approx. 8 x 10 to the power 7 revertants/kg of tire burned) was 3-4 orders of magnitude greater than the values for the combustion of oil, coal, or wood in utility boilers; it was most similar to values for the open burning of wood or plastic. These results demonstrate for the first time that the open burning of scrap rubber tires produces a high mutagenic emission factor, posing potential environmental and health effects. (A)

Characterization of air pollutants emitted from a simulated scrap tire fire

Discarded automobile tires have become a concern to the general public, largely because the growing number of stockpile fires has focused attention on the potentially harmful combustion products as well as products of incomplete combustion (PICs) emitted into the atmosphere from uncontrolled burning of scrap tires. This paper describes a small-scale combustion study that was designed to collect, identify, and quantify the products emitted during the simulated open combustion of scrap tires. During the study, it was found that total estimated emissions of semivolatile organics ranged from 10 to 50 g/kg of tire material burned. Alkyl-substituted mono- and polyaromatic hydrocarbons were the predominant emission products identified. Elevated levels of zinc and lead were also measured.

Behavior of Mercury Emissions from a Commercial Coal-Fired Power Plant: The Relationship between Stack Speciation and Near-Field Plume Measurements

The reduction of divalent gaseous mercury (Hg(II)) to elemental gaseous mercury (Hg(0)) in a commercial coal-fired power plant (CFPP) exhaust plume was investigated by simultaneous measurement in-stack and in-plume as part of a collaborative study among the U.S. EPA, EPRI, EERC, and Southern Company. In-stack continuous emission monitoring data were used to establish the CFPPs real-time mercury speciation and plume dilution tracer species (SO2, NOX) emission rates, and an airship was utilized as an airborne sampling platform to maintain static position with respect to the exhaust plume centerline for semicontinuous measurement of target species. Varying levels of Hg(II) concentration (2.39-3.90 μg m(-3)) and percent abundance (∼ 87-99%) in flue gas and in-plume reduction were observed. The existence and magnitude of Hg(II) reduction to Hg(0) (0-55%) observed varied with respect to the types and relative amounts of coals combusted, suggesting that exhaust plume reduction occurring downwind of the CFPP is influenced by coal chemical composition and characteristics.

Chemical and biological characterization of products of incomplete combustion from the simulated field burning of agricultural plastic

Chemical and biological analyses were performed to characterize products of incomplete combustion emitted during the simulated open field burning of agricultural plastic. A small utility shed equipped with an air delivery system was used to simulate pile burning and forced-air-curtain incineration of a nonhalogenated agricultural plastic that reportedly consisted of polyethylene and carbon black. Emissions were analyzed for combustion gases; volatile, semi-volatile, and particulate organics; and toxic and mutagenic properties. Emission samples, as well as samples of the used (possibly pesticide-contaminated) plastic, were analyzed for the presence of several pesticides to which the plastic may have been exposed. Although a variety of alkanes, alkenes, and aromatic and polycyclic aromatic hydrocarbon (PAH) compounds were identified in the volatile, semi-volatile, and particulate fractions of these emissions, a substantial fraction of higher molecular weight organic material was not identified. No pesticides were identified in either combustion emission samples or dichloromethane washes of the used plastic. When mutagenicity was evaluated by exposing Salmonella bacteria (Ames assay) to whole vapor and vapor/particulate emissions, no toxic or mutagenic effects were observed. However, organic extracts of the particulate samples were moderately mutagenic. This mutagenicity compares approximately to that measured from residential wood heating on a revertant per unit heat release basis. Compared to pile burning, forced air slightly decreased the time necessary to burn a charge of plastic. There was not a substantial difference, however, in the variety or concentrations of organic compounds identified in samples from these two burn conditions. This study highlights the benefits of a combined chemical/biological approach to the characterization of complex, multi-component combustion emissions. These results may not reflect those of other types of plastic that may be used for agricultural purposes, especially those containing halogens.